diff --git a/include/media/MediaPlayerInterface.h b/include/media/MediaPlayerInterface.h
index a5a1bb8..be06e33 100644
--- a/include/media/MediaPlayerInterface.h
+++ b/include/media/MediaPlayerInterface.h
@@ -62,7 +62,8 @@
     // AudioSink: abstraction layer for audio output
     class AudioSink : public RefBase {
     public:
-        typedef void (*AudioCallback)(
+        // Callback returns the number of bytes actually written to the buffer.
+        typedef size_t (*AudioCallback)(
                 AudioSink *audioSink, void *buffer, size_t size, void *cookie);
 
         virtual             ~AudioSink() {}
@@ -77,8 +78,7 @@
         virtual status_t    getPosition(uint32_t *position) = 0;
 
         // If no callback is specified, use the "write" API below to submit
-        // audio data. Otherwise return a full buffer of audio data on each
-        // callback.
+        // audio data.
         virtual status_t    open(
                 uint32_t sampleRate, int channelCount,
                 int format=AudioSystem::PCM_16_BIT,
diff --git a/include/media/stagefright/AudioPlayer.h b/include/media/stagefright/AudioPlayer.h
index 843e051..8e5f05f 100644
--- a/include/media/stagefright/AudioPlayer.h
+++ b/include/media/stagefright/AudioPlayer.h
@@ -90,11 +90,11 @@
     static void AudioCallback(int event, void *user, void *info);
     void AudioCallback(int event, void *info);
 
-    static void AudioSinkCallback(
+    static size_t AudioSinkCallback(
             MediaPlayerBase::AudioSink *audioSink,
             void *data, size_t size, void *me);
 
-    void fillBuffer(void *data, size_t size);
+    size_t fillBuffer(void *data, size_t size);
 
     int64_t getRealTimeUsLocked() const;