diff --git a/services/audioflinger/AudioFlinger.cpp b/services/audioflinger/AudioFlinger.cpp
index 280281e..589d379 100644
--- a/services/audioflinger/AudioFlinger.cpp
+++ b/services/audioflinger/AudioFlinger.cpp
@@ -433,8 +433,8 @@
     for (const auto& [trackId, secondaryOutputs] : trackSecondaryOutputs) {
         size_t i = 0;
         for (; i < mPlaybackThreads.size(); ++i) {
-            PlaybackThread *thread = mPlaybackThreads.valueAt(i).get();
-            Mutex::Autolock _tl(thread->mLock);
+            IAfPlaybackThread* thread = mPlaybackThreads.valueAt(i).get();
+            Mutex::Autolock _tl(thread->mutex());
             sp<IAfTrack> track = thread->getTrackById_l(trackId);
             if (track != nullptr) {
                 ALOGD("%s trackId: %u", __func__, trackId);
@@ -1191,7 +1191,7 @@
 
     {
         Mutex::Autolock _l(mLock);
-        PlaybackThread *thread = checkPlaybackThread_l(output.outputId);
+        IAfPlaybackThread* thread = checkPlaybackThread_l(output.outputId);
         if (thread == NULL) {
             ALOGE("no playback thread found for output handle %d", output.outputId);
             lStatus = BAD_VALUE;
@@ -1200,14 +1200,14 @@
 
         client = registerPid(clientPid);
 
-        PlaybackThread *effectThread = NULL;
+        IAfPlaybackThread* effectThread = nullptr;
         // check if an effect chain with the same session ID is present on another
         // output thread and move it here.
         for (size_t i = 0; i < mPlaybackThreads.size(); i++) {
-            sp<PlaybackThread> t = mPlaybackThreads.valueAt(i);
+            sp<IAfPlaybackThread> t = mPlaybackThreads.valueAt(i);
             if (mPlaybackThreads.keyAt(i) != output.outputId) {
                 uint32_t sessions = t->hasAudioSession(sessionId);
-                if (sessions & ThreadBase::EFFECT_SESSION) {
+                if (sessions & IAfThreadBase::EFFECT_SESSION) {
                     effectThread = t.get();
                     break;
                 }
@@ -1242,7 +1242,7 @@
 
         if (lStatus == NO_ERROR) {
             // no risk of deadlock because AudioFlinger::mLock is held
-            Mutex::Autolock _dl(thread->mLock);
+            Mutex::Autolock _dl(thread->mutex());
             // Connect secondary outputs. Failure on a secondary output must not imped the primary
             // Any secondary output setup failure will lead to a desync between the AP and AF until
             // the track is destroyed.
@@ -1250,7 +1250,7 @@
             // move effect chain to this output thread if an effect on same session was waiting
             // for a track to be created
             if (effectThread != nullptr) {
-                Mutex::Autolock _sl(effectThread->mLock);
+                Mutex::Autolock _sl(effectThread->mutex());
                 if (moveEffectChain_l(sessionId, effectThread, thread) == NO_ERROR) {
                     effectThreadId = thread->id();
                     effectIds = thread->getEffectIds_l(sessionId);
@@ -1310,7 +1310,7 @@
 uint32_t AudioFlinger::sampleRate(audio_io_handle_t ioHandle) const
 {
     Mutex::Autolock _l(mLock);
-    ThreadBase *thread = checkThread_l(ioHandle);
+    IAfThreadBase* const thread = checkThread_l(ioHandle);
     if (thread == NULL) {
         ALOGW("sampleRate() unknown thread %d", ioHandle);
         return 0;
@@ -1321,7 +1321,7 @@
 audio_format_t AudioFlinger::format(audio_io_handle_t output) const
 {
     Mutex::Autolock _l(mLock);
-    PlaybackThread *thread = checkPlaybackThread_l(output);
+    IAfPlaybackThread* const thread = checkPlaybackThread_l(output);
     if (thread == NULL) {
         ALOGW("format() unknown thread %d", output);
         return AUDIO_FORMAT_INVALID;
@@ -1332,7 +1332,7 @@
 size_t AudioFlinger::frameCount(audio_io_handle_t ioHandle) const
 {
     Mutex::Autolock _l(mLock);
-    ThreadBase *thread = checkThread_l(ioHandle);
+    IAfThreadBase* const thread = checkThread_l(ioHandle);
     if (thread == NULL) {
         ALOGW("frameCount() unknown thread %d", ioHandle);
         return 0;
@@ -1345,7 +1345,7 @@
 size_t AudioFlinger::frameCountHAL(audio_io_handle_t ioHandle) const
 {
     Mutex::Autolock _l(mLock);
-    ThreadBase *thread = checkThread_l(ioHandle);
+    IAfThreadBase* const thread = checkThread_l(ioHandle);
     if (thread == NULL) {
         ALOGW("frameCountHAL() unknown thread %d", ioHandle);
         return 0;
@@ -1356,7 +1356,7 @@
 uint32_t AudioFlinger::latency(audio_io_handle_t output) const
 {
     Mutex::Autolock _l(mLock);
-    PlaybackThread *thread = checkPlaybackThread_l(output);
+    IAfPlaybackThread* const thread = checkPlaybackThread_l(output);
     if (thread == NULL) {
         ALOGW("latency(): no playback thread found for output handle %d", output);
         return 0;
@@ -1676,7 +1676,7 @@
         return BAD_VALUE;
     }
     AutoMutex lock(mLock);
-    PlaybackThread *thread = checkPlaybackThread_l(output);
+    IAfPlaybackThread* const thread = checkPlaybackThread_l(output);
     if (thread == nullptr) {
         return BAD_VALUE;
     }
@@ -1689,7 +1689,7 @@
         return BAD_VALUE;
     }
     AutoMutex lock(mLock);
-    PlaybackThread *thread = checkPlaybackThread_l(output);
+    IAfPlaybackThread* const thread = checkPlaybackThread_l(output);
     if (thread == nullptr) {
         return BAD_VALUE;
     }
@@ -1820,14 +1820,15 @@
 // forwardAudioHwSyncToDownstreamPatches_l() must be called with AudioFlinger::mLock held
 void AudioFlinger::forwardParametersToDownstreamPatches_l(
         audio_io_handle_t upStream, const String8& keyValuePairs,
-        const std::function<bool(const sp<PlaybackThread>&)>& useThread)
+        const std::function<bool(const sp<IAfPlaybackThread>&)>& useThread)
 {
     std::vector<PatchPanel::SoftwarePatch> swPatches;
     if (mPatchPanel.getDownstreamSoftwarePatches(upStream, &swPatches) != OK) return;
     ALOGV_IF(!swPatches.empty(), "%s found %zu downstream patches for stream ID %d",
             __func__, swPatches.size(), upStream);
     for (const auto& swPatch : swPatches) {
-        sp<PlaybackThread> downStream = checkPlaybackThread_l(swPatch.getPlaybackThreadHandle());
+        const sp<IAfPlaybackThread> downStream =
+                checkPlaybackThread_l(swPatch.getPlaybackThreadHandle());
         if (downStream != NULL && (useThread == nullptr || useThread(downStream))) {
             downStream->setParameters(keyValuePairs);
         }
@@ -1839,7 +1840,7 @@
                                              const std::set<audio_io_handle_t>& streams)
 {
     for (const audio_io_handle_t stream : streams) {
-        PlaybackThread *playbackThread = checkPlaybackThread_l(stream);
+        IAfPlaybackThread* const playbackThread = checkPlaybackThread_l(stream);
         if (playbackThread == nullptr || !playbackThread->isMsdDevice()) {
             continue;
         }
@@ -1962,7 +1963,7 @@
 
     // hold a strong ref on thread in case closeOutput() or closeInput() is called
     // and the thread is exited once the lock is released
-    sp<ThreadBase> thread;
+    sp<IAfThreadBase> thread;
     {
         Mutex::Autolock _l(mLock);
         thread = checkPlaybackThread_l(ioHandle);
@@ -2011,11 +2012,11 @@
         return out_s8;
     }
 
-    ThreadBase *thread = (ThreadBase *)checkPlaybackThread_l(ioHandle);
+    IAfThreadBase* thread = checkPlaybackThread_l(ioHandle);
     if (thread == NULL) {
-        thread = (ThreadBase *)checkRecordThread_l(ioHandle);
+        thread = checkRecordThread_l(ioHandle);
         if (thread == NULL) {
-            thread = (ThreadBase *)checkMmapThread_l(ioHandle);
+            thread = checkMmapThread_l(ioHandle);
             if (thread == NULL) {
                 return String8("");
             }
@@ -2111,7 +2112,7 @@
 {
     Mutex::Autolock _l(mLock);
 
-    RecordThread *recordThread = checkRecordThread_l(ioHandle);
+    IAfRecordThread* const recordThread = checkRecordThread_l(ioHandle);
     if (recordThread != NULL) {
         return recordThread->getInputFramesLost();
     }
@@ -2151,7 +2152,7 @@
 {
     Mutex::Autolock _l(mLock);
 
-    PlaybackThread *playbackThread = checkPlaybackThread_l(output);
+    IAfPlaybackThread* const playbackThread = checkPlaybackThread_l(output);
     if (playbackThread != NULL) {
         return playbackThread->getRenderPosition(halFrames, dspFrames);
     }
@@ -2274,10 +2275,10 @@
 }
 
 // getEffectThread_l() must be called with AudioFlinger::mLock held
-sp<AudioFlinger::ThreadBase> AudioFlinger::getEffectThread_l(audio_session_t sessionId,
+sp<IAfThreadBase> AudioFlinger::getEffectThread_l(audio_session_t sessionId,
         int effectId)
 {
-    sp<ThreadBase> thread;
+    sp<IAfThreadBase> thread;
 
     for (size_t i = 0; i < mPlaybackThreads.size(); i++) {
         if (mPlaybackThreads.valueAt(i)->getEffect(sessionId, effectId) != 0) {
@@ -2480,7 +2481,7 @@
 
     {
         Mutex::Autolock _l(mLock);
-        RecordThread *thread = checkRecordThread_l(output.inputId);
+        IAfRecordThread* const thread = checkRecordThread_l(output.inputId);
         if (thread == NULL) {
             ALOGW("createRecord() checkRecordThread_l failed, input handle %d", output.inputId);
             lStatus = FAILED_TRANSACTION;
@@ -2536,7 +2537,7 @@
         // session and move it to this thread.
         sp<IAfEffectChain> chain = getOrphanEffectChain_l(sessionId);
         if (chain != 0) {
-            Mutex::Autolock _l2(thread->mLock);
+            Mutex::Autolock _l2(thread->mutex());
             thread->addEffectChain_l(chain);
         }
         break;
@@ -2738,14 +2739,14 @@
 uint32_t AudioFlinger::getPrimaryOutputSamplingRate()
 {
     Mutex::Autolock _l(mLock);
-    PlaybackThread *thread = fastPlaybackThread_l();
+    IAfPlaybackThread* const thread = fastPlaybackThread_l();
     return thread != NULL ? thread->sampleRate() : 0;
 }
 
 size_t AudioFlinger::getPrimaryOutputFrameCount()
 {
     Mutex::Autolock _l(mLock);
-    PlaybackThread *thread = fastPlaybackThread_l();
+    IAfPlaybackThread* const thread = fastPlaybackThread_l();
     return thread != NULL ? thread->frameCountHAL() : 0;
 }
 
@@ -2870,15 +2871,15 @@
     mHwAvSyncIds.add(sessionId, value);
 
     for (size_t i = 0; i < mPlaybackThreads.size(); i++) {
-        sp<PlaybackThread> thread = mPlaybackThreads.valueAt(i);
+        const sp<IAfPlaybackThread> thread = mPlaybackThreads.valueAt(i);
         uint32_t sessions = thread->hasAudioSession(sessionId);
-        if (sessions & ThreadBase::TRACK_SESSION) {
+        if (sessions & IAfThreadBase::TRACK_SESSION) {
             AudioParameter param = AudioParameter();
             param.addInt(String8(AudioParameter::keyStreamHwAvSync), value);
             String8 keyValuePairs = param.toString();
             thread->setParameters(keyValuePairs);
             forwardParametersToDownstreamPatches_l(thread->id(), keyValuePairs,
-                    [](const sp<PlaybackThread>& thread) { return thread->usesHwAvSync(); });
+                    [](const sp<IAfPlaybackThread>& thread) { return thread->usesHwAvSync(); });
             break;
         }
     }
@@ -2897,15 +2898,15 @@
     }
     mSystemReady = true;
     for (size_t i = 0; i < mPlaybackThreads.size(); i++) {
-        ThreadBase *thread = (ThreadBase *)mPlaybackThreads.valueAt(i).get();
+        IAfThreadBase* const thread = mPlaybackThreads.valueAt(i).get();
         thread->systemReady();
     }
     for (size_t i = 0; i < mRecordThreads.size(); i++) {
-        ThreadBase *thread = (ThreadBase *)mRecordThreads.valueAt(i).get();
+        IAfThreadBase* const thread = mRecordThreads.valueAt(i).get();
         thread->systemReady();
     }
     for (size_t i = 0; i < mMmapThreads.size(); i++) {
-        ThreadBase *thread = (ThreadBase *)mMmapThreads.valueAt(i).get();
+        IAfThreadBase* const thread = mMmapThreads.valueAt(i).get();
         thread->systemReady();
     }
 
@@ -2957,7 +2958,8 @@
 }
 
 // setAudioHwSyncForSession_l() must be called with AudioFlinger::mLock held
-void AudioFlinger::setAudioHwSyncForSession_l(PlaybackThread *thread, audio_session_t sessionId)
+void AudioFlinger::setAudioHwSyncForSession_l(
+        IAfPlaybackThread* const thread, audio_session_t sessionId)
 {
     ssize_t index = mHwAvSyncIds.indexOfKey(sessionId);
     if (index >= 0) {
@@ -2968,7 +2970,7 @@
         String8 keyValuePairs = param.toString();
         thread->setParameters(keyValuePairs);
         forwardParametersToDownstreamPatches_l(thread->id(), keyValuePairs,
-                [](const sp<PlaybackThread>& thread) { return thread->usesHwAvSync(); });
+                [](const sp<IAfPlaybackThread>& thread) { return thread->usesHwAvSync(); });
     }
 }
 
@@ -2976,7 +2978,7 @@
 // ----------------------------------------------------------------------------
 
 
-sp<AudioFlinger::ThreadBase> AudioFlinger::openOutput_l(audio_module_handle_t module,
+sp<IAfThreadBase> AudioFlinger::openOutput_l(audio_module_handle_t module,
                                                         audio_io_handle_t *output,
                                                         audio_config_t *halConfig,
                                                         audio_config_base_t *mixerConfig,
@@ -3041,7 +3043,7 @@
                   *output, thread.get());
             return thread;
         } else {
-            sp<PlaybackThread> thread;
+            sp<IAfPlaybackThread> thread;
             if (flags & AUDIO_OUTPUT_FLAG_BIT_PERFECT) {
                 thread = sp<BitPerfectThread>::make(this, outputStream, *output, mSystemReady);
                 ALOGV("%s() created bit-perfect output: ID %d thread %p",
@@ -3116,12 +3118,12 @@
 
     Mutex::Autolock _l(mLock);
 
-    sp<ThreadBase> thread = openOutput_l(module, &output, &halConfig,
+    const sp<IAfThreadBase> thread = openOutput_l(module, &output, &halConfig,
             &mixerConfig, deviceType, address, flags);
     if (thread != 0) {
         uint32_t latencyMs = 0;
         if ((flags & AUDIO_OUTPUT_FLAG_MMAP_NOIRQ) == 0) {
-            PlaybackThread *playbackThread = (PlaybackThread *)thread.get();
+            const auto playbackThread = thread->asIAfPlaybackThread();
             latencyMs = playbackThread->latency();
 
             // notify client processes of the new output creation
@@ -3139,8 +3141,7 @@
                 mHardwareStatus = AUDIO_HW_IDLE;
             }
         } else {
-            MmapThread *mmapThread = (MmapThread *)thread.get();
-            mmapThread->ioConfigChanged(AUDIO_OUTPUT_OPENED);
+            thread->ioConfigChanged(AUDIO_OUTPUT_OPENED);
         }
         response->output = VALUE_OR_RETURN_STATUS(legacy2aidl_audio_io_handle_t_int32_t(output));
         response->config = VALUE_OR_RETURN_STATUS(
@@ -3158,8 +3159,8 @@
         audio_io_handle_t output2)
 {
     Mutex::Autolock _l(mLock);
-    MixerThread *thread1 = checkMixerThread_l(output1);
-    MixerThread *thread2 = checkMixerThread_l(output2);
+    IAfPlaybackThread* const thread1 = checkMixerThread_l(output1);
+    IAfPlaybackThread* const thread2 = checkMixerThread_l(output2);
 
     if (thread1 == NULL || thread2 == NULL) {
         ALOGW("openDuplicateOutput() wrong output mixer type for output %d or %d", output1,
@@ -3168,7 +3169,7 @@
     }
 
     audio_io_handle_t id = nextUniqueId(AUDIO_UNIQUE_ID_USE_OUTPUT);
-    DuplicatingThread *thread = new DuplicatingThread(this, thread1, id, mSystemReady);
+    IAfDuplicatingThread* const thread = new DuplicatingThread(this, thread1, id, mSystemReady);
     thread->addOutputTrack(thread2);
     mPlaybackThreads.add(id, thread);
     // notify client processes of the new output creation
@@ -3185,7 +3186,7 @@
 {
     // keep strong reference on the playback thread so that
     // it is not destroyed while exit() is executed
-    sp<PlaybackThread> playbackThread;
+    sp<IAfPlaybackThread> playbackThread;
     sp<MmapPlaybackThread> mmapThread;
     {
         Mutex::Autolock _l(mLock);
@@ -3195,12 +3196,12 @@
 
             dumpToThreadLog_l(playbackThread);
 
-            if (playbackThread->type() == ThreadBase::MIXER) {
+            if (playbackThread->type() == IAfThreadBase::MIXER) {
                 for (size_t i = 0; i < mPlaybackThreads.size(); i++) {
                     if (mPlaybackThreads.valueAt(i)->isDuplicating()) {
-                        DuplicatingThread *dupThread =
-                                (DuplicatingThread *)mPlaybackThreads.valueAt(i).get();
-                        dupThread->removeOutputTrack((MixerThread *)playbackThread.get());
+                        IAfDuplicatingThread* const dupThread =
+                                mPlaybackThreads.valueAt(i)->asIAfDuplicatingThread().get();
+                        dupThread->removeOutputTrack(playbackThread.get());
                     }
                 }
             }
@@ -3209,11 +3210,12 @@
             mPlaybackThreads.removeItem(output);
             // save all effects to the default thread
             if (mPlaybackThreads.size()) {
-                PlaybackThread *dstThread = checkPlaybackThread_l(mPlaybackThreads.keyAt(0));
+                IAfPlaybackThread* const dstThread =
+                        checkPlaybackThread_l(mPlaybackThreads.keyAt(0));
                 if (dstThread != NULL) {
                     // audioflinger lock is held so order of thread lock acquisition doesn't matter
-                    Mutex::Autolock _dl(dstThread->mLock);
-                    Mutex::Autolock _sl(playbackThread->mLock);
+                    Mutex::Autolock _dl(dstThread->mutex());
+                    Mutex::Autolock _sl(playbackThread->mutex());
                     Vector<sp<IAfEffectChain>> effectChains = playbackThread->getEffectChains_l();
                     for (size_t i = 0; i < effectChains.size(); i ++) {
                         moveEffectChain_l(effectChains[i]->sessionId(), playbackThread.get(),
@@ -3234,7 +3236,7 @@
         mPatchPanel.notifyStreamClosed(output);
     }
     // The thread entity (active unit of execution) is no longer running here,
-    // but the ThreadBase container still exists.
+    // but the IAfThreadBase container still exists.
 
     if (playbackThread != 0) {
         playbackThread->exit();
@@ -3252,7 +3254,7 @@
     return NO_ERROR;
 }
 
-void AudioFlinger::closeOutputFinish(const sp<PlaybackThread>& thread)
+void AudioFlinger::closeOutputFinish(const sp<IAfPlaybackThread>& thread)
 {
     AudioStreamOut *out = thread->clearOutput();
     ALOG_ASSERT(out != NULL, "out shouldn't be NULL");
@@ -3260,9 +3262,9 @@
     delete out;
 }
 
-void AudioFlinger::closeThreadInternal_l(const sp<PlaybackThread>& thread)
+void AudioFlinger::closeThreadInternal_l(const sp<IAfPlaybackThread>& thread)
 {
-    mPlaybackThreads.removeItem(thread->mId);
+    mPlaybackThreads.removeItem(thread->id());
     thread->exit();
     closeOutputFinish(thread);
 }
@@ -3270,7 +3272,7 @@
 status_t AudioFlinger::suspendOutput(audio_io_handle_t output)
 {
     Mutex::Autolock _l(mLock);
-    PlaybackThread *thread = checkPlaybackThread_l(output);
+    IAfPlaybackThread* const thread = checkPlaybackThread_l(output);
 
     if (thread == NULL) {
         return BAD_VALUE;
@@ -3285,7 +3287,7 @@
 status_t AudioFlinger::restoreOutput(audio_io_handle_t output)
 {
     Mutex::Autolock _l(mLock);
-    PlaybackThread *thread = checkPlaybackThread_l(output);
+    IAfPlaybackThread* const thread = checkPlaybackThread_l(output);
 
     if (thread == NULL) {
         return BAD_VALUE;
@@ -3314,7 +3316,7 @@
     audio_config_t config = VALUE_OR_RETURN_STATUS(
             aidl2legacy_AudioConfig_audio_config_t(request.config, true /*isInput*/));
 
-    sp<ThreadBase> thread = openInput_l(
+    const sp<IAfThreadBase> thread = openInput_l(
             VALUE_OR_RETURN_STATUS(aidl2legacy_int32_t_audio_module_handle_t(request.module)),
             &input,
             &config,
@@ -3338,7 +3340,7 @@
     return NO_INIT;
 }
 
-sp<AudioFlinger::ThreadBase> AudioFlinger::openInput_l(audio_module_handle_t module,
+sp<IAfThreadBase> AudioFlinger::openInput_l(audio_module_handle_t module,
                                                          audio_io_handle_t *input,
                                                          audio_config_t *config,
                                                          audio_devices_t devices,
@@ -3412,9 +3414,10 @@
             return thread;
         } else {
             // Start record thread
-            // RecordThread requires both input and output device indication to forward to audio
-            // pre processing modules
-            sp<RecordThread> thread = new RecordThread(this, inputStream, *input, mSystemReady);
+            // IAfRecordThread requires both input and output device indication
+            // to forward to audio pre processing modules
+            const sp<IAfRecordThread> thread =
+                    IAfRecordThread::create(this, inputStream, *input, mSystemReady);
             mRecordThreads.add(*input, thread);
             ALOGV("openInput_l() created record thread: ID %d thread %p", *input, thread.get());
             return thread;
@@ -3434,7 +3437,7 @@
 {
     // keep strong reference on the record thread so that
     // it is not destroyed while exit() is executed
-    sp<RecordThread> recordThread;
+    sp<IAfRecordThread> recordThread;
     sp<MmapCaptureThread> mmapThread;
     {
         Mutex::Autolock _l(mLock);
@@ -3450,8 +3453,8 @@
             // new capture on the same session
             sp<IAfEffectChain> chain;
             {
-                Mutex::Autolock _sl(recordThread->mLock);
-                Vector< sp<IAfEffectChain> > effectChains = recordThread->getEffectChains_l();
+                Mutex::Autolock _sl(recordThread->mutex());
+                const Vector<sp<IAfEffectChain>> effectChains = recordThread->getEffectChains_l();
                 // Note: maximum one chain per record thread
                 if (effectChains.size() != 0) {
                     chain = effectChains[0];
@@ -3463,12 +3466,12 @@
                 // creation of its replacement
                 size_t i;
                 for (i = 0; i < mRecordThreads.size(); i++) {
-                    sp<RecordThread> t = mRecordThreads.valueAt(i);
+                    const sp<IAfRecordThread> t = mRecordThreads.valueAt(i);
                     if (t == recordThread) {
                         continue;
                     }
                     if (t->hasAudioSession(chain->sessionId()) != 0) {
-                        Mutex::Autolock _l2(t->mLock);
+                        Mutex::Autolock _l2(t->mutex());
                         ALOGV("closeInput() found thread %d for effect session %d",
                               t->id(), chain->sessionId());
                         t->addEffectChain_l(chain);
@@ -3505,7 +3508,7 @@
     return NO_ERROR;
 }
 
-void AudioFlinger::closeInputFinish(const sp<RecordThread>& thread)
+void AudioFlinger::closeInputFinish(const sp<IAfRecordThread>& thread)
 {
     thread->exit();
     AudioStreamIn *in = thread->clearInput();
@@ -3514,9 +3517,9 @@
     delete in;
 }
 
-void AudioFlinger::closeThreadInternal_l(const sp<RecordThread>& thread)
+void AudioFlinger::closeThreadInternal_l(const sp<IAfRecordThread>& thread)
 {
-    mRecordThreads.removeItem(thread->mId);
+    mRecordThreads.removeItem(thread->id());
     closeInputFinish(thread);
 }
 
@@ -3526,7 +3529,7 @@
 
     std::set<audio_port_handle_t> portIdSet(portIds.begin(), portIds.end());
     for (size_t i = 0; i < mPlaybackThreads.size(); i++) {
-        PlaybackThread *thread = mPlaybackThreads.valueAt(i).get();
+        IAfPlaybackThread* const thread = mPlaybackThreads.valueAt(i).get();
         thread->invalidateTracks(portIdSet);
         if (portIdSet.empty()) {
             return NO_ERROR;
@@ -3646,14 +3649,15 @@
 
     ALOGV("purging stale effects");
 
-    Vector< sp<IAfEffectChain> > chains;
+    Vector<sp<IAfEffectChain>> chains;
     std::vector< sp<IAfEffectModule> > removedEffects;
 
     for (size_t i = 0; i < mPlaybackThreads.size(); i++) {
-        sp<PlaybackThread> t = mPlaybackThreads.valueAt(i);
-        Mutex::Autolock _l(t->mLock);
-        for (size_t j = 0; j < t->mEffectChains.size(); j++) {
-            sp<IAfEffectChain> ec = t->mEffectChains[j];
+        sp<IAfPlaybackThread> t = mPlaybackThreads.valueAt(i);
+        Mutex::Autolock _l(t->mutex());
+        const Vector<sp<IAfEffectChain>> threadChains = t->getEffectChains_l();
+        for (size_t j = 0; j < threadChains.size(); j++) {
+            sp<IAfEffectChain> ec = threadChains[j];
             if (!audio_is_global_session(ec->sessionId())) {
                 chains.push(ec);
             }
@@ -3661,19 +3665,21 @@
     }
 
     for (size_t i = 0; i < mRecordThreads.size(); i++) {
-        sp<RecordThread> t = mRecordThreads.valueAt(i);
-        Mutex::Autolock _l(t->mLock);
-        for (size_t j = 0; j < t->mEffectChains.size(); j++) {
-            sp<IAfEffectChain> ec = t->mEffectChains[j];
+        sp<IAfRecordThread> t = mRecordThreads.valueAt(i);
+        Mutex::Autolock _l(t->mutex());
+        const Vector<sp<IAfEffectChain>> threadChains = t->getEffectChains_l();
+        for (size_t j = 0; j < threadChains.size(); j++) {
+            sp<IAfEffectChain> ec = threadChains[j];
             chains.push(ec);
         }
     }
 
     for (size_t i = 0; i < mMmapThreads.size(); i++) {
         sp<MmapThread> t = mMmapThreads.valueAt(i);
-        Mutex::Autolock _l(t->mLock);
-        for (size_t j = 0; j < t->mEffectChains.size(); j++) {
-            sp<IAfEffectChain> ec = t->mEffectChains[j];
+        Mutex::Autolock _l(t->mutex());
+        const Vector<sp<IAfEffectChain>> threadChains = t->getEffectChains_l();
+        for (size_t j = 0; j < threadChains.size(); j++) {
+            sp<IAfEffectChain> ec = threadChains[j];
             chains.push(ec);
         }
     }
@@ -3682,7 +3688,7 @@
          // clang-tidy suggests const ref
         sp<IAfEffectChain> ec = chains[i];  // NOLINT(performance-unnecessary-copy-initialization)
         int sessionid = ec->sessionId();
-        sp<ThreadBase> t = sp<ThreadBase>::cast(ec->thread().promote()); // TODO(b/288339104)
+        const auto t = sp<IAfThreadBase>::cast(ec->thread().promote()); // TODO(b/288339104)
         if (t == 0) {
             continue;
         }
@@ -3698,7 +3704,7 @@
             }
         }
         if (!found) {
-            Mutex::Autolock _l(t->mLock);
+            Mutex::Autolock _l(t->mutex());
             // remove all effects from the chain
             while (ec->numberOfEffects()) {
                 sp<IAfEffectModule> effect = ec->getEffectModule(0);
@@ -3715,7 +3721,7 @@
 }
 
 // dumpToThreadLog_l() must be called with AudioFlinger::mLock held
-void AudioFlinger::dumpToThreadLog_l(const sp<ThreadBase> &thread)
+void AudioFlinger::dumpToThreadLog_l(const sp<IAfThreadBase> &thread)
 {
     constexpr int THREAD_DUMP_TIMEOUT_MS = 2;
     audio_utils::FdToString fdToString("- ", THREAD_DUMP_TIMEOUT_MS);
@@ -3727,9 +3733,9 @@
 }
 
 // checkThread_l() must be called with AudioFlinger::mLock held
-AudioFlinger::ThreadBase *AudioFlinger::checkThread_l(audio_io_handle_t ioHandle) const
+IAfThreadBase* AudioFlinger::checkThread_l(audio_io_handle_t ioHandle) const
 {
-    ThreadBase *thread = checkMmapThread_l(ioHandle);
+    IAfThreadBase* thread = checkMmapThread_l(ioHandle);
     if (thread == 0) {
         switch (audio_unique_id_get_use(ioHandle)) {
         case AUDIO_UNIQUE_ID_USE_OUTPUT:
@@ -3746,13 +3752,13 @@
 }
 
 // checkOutputThread_l() must be called with AudioFlinger::mLock held
-sp<AudioFlinger::ThreadBase> AudioFlinger::checkOutputThread_l(audio_io_handle_t ioHandle) const
+sp<IAfThreadBase> AudioFlinger::checkOutputThread_l(audio_io_handle_t ioHandle) const
 {
     if (audio_unique_id_get_use(ioHandle) != AUDIO_UNIQUE_ID_USE_OUTPUT) {
         return nullptr;
     }
 
-    sp<AudioFlinger::ThreadBase> thread = mPlaybackThreads.valueFor(ioHandle);
+    sp<IAfThreadBase> thread = mPlaybackThreads.valueFor(ioHandle);
     if (thread == nullptr) {
         thread = mMmapThreads.valueFor(ioHandle);
     }
@@ -3760,20 +3766,20 @@
 }
 
 // checkPlaybackThread_l() must be called with AudioFlinger::mLock held
-AudioFlinger::PlaybackThread *AudioFlinger::checkPlaybackThread_l(audio_io_handle_t output) const
+IAfPlaybackThread* AudioFlinger::checkPlaybackThread_l(audio_io_handle_t output) const
 {
     return mPlaybackThreads.valueFor(output).get();
 }
 
 // checkMixerThread_l() must be called with AudioFlinger::mLock held
-AudioFlinger::MixerThread *AudioFlinger::checkMixerThread_l(audio_io_handle_t output) const
+IAfPlaybackThread* AudioFlinger::checkMixerThread_l(audio_io_handle_t output) const
 {
-    PlaybackThread *thread = checkPlaybackThread_l(output);
-    return thread != NULL && thread->type() != ThreadBase::DIRECT ? (MixerThread *) thread : NULL;
+    IAfPlaybackThread * const thread = checkPlaybackThread_l(output);
+    return thread != nullptr && thread->type() != IAfThreadBase::DIRECT ? thread : nullptr;
 }
 
 // checkRecordThread_l() must be called with AudioFlinger::mLock held
-AudioFlinger::RecordThread *AudioFlinger::checkRecordThread_l(audio_io_handle_t input) const
+IAfRecordThread* AudioFlinger::checkRecordThread_l(audio_io_handle_t input) const
 {
     return mRecordThreads.valueFor(input).get();
 }
@@ -3839,14 +3845,14 @@
     // TODO Use a floor after wraparound.  This may need a mutex.
 }
 
-AudioFlinger::PlaybackThread *AudioFlinger::primaryPlaybackThread_l() const
+IAfPlaybackThread* AudioFlinger::primaryPlaybackThread_l() const
 {
     AutoMutex lock(mHardwareLock);
     if (mPrimaryHardwareDev == nullptr) {
         return nullptr;
     }
     for (size_t i = 0; i < mPlaybackThreads.size(); i++) {
-        PlaybackThread *thread = mPlaybackThreads.valueAt(i).get();
+        IAfPlaybackThread* const thread = mPlaybackThreads.valueAt(i).get();
         if(thread->isDuplicating()) {
             continue;
         }
@@ -3860,7 +3866,7 @@
 
 DeviceTypeSet AudioFlinger::primaryOutputDevice_l() const
 {
-    PlaybackThread *thread = primaryPlaybackThread_l();
+    IAfPlaybackThread* const thread = primaryPlaybackThread_l();
 
     if (thread == NULL) {
         return {};
@@ -3869,12 +3875,12 @@
     return thread->outDeviceTypes();
 }
 
-AudioFlinger::PlaybackThread *AudioFlinger::fastPlaybackThread_l() const
+IAfPlaybackThread* AudioFlinger::fastPlaybackThread_l() const
 {
     size_t minFrameCount = 0;
-    PlaybackThread *minThread = NULL;
+    IAfPlaybackThread* minThread = nullptr;
     for (size_t i = 0; i < mPlaybackThreads.size(); i++) {
-        PlaybackThread *thread = mPlaybackThreads.valueAt(i).get();
+        IAfPlaybackThread* const thread = mPlaybackThreads.valueAt(i).get();
         if (!thread->isDuplicating()) {
             size_t frameCount = thread->frameCountHAL();
             if (frameCount != 0 && (minFrameCount == 0 || frameCount < minFrameCount ||
@@ -3888,9 +3894,9 @@
     return minThread;
 }
 
-AudioFlinger::ThreadBase *AudioFlinger::hapticPlaybackThread_l() const {
+IAfThreadBase* AudioFlinger::hapticPlaybackThread_l() const {
     for (size_t i  = 0; i < mPlaybackThreads.size(); ++i) {
-        PlaybackThread *thread = mPlaybackThreads.valueAt(i).get();
+        IAfPlaybackThread* const thread = mPlaybackThreads.valueAt(i).get();
         if (thread->hapticChannelMask() != AUDIO_CHANNEL_NONE) {
             return thread;
         }
@@ -3900,11 +3906,11 @@
 
 void AudioFlinger::updateSecondaryOutputsForTrack_l(
         IAfTrack* track,
-        PlaybackThread* thread,
+        IAfPlaybackThread* thread,
         const std::vector<audio_io_handle_t> &secondaryOutputs) const {
     TeePatches teePatches;
     for (audio_io_handle_t secondaryOutput : secondaryOutputs) {
-        PlaybackThread *secondaryThread = checkPlaybackThread_l(secondaryOutput);
+        IAfPlaybackThread* const secondaryThread = checkPlaybackThread_l(secondaryOutput);
         if (secondaryThread == nullptr) {
             ALOGE("no playback thread found for secondary output %d", thread->id());
             continue;
@@ -3930,10 +3936,10 @@
         // The frameCount should also not be smaller than the secondary thread min frame
         // count
         size_t minFrameCount = AudioSystem::calculateMinFrameCount(
-                    [&] { Mutex::Autolock _l(secondaryThread->mLock);
+                    [&] { Mutex::Autolock _l(secondaryThread->mutex());
                           return secondaryThread->latency_l(); }(),
-                    secondaryThread->mNormalFrameCount,
-                    secondaryThread->mSampleRate,
+                    secondaryThread->frameCount(), // normal frame count
+                    secondaryThread->sampleRate(),
                     track->sampleRate(),
                     track->getSpeed());
         frameCount = std::max(frameCount, minFrameCount);
@@ -4182,7 +4188,7 @@
             lStatus = BAD_VALUE;
             goto Exit;
         }
-        PlaybackThread *thread = checkPlaybackThread_l(io);
+        IAfPlaybackThread* const thread = checkPlaybackThread_l(io);
         if (thread == nullptr) {
             ALOGE("%s: invalid output %d specified for AUDIO_SESSION_OUTPUT_STAGE", __func__, io);
             lStatus = BAD_VALUE;
@@ -4351,7 +4357,7 @@
                 }
                 const uint32_t sessionType =
                         mPlaybackThreads.valueAt(i)->hasAudioSession(sessionId);
-                if ((sessionType & ThreadBase::EFFECT_SESSION) != 0) {
+                if ((sessionType & IAfThreadBase::EFFECT_SESSION) != 0) {
                     ALOGE("%s: effect %s io %d denied because session %d effect exists on io %d",
                           __func__, descOut.name, (int) io, (int) sessionId, (int) checkIo);
                     android_errorWriteLog(0x534e4554, "123237974");
@@ -4360,7 +4366,7 @@
                 }
             }
         }
-        ThreadBase *thread = checkRecordThread_l(io);
+        IAfThreadBase* thread = checkRecordThread_l(io);
         if (thread == NULL) {
             thread = checkPlaybackThread_l(io);
             if (thread == NULL) {
@@ -4376,7 +4382,7 @@
             // session and used it instead of creating a new one.
             sp<IAfEffectChain> chain = getOrphanEffectChain_l(sessionId);
             if (chain != 0) {
-                Mutex::Autolock _l2(thread->mLock);
+                Mutex::Autolock _l2(thread->mutex());
                 thread->addEffectChain_l(chain);
             }
         }
@@ -4385,9 +4391,9 @@
 
         // create effect on selected output thread
         bool pinned = !audio_is_global_session(sessionId) && isSessionAcquired_l(sessionId);
-        ThreadBase *oriThread = nullptr;
+        IAfThreadBase* oriThread = nullptr;
         if (hapticPlaybackRequired && thread->hapticChannelMask() == AUDIO_CHANNEL_NONE) {
-            ThreadBase *hapticThread = hapticPlaybackThread_l();
+            IAfThreadBase* const hapticThread = hapticPlaybackThread_l();
             if (hapticThread == nullptr) {
                 ALOGE("%s haptic thread not found while it is required", __func__);
                 lStatus = INVALID_OPERATION;
@@ -4450,26 +4456,26 @@
 status_t AudioFlinger::moveEffects(audio_session_t sessionId, audio_io_handle_t srcOutput,
         audio_io_handle_t dstOutput)
 {
-    ALOGV("moveEffects() session %d, srcOutput %d, dstOutput %d",
-            sessionId, srcOutput, dstOutput);
+    ALOGV("%s() session %d, srcOutput %d, dstOutput %d",
+            __func__, sessionId, srcOutput, dstOutput);
     Mutex::Autolock _l(mLock);
     if (srcOutput == dstOutput) {
-        ALOGW("moveEffects() same dst and src outputs %d", dstOutput);
+        ALOGW("%s() same dst and src outputs %d", __func__, dstOutput);
         return NO_ERROR;
     }
-    PlaybackThread *srcThread = checkPlaybackThread_l(srcOutput);
-    if (srcThread == NULL) {
-        ALOGW("moveEffects() bad srcOutput %d", srcOutput);
+    IAfPlaybackThread* const srcThread = checkPlaybackThread_l(srcOutput);
+    if (srcThread == nullptr) {
+        ALOGW("%s() bad srcOutput %d", __func__, srcOutput);
         return BAD_VALUE;
     }
-    PlaybackThread *dstThread = checkPlaybackThread_l(dstOutput);
-    if (dstThread == NULL) {
-        ALOGW("moveEffects() bad dstOutput %d", dstOutput);
+    IAfPlaybackThread* const dstThread = checkPlaybackThread_l(dstOutput);
+    if (dstThread == nullptr) {
+        ALOGW("%s() bad dstOutput %d", __func__, dstOutput);
         return BAD_VALUE;
     }
 
-    Mutex::Autolock _dl(dstThread->mLock);
-    Mutex::Autolock _sl(srcThread->mLock);
+    Mutex::Autolock _dl(dstThread->mutex());
+    Mutex::Autolock _sl(srcThread->mutex());
     return moveEffectChain_l(sessionId, srcThread, dstThread);
 }
 
@@ -4480,11 +4486,11 @@
 {
     Mutex::Autolock _l(mLock);
 
-    sp<ThreadBase> thread = getEffectThread_l(sessionId, effectId);
+    sp<IAfThreadBase> thread = getEffectThread_l(sessionId, effectId);
     if (thread == nullptr) {
       return;
     }
-    Mutex::Autolock _sl(thread->mLock);
+    Mutex::Autolock _sl(thread->mutex());
     sp<IAfEffectModule> effect = thread->getEffect_l(sessionId, effectId);
     thread->setEffectSuspended_l(&effect->desc().type, suspended, sessionId);
 }
@@ -4492,8 +4498,7 @@
 
 // moveEffectChain_l must be called with both srcThread and dstThread mLocks held
 status_t AudioFlinger::moveEffectChain_l(audio_session_t sessionId,
-                                   AudioFlinger::PlaybackThread *srcThread,
-                                   AudioFlinger::PlaybackThread *dstThread)
+        IAfPlaybackThread* srcThread, IAfPlaybackThread* dstThread)
 NO_THREAD_SAFETY_ANALYSIS // requires srcThread and dstThread locks
 {
     ALOGV("moveEffectChain_l() session %d from thread %p to thread %p",
@@ -4603,17 +4608,16 @@
 }
 
 status_t AudioFlinger::moveAuxEffectToIo(int EffectId,
-                                         const sp<PlaybackThread>& dstThread,
-                                         sp<PlaybackThread> *srcThread)
+        const sp<IAfPlaybackThread>& dstThread, sp<IAfPlaybackThread>* srcThread)
 {
     status_t status = NO_ERROR;
     Mutex::Autolock _l(mLock);
-    sp<PlaybackThread> thread =
-        static_cast<PlaybackThread *>(getEffectThread_l(AUDIO_SESSION_OUTPUT_MIX, EffectId).get());
+    const sp<IAfThreadBase> threadBase = getEffectThread_l(AUDIO_SESSION_OUTPUT_MIX, EffectId);
+    const sp<IAfPlaybackThread> thread = threadBase ? threadBase->asIAfPlaybackThread() : nullptr;
 
     if (EffectId != 0 && thread != 0 && dstThread != thread.get()) {
-        Mutex::Autolock _dl(dstThread->mLock);
-        Mutex::Autolock _sl(thread->mLock);
+        Mutex::Autolock _dl(dstThread->mutex());
+        Mutex::Autolock _sl(thread->mutex());
         sp<IAfEffectChain> srcChain = thread->getEffectChain_l(AUDIO_SESSION_OUTPUT_MIX);
         sp<IAfEffectChain> dstChain;
         if (srcChain == 0) {
@@ -4677,8 +4681,8 @@
     mGlobalEffectEnableTime = systemTime();
 
     for (size_t i = 0; i < mPlaybackThreads.size(); i++) {
-        sp<PlaybackThread> t = mPlaybackThreads.valueAt(i);
-        if (t->mType == ThreadBase::OFFLOAD) {
+        const sp<IAfPlaybackThread> t = mPlaybackThreads.valueAt(i);
+        if (t->type() == IAfThreadBase::OFFLOAD) {
             t->invalidateTracks(AUDIO_STREAM_MUSIC);
         }
     }
diff --git a/services/audioflinger/AudioFlinger.h b/services/audioflinger/AudioFlinger.h
index 02ebbc2..91ef34d 100644
--- a/services/audioflinger/AudioFlinger.h
+++ b/services/audioflinger/AudioFlinger.h
@@ -499,11 +499,7 @@
 
     SimpleLog mThreadLog{16}; // 16 Thread history limit
 
-public:
-    // TODO(b/288339104)
-    class ThreadBase;
-private:
-    void dumpToThreadLog_l(const sp<ThreadBase> &thread);
+    void dumpToThreadLog_l(const sp<IAfThreadBase>& thread);
 
     // --- Notification Client ---
     class NotificationClient : public IBinder::DeathRecipient {
@@ -609,7 +605,7 @@
             const uint32_t sessionType = threads.valueAt(i)->hasAudioSession(sessionId);
             if (sessionType != 0) {
                 io = threads.keyAt(i);
-                if ((sessionType & AudioFlinger::ThreadBase::EFFECT_SESSION) != 0) {
+                if ((sessionType & IAfThreadBase::EFFECT_SESSION) != 0) {
                     break; // effect chain here.
                 }
             }
@@ -640,17 +636,16 @@
         const sp<MmapThread> mThread;
     };
 
-              ThreadBase *checkThread_l(audio_io_handle_t ioHandle) const;
-              sp<AudioFlinger::ThreadBase> checkOutputThread_l(audio_io_handle_t ioHandle) const
-                      REQUIRES(mLock);
-              PlaybackThread *checkPlaybackThread_l(audio_io_handle_t output) const;
-              MixerThread *checkMixerThread_l(audio_io_handle_t output) const;
-              RecordThread *checkRecordThread_l(audio_io_handle_t input) const;
+    IAfThreadBase* checkThread_l(audio_io_handle_t ioHandle) const;
+    sp<IAfThreadBase> checkOutputThread_l(audio_io_handle_t ioHandle) const REQUIRES(mLock);
+    IAfPlaybackThread* checkPlaybackThread_l(audio_io_handle_t output) const;
+    IAfPlaybackThread* checkMixerThread_l(audio_io_handle_t output) const;
+    IAfRecordThread* checkRecordThread_l(audio_io_handle_t input) const;
               MmapThread *checkMmapThread_l(audio_io_handle_t io) const;
               sp<VolumeInterface> getVolumeInterface_l(audio_io_handle_t output) const;
               std::vector<sp<VolumeInterface>> getAllVolumeInterfaces_l() const;
 
-              sp<ThreadBase> openInput_l(audio_module_handle_t module,
+    sp<IAfThreadBase> openInput_l(audio_module_handle_t module,
                                            audio_io_handle_t *input,
                                            audio_config_t *config,
                                            audio_devices_t device,
@@ -659,7 +654,7 @@
                                            audio_input_flags_t flags,
                                            audio_devices_t outputDevice,
                                            const String8& outputDeviceAddress);
-              sp<ThreadBase> openOutput_l(audio_module_handle_t module,
+    sp<IAfThreadBase> openOutput_l(audio_module_handle_t module,
                                           audio_io_handle_t *output,
                                           audio_config_t *halConfig,
                                           audio_config_base_t *mixerConfig,
@@ -667,8 +662,8 @@
                                           const String8& address,
                                           audio_output_flags_t flags);
 
-              void closeOutputFinish(const sp<PlaybackThread>& thread);
-              void closeInputFinish(const sp<RecordThread>& thread);
+    void closeOutputFinish(const sp<IAfPlaybackThread>& thread);
+    void closeInputFinish(const sp<IAfRecordThread>& thread);
 
               // no range check, AudioFlinger::mLock held
               bool streamMute_l(audio_stream_type_t stream) const
@@ -693,30 +688,28 @@
               audio_unique_id_t nextUniqueId(audio_unique_id_use_t use);
 
               status_t moveEffectChain_l(audio_session_t sessionId,
-                                     PlaybackThread *srcThread,
-                                     PlaybackThread *dstThread);
+            IAfPlaybackThread* srcThread, IAfPlaybackThread* dstThread);
 
 public:
     // TODO(b/288339104) cluster together
               status_t moveAuxEffectToIo(int EffectId,
-                                         const sp<PlaybackThread>& dstThread,
-                                         sp<PlaybackThread> *srcThread);
+            const sp<IAfPlaybackThread>& dstThread, sp<IAfPlaybackThread>* srcThread);
 private:
 
               // return thread associated with primary hardware device, or NULL
-              PlaybackThread *primaryPlaybackThread_l() const;
+              IAfPlaybackThread* primaryPlaybackThread_l() const;
               DeviceTypeSet primaryOutputDevice_l() const;
 
               // return the playback thread with smallest HAL buffer size, and prefer fast
-              PlaybackThread *fastPlaybackThread_l() const;
+              IAfPlaybackThread* fastPlaybackThread_l() const;
 
-              sp<ThreadBase> getEffectThread_l(audio_session_t sessionId, int effectId);
+              sp<IAfThreadBase> getEffectThread_l(audio_session_t sessionId, int effectId);
 
-              ThreadBase *hapticPlaybackThread_l() const;
+              IAfThreadBase* hapticPlaybackThread_l() const;
 
               void updateSecondaryOutputsForTrack_l(
                       IAfTrack* track,
-                      PlaybackThread* thread,
+                      IAfPlaybackThread* thread,
                       const std::vector<audio_io_handle_t>& secondaryOutputs) const;
 
 
@@ -754,7 +747,7 @@
                 void updateOutDevicesForRecordThreads_l(const DeviceDescriptorBaseVector& devices);
                 void forwardParametersToDownstreamPatches_l(
                         audio_io_handle_t upStream, const String8& keyValuePairs,
-                        const std::function<bool(const sp<PlaybackThread>&)>& useThread = nullptr);
+            const std::function<bool(const sp<IAfPlaybackThread>&)>& useThread = nullptr);
 
     struct TeePatch {
         sp<IAfPatchRecord> patchRecord;
@@ -827,7 +820,7 @@
     mutable     hardware_call_state                 mHardwareStatus;    // for dump only
 
 
-                DefaultKeyedVector< audio_io_handle_t, sp<PlaybackThread> >  mPlaybackThreads;
+    DefaultKeyedVector<audio_io_handle_t, sp<IAfPlaybackThread>> mPlaybackThreads;
                 stream_type_t                       mStreamTypes[AUDIO_STREAM_CNT];
 
                 // member variables below are protected by mLock
@@ -836,7 +829,7 @@
                 float                               mMasterBalance = 0.f;
                 // end of variables protected by mLock
 
-                DefaultKeyedVector< audio_io_handle_t, sp<RecordThread> >    mRecordThreads;
+    DefaultKeyedVector<audio_io_handle_t, sp<IAfRecordThread>> mRecordThreads;
 
                 // protected by mClientLock
                 DefaultKeyedVector< pid_t, sp<NotificationClient> >    mNotificationClients;
@@ -874,10 +867,10 @@
 
     // for use from destructor
     status_t    closeOutput_nonvirtual(audio_io_handle_t output);
-    void        closeThreadInternal_l(const sp<PlaybackThread>& thread);
+    void closeThreadInternal_l(const sp<IAfPlaybackThread>& thread);
     status_t    closeInput_nonvirtual(audio_io_handle_t input);
-    void        closeThreadInternal_l(const sp<RecordThread>& thread);
-    void        setAudioHwSyncForSession_l(PlaybackThread *thread, audio_session_t sessionId);
+    void closeThreadInternal_l(const sp<IAfRecordThread>& thread);
+    void setAudioHwSyncForSession_l(IAfPlaybackThread* thread, audio_session_t sessionId);
 
     status_t    checkStreamType(audio_stream_type_t stream) const;
 
diff --git a/services/audioflinger/Effects.cpp b/services/audioflinger/Effects.cpp
index 1f26cb0..6b8e905 100644
--- a/services/audioflinger/Effects.cpp
+++ b/services/audioflinger/Effects.cpp
@@ -2116,21 +2116,21 @@
 
 /* static */
 sp<IAfEffectChain> IAfEffectChain::create(
-        const wp<Thread /*ThreadBase*/>& wThread,  // TODO(b/288339104) update type
+        const wp<IAfThreadBase>& wThread,
         audio_session_t sessionId)
 {
     // TODO(b/288339104) no weak pointer cast.
-    return sp<EffectChain>::make(sp<AudioFlinger::ThreadBase>::cast(wThread.promote()), sessionId);
+    return sp<EffectChain>::make(wThread, sessionId);
 }
 
-EffectChain::EffectChain(const wp<AudioFlinger::ThreadBase>& thread,
+EffectChain::EffectChain(const wp<IAfThreadBase>& thread,
                                        audio_session_t sessionId)
     : mSessionId(sessionId), mActiveTrackCnt(0), mTrackCnt(0), mTailBufferCount(0),
       mVolumeCtrlIdx(-1), mLeftVolume(UINT_MAX), mRightVolume(UINT_MAX),
       mNewLeftVolume(UINT_MAX), mNewRightVolume(UINT_MAX),
       mEffectCallback(new EffectCallback(wp<EffectChain>(this), thread))
 {
-    sp<AudioFlinger::ThreadBase> p = thread.promote();
+    const sp<IAfThreadBase> p = thread.promote();
     if (p == nullptr) {
         return;
     }
@@ -2143,7 +2143,7 @@
 {
 }
 
-// getEffectFromDesc_l() must be called with AudioFlinger::ThreadBase::mLock held
+// getEffectFromDesc_l() must be called with IAfThreadBase::mutex() held
 sp<IAfEffectModule> EffectChain::getEffectFromDesc_l(
         effect_descriptor_t *descriptor) const
 {
@@ -2157,7 +2157,7 @@
     return 0;
 }
 
-// getEffectFromId_l() must be called with AudioFlinger::ThreadBase::mLock held
+// getEffectFromId_l() must be called with IAfThreadBase::mutex() held
 sp<IAfEffectModule> EffectChain::getEffectFromId_l(int id) const
 {
     size_t size = mEffects.size();
@@ -2171,7 +2171,7 @@
     return 0;
 }
 
-// getEffectFromType_l() must be called with AudioFlinger::ThreadBase::mLock held
+// getEffectFromType_l() must be called with IAfThreadBase::mutex() held
 sp<IAfEffectModule> EffectChain::getEffectFromType_l(
         const effect_uuid_t *type) const
 {
@@ -2266,7 +2266,7 @@
     }
 }
 
-// createEffect_l() must be called with AudioFlinger::ThreadBase::mLock held
+// createEffect_l() must be called with IAfThreadBase::mutex() held
 status_t EffectChain::createEffect_l(sp<IAfEffectModule>& effect,
                                                    effect_descriptor_t *desc,
                                                    int id,
@@ -2285,13 +2285,13 @@
     return lStatus;
 }
 
-// addEffect_l() must be called with AudioFlinger::ThreadBase::mLock held
+// addEffect_l() must be called with IAfThreadBase::mutex() held
 status_t EffectChain::addEffect_l(const sp<IAfEffectModule>& effect)
 {
     Mutex::Autolock _l(mLock);
     return addEffect_ll(effect);
 }
-// addEffect_l() must be called with AudioFlinger::ThreadBase::mLock and EffectChain::mLock held
+// addEffect_l() must be called with IAfThreadBase::mLock and EffectChain::mutex() held
 status_t EffectChain::addEffect_ll(const sp<IAfEffectModule>& effect)
 {
     effect->setCallback(mEffectCallback);
@@ -2445,7 +2445,7 @@
     return idx_insert;
 }
 
-// removeEffect_l() must be called with AudioFlinger::ThreadBase::mLock held
+// removeEffect_l() must be called with IAfThreadBase::mutex() held
 size_t EffectChain::removeEffect_l(const sp<IAfEffectModule>& effect,
                                                  bool release)
 {
@@ -2493,7 +2493,7 @@
     return mEffects.size();
 }
 
-// setDevices_l() must be called with AudioFlinger::ThreadBase::mLock held
+// setDevices_l() must be called with IAfThreadBase::mutex() held
 void EffectChain::setDevices_l(const AudioDeviceTypeAddrVector &devices)
 {
     size_t size = mEffects.size();
@@ -2502,7 +2502,7 @@
     }
 }
 
-// setInputDevice_l() must be called with AudioFlinger::ThreadBase::mLock held
+// setInputDevice_l() must be called with IAfThreadBase::mutex() held
 void EffectChain::setInputDevice_l(const AudioDeviceTypeAddr &device)
 {
     size_t size = mEffects.size();
@@ -2511,7 +2511,7 @@
     }
 }
 
-// setMode_l() must be called with AudioFlinger::ThreadBase::mLock held
+// setMode_l() must be called with IAfThreadBase::mutex() held
 void EffectChain::setMode_l(audio_mode_t mode)
 {
     size_t size = mEffects.size();
@@ -2520,7 +2520,7 @@
     }
 }
 
-// setAudioSource_l() must be called with AudioFlinger::ThreadBase::mLock held
+// setAudioSource_l() must be called with IAfThreadBase::mutex() held
 void EffectChain::setAudioSource_l(audio_source_t source)
 {
     size_t size = mEffects.size();
@@ -2536,7 +2536,7 @@
     return false;
 }
 
-// setVolume_l() must be called with AudioFlinger::ThreadBase::mLock or EffectChain::mLock held
+// setVolume_l() must be called with IAfThreadBase::mLock or EffectChain::mLock held
 bool EffectChain::setVolume_l(uint32_t *left, uint32_t *right, bool force)
 {
     uint32_t newLeft = *left;
@@ -2603,7 +2603,7 @@
     return hasControl;
 }
 
-// resetVolume_l() must be called with AudioFlinger::ThreadBase::mLock or EffectChain::mLock held
+// resetVolume_l() must be called with IAfThreadBase::mutex() or EffectChain::mLock held
 void EffectChain::resetVolume_l()
 {
     if ((mLeftVolume != UINT_MAX) && (mRightVolume != UINT_MAX)) {
@@ -2614,7 +2614,7 @@
 }
 
 // containsHapticGeneratingEffect_l must be called with
-// AudioFlinger::ThreadBase::mLock or EffectChain::mLock held
+// IAfThreadBase::mutex() or EffectChain::mLock held
 bool EffectChain::containsHapticGeneratingEffect_l()
 {
     for (size_t i = 0; i < mEffects.size(); ++i) {
@@ -2683,7 +2683,7 @@
     }
 }
 
-// must be called with AudioFlinger::ThreadBase::mLock held
+// must be called with IAfThreadBase::mutex() held
 void EffectChain::setEffectSuspended_l(
         const effect_uuid_t *type, bool suspend)
 {
@@ -2739,7 +2739,7 @@
     }
 }
 
-// must be called with AudioFlinger::ThreadBase::mLock held
+// must be called with IAfThreadBase::mutex() held
 void EffectChain::setEffectSuspendedAll_l(bool suspend)
 {
     sp<SuspendedEffectDesc> desc;
@@ -2895,7 +2895,7 @@
     return false;
 }
 
-void EffectChain::setThread(const sp<AudioFlinger::ThreadBase>& thread)
+void EffectChain::setThread(const sp<IAfThreadBase>& thread)
 {
     Mutex::Autolock _l(mLock);
     mEffectCallback->setThread(thread);
@@ -2962,7 +2962,7 @@
 }
 
 // isCompatibleWithThread_l() must be called with thread->mLock held
-bool EffectChain::isCompatibleWithThread_l(const sp<AudioFlinger::ThreadBase>& thread) const
+bool EffectChain::isCompatibleWithThread_l(const sp<IAfThreadBase>& thread) const
 {
     Mutex::Autolock _l(mLock);
     for (size_t i = 0; i < mEffects.size(); i++) {
@@ -3000,7 +3000,7 @@
 status_t EffectChain::EffectCallback::addEffectToHal(
         const sp<EffectHalInterface>& effect) {
     status_t result = NO_INIT;
-    sp<AudioFlinger::ThreadBase> t = thread().promote();
+    const sp<IAfThreadBase> t = thread().promote();
     if (t == nullptr) {
         return result;
     }
@@ -3016,7 +3016,7 @@
 status_t EffectChain::EffectCallback::removeEffectFromHal(
         const sp<EffectHalInterface>& effect) {
     status_t result = NO_INIT;
-    sp<AudioFlinger::ThreadBase> t = thread().promote();
+    const sp<IAfThreadBase> t = thread().promote();
     if (t == nullptr) {
         return result;
     }
@@ -3030,7 +3030,7 @@
 }
 
 audio_io_handle_t EffectChain::EffectCallback::io() const {
-    sp<AudioFlinger::ThreadBase> t = thread().promote();
+    const sp<IAfThreadBase> t = thread().promote();
     if (t == nullptr) {
         return AUDIO_IO_HANDLE_NONE;
     }
@@ -3038,7 +3038,7 @@
 }
 
 bool EffectChain::EffectCallback::isOutput() const {
-    sp<AudioFlinger::ThreadBase> t = thread().promote();
+    const sp<IAfThreadBase> t = thread().promote();
     if (t == nullptr) {
         return true;
     }
@@ -3046,19 +3046,19 @@
 }
 
 bool EffectChain::EffectCallback::isOffload() const {
-    return mThreadType == AudioFlinger::ThreadBase::OFFLOAD;
+    return mThreadType == IAfThreadBase::OFFLOAD;
 }
 
 bool EffectChain::EffectCallback::isOffloadOrDirect() const {
-    return mThreadType == AudioFlinger::ThreadBase::OFFLOAD
-            || mThreadType == AudioFlinger::ThreadBase::DIRECT;
+    return mThreadType == IAfThreadBase::OFFLOAD
+            || mThreadType == IAfThreadBase::DIRECT;
 }
 
 bool EffectChain::EffectCallback::isOffloadOrMmap() const {
     switch (mThreadType) {
-    case AudioFlinger::ThreadBase::OFFLOAD:
-    case AudioFlinger::ThreadBase::MMAP_PLAYBACK:
-    case AudioFlinger::ThreadBase::MMAP_CAPTURE:
+    case IAfThreadBase::OFFLOAD:
+    case IAfThreadBase::MMAP_PLAYBACK:
+    case IAfThreadBase::MMAP_CAPTURE:
         return true;
     default:
         return false;
@@ -3066,11 +3066,11 @@
 }
 
 bool EffectChain::EffectCallback::isSpatializer() const {
-    return mThreadType == AudioFlinger::ThreadBase::SPATIALIZER;
+    return mThreadType == IAfThreadBase::SPATIALIZER;
 }
 
 uint32_t EffectChain::EffectCallback::sampleRate() const {
-    sp<AudioFlinger::ThreadBase> t = thread().promote();
+    const sp<IAfThreadBase> t = thread().promote();
     if (t == nullptr) {
         return 0;
     }
@@ -3078,7 +3078,7 @@
 }
 
 audio_channel_mask_t EffectChain::EffectCallback::inChannelMask(int id) const {
-    sp<AudioFlinger::ThreadBase> t = thread().promote();
+    const sp<IAfThreadBase> t = thread().promote();
     if (t == nullptr) {
         return AUDIO_CHANNEL_NONE;
     }
@@ -3087,7 +3087,7 @@
         return AUDIO_CHANNEL_NONE;
     }
 
-    if (mThreadType == AudioFlinger::ThreadBase::SPATIALIZER) {
+    if (mThreadType == IAfThreadBase::SPATIALIZER) {
         if (c->sessionId() == AUDIO_SESSION_OUTPUT_STAGE) {
             if (c->isFirstEffect(id)) {
                 return t->mixerChannelMask();
@@ -3096,7 +3096,7 @@
             }
         } else if (!audio_is_global_session(c->sessionId())) {
             if ((t->hasAudioSession_l(c->sessionId())
-                    & AudioFlinger::ThreadBase::SPATIALIZED_SESSION) != 0) {
+                    & IAfThreadBase::SPATIALIZED_SESSION) != 0) {
                 return t->mixerChannelMask();
             } else {
                 return t->channelMask();
@@ -3114,7 +3114,7 @@
 }
 
 audio_channel_mask_t EffectChain::EffectCallback::outChannelMask() const {
-    sp<AudioFlinger::ThreadBase> t = thread().promote();
+    const sp<IAfThreadBase> t = thread().promote();
     if (t == nullptr) {
         return AUDIO_CHANNEL_NONE;
     }
@@ -3123,10 +3123,10 @@
         return AUDIO_CHANNEL_NONE;
     }
 
-    if (mThreadType == AudioFlinger::ThreadBase::SPATIALIZER) {
+    if (mThreadType == IAfThreadBase::SPATIALIZER) {
         if (!audio_is_global_session(c->sessionId())) {
             if ((t->hasAudioSession_l(c->sessionId())
-                    & AudioFlinger::ThreadBase::SPATIALIZED_SESSION) != 0) {
+                    & IAfThreadBase::SPATIALIZED_SESSION) != 0) {
                 return t->mixerChannelMask();
             } else {
                 return t->channelMask();
@@ -3144,7 +3144,7 @@
 }
 
 audio_channel_mask_t EffectChain::EffectCallback::hapticChannelMask() const {
-    sp<AudioFlinger::ThreadBase> t = thread().promote();
+    const sp<IAfThreadBase> t = thread().promote();
     if (t == nullptr) {
         return AUDIO_CHANNEL_NONE;
     }
@@ -3152,7 +3152,7 @@
 }
 
 size_t EffectChain::EffectCallback::frameCount() const {
-    sp<AudioFlinger::ThreadBase> t = thread().promote();
+    const sp<IAfThreadBase> t = thread().promote();
     if (t == nullptr) {
         return 0;
     }
@@ -3162,7 +3162,7 @@
 uint32_t EffectChain::EffectCallback::latency() const
 NO_THREAD_SAFETY_ANALYSIS  // latency_l() access
 {
-    sp<AudioFlinger::ThreadBase> t = thread().promote();
+    const sp<IAfThreadBase> t = thread().promote();
     if (t == nullptr) {
         return 0;
     }
@@ -3173,7 +3173,7 @@
 void EffectChain::EffectCallback::setVolumeForOutput(float left, float right) const
 NO_THREAD_SAFETY_ANALYSIS  // setVolumeForOutput_l() access
 {
-    sp<AudioFlinger::ThreadBase> t = thread().promote();
+    const sp<IAfThreadBase> t = thread().promote();
     if (t == nullptr) {
         return;
     }
@@ -3182,7 +3182,7 @@
 
 void EffectChain::EffectCallback::checkSuspendOnEffectEnabled(
         const sp<IAfEffectBase>& effect, bool enabled, bool threadLocked) {
-    sp<AudioFlinger::ThreadBase> t = thread().promote();
+    const sp<IAfThreadBase> t = thread().promote();
     if (t == nullptr) {
         return;
     }
@@ -3197,7 +3197,7 @@
 }
 
 void EffectChain::EffectCallback::onEffectEnable(const sp<IAfEffectBase>& effect) {
-    sp<AudioFlinger::ThreadBase> t = thread().promote();
+    const sp<IAfThreadBase> t = thread().promote();
     if (t == nullptr) {
         return;
     }
@@ -3208,7 +3208,7 @@
 void EffectChain::EffectCallback::onEffectDisable(const sp<IAfEffectBase>& effect) {
     checkSuspendOnEffectEnabled(effect, false, false /*threadLocked*/);
 
-    sp<AudioFlinger::ThreadBase> t = thread().promote();
+    const sp<IAfThreadBase> t = thread().promote();
     if (t == nullptr) {
         return;
     }
@@ -3217,7 +3217,7 @@
 
 bool EffectChain::EffectCallback::disconnectEffectHandle(IAfEffectHandle *handle,
                                                       bool unpinIfLast) {
-    sp<AudioFlinger::ThreadBase> t = thread().promote();
+    const sp<IAfThreadBase> t = thread().promote();
     if (t == nullptr) {
         return false;
     }
@@ -3376,7 +3376,7 @@
             mDevicePort.id = AUDIO_PORT_HANDLE_NONE;
         }
     } else if (patch.isSoftware() || patch.thread().promote() != nullptr) {
-        sp <AudioFlinger::ThreadBase> thread;
+        sp<IAfThreadBase> thread;
         if (audio_port_config_has_input_direction(port)) {
             if (patch.isSoftware()) {
                 thread = patch.mRecord.thread();
diff --git a/services/audioflinger/Effects.h b/services/audioflinger/Effects.h
index 07790be..ae87346 100644
--- a/services/audioflinger/Effects.h
+++ b/services/audioflinger/Effects.h
@@ -382,7 +382,7 @@
 // it also provide it's own input buffer used by the track as accumulation buffer.
 class EffectChain : public IAfEffectChain {
 public:
-    EffectChain(const wp<AudioFlinger::ThreadBase>& wThread, audio_session_t sessionId);
+    EffectChain(const wp<IAfThreadBase>& wThread, audio_session_t sessionId);
     ~EffectChain() override;
 
     void process_l() final;
@@ -479,12 +479,7 @@
     bool isBitPerfectCompatible() const final;
 
     // isCompatibleWithThread_l() must be called with thread->mLock held
-    // TODO(b/288339104) type
-    bool isCompatibleWithThread_l(const sp<Thread>& thread) const final {
-        return isCompatibleWithThread_l(sp<AudioFlinger::ThreadBase>::cast(thread));
-    }
-
-    bool isCompatibleWithThread_l(const sp<AudioFlinger::ThreadBase>& thread) const;
+    bool isCompatibleWithThread_l(const sp<IAfThreadBase>& thread) const final;
 
     bool containsHapticGeneratingEffect_l() final;
 
@@ -492,8 +487,7 @@
 
     sp<EffectCallbackInterface> effectCallback() const final { return mEffectCallback; }
 
-    // TODO(b/288339104) type
-    wp<Thread> thread() const final { return mEffectCallback->thread(); }
+    wp<IAfThreadBase> thread() const final { return mEffectCallback->thread(); }
 
     bool isFirstEffect(int id) const final {
         return !mEffects.isEmpty() && id == mEffects[0]->id();
@@ -507,12 +501,7 @@
         return mEffects[index];
     }
 
-    // TODO(b/288339104) type
-    void setThread(const sp<Thread>& thread) final {
-        setThread(sp<AudioFlinger::ThreadBase>::cast(thread));
-    }
-
-    void setThread(const sp<AudioFlinger::ThreadBase>& thread);
+    void setThread(const sp<IAfThreadBase>& thread) final;
 
 private:
 
@@ -527,15 +516,15 @@
         // Note: ctors taking a weak pointer to their owner must not promote it
         // during construction (but may keep a reference for later promotion).
         EffectCallback(const wp<EffectChain>& owner,
-                       const wp<AudioFlinger::ThreadBase>& thread)
+                const wp<IAfThreadBase>& thread)
             : mChain(owner)
             , mThread(thread)
             , mAudioFlinger(*AudioFlinger::gAudioFlinger) {
-            sp<AudioFlinger::ThreadBase> base = thread.promote();
+            const sp<IAfThreadBase> base = thread.promote();
             if (base != nullptr) {
                 mThreadType = base->type();
             } else {
-                mThreadType = AudioFlinger::ThreadBase::MIXER;  // assure a consistent value.
+                mThreadType = IAfThreadBase::MIXER;  // assure a consistent value.
             }
         }
 
@@ -580,18 +569,18 @@
             return mAudioFlinger.isAudioPolicyReady();
         }
 
-        wp<AudioFlinger::ThreadBase> thread() const { return mThread.load(); }
+        wp<IAfThreadBase> thread() const { return mThread.load(); }
 
-        void setThread(const sp<AudioFlinger::ThreadBase>& thread) {
+        void setThread(const sp<IAfThreadBase>& thread) {
             mThread = thread;
             mThreadType = thread->type();
         }
 
     private:
         const wp<IAfEffectChain> mChain;
-        mediautils::atomic_wp<AudioFlinger::ThreadBase> mThread;
+        mediautils::atomic_wp<IAfThreadBase> mThread;
         AudioFlinger &mAudioFlinger;  // implementation detail: outer instance always exists.
-        AudioFlinger::ThreadBase::type_t mThreadType;
+        IAfThreadBase::type_t mThreadType;
     };
 
     DISALLOW_COPY_AND_ASSIGN(EffectChain);
diff --git a/services/audioflinger/IAfEffect.h b/services/audioflinger/IAfEffect.h
index 75112ca..069c5a4 100644
--- a/services/audioflinger/IAfEffect.h
+++ b/services/audioflinger/IAfEffect.h
@@ -23,6 +23,7 @@
 class IAfEffectChain;
 class IAfEffectHandle;
 class IAfEffectModule;
+class IAfThreadBase;
 
 // Interface implemented by the EffectModule parent or owner (e.g an EffectChain) to abstract
 // interactions between the EffectModule and the reset of the audio framework.
@@ -190,7 +191,7 @@
     // Most of these methods are accessed from AudioFlinger::Thread
 public:
     static sp<IAfEffectChain> create(
-            const wp<Thread /*ThreadBase*/>& wThread,  // TODO(b/288339104) type
+            const wp<IAfThreadBase>& wThread,
             audio_session_t sessionId);
 
     // special key used for an entry in mSuspendedEffects keyed vector
@@ -279,8 +280,7 @@
     virtual bool isBitPerfectCompatible() const = 0;
 
     // isCompatibleWithThread_l() must be called with thread->mLock held
-    //  TODO(b/288339104) type
-    virtual bool isCompatibleWithThread_l(const sp<Thread>& thread) const = 0;
+    virtual bool isCompatibleWithThread_l(const sp<IAfThreadBase>& thread) const = 0;
 
     virtual bool containsHapticGeneratingEffect_l() = 0;
 
@@ -288,8 +288,8 @@
 
     virtual sp<EffectCallbackInterface> effectCallback() const = 0;
 
-    virtual wp<Thread> thread() const = 0;  // TODO(b/288339104) type
-    virtual void setThread(const sp<Thread>& thread) = 0;  // TODO(b/288339104) type
+    virtual wp<IAfThreadBase> thread() const = 0;
+    virtual void setThread(const sp<IAfThreadBase>& thread) = 0;
 
     virtual bool isFirstEffect(int id) const = 0;
 
diff --git a/services/audioflinger/IAfThread.h b/services/audioflinger/IAfThread.h
index 449ed90..e8f2349 100644
--- a/services/audioflinger/IAfThread.h
+++ b/services/audioflinger/IAfThread.h
@@ -20,6 +20,11 @@
 
 namespace android {
 
+class IAfDirectOutputThread;
+class IAfDuplicatingThread;
+class IAfPlaybackThread;
+class IAfRecordThread;
+
 class IAfThreadBase : public virtual RefBase {
 public:
     enum type_t {
@@ -52,6 +57,7 @@
     // and returns the [normal mix] buffer's frame count.
     virtual size_t frameCount() const = 0;
     virtual audio_channel_mask_t hapticChannelMask() const = 0;
+    virtual uint32_t hapticChannelCount() const = 0;
     virtual uint32_t latency_l() const = 0;
     virtual void setVolumeForOutput_l(float left, float right) const = 0;
 
@@ -233,10 +239,22 @@
     virtual void stopMelComputation_l() = 0;
 
     virtual product_strategy_t getStrategyForStream(audio_stream_type_t stream) const = 0;
+
+    virtual void setEffectSuspended_l(
+            const effect_uuid_t* type, bool suspend, audio_session_t sessionId) = 0;
+
+    // Dynamic cast to derived interface
+    virtual sp<IAfDirectOutputThread> asIAfDirectOutputThread() { return nullptr; }
+    virtual sp<IAfDuplicatingThread> asIAfDuplicatingThread() { return nullptr; }
+    virtual sp<IAfPlaybackThread> asIAfPlaybackThread() { return nullptr; }
+    virtual sp<IAfRecordThread> asIAfRecordThread() { return nullptr; }
+    virtual AudioFlinger* audioFlinger() const = 0;
 };
 
-class IAfPlaybackThread : public virtual IAfThreadBase {
+class IAfPlaybackThread : public virtual IAfThreadBase, public virtual VolumeInterface {
 public:
+    static constexpr int8_t kMaxTrackStopRetriesOffload = 2;
+
     enum mixer_state {
         MIXER_IDLE,            // no active tracks
         MIXER_TRACKS_ENABLED,  // at least one active track, but no track has any data ready
@@ -250,6 +268,8 @@
     // return estimated latency in milliseconds, as reported by HAL
     virtual uint32_t latency() const = 0;  // should be in IAfThreadBase?
 
+    virtual uint32_t& fastTrackAvailMask_l() = 0;
+
     virtual sp<IAfTrack> createTrack_l(
             const sp<Client>& client,
             audio_stream_type_t streamType,
@@ -273,9 +293,14 @@
             bool isSpatialized,
             bool isBitPerfect) = 0;
 
+    virtual status_t addTrack_l(const sp<IAfTrack>& track) = 0;
+    virtual bool destroyTrack_l(const sp<IAfTrack>& track) = 0;
+    virtual bool isTrackActive(const sp<IAfTrack>& track) const = 0;
+    virtual void addOutputTrack_l(const sp<IAfTrack>& track) = 0;
+
+    virtual AudioStreamOut* getOutput_l() const = 0;
     virtual AudioStreamOut* getOutput() const = 0;
     virtual AudioStreamOut* clearOutput() = 0;
-    virtual sp<StreamHalInterface> stream() const = 0;
 
     // a very large number of suspend() will eventually wraparound, but unlikely
     virtual void suspend() = 0;
@@ -329,6 +354,79 @@
     virtual bool hasFastMixer() const = 0;
     virtual FastTrackUnderruns getFastTrackUnderruns(size_t fastIndex) const = 0;
     virtual const std::atomic<int64_t>& framesWritten() const = 0;
+
+    virtual bool usesHwAvSync() const = 0;
+};
+
+class IAfDirectOutputThread : public virtual IAfPlaybackThread {
+public:
+    virtual status_t selectPresentation(int presentationId, int programId) = 0;
+};
+
+class IAfDuplicatingThread : public virtual IAfPlaybackThread {
+public:
+    virtual void addOutputTrack(IAfPlaybackThread* thread) = 0;
+    virtual uint32_t waitTimeMs() const = 0;
+    virtual void removeOutputTrack(IAfPlaybackThread* thread) = 0;
+};
+
+class IAfRecordThread : public virtual IAfThreadBase {
+public:
+    static sp<IAfRecordThread> create(
+            const sp<AudioFlinger>& audioFlinger, AudioStreamIn* input, audio_io_handle_t id,
+            bool systemReady);
+
+    virtual sp<IAfRecordTrack> createRecordTrack_l(
+            const sp<Client>& client,
+            const audio_attributes_t& attr,
+            uint32_t* pSampleRate,
+            audio_format_t format,
+            audio_channel_mask_t channelMask,
+            size_t* pFrameCount,
+            audio_session_t sessionId,
+            size_t* pNotificationFrameCount,
+            pid_t creatorPid,
+            const AttributionSourceState& attributionSource,
+            audio_input_flags_t* flags,
+            pid_t tid,
+            status_t* status /*non-NULL*/,
+            audio_port_handle_t portId,
+            int32_t maxSharedAudioHistoryMs) = 0;
+    virtual void destroyTrack_l(const sp<IAfRecordTrack>& track) = 0;
+    virtual void removeTrack_l(const sp<IAfRecordTrack>& track) = 0;
+
+    virtual status_t start(
+            IAfRecordTrack* recordTrack, AudioSystem::sync_event_t event,
+            audio_session_t triggerSession) = 0;
+
+    // ask the thread to stop the specified track, and
+    // return true if the caller should then do it's part of the stopping process
+    virtual bool stop(IAfRecordTrack* recordTrack) = 0;
+
+    virtual AudioStreamIn* getInput() const = 0;
+    virtual AudioStreamIn* clearInput() = 0;
+
+    virtual status_t getActiveMicrophones(
+            std::vector<media::MicrophoneInfoFw>* activeMicrophones) const = 0;
+    virtual status_t setPreferredMicrophoneDirection(audio_microphone_direction_t direction) = 0;
+    virtual status_t setPreferredMicrophoneFieldDimension(float zoom) = 0;
+
+    virtual void addPatchTrack(const sp<IAfPatchRecord>& record) = 0;
+    virtual void deletePatchTrack(const sp<IAfPatchRecord>& record) = 0;
+    virtual bool fastTrackAvailable() const = 0;
+    virtual void setFastTrackAvailable(bool available) = 0;
+
+    virtual void setRecordSilenced(audio_port_handle_t portId, bool silenced) = 0;
+    virtual bool hasFastCapture() const = 0;
+
+    virtual void checkBtNrec() = 0;
+    virtual uint32_t getInputFramesLost() const = 0;
+
+    virtual status_t shareAudioHistory(
+            const std::string& sharedAudioPackageName,
+            audio_session_t sharedSessionId = AUDIO_SESSION_NONE,
+            int64_t sharedAudioStartMs = -1) = 0;
+    virtual void resetAudioHistory_l() = 0;
 };
 
 }  // namespace android
diff --git a/services/audioflinger/IAfTrack.h b/services/audioflinger/IAfTrack.h
index 4718474..9ca13ca 100644
--- a/services/audioflinger/IAfTrack.h
+++ b/services/audioflinger/IAfTrack.h
@@ -18,6 +18,11 @@
 
 namespace android {
 
+class IAfDuplicatingThread;
+class IAfPlaybackThread;
+class IAfRecordThread;
+class IAfThreadBase;
+
 // Common interface to all Playback and Record tracks.
 class IAfTrackBase : public virtual RefBase {
 public:
@@ -97,8 +102,7 @@
     virtual void releaseBuffer(AudioBufferProvider::Buffer* buffer) = 0;
 
     // Added for RecordTrack and OutputTrack
-    // TODO(b/288339104) type
-    virtual wp<Thread> thread() const = 0;
+    virtual wp<IAfThreadBase> thread() const = 0;
     virtual const sp<ServerProxy>& serverProxy() const = 0;
 
     // TEE_SINK
@@ -233,8 +237,8 @@
     // Only one AIDL IAudioTrack interface adapter should be created per Track.
     static sp<media::IAudioTrack> createIAudioTrackAdapter(const sp<IAfTrack>& track);
 
-    static sp<IAfTrack> create( // TODO(b/288339104) void*
-            void* /* AudioFlinger::PlaybackThread */ thread,
+    static sp<IAfTrack> create(
+            IAfPlaybackThread* thread,
             const sp<Client>& client,
             audio_stream_type_t streamType,
             const audio_attributes_t& attr,
@@ -399,8 +403,8 @@
 public:
     // TODO(b/288339104) void*
     static sp<IAfOutputTrack> create(
-            void* /* AudioFlinger::PlaybackThread */ playbackThread,
-            void* /* AudioFlinger::DuplicatingThread */ sourceThread, uint32_t sampleRate,
+            IAfPlaybackThread* playbackThread,
+            IAfDuplicatingThread* sourceThread, uint32_t sampleRate,
             audio_format_t format, audio_channel_mask_t channelMask, size_t frameCount,
             const AttributionSourceState& attributionSource);
 
@@ -417,7 +421,7 @@
 class IAfMmapTrack : public virtual IAfTrackBase {
 public:
     // TODO(b/288339104) void*
-    static sp<IAfMmapTrack> create(void* /*AudioFlinger::ThreadBase */ thread,
+    static sp<IAfMmapTrack> create(IAfThreadBase* thread,
             const audio_attributes_t& attr,
             uint32_t sampleRate,
             audio_format_t format,
@@ -455,7 +459,7 @@
     static sp<media::IAudioRecord> createIAudioRecordAdapter(const sp<IAfRecordTrack>& recordTrack);
 
     // TODO(b/288339104) void*
-    static sp<IAfRecordTrack> create(void* /* AudioFlinger::RecordThread */ thread,
+    static sp<IAfRecordTrack> create(IAfRecordThread* thread,
             const sp<Client>& client,
             const audio_attributes_t& attr,
             uint32_t sampleRate,
@@ -533,7 +537,7 @@
 class IAfPatchTrack : public virtual IAfTrack, public virtual IAfPatchTrackBase {
 public:
     static sp<IAfPatchTrack> create(
-            void * /* PlaybackThread */ playbackThread, // TODO(b/288339104)
+            IAfPlaybackThread* playbackThread,
             audio_stream_type_t streamType,
             uint32_t sampleRate,
             audio_channel_mask_t channelMask,
@@ -552,7 +556,7 @@
 class IAfPatchRecord : public virtual IAfRecordTrack, public virtual IAfPatchTrackBase {
 public:
     static sp<IAfPatchRecord> create(
-            void* /* RecordThread */ recordThread, // TODO(b/288339104)
+            IAfRecordThread* recordThread,
             uint32_t sampleRate,
             audio_channel_mask_t channelMask,
             audio_format_t format,
@@ -564,7 +568,7 @@
             audio_source_t source = AUDIO_SOURCE_DEFAULT);
 
     static sp<IAfPatchRecord> createPassThru(
-            void* /* RecordThread */ recordThread, // TODO(b/288339104)
+            IAfRecordThread* recordThread,
             uint32_t sampleRate,
             audio_channel_mask_t channelMask,
             audio_format_t format,
diff --git a/services/audioflinger/MelReporter.cpp b/services/audioflinger/MelReporter.cpp
index 3af8828..5589ff5 100644
--- a/services/audioflinger/MelReporter.cpp
+++ b/services/audioflinger/MelReporter.cpp
@@ -184,9 +184,9 @@
                         mSoundDoseManager->getOrCreateProcessorForDevice(
                                 device.first,
                                 patch.streamHandle,
-                                outputThread->mSampleRate,
-                                outputThread->mChannelCount,
-                                outputThread->mFormat));
+                                outputThread->sampleRate(),
+                                outputThread->channelCount(),
+                                outputThread->format()));
             }
         }
     }
diff --git a/services/audioflinger/MmapTracks.h b/services/audioflinger/MmapTracks.h
index 081af74..0cee3f8 100644
--- a/services/audioflinger/MmapTracks.h
+++ b/services/audioflinger/MmapTracks.h
@@ -22,7 +22,7 @@
 // playback track
 class MmapTrack : public TrackBase, public IAfMmapTrack {
 public:
-                MmapTrack(AudioFlinger::ThreadBase* thread,
+    MmapTrack(IAfThreadBase* thread,
                             const audio_attributes_t& attr,
                             uint32_t sampleRate,
                             audio_format_t format,
diff --git a/services/audioflinger/PatchPanel.cpp b/services/audioflinger/PatchPanel.cpp
index cb74292..9de9dc5 100644
--- a/services/audioflinger/PatchPanel.cpp
+++ b/services/audioflinger/PatchPanel.cpp
@@ -135,7 +135,7 @@
 status_t AudioFlinger::PatchPanel::createAudioPatch(const struct audio_patch *patch,
                                    audio_patch_handle_t *handle,
                                    bool endpointPatch)
- //unlocks AudioFlinger::mLock when calling ThreadBase::sendCreateAudioPatchConfigEvent
+ //unlocks AudioFlinger::mLock when calling IAfThreadBase::sendCreateAudioPatchConfigEvent
  //to avoid deadlocks if the thread loop needs to acquire AudioFlinger::mLock
  //before processing the create patch request.
  NO_THREAD_SAFETY_ANALYSIS
@@ -249,7 +249,7 @@
                         status = INVALID_OPERATION;
                         goto exit;
                     }
-                    sp<ThreadBase> thread =
+                    const sp<IAfThreadBase> thread =
                             mAudioFlinger.checkPlaybackThread_l(patch->sources[1].ext.mix.handle);
                     if (thread == 0) {
                         ALOGW("%s() cannot get playback thread", __func__);
@@ -258,7 +258,7 @@
                     }
                     // existing playback thread is reused, so it is not closed when patch is cleared
                     newPatch.mPlayback.setThread(
-                            reinterpret_cast<PlaybackThread*>(thread.get()), false /*closeThread*/);
+                            thread->asIAfPlaybackThread().get(), false /*closeThread*/);
                 } else {
                     audio_config_t config = AUDIO_CONFIG_INITIALIZER;
                     audio_config_base_t mixerConfig = AUDIO_CONFIG_BASE_INITIALIZER;
@@ -276,7 +276,7 @@
                     if (patch->sinks[0].config_mask & AUDIO_PORT_CONFIG_FLAGS) {
                         flags = patch->sinks[0].flags.output;
                     }
-                    sp<ThreadBase> thread = mAudioFlinger.openOutput_l(
+                    const sp<IAfThreadBase> thread = mAudioFlinger.openOutput_l(
                                                             patch->sinks[0].ext.device.hw_module,
                                                             &output,
                                                             &config,
@@ -289,7 +289,7 @@
                         status = NO_MEMORY;
                         goto exit;
                     }
-                    newPatch.mPlayback.setThread(reinterpret_cast<PlaybackThread*>(thread.get()));
+                    newPatch.mPlayback.setThread(thread->asIAfPlaybackThread().get());
                 }
                 audio_devices_t device = patch->sources[0].ext.device.type;
                 String8 address = String8(patch->sources[0].ext.device.address);
@@ -323,7 +323,7 @@
                                 == AUDIO_STREAM_VOICE_CALL) {
                     source = AUDIO_SOURCE_VOICE_COMMUNICATION;
                 }
-                sp<ThreadBase> thread = mAudioFlinger.openInput_l(srcModule,
+                const sp<IAfThreadBase> thread = mAudioFlinger.openInput_l(srcModule,
                                                                     &input,
                                                                     &config,
                                                                     device,
@@ -338,7 +338,7 @@
                     status = NO_MEMORY;
                     goto exit;
                 }
-                newPatch.mRecord.setThread(reinterpret_cast<RecordThread*>(thread.get()));
+                newPatch.mRecord.setThread(thread->asIAfRecordThread().get());
                 status = newPatch.createConnections(this);
                 if (status != NO_ERROR) {
                     goto exit;
@@ -348,7 +348,7 @@
                 }
             } else {
                 if (patch->sinks[0].type == AUDIO_PORT_TYPE_MIX) {
-                    sp<ThreadBase> thread = mAudioFlinger.checkRecordThread_l(
+                    sp<IAfThreadBase> thread = mAudioFlinger.checkRecordThread_l(
                                                               patch->sinks[0].ext.mix.handle);
                     if (thread == 0) {
                         thread = mAudioFlinger.checkMmapThread_l(patch->sinks[0].ext.mix.handle);
@@ -411,7 +411,7 @@
                 device->applyAudioPortConfig(&patch->sinks[i]);
                 devices.push_back(device);
             }
-            sp<ThreadBase> thread =
+            sp<IAfThreadBase> thread =
                             mAudioFlinger.checkPlaybackThread_l(patch->sources[0].ext.mix.handle);
             if (thread == 0) {
                 thread = mAudioFlinger.checkMmapThread_l(patch->sources[0].ext.mix.handle);
@@ -735,7 +735,7 @@
 
 /* Disconnect a patch */
 status_t AudioFlinger::PatchPanel::releaseAudioPatch(audio_patch_handle_t handle)
- //unlocks AudioFlinger::mLock when calling ThreadBase::sendReleaseAudioPatchConfigEvent
+ //unlocks AudioFlinger::mLock when calling IAfThreadBase::sendReleaseAudioPatchConfigEvent
  //to avoid deadlocks if the thread loop needs to acquire AudioFlinger::mLock
  //before processing the release patch request.
  NO_THREAD_SAFETY_ANALYSIS
@@ -767,7 +767,7 @@
 
             if (patch.sinks[0].type == AUDIO_PORT_TYPE_MIX) {
                 audio_io_handle_t ioHandle = patch.sinks[0].ext.mix.handle;
-                sp<ThreadBase> thread = mAudioFlinger.checkRecordThread_l(ioHandle);
+                sp<IAfThreadBase> thread = mAudioFlinger.checkRecordThread_l(ioHandle);
                 if (thread == 0) {
                     thread = mAudioFlinger.checkMmapThread_l(ioHandle);
                     if (thread == 0) {
@@ -790,7 +790,7 @@
                 break;
             }
             audio_io_handle_t ioHandle = src.ext.mix.handle;
-            sp<ThreadBase> thread = mAudioFlinger.checkPlaybackThread_l(ioHandle);
+            sp<IAfThreadBase> thread = mAudioFlinger.checkPlaybackThread_l(ioHandle);
             if (thread == 0) {
                 thread = mAudioFlinger.checkMmapThread_l(ioHandle);
                 if (thread == 0) {
diff --git a/services/audioflinger/PatchPanel.h b/services/audioflinger/PatchPanel.h
index e693486..4bb11b0 100644
--- a/services/audioflinger/PatchPanel.h
+++ b/services/audioflinger/PatchPanel.h
@@ -199,8 +199,8 @@
             return mRecord.handle() != AUDIO_PATCH_HANDLE_NONE ||
                     mPlayback.handle() != AUDIO_PATCH_HANDLE_NONE; }
 
-        void setThread(const sp<ThreadBase>& thread) { mThread = thread; }
-        wp<ThreadBase> thread() const { return mThread; }
+        void setThread(const sp<IAfThreadBase>& thread) { mThread = thread; }
+        wp<IAfThreadBase> thread() const { return mThread; }
 
         // returns the latency of the patch (from record to playback).
         status_t getLatencyMs(double *latencyMs) const;
@@ -216,11 +216,11 @@
         // the objects are created by createConnections() and released by clearConnections()
         // playback thread is created if no existing playback thread can be used
         // connects playback thread output to sink device
-        Endpoint<PlaybackThread, IAfPatchTrack> mPlayback;
+        Endpoint<IAfPlaybackThread, IAfPatchTrack> mPlayback;
         // connects source device to record thread input
-        Endpoint<RecordThread, IAfPatchRecord> mRecord;
+        Endpoint<IAfRecordThread, IAfPatchRecord> mRecord;
 
-        wp<ThreadBase> mThread;
+        wp<IAfThreadBase> mThread;
         bool mIsEndpointPatch;
     };
 
diff --git a/services/audioflinger/PlaybackTracks.h b/services/audioflinger/PlaybackTracks.h
index c549f3f..6a2887d 100644
--- a/services/audioflinger/PlaybackTracks.h
+++ b/services/audioflinger/PlaybackTracks.h
@@ -29,13 +29,13 @@
     bool hasOpPlayAudio() const;
 
     static sp<OpPlayAudioMonitor> createIfNeeded(
-            AudioFlinger::ThreadBase* thread,
+            IAfThreadBase* thread,
             const AttributionSourceState& attributionSource,
             const audio_attributes_t& attr, int id,
             audio_stream_type_t streamType);
 
 private:
-    OpPlayAudioMonitor(AudioFlinger::ThreadBase* thread,
+    OpPlayAudioMonitor(IAfThreadBase* thread,
                        const AttributionSourceState& attributionSource,
                        audio_usage_t usage, int id, uid_t uid);
     void onFirstRef() override;
@@ -56,7 +56,7 @@
     // called by PlayAudioOpCallback when OP_PLAY_AUDIO is updated in AppOp callback
     void checkPlayAudioForUsage();
 
-    wp<AudioFlinger::ThreadBase> mThread;
+    wp<IAfThreadBase> mThread;
     std::atomic_bool mHasOpPlayAudio;
     const AttributionSourceState mAttributionSource;
     const int32_t mUsage; // on purpose not audio_usage_t because always checked in appOps as int32_t
@@ -68,7 +68,7 @@
 // playback track
 class Track : public TrackBase, public virtual IAfTrack, public VolumeProvider {
 public:
-                        Track(AudioFlinger::PlaybackThread* thread,
+    Track(IAfPlaybackThread* thread,
                                 const sp<Client>& client,
                                 audio_stream_type_t streamType,
                                 const audio_attributes_t& attr,
@@ -310,7 +310,7 @@
     mutable FillingStatus mFillingStatus;
     int8_t              mRetryCount;
 
-    // see comment at AudioFlinger::PlaybackThread::Track::~Track for why this can't be const
+    // see comment at ~Track for why this can't be const
     sp<IMemory>         mSharedBuffer;
 
     bool                mResetDone;
@@ -411,8 +411,8 @@
         void *mBuffer;
     };
 
-                        OutputTrack(AudioFlinger::PlaybackThread* thread,
-                                AudioFlinger::DuplicatingThread* sourceThread,
+    OutputTrack(IAfPlaybackThread* thread,
+            IAfDuplicatingThread* sourceThread,
                                 uint32_t sampleRate,
                                 audio_format_t format,
                                 audio_channel_mask_t channelMask,
@@ -457,7 +457,7 @@
     Vector < Buffer* >          mBufferQueue;
     AudioBufferProvider::Buffer mOutBuffer;
     bool                        mActive;
-    AudioFlinger::DuplicatingThread* const mSourceThread; // for waitTimeMs() in write()
+    IAfDuplicatingThread* const mSourceThread; // for waitTimeMs() in write()
     sp<AudioTrackClientProxy>   mClientProxy;
 
     /** Attributes of the source tracks.
@@ -479,7 +479,7 @@
 // playback track, used by PatchPanel
 class PatchTrack : public Track, public PatchTrackBase, public IAfPatchTrack {
 public:
-                        PatchTrack(AudioFlinger::PlaybackThread* playbackThread,
+    PatchTrack(IAfPlaybackThread* playbackThread,
                                    audio_stream_type_t streamType,
                                    uint32_t sampleRate,
                                    audio_channel_mask_t channelMask,
diff --git a/services/audioflinger/RecordTracks.h b/services/audioflinger/RecordTracks.h
index 9d25ba4..5cf09c5 100644
--- a/services/audioflinger/RecordTracks.h
+++ b/services/audioflinger/RecordTracks.h
@@ -24,7 +24,7 @@
 // record track
 class RecordTrack : public TrackBase, public virtual IAfRecordTrack {
 public:
-                        RecordTrack(AudioFlinger::RecordThread* thread,
+    RecordTrack(IAfRecordThread* thread,
                                 const sp<Client>& client,
                                 const audio_attributes_t& attr,
                                 uint32_t sampleRate,
@@ -133,7 +133,7 @@
 // playback track, used by PatchPanel
 class PatchRecord : public RecordTrack, public PatchTrackBase, public IAfPatchRecord {
 public:
-    PatchRecord(AudioFlinger::RecordThread* recordThread,
+    PatchRecord(IAfRecordThread* recordThread,
                 uint32_t sampleRate,
                 audio_channel_mask_t channelMask,
                 audio_format_t format,
@@ -169,7 +169,7 @@
 
 class PassthruPatchRecord : public PatchRecord, public Source {
 public:
-    PassthruPatchRecord(AudioFlinger::RecordThread* recordThread,
+    PassthruPatchRecord(IAfRecordThread* recordThread,
                         uint32_t sampleRate,
                         audio_channel_mask_t channelMask,
                         audio_format_t format,
@@ -212,7 +212,7 @@
         PassthruPatchRecord& mPassthru;
     };
 
-    sp<StreamInHalInterface> obtainStream(sp<AudioFlinger::ThreadBase>* thread);
+    sp<StreamInHalInterface> obtainStream(sp<IAfThreadBase>* thread);
 
     PatchRecordAudioBufferProvider mPatchRecordAudioBufferProvider;
     std::unique_ptr<void, decltype(free)*> mSinkBuffer;  // frame size aligned continuous buffer
diff --git a/services/audioflinger/Threads.cpp b/services/audioflinger/Threads.cpp
index 1688af4..3588d3c 100644
--- a/services/audioflinger/Threads.cpp
+++ b/services/audioflinger/Threads.cpp
@@ -7387,7 +7387,7 @@
 // ----------------------------------------------------------------------------
 
 AudioFlinger::DuplicatingThread::DuplicatingThread(const sp<AudioFlinger>& audioFlinger,
-        AudioFlinger::MixerThread* mainThread, audio_io_handle_t id, bool systemReady)
+       IAfPlaybackThread* mainThread, audio_io_handle_t id, bool systemReady)
     :   MixerThread(audioFlinger, mainThread->getOutput(), id,
                     systemReady, DUPLICATING),
         mWaitTimeMs(UINT_MAX)
@@ -7487,7 +7487,7 @@
         ss << ":";
         for (const auto &track : mOutputTracks) {
             // TODO(b/288339104) type
-            const auto thread = sp<ThreadBase>::cast(track->thread().promote());
+            const auto thread = track->thread().promote();
             ss << " (" << track->id() << " : ";
             if (thread.get() != nullptr) {
                 ss << thread.get() << ", " << thread->id();
@@ -7512,7 +7512,7 @@
     outputTracks.clear();
 }
 
-void AudioFlinger::DuplicatingThread::addOutputTrack(MixerThread *thread)
+void AudioFlinger::DuplicatingThread::addOutputTrack(IAfPlaybackThread* thread)
 {
     Mutex::Autolock _l(mLock);
     // The downstream MixerThread consumes thread->frameCount() amount of frames per mix pass.
@@ -7549,7 +7549,7 @@
     updateWaitTime_l();
 }
 
-void AudioFlinger::DuplicatingThread::removeOutputTrack(MixerThread *thread)
+void AudioFlinger::DuplicatingThread::removeOutputTrack(IAfPlaybackThread* thread)
 {
     Mutex::Autolock _l(mLock);
     for (size_t i = 0; i < mOutputTracks.size(); i++) {
@@ -7572,7 +7572,7 @@
     mWaitTimeMs = UINT_MAX;
     for (size_t i = 0; i < mOutputTracks.size(); i++) {
         // TODO(b/288339104) type
-        const auto strong = sp<ThreadBase>::cast(mOutputTracks[i]->thread().promote());
+        const auto strong = mOutputTracks[i]->thread().promote();
         if (strong != 0) {
             uint32_t waitTimeMs = (strong->frameCount() * 2 * 1000) / strong->sampleRate();
             if (waitTimeMs < mWaitTimeMs) {
@@ -7585,14 +7585,13 @@
 bool AudioFlinger::DuplicatingThread::outputsReady()
 {
     for (size_t i = 0; i < outputTracks.size(); i++) {
-        // TODO(b/288339104) type
-        const auto thread = sp<ThreadBase>::cast(outputTracks[i]->thread().promote());
+        const auto thread = outputTracks[i]->thread().promote();
         if (thread == 0) {
             ALOGW("DuplicatingThread::outputsReady() could not promote thread on output track %p",
                     outputTracks[i].get());
             return false;
         }
-        PlaybackThread *playbackThread = (PlaybackThread *)thread.get();
+        IAfPlaybackThread* const playbackThread = thread->asIAfPlaybackThread().get();
         // see note at standby() declaration
         if (playbackThread->inStandby() && !playbackThread->isSuspended()) {
             ALOGV("DuplicatingThread output track %p on thread %p Not Ready", outputTracks[i].get(),
@@ -7753,6 +7752,13 @@
 //      Record
 // ----------------------------------------------------------------------------
 
+sp<IAfRecordThread> IAfRecordThread::create(const sp<AudioFlinger>& audioFlinger,
+        AudioStreamIn* input,
+        audio_io_handle_t id,
+        bool systemReady) {
+    return sp<AudioFlinger::RecordThread>::make(audioFlinger, input, id, systemReady);
+}
+
 AudioFlinger::RecordThread::RecordThread(const sp<AudioFlinger>& audioFlinger,
                                          AudioStreamIn *input,
                                          audio_io_handle_t id,
@@ -8936,7 +8942,7 @@
 }
 
 status_t AudioFlinger::RecordThread::getActiveMicrophones(
-        std::vector<media::MicrophoneInfoFw>* activeMicrophones)
+        std::vector<media::MicrophoneInfoFw>* activeMicrophones) const
 {
     ALOGV("RecordThread::getActiveMicrophones");
     AutoMutex _l(mLock);
@@ -9148,8 +9154,9 @@
 
 void ResamplerBufferProvider::reset()
 {
-    const auto threadBase = sp<AudioFlinger::ThreadBase>::cast(mRecordTrack->thread().promote());
-    auto* const recordThread = static_cast<AudioFlinger::RecordThread *>(threadBase.get());
+    const auto threadBase = mRecordTrack->thread().promote();
+    auto* const recordThread =
+            static_cast<AudioFlinger::RecordThread *>(threadBase->asIAfRecordThread().get());
     mRsmpInUnrel = 0;
     const int32_t rear = recordThread->mRsmpInRear;
     ssize_t deltaFrames = 0;
@@ -9172,8 +9179,9 @@
 void ResamplerBufferProvider::sync(
         size_t *framesAvailable, bool *hasOverrun)
 {
-    const auto threadBase = sp<AudioFlinger::ThreadBase>::cast(mRecordTrack->thread().promote());
-    auto* const recordThread = static_cast<AudioFlinger::RecordThread *>(threadBase.get());
+    const auto threadBase = mRecordTrack->thread().promote();
+    auto* const recordThread =
+            static_cast<AudioFlinger::RecordThread *>(threadBase->asIAfRecordThread().get());
     const int32_t rear = recordThread->mRsmpInRear;
     const int32_t front = mRsmpInFront;
     const ssize_t filled = audio_utils::safe_sub_overflow(rear, front);
@@ -9206,13 +9214,14 @@
 status_t ResamplerBufferProvider::getNextBuffer(
         AudioBufferProvider::Buffer* buffer)
 {
-    const auto threadBase = sp<AudioFlinger::ThreadBase>::cast(mRecordTrack->thread().promote());
+    const auto threadBase = mRecordTrack->thread().promote();
     if (threadBase == 0) {
         buffer->frameCount = 0;
         buffer->raw = NULL;
         return NOT_ENOUGH_DATA;
     }
-    auto* const recordThread = static_cast<AudioFlinger::RecordThread *>(threadBase.get());
+    auto* const recordThread =
+            static_cast<AudioFlinger::RecordThread *>(threadBase->asIAfRecordThread().get());
     int32_t rear = recordThread->mRsmpInRear;
     int32_t front = mRsmpInFront;
     ssize_t filled = audio_utils::safe_sub_overflow(rear, front);
@@ -9445,7 +9454,7 @@
         .record();
 }
 
-uint32_t AudioFlinger::RecordThread::getInputFramesLost()
+uint32_t AudioFlinger::RecordThread::getInputFramesLost() const
 {
     Mutex::Autolock _l(mLock);
     uint32_t result;
diff --git a/services/audioflinger/Threads.h b/services/audioflinger/Threads.h
index eaee663..0be020a 100644
--- a/services/audioflinger/Threads.h
+++ b/services/audioflinger/Threads.h
@@ -31,6 +31,8 @@
 public:
     static const char *threadTypeToString(type_t type);
 
+    AudioFlinger* audioFlinger() const final { return mAudioFlinger.get(); }
+
     ThreadBase(const sp<AudioFlinger>& audioFlinger, audio_io_handle_t id,
                type_t type, bool systemReady, bool isOut);
     ~ThreadBase() override;
@@ -294,6 +296,7 @@
     audio_format_t format() const final { return mHALFormat; }
     uint32_t channelCount() const final { return mChannelCount; }
     audio_channel_mask_t hapticChannelMask() const override { return AUDIO_CHANNEL_NONE; }
+    uint32_t hapticChannelCount() const override { return 0; }
     uint32_t latency_l() const override { return 0; }
     void setVolumeForOutput_l(float /* left */, float /* right */) const override {}
 
@@ -543,7 +546,7 @@
                 // occurs when all suspend requests are cancelled.
                 void setEffectSuspended_l(const effect_uuid_t *type,
                                           bool suspend,
-                                          audio_session_t sessionId);
+                                          audio_session_t sessionId) final;
                 // updated mSuspendedSessions when an effect is suspended or restored
                 void        updateSuspendedSessions_l(const effect_uuid_t *type,
                                                       bool suspend,
@@ -725,7 +728,7 @@
                     bool            isEmpty() const {
                         return mActiveTracks.isEmpty();
                     }
-                    ssize_t         indexOf(const sp<T>& item) {
+                    ssize_t indexOf(const sp<T>& item) const {
                         return mActiveTracks.indexOf(item);
                     }
                     sp<T>           operator[](size_t index) const {
@@ -789,11 +792,14 @@
 // --- PlaybackThread ---
 class PlaybackThread : public ThreadBase, public virtual IAfPlaybackThread,
                        public StreamOutHalInterfaceCallback,
-                       public VolumeInterface, public StreamOutHalInterfaceEventCallback {
+                       public virtual VolumeInterface, public StreamOutHalInterfaceEventCallback {
     // TODO(b/288339104) remove friends
     friend class OutputTrack;
     friend class Track;
 public:
+    sp<IAfPlaybackThread> asIAfPlaybackThread() final {
+        return sp<IAfPlaybackThread>::fromExisting(this);
+    }
 
     // retry count before removing active track in case of underrun on offloaded thread:
     // we need to make sure that AudioTrack client has enough time to send large buffers
@@ -801,7 +807,6 @@
     // handled for offloaded tracks
     static const int8_t kMaxTrackRetriesOffload = 20;
     static const int8_t kMaxTrackStartupRetriesOffload = 100;
-    static const int8_t kMaxTrackStopRetriesOffload = 2;
     static constexpr uint32_t kMaxTracksPerUid = 40;
     static constexpr size_t kMaxTracks = 256;
 
@@ -825,6 +830,10 @@
     status_t checkEffectCompatibility_l(
             const effect_descriptor_t* desc, audio_session_t sessionId) final;
 
+    void addOutputTrack_l(const sp<IAfTrack>& track) final {
+        mTracks.add(track);
+    }
+
 protected:
     // Code snippets that were lifted up out of threadLoop()
     virtual     void        threadLoop_mix() = 0;
@@ -918,6 +927,11 @@
                                 bool isSpatialized,
                                 bool isBitPerfect) final;
 
+    bool isTrackActive(const sp<IAfTrack>& track) const final {
+        return mActiveTracks.indexOf(track) >= 0;
+    }
+
+    AudioStreamOut* getOutput_l() const final { return mOutput; }
     AudioStreamOut* getOutput() const final;
     AudioStreamOut* clearOutput() final;
     sp<StreamHalInterface> stream() const final;
@@ -968,7 +982,7 @@
                 // the given set if the corresponding track is found and invalidated.
     void invalidateTracks(std::set<audio_port_handle_t>& portIds) override;
 
-    size_t frameCount() const final{ return mNormalFrameCount; }
+    size_t frameCount() const final { return mNormalFrameCount; }
 
     audio_channel_mask_t mixerChannelMask() const final {
                     return mMixerChannelMask;
@@ -1005,6 +1019,11 @@
     audio_channel_mask_t hapticChannelMask() const final {
                                          return mHapticChannelMask;
                                      }
+
+    uint32_t hapticChannelCount() const final {
+        return mHapticChannelCount;
+    }
+
     bool supportsHapticPlayback() const final {
                     return (mHapticChannelMask & AUDIO_CHANNEL_HAPTIC_ALL) != AUDIO_CHANNEL_NONE;
                 }
@@ -1205,7 +1224,7 @@
                                    audio_patch_handle_t *handle);
     virtual     status_t    releaseAudioPatch_l(const audio_patch_handle_t handle);
 
-                bool        usesHwAvSync() const { return (mType == DIRECT) && (mOutput != NULL)
+    bool usesHwAvSync() const final { return mType == DIRECT && mOutput != nullptr
                                     && mHwSupportsPause
                                     && (mOutput->flags & AUDIO_OUTPUT_FLAG_HW_AV_SYNC); }
 
@@ -1222,8 +1241,9 @@
 
     DISALLOW_COPY_AND_ASSIGN(PlaybackThread);
 
-    status_t    addTrack_l(const sp<IAfTrack>& track);
-    bool        destroyTrack_l(const sp<IAfTrack>& track);
+    status_t addTrack_l(const sp<IAfTrack>& track) final;
+    bool destroyTrack_l(const sp<IAfTrack>& track) final;
+
     void        removeTrack_l(const sp<IAfTrack>& track);
 
     void        readOutputParameters_l();
@@ -1375,7 +1395,8 @@
 
 protected:
                 // accessed by both binder threads and within threadLoop(), lock on mutex needed
-                unsigned    mFastTrackAvailMask;    // bit i set if fast track [i] is available
+     uint32_t& fastTrackAvailMask_l() final { return mFastTrackAvailMask; }
+     uint32_t mFastTrackAvailMask;  // bit i set if fast track [i] is available
                 bool        mHwSupportsPause;
                 bool        mHwPaused;
                 bool        mFlushPending;
@@ -1549,9 +1570,13 @@
                 void       setHalLatencyMode_l() override;
 };
 
-class DirectOutputThread : public PlaybackThread {
+class DirectOutputThread : public PlaybackThread, public virtual IAfDirectOutputThread {
 public:
 
+    sp<IAfDirectOutputThread> asIAfDirectOutputThread() final {
+        return sp<IAfDirectOutputThread>::fromExisting(this);
+    }
+
     DirectOutputThread(const sp<AudioFlinger>& audioFlinger, AudioStreamOut* output,
                        audio_io_handle_t id, bool systemReady,
                        const audio_offload_info_t& offloadInfo)
@@ -1559,7 +1584,7 @@
 
     virtual                 ~DirectOutputThread();
 
-                status_t    selectPresentation(int presentationId, int programId);
+    status_t selectPresentation(int presentationId, int programId) final;
 
     // Thread virtuals
 
@@ -1692,16 +1717,20 @@
     bool                       mAsyncError;
 };
 
-class DuplicatingThread : public MixerThread {
+class DuplicatingThread : public MixerThread, public IAfDuplicatingThread {
 public:
-    DuplicatingThread(const sp<AudioFlinger>& audioFlinger, MixerThread* mainThread,
+    DuplicatingThread(const sp<AudioFlinger>& audioFlinger, IAfPlaybackThread* mainThread,
                       audio_io_handle_t id, bool systemReady);
-    virtual                 ~DuplicatingThread();
+    ~DuplicatingThread() override;
+
+    sp<IAfDuplicatingThread> asIAfDuplicatingThread() final {
+        return sp<IAfDuplicatingThread>::fromExisting(this);
+    }
 
     // Thread virtuals
-                void        addOutputTrack(MixerThread* thread);
-                void        removeOutputTrack(MixerThread* thread);
-                uint32_t    waitTimeMs() const { return mWaitTimeMs; }
+    void addOutputTrack(IAfPlaybackThread* thread) final;
+    void removeOutputTrack(IAfPlaybackThread* thread) final;
+    uint32_t waitTimeMs() const final { return mWaitTimeMs; }
 
                 void        sendMetadataToBackend_l(
                         const StreamOutHalInterface::SourceMetadata& metadata) override;
@@ -1777,14 +1806,16 @@
 };
 
 // record thread
-class RecordThread : public ThreadBase
+class RecordThread : public IAfRecordThread, public ThreadBase
 {
     // TODO(b/288339104) remove friends
     friend class PassthruPatchRecord;
     friend class RecordTrack;
     friend class ResamplerBufferProvider;
 public:
-
+    sp<IAfRecordThread> asIAfRecordThread() final {
+        return sp<IAfRecordThread>::fromExisting(this);
+    }
 
             RecordThread(const sp<AudioFlinger>& audioFlinger,
                     AudioStreamIn *input,
@@ -1794,8 +1825,8 @@
     ~RecordThread() override;
 
     // no addTrack_l ?
-    void        destroyTrack_l(const sp<IAfRecordTrack>& track);
-    void        removeTrack_l(const sp<IAfRecordTrack>& track);
+    void destroyTrack_l(const sp<IAfRecordTrack>& track) final;
+    void removeTrack_l(const sp<IAfRecordTrack>& track) final;
 
     // Thread virtuals
     bool threadLoop() final;
@@ -1810,7 +1841,7 @@
 
     sp<IMemory> pipeMemory() const final { return mPipeMemory; }
 
-            sp<IAfRecordTrack> createRecordTrack_l(
+    sp<IAfRecordTrack> createRecordTrack_l(
                     const sp<Client>& client,
                     const audio_attributes_t& attr,
                     uint32_t *pSampleRate,
@@ -1825,17 +1856,19 @@
                     pid_t tid,
                     status_t *status /*non-NULL*/,
                     audio_port_handle_t portId,
-                    int32_t maxSharedAudioHistoryMs);
+                    int32_t maxSharedAudioHistoryMs) final;
 
             status_t start(IAfRecordTrack* recordTrack,
                               AudioSystem::sync_event_t event,
-                              audio_session_t triggerSession);
+                              audio_session_t triggerSession) final;
 
             // ask the thread to stop the specified track, and
             // return true if the caller should then do it's part of the stopping process
-            bool stop(IAfRecordTrack* recordTrack);
+    bool stop(IAfRecordTrack* recordTrack) final;
+    AudioStreamIn* getInput() const final { return mInput; }
+    AudioStreamIn* clearInput() final;
 
-            AudioStreamIn* clearInput();
+            // TODO(b/288339104) Unify with IAfThreadBase
             virtual sp<StreamHalInterface> stream() const;
 
 
@@ -1843,19 +1876,19 @@
                                                status_t& status);
     virtual void        cacheParameters_l() {}
     virtual String8     getParameters(const String8& keys);
-    virtual void        ioConfigChanged(audio_io_config_event_t event, pid_t pid = 0,
-                                        audio_port_handle_t portId = AUDIO_PORT_HANDLE_NONE);
+    void ioConfigChanged(audio_io_config_event_t event, pid_t pid = 0,
+            audio_port_handle_t portId = AUDIO_PORT_HANDLE_NONE) final;
     virtual status_t    createAudioPatch_l(const struct audio_patch *patch,
                                            audio_patch_handle_t *handle);
     virtual status_t    releaseAudioPatch_l(const audio_patch_handle_t handle);
             void        updateOutDevices(const DeviceDescriptorBaseVector& outDevices) override;
             void        resizeInputBuffer_l(int32_t maxSharedAudioHistoryMs) override;
 
-            void        addPatchTrack(const sp<IAfPatchRecord>& record);
-            void        deletePatchTrack(const sp<IAfPatchRecord>& record);
+    void addPatchTrack(const sp<IAfPatchRecord>& record) final;
+    void deletePatchTrack(const sp<IAfPatchRecord>& record) final;
 
             void        readInputParameters_l();
-    virtual uint32_t    getInputFramesLost();
+    uint32_t getInputFramesLost() const final;
 
     virtual status_t addEffectChain_l(const sp<IAfEffectChain>& chain);
     virtual size_t removeEffectChain_l(const sp<IAfEffectChain>& chain);
@@ -1874,7 +1907,7 @@
     static void syncStartEventCallback(const wp<audioflinger::SyncEvent>& event);
 
     virtual size_t      frameCount() const { return mFrameCount; }
-            bool        hasFastCapture() const { return mFastCapture != 0; }
+    bool hasFastCapture() const final { return mFastCapture != 0; }
     virtual void        toAudioPortConfig(struct audio_port_config *config);
 
     virtual status_t    checkEffectCompatibility_l(const effect_descriptor_t *desc,
@@ -1885,20 +1918,20 @@
                             mActiveTracks.updatePowerState(this, true /* force */);
                         }
 
-            void        checkBtNrec();
+    void checkBtNrec() final;
 
             // Sets the UID records silence
-            void        setRecordSilenced(audio_port_handle_t portId, bool silenced);
+    void setRecordSilenced(audio_port_handle_t portId, bool silenced) final;
 
-            status_t    getActiveMicrophones(
-                    std::vector<media::MicrophoneInfoFw>* activeMicrophones);
-
-            status_t    setPreferredMicrophoneDirection(audio_microphone_direction_t direction);
-            status_t    setPreferredMicrophoneFieldDimension(float zoom);
+    status_t getActiveMicrophones(
+            std::vector<media::MicrophoneInfoFw>* activeMicrophones) const final;
+    status_t setPreferredMicrophoneDirection(audio_microphone_direction_t direction) final;
+    status_t setPreferredMicrophoneFieldDimension(float zoom) final;
 
             MetadataUpdate        updateMetadata_l() override;
 
-            bool        fastTrackAvailable() const { return mFastTrackAvail; }
+    bool fastTrackAvailable() const final { return mFastTrackAvail; }
+    void setFastTrackAvailable(bool available) final { mFastTrackAvail = available; }
 
             bool        isTimestampCorrectionEnabled() const override {
                             // checks popcount for exactly one device.
@@ -1908,13 +1941,13 @@
                                     && inDeviceType() == mTimestampCorrectedDevice;
                         }
 
-            status_t    shareAudioHistory(const std::string& sharedAudioPackageName,
+    status_t shareAudioHistory(const std::string& sharedAudioPackageName,
                                           audio_session_t sharedSessionId = AUDIO_SESSION_NONE,
-                                          int64_t sharedAudioStartMs = -1);
+            int64_t sharedAudioStartMs = -1) final;
             status_t    shareAudioHistory_l(const std::string& sharedAudioPackageName,
                                           audio_session_t sharedSessionId = AUDIO_SESSION_NONE,
                                           int64_t sharedAudioStartMs = -1);
-            void        resetAudioHistory_l();
+    void resetAudioHistory_l() final;
 
     bool isStreamInitialized() const final {
                             return !(mInput == nullptr || mInput->stream == nullptr);
diff --git a/services/audioflinger/TrackBase.h b/services/audioflinger/TrackBase.h
index 8f31468..bd569e6 100644
--- a/services/audioflinger/TrackBase.h
+++ b/services/audioflinger/TrackBase.h
@@ -22,7 +22,7 @@
 // base for record and playback
 class TrackBase : public ExtendedAudioBufferProvider, public virtual IAfTrackBase {
 public:
-                        TrackBase(AudioFlinger::ThreadBase* thread,
+    TrackBase(IAfThreadBase* thread,
                                 const sp<Client>& client,
                                 const audio_attributes_t& mAttr,
                                 uint32_t sampleRate,
@@ -69,8 +69,7 @@
     bool isSpatialized() const override { return false; }
     bool isBitPerfect() const override { return false; }
 
-    // TODO(b/288339104) type
-    wp<Thread> thread() const final { return mThread; }
+    wp<IAfThreadBase> thread() const final { return mThread; }
 
     const sp<ServerProxy>& serverProxy() const final { return mServerProxy; }
 
@@ -322,7 +321,7 @@
                                     // true for Track, false for RecordTrack,
                                     // this could be a track type if needed later
 
-    const wp<AudioFlinger::ThreadBase> mThread;
+    const wp<IAfThreadBase> mThread;
     const alloc_type     mAllocType;
     /*const*/ sp<Client> mClient;   // see explanation at ~TrackBase() why not const
     sp<IMemory>         mCblkMemory;
@@ -392,7 +391,7 @@
 {
 public:
                         PatchTrackBase(const sp<ClientProxy>& proxy,
-                                       const AudioFlinger::ThreadBase& thread,
+                                       const IAfThreadBase& thread,
                                        const Timeout& timeout);
             void setPeerTimeout(std::chrono::nanoseconds timeout) final;
             void setPeerProxy(const sp<IAfPatchTrackBase>& proxy, bool holdReference) final {
diff --git a/services/audioflinger/Tracks.cpp b/services/audioflinger/Tracks.cpp
index 6b16a01..e838076 100644
--- a/services/audioflinger/Tracks.cpp
+++ b/services/audioflinger/Tracks.cpp
@@ -81,7 +81,7 @@
 
 // TrackBase constructor must be called with AudioFlinger::mLock held
 TrackBase::TrackBase(
-            AudioFlinger::ThreadBase *thread,
+        IAfThreadBase *thread,
             const sp<Client>& client,
             const audio_attributes_t& attr,
             uint32_t sampleRate,
@@ -315,7 +315,7 @@
 }
 
 PatchTrackBase::PatchTrackBase(const sp<ClientProxy>& proxy,
-        const AudioFlinger::ThreadBase& thread, const Timeout& timeout)
+        const IAfThreadBase& thread, const Timeout& timeout)
     : mProxy(proxy)
 {
     if (timeout) {
@@ -559,7 +559,7 @@
 
 // static
 sp<OpPlayAudioMonitor> OpPlayAudioMonitor::createIfNeeded(
-            AudioFlinger::ThreadBase* thread,
+            IAfThreadBase* thread,
             const AttributionSourceState& attributionSource, const audio_attributes_t& attr, int id,
             audio_stream_type_t streamType)
 {
@@ -589,11 +589,10 @@
     return sp<OpPlayAudioMonitor>::make(thread, attributionSource, attr.usage, id, uid);
 }
 
-OpPlayAudioMonitor::OpPlayAudioMonitor(
-        AudioFlinger::ThreadBase* thread,
-        const AttributionSourceState& attributionSource,
-        audio_usage_t usage, int id, uid_t uid)
-    : mThread(wp<AudioFlinger::ThreadBase>::fromExisting(thread)),
+OpPlayAudioMonitor::OpPlayAudioMonitor(IAfThreadBase* thread,
+                                       const AttributionSourceState& attributionSource,
+                                       audio_usage_t usage, int id, uid_t uid)
+    : mThread(wp<IAfThreadBase>::fromExisting(thread)),
       mHasOpPlayAudio(true),
       mAttributionSource(attributionSource),
       mUsage((int32_t)usage),
@@ -640,7 +639,7 @@
         auto thread = mThread.promote();
         if (thread != nullptr && thread->type() == AudioFlinger::ThreadBase::OFFLOAD) {
             // Wake up Thread if offloaded, otherwise it may be several seconds for update.
-            Mutex::Autolock _l(thread->mLock);
+            Mutex::Autolock _l(thread->mutex());
             thread->broadcast_l();
         }
     }
@@ -676,8 +675,8 @@
 #define LOG_TAG "AF::Track"
 
 /* static */
-sp<IAfTrack> IAfTrack::create( // TODO(b/288339104) void*
-        void * /* AudioFlinger::PlaybackThread */ thread,
+sp<IAfTrack> IAfTrack::create(
+        IAfPlaybackThread* thread,
         const sp<Client>& client,
         audio_stream_type_t streamType,
         const audio_attributes_t& attr,
@@ -700,7 +699,7 @@
         float speed,
         bool isSpatialized,
         bool isBitPerfect) {
-    return sp<Track>::make(reinterpret_cast<AudioFlinger::PlaybackThread*>(thread),
+    return sp<Track>::make(thread,
             client,
             streamType,
             attr,
@@ -725,7 +724,7 @@
 
 // Track constructor must be called with AudioFlinger::mLock and ThreadBase::mLock held
 Track::Track(
-            AudioFlinger::PlaybackThread *thread,
+        IAfPlaybackThread* thread,
             const sp<Client>& client,
             audio_stream_type_t streamType,
             const audio_attributes_t& attr,
@@ -816,15 +815,15 @@
         // race with setSyncEvent(). However, if we call it, we cannot properly start
         // static fast tracks (SoundPool) immediately after stopping.
         //mAudioTrackServerProxy->framesReadyIsCalledByMultipleThreads();
-        ALOG_ASSERT(thread->mFastTrackAvailMask != 0);
-        int i = __builtin_ctz(thread->mFastTrackAvailMask);
+        ALOG_ASSERT(thread->fastTrackAvailMask_l() != 0);
+        const int i = __builtin_ctz(thread->fastTrackAvailMask_l());
         ALOG_ASSERT(0 < i && i < (int)FastMixerState::sMaxFastTracks);
         // FIXME This is too eager.  We allocate a fast track index before the
         //       fast track becomes active.  Since fast tracks are a scarce resource,
         //       this means we are potentially denying other more important fast tracks from
         //       being created.  It would be better to allocate the index dynamically.
         mFastIndex = i;
-        thread->mFastTrackAvailMask &= ~(1 << i);
+        thread->fastTrackAvailMask_l() &= ~(1 << i);
     }
 
     mServerLatencySupported = checkServerLatencySupported(format, flags);
@@ -884,10 +883,10 @@
     sp<Track> keep(this);
     { // scope for mLock
         bool wasActive = false;
-        sp<AudioFlinger::ThreadBase> thread = mThread.promote();
+        const sp<IAfThreadBase> thread = mThread.promote();
         if (thread != 0) {
-            Mutex::Autolock _l(thread->mLock);
-            auto* const playbackThread = static_cast<AudioFlinger::PlaybackThread*>(thread.get());
+            Mutex::Autolock _l(thread->mutex());
+            auto* const playbackThread = thread->asIAfPlaybackThread().get();
             wasActive = playbackThread->destroyTrack_l(this);
             forEachTeePatchTrack_l([](const auto& patchTrack) { patchTrack->destroy(); });
         }
@@ -1163,19 +1162,19 @@
     ALOGV("%s(%d): calling pid %d session %d",
             __func__, mId, IPCThreadState::self()->getCallingPid(), mSessionId);
 
-    sp<AudioFlinger::ThreadBase> thread = mThread.promote();
+    const sp<IAfThreadBase> thread = mThread.promote();
     if (thread != 0) {
         if (isOffloaded()) {
-            Mutex::Autolock _laf(thread->mAudioFlinger->mLock);
-            Mutex::Autolock _lth(thread->mLock);
+            Mutex::Autolock _laf(thread->audioFlinger()->mLock);
+            Mutex::Autolock _lth(thread->mutex());
             sp<IAfEffectChain> ec = thread->getEffectChain_l(mSessionId);
-            if (thread->mAudioFlinger->isNonOffloadableGlobalEffectEnabled_l() ||
+            if (thread->audioFlinger()->isNonOffloadableGlobalEffectEnabled_l() ||
                     (ec != 0 && ec->isNonOffloadableEnabled())) {
                 invalidate();
                 return PERMISSION_DENIED;
             }
         }
-        Mutex::Autolock _lth(thread->mLock);
+        Mutex::Autolock _lth(thread->mutex());
         track_state state = mState;
         // here the track could be either new, or restarted
         // in both cases "unstop" the track
@@ -1207,7 +1206,7 @@
                     __func__, mId, (int)mThreadIoHandle);
         }
 
-        auto* const playbackThread = static_cast<AudioFlinger::PlaybackThread*>(thread.get());
+        auto* const playbackThread = thread->asIAfPlaybackThread().get();
 
         // states to reset position info for pcm tracks
         if (audio_is_linear_pcm(mFormat)
@@ -1275,7 +1274,7 @@
     }
     if (status == NO_ERROR) {
         // send format to AudioManager for playback activity monitoring
-        sp<IAudioManager> audioManager = thread->mAudioFlinger->getOrCreateAudioManager();
+        const sp<IAudioManager> audioManager = thread->audioFlinger()->getOrCreateAudioManager();
         if (audioManager && mPortId != AUDIO_PORT_HANDLE_NONE) {
             std::unique_ptr<os::PersistableBundle> bundle =
                     std::make_unique<os::PersistableBundle>();
@@ -1297,14 +1296,14 @@
 void Track::stop()
 {
     ALOGV("%s(%d): calling pid %d", __func__, mId, IPCThreadState::self()->getCallingPid());
-    sp<AudioFlinger::ThreadBase> thread = mThread.promote();
+    const sp<IAfThreadBase> thread = mThread.promote();
     if (thread != 0) {
-        Mutex::Autolock _l(thread->mLock);
+        Mutex::Autolock _l(thread->mutex());
         track_state state = mState;
         if (state == RESUMING || state == ACTIVE || state == PAUSING || state == PAUSED) {
             // If the track is not active (PAUSED and buffers full), flush buffers
-            auto* const playbackThread = static_cast<AudioFlinger::PlaybackThread*>(thread.get());
-            if (playbackThread->mActiveTracks.indexOf(this) < 0) {
+            auto* const playbackThread = thread->asIAfPlaybackThread().get();
+            if (!playbackThread->isTrackActive(this)) {
                 reset();
                 mState = STOPPED;
             } else if (!isFastTrack() && !isOffloaded() && !isDirect()) {
@@ -1316,7 +1315,7 @@
                 // move to STOPPING_2 when drain completes and then STOPPED
                 mState = STOPPING_1;
                 if (isOffloaded()) {
-                    mRetryCount = AudioFlinger::PlaybackThread::kMaxTrackStopRetriesOffload;
+                    mRetryCount = IAfPlaybackThread::kMaxTrackStopRetriesOffload;
                 }
             }
             playbackThread->broadcast_l();
@@ -1330,10 +1329,10 @@
 void Track::pause()
 {
     ALOGV("%s(%d): calling pid %d", __func__, mId, IPCThreadState::self()->getCallingPid());
-    sp<AudioFlinger::ThreadBase> thread = mThread.promote();
+    const sp<IAfThreadBase> thread = mThread.promote();
     if (thread != 0) {
-        Mutex::Autolock _l(thread->mLock);
-        auto* const playbackThread = static_cast<AudioFlinger::PlaybackThread*>(thread.get());
+        Mutex::Autolock _l(thread->mutex());
+        auto* const playbackThread = thread->asIAfPlaybackThread().get();
         switch (mState) {
         case STOPPING_1:
         case STOPPING_2:
@@ -1367,15 +1366,15 @@
 void Track::flush()
 {
     ALOGV("%s(%d)", __func__, mId);
-    sp<AudioFlinger::ThreadBase> thread = mThread.promote();
+    const sp<IAfThreadBase> thread = mThread.promote();
     if (thread != 0) {
-        Mutex::Autolock _l(thread->mLock);
-        auto* const playbackThread = static_cast<AudioFlinger::PlaybackThread*>(thread.get());
+        Mutex::Autolock _l(thread->mutex());
+        auto* const playbackThread = thread->asIAfPlaybackThread().get();
 
         // Flush the ring buffer now if the track is not active in the PlaybackThread.
         // Otherwise the flush would not be done until the track is resumed.
         // Requires FastTrack removal be BLOCK_UNTIL_ACKED
-        if (playbackThread->mActiveTracks.indexOf(this) < 0) {
+        if (!playbackThread->isTrackActive(this)) {
             (void)mServerProxy->flushBufferIfNeeded();
         }
 
@@ -1414,7 +1413,7 @@
             if (isDirect()) {
                 mFlushHwPending = true;
             }
-            if (playbackThread->mActiveTracks.indexOf(this) < 0) {
+            if (!playbackThread->isTrackActive(this)) {
                 reset();
             }
         }
@@ -1465,12 +1464,12 @@
 
 status_t Track::setParameters(const String8& keyValuePairs)
 {
-    sp<AudioFlinger::ThreadBase> thread = mThread.promote();
+    const sp<IAfThreadBase> thread = mThread.promote();
     if (thread == 0) {
         ALOGE("%s(%d): thread is dead", __func__, mId);
         return FAILED_TRANSACTION;
-    } else if ((thread->type() == AudioFlinger::ThreadBase::DIRECT) ||
-                    (thread->type() == AudioFlinger::ThreadBase::OFFLOAD)) {
+    } else if (thread->type() == IAfThreadBase::DIRECT
+            || thread->type() == IAfThreadBase::OFFLOAD) {
         return thread->setParameters(keyValuePairs);
     } else {
         return PERMISSION_DENIED;
@@ -1479,13 +1478,13 @@
 
 status_t Track::selectPresentation(int presentationId,
         int programId) {
-    sp<AudioFlinger::ThreadBase> thread = mThread.promote();
+    const sp<IAfThreadBase> thread = mThread.promote();
     if (thread == 0) {
         ALOGE("thread is dead");
         return FAILED_TRANSACTION;
-    } else if ((thread->type() == AudioFlinger::ThreadBase::DIRECT)
-            || (thread->type() == AudioFlinger::ThreadBase::OFFLOAD)) {
-        auto directOutputThread = static_cast<AudioFlinger::DirectOutputThread*>(thread.get());
+    } else if (thread->type() == IAfThreadBase::DIRECT
+            || thread->type() == IAfThreadBase::OFFLOAD) {
+        auto directOutputThread = thread->asIAfDirectOutputThread().get();
         return directOutputThread->selectPresentation(presentationId, programId);
     }
     return INVALID_OPERATION;
@@ -1499,9 +1498,9 @@
 
     if (isOffloadedOrDirect()) {
         // Signal thread to fetch new volume.
-        sp<AudioFlinger::ThreadBase> thread = mThread.promote();
+        const sp<IAfThreadBase> thread = mThread.promote();
         if (thread != 0) {
-            Mutex::Autolock _l(thread->mLock);
+            Mutex::Autolock _l(thread->mutex());
             thread->broadcast_l();
         }
     }
@@ -1660,26 +1659,26 @@
     if (!isOffloaded() && !isDirect()) {
         return INVALID_OPERATION; // normal tracks handled through SSQ
     }
-    sp<AudioFlinger::ThreadBase> thread = mThread.promote();
+    const sp<IAfThreadBase> thread = mThread.promote();
     if (thread == 0) {
         return INVALID_OPERATION;
     }
 
-    Mutex::Autolock _l(thread->mLock);
-    auto* const playbackThread = static_cast<AudioFlinger::PlaybackThread*>(thread.get());
+    Mutex::Autolock _l(thread->mutex());
+    auto* const playbackThread = thread->asIAfPlaybackThread().get();
     return playbackThread->getTimestamp_l(timestamp);
 }
 
 status_t Track::attachAuxEffect(int EffectId)
 {
-    sp<AudioFlinger::ThreadBase> thread = mThread.promote();
+    const sp<IAfThreadBase> thread = mThread.promote();
     if (thread == nullptr) {
         return DEAD_OBJECT;
     }
 
-    auto dstThread = sp<AudioFlinger::PlaybackThread>::cast(thread);
+    auto dstThread = thread->asIAfPlaybackThread();
     // srcThread is initialized by call to moveAuxEffectToIo()
-    sp<AudioFlinger::PlaybackThread> srcThread;
+    sp<IAfPlaybackThread> srcThread;
     sp<AudioFlinger> af = mClient->audioFlinger();
     status_t status = af->moveAuxEffectToIo(EffectId, dstThread, &srcThread);
 
@@ -1865,10 +1864,10 @@
 
 void Track::signal()
 {
-    sp<AudioFlinger::ThreadBase> thread = mThread.promote();
+    const sp<IAfThreadBase> thread = mThread.promote();
     if (thread != 0) {
-        auto* const t = static_cast<AudioFlinger::PlaybackThread*>(thread.get());
-        Mutex::Autolock _l(t->mLock);
+        auto* const t = thread->asIAfPlaybackThread().get();
+        Mutex::Autolock _l(t->mutex());
         t->broadcast_l();
     }
 }
@@ -1877,11 +1876,11 @@
 {
     status_t status = INVALID_OPERATION;
     if (isOffloadedOrDirect()) {
-        sp<AudioFlinger::ThreadBase> thread = mThread.promote();
+        const sp<IAfThreadBase> thread = mThread.promote();
         if (thread != nullptr) {
-            auto* const t = static_cast<AudioFlinger::PlaybackThread*>(thread.get());
-            Mutex::Autolock _l(t->mLock);
-            status = t->mOutput->stream->getDualMonoMode(mode);
+            auto* const t = thread->asIAfPlaybackThread().get();
+            Mutex::Autolock _l(t->mutex());
+            status = t->getOutput_l()->stream->getDualMonoMode(mode);
             ALOGD_IF((status == NO_ERROR) && (mDualMonoMode != *mode),
                     "%s: mode %d inconsistent", __func__, mDualMonoMode);
         }
@@ -1893,11 +1892,11 @@
 {
     status_t status = INVALID_OPERATION;
     if (isOffloadedOrDirect()) {
-        sp<AudioFlinger::ThreadBase> thread = mThread.promote();
+        const sp<IAfThreadBase> thread = mThread.promote();
         if (thread != nullptr) {
-            auto* const t = static_cast<AudioFlinger::PlaybackThread*>(thread.get());
-            Mutex::Autolock lock(t->mLock);
-            status = t->mOutput->stream->setDualMonoMode(mode);
+            auto* const t = thread->asIAfPlaybackThread().get();
+            Mutex::Autolock lock(t->mutex());
+            status = t->getOutput_l()->stream->setDualMonoMode(mode);
             if (status == NO_ERROR) {
                 mDualMonoMode = mode;
             }
@@ -1910,11 +1909,11 @@
 {
     status_t status = INVALID_OPERATION;
     if (isOffloadedOrDirect()) {
-        sp<AudioFlinger::ThreadBase> thread = mThread.promote();
+        sp<IAfThreadBase> thread = mThread.promote();
         if (thread != nullptr) {
-            auto* const t = static_cast<AudioFlinger::PlaybackThread*>(thread.get());
-            Mutex::Autolock lock(t->mLock);
-            status = t->mOutput->stream->getAudioDescriptionMixLevel(leveldB);
+            auto* const t = thread->asIAfPlaybackThread().get();
+            Mutex::Autolock lock(t->mutex());
+            status = t->getOutput_l()->stream->getAudioDescriptionMixLevel(leveldB);
             ALOGD_IF((status == NO_ERROR) && (mAudioDescriptionMixLevel != *leveldB),
                     "%s: level %.3f inconsistent", __func__, mAudioDescriptionMixLevel);
         }
@@ -1926,11 +1925,11 @@
 {
     status_t status = INVALID_OPERATION;
     if (isOffloadedOrDirect()) {
-        sp<AudioFlinger::ThreadBase> thread = mThread.promote();
+        const sp<IAfThreadBase> thread = mThread.promote();
         if (thread != nullptr) {
-            auto* const t = static_cast<AudioFlinger::PlaybackThread*>(thread.get());
-            Mutex::Autolock lock(t->mLock);
-            status = t->mOutput->stream->setAudioDescriptionMixLevel(leveldB);
+            auto* const t = thread->asIAfPlaybackThread().get();
+            Mutex::Autolock lock(t->mutex());
+            status = t->getOutput_l()->stream->setAudioDescriptionMixLevel(leveldB);
             if (status == NO_ERROR) {
                 mAudioDescriptionMixLevel = leveldB;
             }
@@ -1944,11 +1943,11 @@
 {
     status_t status = INVALID_OPERATION;
     if (isOffloadedOrDirect()) {
-        sp<AudioFlinger::ThreadBase> thread = mThread.promote();
+        const sp<IAfThreadBase> thread = mThread.promote();
         if (thread != nullptr) {
-            auto* const t = static_cast<AudioFlinger::PlaybackThread*>(thread.get());
-            Mutex::Autolock lock(t->mLock);
-            status = t->mOutput->stream->getPlaybackRateParameters(playbackRate);
+            auto* const t = thread->asIAfPlaybackThread().get();
+            Mutex::Autolock lock(t->mutex());
+            status = t->getOutput_l()->stream->getPlaybackRateParameters(playbackRate);
             ALOGD_IF((status == NO_ERROR) &&
                     !isAudioPlaybackRateEqual(mPlaybackRateParameters, *playbackRate),
                     "%s: playbackRate inconsistent", __func__);
@@ -1962,11 +1961,11 @@
 {
     status_t status = INVALID_OPERATION;
     if (isOffloadedOrDirect()) {
-        sp<AudioFlinger::ThreadBase> thread = mThread.promote();
+        const sp<IAfThreadBase> thread = mThread.promote();
         if (thread != nullptr) {
-            auto* const t = static_cast<AudioFlinger::PlaybackThread*>(thread.get());
-            Mutex::Autolock lock(t->mLock);
-            status = t->mOutput->stream->setPlaybackRateParameters(playbackRate);
+            auto* const t = thread->asIAfPlaybackThread().get();
+            Mutex::Autolock lock(t->mutex());
+            status = t->getOutput_l()->stream->setPlaybackRateParameters(playbackRate);
             if (status == NO_ERROR) {
                 mPlaybackRateParameters = playbackRate;
             }
@@ -2085,13 +2084,13 @@
 }
 
 bool Track::AudioVibrationController::setMute(bool muted) {
-    sp<AudioFlinger::ThreadBase> thread = mTrack->mThread.promote();
+    const sp<IAfThreadBase> thread = mTrack->mThread.promote();
     if (thread != 0) {
         // Lock for updating mHapticPlaybackEnabled.
-        Mutex::Autolock _l(thread->mLock);
-        auto* const playbackThread = static_cast<AudioFlinger::PlaybackThread*>(thread.get());
+        Mutex::Autolock _l(thread->mutex());
+        auto* const playbackThread = thread->asIAfPlaybackThread().get();
         if ((mTrack->channelMask() & AUDIO_CHANNEL_HAPTIC_ALL) != AUDIO_CHANNEL_NONE
-                && playbackThread->mHapticChannelCount > 0) {
+                && playbackThread->hapticChannelCount() > 0) {
             ALOGD("%s, haptic playback was %s for track %d",
                     __func__, muted ? "muted" : "unmuted", mTrack->id());
             mTrack->setHapticPlaybackEnabled(!muted);
@@ -2118,17 +2117,17 @@
 #define LOG_TAG "AF::OutputTrack"
 
 /* static */
-sp<IAfOutputTrack> IAfOutputTrack::create(  // TODO(b/288339104) void*
-        void* /* AudioFlinger::PlaybackThread */ playbackThread,
-        void* /* AudioFlinger::DuplicatingThread */ sourceThread,
+sp<IAfOutputTrack> IAfOutputTrack::create(
+        IAfPlaybackThread* playbackThread,
+        IAfDuplicatingThread* sourceThread,
         uint32_t sampleRate,
         audio_format_t format,
         audio_channel_mask_t channelMask,
         size_t frameCount,
         const AttributionSourceState& attributionSource) {
     return sp<OutputTrack>::make(
-            reinterpret_cast<AudioFlinger::PlaybackThread*>(playbackThread),
-            reinterpret_cast<AudioFlinger::DuplicatingThread*>(sourceThread),
+            playbackThread,
+            sourceThread,
             sampleRate,
             format,
             channelMask,
@@ -2137,8 +2136,8 @@
 }
 
 OutputTrack::OutputTrack(
-            AudioFlinger::PlaybackThread *playbackThread,
-            AudioFlinger::DuplicatingThread *sourceThread,
+            IAfPlaybackThread* playbackThread,
+            IAfDuplicatingThread* sourceThread,
             uint32_t sampleRate,
             audio_format_t format,
             audio_channel_mask_t channelMask,
@@ -2155,7 +2154,7 @@
 
     if (mCblk != NULL) {
         mOutBuffer.frameCount = 0;
-        playbackThread->mTracks.add(this);
+        playbackThread->addOutputTrack_l(this);
         ALOGV("%s(): mCblk %p, mBuffer %p, "
                 "frameCount %zu, mChannelMask 0x%08x",
                 __func__, mCblk, mBuffer,
@@ -2203,7 +2202,7 @@
 ssize_t OutputTrack::write(void* data, uint32_t frames)
 {
     if (!mActive && frames != 0) {
-        sp<AudioFlinger::ThreadBase> thread = mThread.promote();
+        const sp<IAfThreadBase> thread = mThread.promote();
         if (thread != nullptr && thread->inStandby()) {
             // preload one silent buffer to trigger mixer on start()
             ClientProxy::Buffer buf { .mFrameCount = mClientProxy->getStartThresholdInFrames() };
@@ -2222,7 +2221,7 @@
             // If another OutputTrack has already started it can underrun but this is OK
             // as only silence has been played so far and the retry count is very high on
             // OutputTrack.
-            auto* const pt = static_cast<AudioFlinger::PlaybackThread*>(thread.get());
+            auto* const pt = thread->asIAfPlaybackThread().get();
             if (!pt->waitForHalStart()) {
                 ALOGW("%s(%d): timeout waiting for thread to exit standby", __func__, mId);
                 stop();
@@ -2311,7 +2310,7 @@
 
     // If we could not write all frames, allocate a buffer and queue it for next time.
     if (inBuffer.frameCount) {
-        sp<AudioFlinger::ThreadBase> thread = mThread.promote();
+        const sp<IAfThreadBase> thread = mThread.promote();
         if (thread != nullptr && !thread->inStandby()) {
             queueBuffer(inBuffer);
         }
@@ -2404,7 +2403,7 @@
 
 /* static */
 sp<IAfPatchTrack> IAfPatchTrack::create(
-        void* /* PlaybackThread */ playbackThread, // TODO(b/288339104)
+        IAfPlaybackThread* playbackThread,
         audio_stream_type_t streamType,
         uint32_t sampleRate,
         audio_channel_mask_t channelMask,
@@ -2420,7 +2419,7 @@
                                          *  even if it might glitch. */)
 {
     return sp<PatchTrack>::make(
-            reinterpret_cast<AudioFlinger::PlaybackThread*>(playbackThread),
+            playbackThread,
             streamType,
             sampleRate,
             channelMask,
@@ -2433,7 +2432,7 @@
             frameCountToBeReady);
 }
 
-PatchTrack::PatchTrack(AudioFlinger::PlaybackThread *playbackThread,
+PatchTrack::PatchTrack(IAfPlaybackThread* playbackThread,
                                                      audio_stream_type_t streamType,
                                                      uint32_t sampleRate,
                                                      audio_channel_mask_t channelMask,
@@ -2551,9 +2550,9 @@
     if (mFillingStatus == FS_ACTIVE
             && audio_is_linear_pcm(mFormat)
             && !isOffloadedOrDirect()) {
-        if (sp<AudioFlinger::ThreadBase> thread = mThread.promote();
+        if (const sp<IAfThreadBase> thread = mThread.promote();
             thread != 0) {
-            auto* const playbackThread = static_cast<AudioFlinger::PlaybackThread*>(thread.get());
+            auto* const playbackThread = thread->asIAfPlaybackThread().get();
             const size_t frameCount = playbackThread->frameCount() * sampleRate()
                     / playbackThread->sampleRate();
             if (framesReady() < frameCount) {
@@ -2669,7 +2668,7 @@
 
 
 /* static */ // TODO(b/288339104)
-sp<IAfRecordTrack> IAfRecordTrack::create(void* /*AudioFlinger::RecordThread */ thread,
+sp<IAfRecordTrack> IAfRecordTrack::create(IAfRecordThread* thread,
         const sp<Client>& client,
         const audio_attributes_t& attr,
         uint32_t sampleRate,
@@ -2687,7 +2686,7 @@
         int32_t startFrames)
 {
     return sp<RecordTrack>::make(
-        reinterpret_cast<AudioFlinger::RecordThread*>(thread),
+        thread,
         client,
         attr,
         sampleRate,
@@ -2707,7 +2706,7 @@
 
 // RecordTrack constructor must be called with AudioFlinger::mLock and ThreadBase::mLock held
 RecordTrack::RecordTrack(
-            AudioFlinger::RecordThread* thread,
+            IAfRecordThread* thread,
             const sp<Client>& client,
             const audio_attributes_t& attr,
             uint32_t sampleRate,
@@ -2746,7 +2745,7 @@
 
     if (!isDirect()) {
         mRecordBufferConverter = new RecordBufferConverter(
-                thread->mChannelMask, thread->mFormat, thread->mSampleRate,
+                thread->channelMask(), thread->format(), thread->sampleRate(),
                 channelMask, format, sampleRate);
         // Check if the RecordBufferConverter construction was successful.
         // If not, don't continue with construction.
@@ -2766,8 +2765,8 @@
     mResamplerBufferProvider = new ResamplerBufferProvider(this);
 
     if (flags & AUDIO_INPUT_FLAG_FAST) {
-        ALOG_ASSERT(thread->mFastTrackAvail);
-        thread->mFastTrackAvail = false;
+        ALOG_ASSERT(thread->fastTrackAvailable());
+        thread->setFastTrackAvailable(false);
     } else {
         // TODO: only Normal Record has timestamps (Fast Record does not).
         mServerLatencySupported = checkServerLatencySupported(mFormat, flags);
@@ -2816,9 +2815,9 @@
 status_t RecordTrack::start(AudioSystem::sync_event_t event,
                                                         audio_session_t triggerSession)
 {
-    sp<AudioFlinger::ThreadBase> thread = mThread.promote();
+    const sp<IAfThreadBase> thread = mThread.promote();
     if (thread != 0) {
-        auto* const recordThread = static_cast<AudioFlinger::RecordThread*>(thread.get());
+        auto* const recordThread = thread->asIAfRecordThread().get();
         return recordThread->start(this, event, triggerSession);
     } else {
         ALOGW("%s track %d: thread was destroyed", __func__, portId());
@@ -2828,9 +2827,9 @@
 
 void RecordTrack::stop()
 {
-    sp<AudioFlinger::ThreadBase> thread = mThread.promote();
+    const sp<IAfThreadBase> thread = mThread.promote();
     if (thread != 0) {
-        auto* const recordThread = static_cast<AudioFlinger::RecordThread*>(thread.get());
+        auto* const recordThread = thread->asIAfRecordThread().get();
         if (recordThread->stop(this) && isExternalTrack()) {
             AudioSystem::stopInput(mPortId);
         }
@@ -2843,10 +2842,10 @@
     sp<RecordTrack> keep(this);
     {
         track_state priorState = mState;
-        sp<AudioFlinger::ThreadBase> thread = mThread.promote();
+        const sp<IAfThreadBase> thread = mThread.promote();
         if (thread != 0) {
-            Mutex::Autolock _l(thread->mLock);
-            auto* const recordThread = static_cast<AudioFlinger::RecordThread*>(thread.get());
+            Mutex::Autolock _l(thread->mutex());
+            auto* const recordThread = thread->asIAfRecordThread().get();
             priorState = mState;
             if (!mSharedAudioPackageName.empty()) {
                 recordThread->resetAudioHistory_l();
@@ -2940,11 +2939,11 @@
         const sp<audioflinger::SyncEvent>& event)
 {
     size_t framesToDrop = 0;
-    sp<AudioFlinger::ThreadBase> threadBase = mThread.promote();
+    const sp<IAfThreadBase> threadBase = mThread.promote();
     if (threadBase != 0) {
         // TODO: use actual buffer filling status instead of 2 buffers when info is available
         // from audio HAL
-        framesToDrop = threadBase->mFrameCount * 2;
+        framesToDrop = threadBase->frameCount() * 2;
     }
 
     mSynchronizedRecordState.onPlaybackFinished(event, framesToDrop);
@@ -2998,9 +2997,9 @@
 status_t RecordTrack::getActiveMicrophones(
         std::vector<media::MicrophoneInfoFw>* activeMicrophones) const
 {
-    sp<AudioFlinger::ThreadBase> thread = mThread.promote();
+    const sp<IAfThreadBase> thread = mThread.promote();
     if (thread != 0) {
-        auto* const recordThread = static_cast<AudioFlinger::RecordThread*>(thread.get());
+        auto* const recordThread = thread->asIAfRecordThread().get();
         return recordThread->getActiveMicrophones(activeMicrophones);
     } else {
         return BAD_VALUE;
@@ -3009,9 +3008,9 @@
 
 status_t RecordTrack::setPreferredMicrophoneDirection(
         audio_microphone_direction_t direction) {
-    sp<AudioFlinger::ThreadBase> thread = mThread.promote();
+    const sp<IAfThreadBase> thread = mThread.promote();
     if (thread != 0) {
-        auto* const recordThread = static_cast<AudioFlinger::RecordThread*>(thread.get());
+        auto* const recordThread = thread->asIAfRecordThread().get();
         return recordThread->setPreferredMicrophoneDirection(direction);
     } else {
         return BAD_VALUE;
@@ -3019,9 +3018,9 @@
 }
 
 status_t RecordTrack::setPreferredMicrophoneFieldDimension(float zoom) {
-    sp<AudioFlinger::ThreadBase> thread = mThread.promote();
+    const sp<IAfThreadBase> thread = mThread.promote();
     if (thread != 0) {
-        auto* const recordThread = static_cast<AudioFlinger::RecordThread*>(thread.get());
+        auto* const recordThread = thread->asIAfRecordThread().get();
         return recordThread->setPreferredMicrophoneFieldDimension(zoom);
     } else {
         return BAD_VALUE;
@@ -3045,9 +3044,9 @@
         return PERMISSION_DENIED;
     }
 
-    sp<AudioFlinger::ThreadBase> thread = mThread.promote();
+    const sp<IAfThreadBase> thread = mThread.promote();
     if (thread != 0) {
-        auto* const recordThread = static_cast<AudioFlinger::RecordThread*>(thread.get());
+        auto* const recordThread = thread->asIAfRecordThread().get();
         status_t status = recordThread->shareAudioHistory(
                 sharedAudioPackageName, mSessionId, sharedAudioStartMs);
         if (status == NO_ERROR) {
@@ -3085,7 +3084,7 @@
 
 /* static */
 sp<IAfPatchRecord> IAfPatchRecord::create(
-        void* /* RecordThread */ recordThread, // TODO(b/288339104)
+        IAfRecordThread* recordThread,
         uint32_t sampleRate,
         audio_channel_mask_t channelMask,
         audio_format_t format,
@@ -3097,7 +3096,7 @@
         audio_source_t source)
 {
     return sp<PatchRecord>::make(
-            reinterpret_cast<AudioFlinger::RecordThread*>(recordThread),
+            recordThread,
             sampleRate,
             channelMask,
             format,
@@ -3109,7 +3108,7 @@
             source);
 }
 
-PatchRecord::PatchRecord(AudioFlinger::RecordThread *recordThread,
+PatchRecord::PatchRecord(IAfRecordThread* recordThread,
                                                      uint32_t sampleRate,
                                                      audio_channel_mask_t channelMask,
                                                      audio_format_t format,
@@ -3228,7 +3227,7 @@
 
 /* static */
 sp<IAfPatchRecord> IAfPatchRecord::createPassThru(
-        void* /* RecordThread */ recordThread, // TODO(b/288339104)
+        IAfRecordThread* recordThread,
         uint32_t sampleRate,
         audio_channel_mask_t channelMask,
         audio_format_t format,
@@ -3237,7 +3236,7 @@
         audio_source_t source)
 {
     return sp<PassthruPatchRecord>::make(
-            reinterpret_cast<AudioFlinger::RecordThread*>(recordThread),
+            recordThread,
             sampleRate,
             channelMask,
             format,
@@ -3247,7 +3246,7 @@
 }
 
 PassthruPatchRecord::PassthruPatchRecord(
-        AudioFlinger::RecordThread* recordThread,
+        IAfRecordThread* recordThread,
         uint32_t sampleRate,
         audio_channel_mask_t channelMask,
         audio_format_t format,
@@ -3264,13 +3263,13 @@
 }
 
 sp<StreamInHalInterface> PassthruPatchRecord::obtainStream(
-        sp<AudioFlinger::ThreadBase>* thread)
+        sp<IAfThreadBase>* thread)
 {
     *thread = mThread.promote();
     if (!*thread) return nullptr;
-    auto* const recordThread = static_cast<AudioFlinger::RecordThread*>((*thread).get());
-    Mutex::Autolock _l(recordThread->mLock);
-    return recordThread->mInput ? recordThread->mInput->stream : nullptr;
+    auto* const recordThread = (*thread)->asIAfRecordThread().get();
+    Mutex::Autolock _l(recordThread->mutex());
+    return recordThread->getInput() ? recordThread->getInput()->stream : nullptr;
 }
 
 // PatchProxyBufferProvider methods are called on DirectOutputThread
@@ -3292,7 +3291,7 @@
     const size_t framesToRead = std::min(buffer->mFrameCount, mFrameCount);
     buffer->mFrameCount = 0;
     buffer->mRaw = nullptr;
-    sp<AudioFlinger::ThreadBase> thread;
+    sp<IAfThreadBase> thread;
     sp<StreamInHalInterface> stream = obtainStream(&thread);
     if (!stream) return NO_INIT;  // If there is no stream, RecordThread is not reading.
 
@@ -3379,7 +3378,7 @@
 status_t PassthruPatchRecord::getCapturePosition(
         int64_t* frames, int64_t* time)
 {
-    sp<AudioFlinger::ThreadBase> thread;
+    sp<IAfThreadBase> thread;
     sp<StreamInHalInterface> stream = obtainStream(&thread);
     return stream ? stream->getCapturePosition(frames, time) : NO_INIT;
 }
@@ -3416,7 +3415,7 @@
 #define LOG_TAG "AF::MmapTrack"
 
 /* static */
-sp<IAfMmapTrack> IAfMmapTrack::create(void* /* AudioFlinger::ThreadBase */ thread,
+sp<IAfMmapTrack> IAfMmapTrack::create(IAfThreadBase* thread,
           const audio_attributes_t& attr,
           uint32_t sampleRate,
           audio_format_t format,
@@ -3428,7 +3427,7 @@
           audio_port_handle_t portId)
 {
     return sp<MmapTrack>::make(
-            reinterpret_cast<AudioFlinger::ThreadBase*>(thread),
+            thread,
             attr,
             sampleRate,
             format,
@@ -3440,7 +3439,7 @@
             portId);
 }
 
-MmapTrack::MmapTrack(AudioFlinger::ThreadBase* thread,
+MmapTrack::MmapTrack(IAfThreadBase* thread,
         const audio_attributes_t& attr,
         uint32_t sampleRate,
         audio_format_t format,