diff --git a/services/oboeservice/AAudioServiceStreamBase.cpp b/services/oboeservice/AAudioServiceStreamBase.cpp
index 4ffc127..a25a791 100644
--- a/services/oboeservice/AAudioServiceStreamBase.cpp
+++ b/services/oboeservice/AAudioServiceStreamBase.cpp
@@ -34,23 +34,25 @@
 #include "AAudioService.h"
 #include "AAudioServiceEndpoint.h"
 #include "AAudioServiceStreamBase.h"
-#include "TimestampScheduler.h"
 
 using namespace android;  // TODO just import names needed
 using namespace aaudio;   // TODO just import names needed
 
 using content::AttributionSourceState;
 
+static const int64_t TIMEOUT_NANOS = 3LL * 1000 * 1000 * 1000;
+
 /**
  * Base class for streams in the service.
  * @return
  */
 
 AAudioServiceStreamBase::AAudioServiceStreamBase(AAudioService &audioService)
-        : mTimestampThread("AATime")
+        : mCommandThread("AACommand")
         , mAtomicStreamTimestamp()
         , mAudioService(audioService) {
     mMmapClient.attributionSource = AttributionSourceState();
+    mThreadEnabled = true;
 }
 
 AAudioServiceStreamBase::~AAudioServiceStreamBase() {
@@ -70,6 +72,13 @@
                         || getState() == AAUDIO_STREAM_STATE_UNINITIALIZED),
                         "service stream %p still open, state = %d",
                         this, getState());
+
+    // Stop the command thread before destroying.
+    if (mThreadEnabled) {
+        mThreadEnabled = false;
+        mCommandQueue.stopWaiting();
+        mCommandThread.stop();
+    }
 }
 
 std::string AAudioServiceStreamBase::dumpHeader() {
@@ -166,6 +175,16 @@
         mFramesPerBurst = mServiceEndpoint->getFramesPerBurst();
         copyFrom(*mServiceEndpoint);
     }
+
+    // Make sure this object does not get deleted before the run() method
+    // can protect it by making a strong pointer.
+    mThreadEnabled = true;
+    incStrong(nullptr); // See run() method.
+    result = mCommandThread.start(this);
+    if (result != AAUDIO_OK) {
+        decStrong(nullptr); // run() can't do it so we have to do it here.
+        goto error;
+    }
     return result;
 
 error:
@@ -174,8 +193,16 @@
 }
 
 aaudio_result_t AAudioServiceStreamBase::close() {
-    std::lock_guard<std::mutex> lock(mLock);
-    return close_l();
+    auto command = std::make_shared<AAudioCommand>(
+            CLOSE, nullptr, true /*waitForReply*/, TIMEOUT_NANOS);
+    aaudio_result_t result = mCommandQueue.sendCommand(command);
+
+    // Stop the command thread as the stream is closed.
+    mThreadEnabled = false;
+    mCommandQueue.stopWaiting();
+    mCommandThread.stop();
+
+    return result;
 }
 
 aaudio_result_t AAudioServiceStreamBase::close_l() {
@@ -183,8 +210,7 @@
         return AAUDIO_OK;
     }
 
-    // This will call stopTimestampThread() and also stop the stream,
-    // just in case it was not already stopped.
+    // This will stop the stream, just in case it was not already stopped.
     stop_l();
 
     aaudio_result_t result = AAUDIO_OK;
@@ -224,8 +250,12 @@
  * An AAUDIO_SERVICE_EVENT_STARTED will be sent to the client when complete.
  */
 aaudio_result_t AAudioServiceStreamBase::start() {
-    std::lock_guard<std::mutex> lock(mLock);
+    auto command = std::make_shared<AAudioCommand>(
+            START, nullptr, true /*waitForReply*/, TIMEOUT_NANOS);
+    return mCommandQueue.sendCommand(command);
+}
 
+aaudio_result_t AAudioServiceStreamBase::start_l() {
     const int64_t beginNs = AudioClock::getNanoseconds();
     aaudio_result_t result = AAUDIO_OK;
 
@@ -261,15 +291,6 @@
     // This should happen at the end of the start.
     sendServiceEvent(AAUDIO_SERVICE_EVENT_STARTED);
     setState(AAUDIO_STREAM_STATE_STARTED);
-    mThreadEnabled.store(true);
-    // Make sure this object does not get deleted before the run() method
-    // can protect it by making a strong pointer.
-    incStrong(nullptr); // See run() method.
-    result = mTimestampThread.start(this);
-    if (result != AAUDIO_OK) {
-        decStrong(nullptr); // run() can't do it so we have to do it here.
-        goto error;
-    }
 
     return result;
 
@@ -279,8 +300,9 @@
 }
 
 aaudio_result_t AAudioServiceStreamBase::pause() {
-    std::lock_guard<std::mutex> lock(mLock);
-    return pause_l();
+    auto command = std::make_shared<AAudioCommand>(
+            PAUSE, nullptr, true /*waitForReply*/, TIMEOUT_NANOS);
+    return mCommandQueue.sendCommand(command);
 }
 
 aaudio_result_t AAudioServiceStreamBase::pause_l() {
@@ -298,12 +320,6 @@
             .set(AMEDIAMETRICS_PROP_STATUS, (int32_t)result)
             .record(); });
 
-    result = stopTimestampThread();
-    if (result != AAUDIO_OK) {
-        disconnect_l();
-        return result;
-    }
-
     sp<AAudioServiceEndpoint> endpoint = mServiceEndpointWeak.promote();
     if (endpoint == nullptr) {
         ALOGE("%s() has no endpoint", __func__);
@@ -322,8 +338,9 @@
 }
 
 aaudio_result_t AAudioServiceStreamBase::stop() {
-    std::lock_guard<std::mutex> lock(mLock);
-    return stop_l();
+    auto command = std::make_shared<AAudioCommand>(
+            STOP, nullptr, true /*waitForReply*/, TIMEOUT_NANOS);
+    return mCommandQueue.sendCommand(command);
 }
 
 aaudio_result_t AAudioServiceStreamBase::stop_l() {
@@ -343,12 +360,6 @@
 
     setState(AAUDIO_STREAM_STATE_STOPPING);
 
-    // Temporarily unlock because we are joining the timestamp thread and it may try
-    // to acquire mLock.
-    mLock.unlock();
-    result = stopTimestampThread();
-    mLock.lock();
-
     if (result != AAUDIO_OK) {
         disconnect_l();
         return result;
@@ -373,17 +384,13 @@
     return result;
 }
 
-aaudio_result_t AAudioServiceStreamBase::stopTimestampThread() {
-    aaudio_result_t result = AAUDIO_OK;
-    // clear flag that tells thread to loop
-    if (mThreadEnabled.exchange(false)) {
-        result = mTimestampThread.stop();
-    }
-    return result;
+aaudio_result_t AAudioServiceStreamBase::flush() {
+    auto command = std::make_shared<AAudioCommand>(
+            FLUSH, nullptr, true /*waitForReply*/, TIMEOUT_NANOS);
+    return mCommandQueue.sendCommand(command);
 }
 
-aaudio_result_t AAudioServiceStreamBase::flush() {
-    std::lock_guard<std::mutex> lock(mLock);
+aaudio_result_t AAudioServiceStreamBase::flush_l() {
     aaudio_result_t result = AAudio_isFlushAllowed(getState());
     if (result != AAUDIO_OK) {
         return result;
@@ -404,48 +411,111 @@
     return AAUDIO_OK;
 }
 
-// implement Runnable, periodically send timestamps to client
+// implement Runnable, periodically send timestamps to client and process commands from queue.
 __attribute__((no_sanitize("integer")))
 void AAudioServiceStreamBase::run() {
-    ALOGD("%s() %s entering >>>>>>>>>>>>>> TIMESTAMPS", __func__, getTypeText());
+    ALOGD("%s() %s entering >>>>>>>>>>>>>> COMMANDS", __func__, getTypeText());
     // Hold onto the ref counted stream until the end.
     android::sp<AAudioServiceStreamBase> holdStream(this);
     TimestampScheduler timestampScheduler;
+    int64_t nextTime;
     // Balance the incStrong from when the thread was launched.
     holdStream->decStrong(nullptr);
 
-    timestampScheduler.setBurstPeriod(mFramesPerBurst, getSampleRate());
-    timestampScheduler.start(AudioClock::getNanoseconds());
-    int64_t nextTime = timestampScheduler.nextAbsoluteTime();
+    // Taking mLock while starting the thread. All the operation must be able to
+    // run with holding the lock.
+    std::scoped_lock<std::mutex> _l(mLock);
+
     int32_t loopCount = 0;
-    aaudio_result_t result = AAUDIO_OK;
-    while(mThreadEnabled.load()) {
+    while (mThreadEnabled.load()) {
         loopCount++;
-        if (AudioClock::getNanoseconds() >= nextTime) {
-            result = sendCurrentTimestamp();
-            if (result != AAUDIO_OK) {
-                ALOGE("%s() timestamp thread got result = %d", __func__, result);
-                break;
+        int64_t timeoutNanos = -1;
+        if (isRunning()) {
+            timeoutNanos = nextTime - AudioClock::getNanoseconds();
+            timeoutNanos = std::max<int64_t>(0, timeoutNanos);
+        }
+
+        auto command = mCommandQueue.waitForCommand(timeoutNanos);
+        if (!mThreadEnabled) {
+            // Break the loop if the thread is disabled.
+            break;
+        }
+
+        if (isRunning() && AudioClock::getNanoseconds() >= nextTime) {
+            // It is time to update timestamp.
+            if (sendCurrentTimestamp_l() != AAUDIO_OK) {
+                ALOGE("Failed to send current timestamp, stop updating timestamp");
+                disconnect_l();
+            } else {
+                nextTime = timestampScheduler.nextAbsoluteTime();
             }
-            nextTime = timestampScheduler.nextAbsoluteTime();
-        } else  {
-            // Sleep until it is time to send the next timestamp.
-            // TODO Wait for a signal with a timeout so that we can stop more quickly.
-            AudioClock::sleepUntilNanoTime(nextTime);
+        }
+
+        if (command != nullptr) {
+            std::scoped_lock<std::mutex> _commandLock(command->lock);
+            switch (command->operationCode) {
+                case START:
+                    command->result = start_l();
+                    timestampScheduler.setBurstPeriod(mFramesPerBurst, getSampleRate());
+                    timestampScheduler.start(AudioClock::getNanoseconds());
+                    nextTime = timestampScheduler.nextAbsoluteTime();
+                    break;
+                case PAUSE:
+                    command->result = pause_l();
+                    break;
+                case STOP:
+                    command->result = stop_l();
+                    break;
+                case FLUSH:
+                    command->result = flush_l();
+                    break;
+                case CLOSE:
+                    command->result = close_l();
+                    break;
+                case DISCONNECT:
+                    disconnect_l();
+                    break;
+                case REGISTER_AUDIO_THREAD: {
+                    RegisterAudioThreadParam *param =
+                            (RegisterAudioThreadParam *) command->parameter.get();
+                    command->result =
+                            param == nullptr ? AAUDIO_ERROR_ILLEGAL_ARGUMENT
+                                             : registerAudioThread_l(param->mOwnerPid,
+                                                                     param->mClientThreadId,
+                                                                     param->mPriority);
+                }
+                    break;
+                case UNREGISTER_AUDIO_THREAD: {
+                    UnregisterAudioThreadParam *param =
+                            (UnregisterAudioThreadParam *) command->parameter.get();
+                    command->result =
+                            param == nullptr ? AAUDIO_ERROR_ILLEGAL_ARGUMENT
+                                             : unregisterAudioThread_l(param->mClientThreadId);
+                }
+                    break;
+                case GET_DESCRIPTION: {
+                    GetDescriptionParam *param = (GetDescriptionParam *) command->parameter.get();
+                    command->result = param == nullptr ? AAUDIO_ERROR_ILLEGAL_ARGUMENT
+                                                        : getDescription_l(param->mParcelable);
+                }
+                    break;
+                default:
+                    ALOGE("Invalid command op code: %d", command->operationCode);
+                    break;
+            }
+            if (command->isWaitingForReply) {
+                command->isWaitingForReply = false;
+                command->conditionVariable.notify_one();
+            }
         }
     }
-    // This was moved from the calls in stop_l() and pause_l(), which could cause a deadlock
-    // if it resulted in a call to disconnect.
-    if (result == AAUDIO_OK) {
-        (void) sendCurrentTimestamp();
-    }
-    ALOGD("%s() %s exiting after %d loops <<<<<<<<<<<<<< TIMESTAMPS",
+    ALOGD("%s() %s exiting after %d loops <<<<<<<<<<<<<< COMMANDS",
           __func__, getTypeText(), loopCount);
 }
 
 void AAudioServiceStreamBase::disconnect() {
-    std::lock_guard<std::mutex> lock(mLock);
-    disconnect_l();
+    auto command = std::make_shared<AAudioCommand>(DISCONNECT);
+    mCommandQueue.sendCommand(command);
 }
 
 void AAudioServiceStreamBase::disconnect_l() {
@@ -461,15 +531,23 @@
     }
 }
 
-aaudio_result_t AAudioServiceStreamBase::registerAudioThread(pid_t clientThreadId,
-        int priority) {
-    std::lock_guard<std::mutex> lock(mLock);
+aaudio_result_t AAudioServiceStreamBase::registerAudioThread(pid_t clientThreadId, int priority) {
+    const pid_t ownerPid = IPCThreadState::self()->getCallingPid(); // TODO review
+    auto command = std::make_shared<AAudioCommand>(
+            REGISTER_AUDIO_THREAD,
+            std::make_shared<RegisterAudioThreadParam>(ownerPid, clientThreadId, priority),
+            true /*waitForReply*/,
+            TIMEOUT_NANOS);
+    return mCommandQueue.sendCommand(command);
+}
+
+aaudio_result_t AAudioServiceStreamBase::registerAudioThread_l(
+        pid_t ownerPid, pid_t clientThreadId, int priority) {
     aaudio_result_t result = AAUDIO_OK;
     if (getRegisteredThread() != AAudioServiceStreamBase::ILLEGAL_THREAD_ID) {
         ALOGE("AAudioService::registerAudioThread(), thread already registered");
         result = AAUDIO_ERROR_INVALID_STATE;
     } else {
-        const pid_t ownerPid = IPCThreadState::self()->getCallingPid(); // TODO review
         setRegisteredThread(clientThreadId);
         int err = android::requestPriority(ownerPid, clientThreadId,
                                            priority, true /* isForApp */);
@@ -483,7 +561,15 @@
 }
 
 aaudio_result_t AAudioServiceStreamBase::unregisterAudioThread(pid_t clientThreadId) {
-    std::lock_guard<std::mutex> lock(mLock);
+    auto command = std::make_shared<AAudioCommand>(
+            UNREGISTER_AUDIO_THREAD,
+            std::make_shared<UnregisterAudioThreadParam>(clientThreadId),
+            true /*waitForReply*/,
+            TIMEOUT_NANOS);
+    return mCommandQueue.sendCommand(command);
+}
+
+aaudio_result_t AAudioServiceStreamBase::unregisterAudioThread_l(pid_t clientThreadId) {
     aaudio_result_t result = AAUDIO_OK;
     if (getRegisteredThread() != clientThreadId) {
         ALOGE("%s(), wrong thread", __func__);
@@ -552,7 +638,7 @@
     return sendServiceEvent(AAUDIO_SERVICE_EVENT_XRUN, (int64_t) xRunCount);
 }
 
-aaudio_result_t AAudioServiceStreamBase::sendCurrentTimestamp() {
+aaudio_result_t AAudioServiceStreamBase::sendCurrentTimestamp_l() {
     AAudioServiceMessage command;
     // It is not worth filling up the queue with timestamps.
     // That can cause the stream to get suspended.
@@ -562,8 +648,8 @@
     }
 
     // Send a timestamp for the clock model.
-    aaudio_result_t result = getFreeRunningPosition(&command.timestamp.position,
-                                                    &command.timestamp.timestamp);
+    aaudio_result_t result = getFreeRunningPosition_l(&command.timestamp.position,
+                                                      &command.timestamp.timestamp);
     if (result == AAUDIO_OK) {
         ALOGV("%s() SERVICE  %8lld at %lld", __func__,
               (long long) command.timestamp.position,
@@ -573,8 +659,8 @@
 
         if (result == AAUDIO_OK) {
             // Send a hardware timestamp for presentation time.
-            result = getHardwareTimestamp(&command.timestamp.position,
-                                          &command.timestamp.timestamp);
+            result = getHardwareTimestamp_l(&command.timestamp.position,
+                                            &command.timestamp.timestamp);
             if (result == AAUDIO_OK) {
                 ALOGV("%s() HARDWARE %8lld at %lld", __func__,
                       (long long) command.timestamp.position,
@@ -596,7 +682,15 @@
  * used to communicate with the underlying HAL or Service.
  */
 aaudio_result_t AAudioServiceStreamBase::getDescription(AudioEndpointParcelable &parcelable) {
-    std::lock_guard<std::mutex> lock(mLock);
+    auto command = std::make_shared<AAudioCommand>(
+            GET_DESCRIPTION,
+            std::make_shared<GetDescriptionParam>(&parcelable),
+            true /*waitForReply*/,
+            TIMEOUT_NANOS);
+    return mCommandQueue.sendCommand(command);
+}
+
+aaudio_result_t AAudioServiceStreamBase::getDescription_l(AudioEndpointParcelable* parcelable) {
     {
         std::lock_guard<std::mutex> lock(mUpMessageQueueLock);
         if (mUpMessageQueue == nullptr) {
@@ -605,9 +699,9 @@
         }
         // Gather information on the message queue.
         mUpMessageQueue->fillParcelable(parcelable,
-                                        parcelable.mUpMessageQueueParcelable);
+                                        parcelable->mUpMessageQueueParcelable);
     }
-    return getAudioDataDescription(parcelable);
+    return getAudioDataDescription_l(parcelable);
 }
 
 void AAudioServiceStreamBase::onVolumeChanged(float volume) {