MediaPlayerService: fix AudioSink latency

The AudioSink latency is currently cached when the associated AudioTrack
is created. However, the AudioTrack latency can change if the AudioTrack is moved
from one output stream to another.
The AudioPlayer must also periodically update its view of the latency
as it is needed to compensate the real audio time used for A/V sync.

This fixes an A/V sync problem seen when switching A2DP on and off while
playing a video.

Change-Id: I28b24049ca114e1af3e24791dcc900f463536ba4

Conflicts:

	media/libmediaplayerservice/MediaPlayerService.cpp

Author: Eric Laurent

media/libmediaplayerservice/MediaPlayerService.cpp

@@ -320,7 +320,7 @@ status_t MediaPlayerService::AudioOutput::dump(int fd, const Vector<String16>& a
             mStreamType, mLeftVolume, mRightVolume);
     result.append(buffer);
     snprintf(buffer, 255, "  msec per frame(%f), latency (%d)\n",
-            mMsecsPerFrame, mLatency);
+            mMsecsPerFrame, (mTrack != 0) ? mTrack->latency() : -1);
     result.append(buffer);
     snprintf(buffer, 255, "  aux effect id(%d), send level (%f)\n",
             mAuxEffectId, mSendLevel);
@@ -1265,7 +1265,6 @@ MediaPlayerService::AudioOutput::AudioOutput(int sessionId)
     mStreamType = AUDIO_STREAM_MUSIC;
     mLeftVolume = 1.0;
     mRightVolume = 1.0;
-    mLatency = 0;
     mMsecsPerFrame = 0;
     mAuxEffectId = 0;
     mSendLevel = 0.0;
@@ -1324,7 +1323,8 @@ ssize_t MediaPlayerService::AudioOutput::frameSize() const
 
 uint32_t MediaPlayerService::AudioOutput::latency () const
 {
-    return mLatency;
+    if (mTrack == 0) return 0;
+    return mTrack->latency();
 }
 
 float MediaPlayerService::AudioOutput::msecsPerFrame() const
@@ -1403,7 +1403,6 @@ status_t MediaPlayerService::AudioOutput::open(
     t->setVolume(mLeftVolume, mRightVolume);
 
     mMsecsPerFrame = 1.e3 / (float) sampleRate;
-    mLatency = t->latency();
     mTrack = t;
 
     t->setAuxEffectSendLevel(mSendLevel);

media/libmediaplayerservice/MediaPlayerService.h

@@ -112,7 +112,6 @@ class MediaPlayerService : public BnMediaPlayerService
         float                   mLeftVolume;
         float                   mRightVolume;
         float                   mMsecsPerFrame;
-        uint32_t                mLatency;
         int                     mSessionId;
         float                   mSendLevel;
         int                     mAuxEffectId;

media/libstagefright/AudioPlayer.cpp

@@ -408,6 +408,12 @@ size_t AudioPlayer::fillBuffer(void *data, size_t size) {
                 break;
             }
 
+            if (mAudioSink != NULL) {
+                mLatencyUs = (int64_t)mAudioSink->latency() * 1000;
+            } else {
+                mLatencyUs = (int64_t)mAudioTrack->latency() * 1000;
+            }
+
             CHECK(mInputBuffer->meta_data()->findInt64(
                         kKeyTime, &mPositionTimeMediaUs));