diff --git a/services/audioflinger/AudioFlinger.cpp b/services/audioflinger/AudioFlinger.cpp
index 98f763e..2b6c848 100644
--- a/services/audioflinger/AudioFlinger.cpp
+++ b/services/audioflinger/AudioFlinger.cpp
@@ -1585,7 +1585,7 @@
     // assigned to HALs which do not have master mute support will apply master mute
     // during the mix operation.  Threads with HALs which do support master mute
     // will simply ignore the setting.
-    Vector<VolumeInterface *> volumeInterfaces = getAllVolumeInterfaces_l();
+    std::vector<sp<VolumeInterface>> volumeInterfaces = getAllVolumeInterfaces_l();
     for (size_t i = 0; i < volumeInterfaces.size(); i++) {
         volumeInterfaces[i]->setMasterMute(muted);
     }
@@ -1661,7 +1661,7 @@
                         "AUDIO_STREAM_PATCH must have full scale volume");
 
     AutoMutex lock(mLock);
-    VolumeInterface *volumeInterface = getVolumeInterface_l(output);
+    sp<VolumeInterface> volumeInterface = getVolumeInterface_l(output);
     if (volumeInterface == NULL) {
         return BAD_VALUE;
     }
@@ -1764,7 +1764,7 @@
 
     AutoMutex lock(mLock);
     mStreamTypes[stream].mute = muted;
-    Vector<VolumeInterface *> volumeInterfaces = getAllVolumeInterfaces_l();
+    std::vector<sp<VolumeInterface>> volumeInterfaces = getAllVolumeInterfaces_l();
     for (size_t i = 0; i < volumeInterfaces.size(); i++) {
         volumeInterfaces[i]->setStreamMute(stream, muted);
     }
@@ -1783,7 +1783,7 @@
     }
 
     AutoMutex lock(mLock);
-    VolumeInterface *volumeInterface = getVolumeInterface_l(output);
+    sp<VolumeInterface> volumeInterface = getVolumeInterface_l(output);
     if (volumeInterface == NULL) {
         return 0.0f;
     }
@@ -3786,9 +3786,9 @@
 
 
 // checkPlaybackThread_l() must be called with AudioFlinger::mLock held
-AudioFlinger::VolumeInterface *AudioFlinger::getVolumeInterface_l(audio_io_handle_t output) const
+sp<VolumeInterface> AudioFlinger::getVolumeInterface_l(audio_io_handle_t output) const
 {
-    VolumeInterface *volumeInterface = mPlaybackThreads.valueFor(output).get();
+    sp<VolumeInterface> volumeInterface = mPlaybackThreads.valueFor(output).get();
     if (volumeInterface == nullptr) {
         MmapThread *mmapThread = mMmapThreads.valueFor(output).get();
         if (mmapThread != nullptr) {
@@ -3802,17 +3802,17 @@
     return volumeInterface;
 }
 
-Vector <AudioFlinger::VolumeInterface *> AudioFlinger::getAllVolumeInterfaces_l() const
+std::vector<sp<VolumeInterface>> AudioFlinger::getAllVolumeInterfaces_l() const
 {
-    Vector <VolumeInterface *> volumeInterfaces;
+    std::vector<sp<VolumeInterface>> volumeInterfaces;
     for (size_t i = 0; i < mPlaybackThreads.size(); i++) {
-        volumeInterfaces.add(mPlaybackThreads.valueAt(i).get());
+        volumeInterfaces.push_back(mPlaybackThreads.valueAt(i).get());
     }
     for (size_t i = 0; i < mMmapThreads.size(); i++) {
         if (mMmapThreads.valueAt(i)->isOutput()) {
             MmapPlaybackThread *mmapPlaybackThread =
                     static_cast<MmapPlaybackThread *>(mMmapThreads.valueAt(i).get());
-            volumeInterfaces.add(mmapPlaybackThread);
+            volumeInterfaces.push_back(mmapPlaybackThread);
         }
     }
     return volumeInterfaces;
diff --git a/services/audioflinger/AudioFlinger.h b/services/audioflinger/AudioFlinger.h
index 6c59df0..3fcf693 100644
--- a/services/audioflinger/AudioFlinger.h
+++ b/services/audioflinger/AudioFlinger.h
@@ -102,6 +102,7 @@
 #include <datapath/SpdifStreamOut.h>
 #include <datapath/ThreadMetrics.h>
 #include <datapath/TrackMetrics.h>
+#include <datapath/VolumeInterface.h>
 #include <fastpath/FastCapture.h>
 #include <fastpath/FastMixer.h>
 #include <media/nbaio/NBAIO.h>
@@ -654,8 +655,8 @@
               MixerThread *checkMixerThread_l(audio_io_handle_t output) const;
               RecordThread *checkRecordThread_l(audio_io_handle_t input) const;
               MmapThread *checkMmapThread_l(audio_io_handle_t io) const;
-              VolumeInterface *getVolumeInterface_l(audio_io_handle_t output) const;
-              Vector <VolumeInterface *> getAllVolumeInterfaces_l() 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,
                                            audio_io_handle_t *input,
diff --git a/services/audioflinger/Threads.h b/services/audioflinger/Threads.h
index 29fb8fe..5925e02 100644
--- a/services/audioflinger/Threads.h
+++ b/services/audioflinger/Threads.h
@@ -848,19 +848,6 @@
                 void dumpEffectChains_l(int fd, const Vector<String16>& args);
 };
 
-class VolumeInterface {
- public:
-
-    virtual ~VolumeInterface() {}
-
-    virtual void        setMasterVolume(float value) = 0;
-    virtual void        setMasterMute(bool muted) = 0;
-    virtual void        setStreamVolume(audio_stream_type_t stream, float value) = 0;
-    virtual void        setStreamMute(audio_stream_type_t stream, bool muted) = 0;
-    virtual float       streamVolume(audio_stream_type_t stream) const = 0;
-
-};
-
 // --- PlaybackThread ---
 class PlaybackThread : public ThreadBase, public StreamOutHalInterfaceCallback,
                        public VolumeInterface, public StreamOutHalInterfaceEventCallback {
diff --git a/services/audioflinger/datapath/VolumeInterface.h b/services/audioflinger/datapath/VolumeInterface.h
new file mode 100644
index 0000000..4635e07
--- /dev/null
+++ b/services/audioflinger/datapath/VolumeInterface.h
@@ -0,0 +1,33 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <system/audio.h>
+
+namespace android {
+
+class VolumeInterface : public virtual RefBase {
+public:
+    virtual void setMasterVolume(float value) = 0;
+    virtual void setMasterMute(bool muted) = 0;
+    virtual void setStreamVolume(audio_stream_type_t stream, float value) = 0;
+    virtual void setStreamMute(audio_stream_type_t stream, bool muted) = 0;
+    // TODO(b/290699744) add "get" prefix for getter below.
+    virtual float streamVolume(audio_stream_type_t stream) const = 0;
+};
+
+}  // namespace android