Fix an issue that audio and video may run out of sync

media/base/android/java/src/org/chromium/media/MediaCodecBridge.java

Index: media/base/android/java/src/org/chromium/media/MediaCodecBridge.java
diff --git a/media/base/android/java/src/org/chromium/media/MediaCodecBridge.java b/media/base/android/java/src/org/chromium/media/MediaCodecBridge.java
index 29181ff69bcb52b1968fbd506119f26ca50a1ebb..25dad12d0fc035a2fa082df8117e3676f10e8c01 100644
--- a/media/base/android/java/src/org/chromium/media/MediaCodecBridge.java
+++ b/media/base/android/java/src/org/chromium/media/MediaCodecBridge.java
@@ -280,6 +280,8 @@ class MediaCodecBridge {
         try {
             mFlushed = true;
             if (mAudioTrack != null) {
+                // Need to call pause() here, or otherwise flush() is a no-op.
+                mAudioTrack.pause();
                 mAudioTrack.flush();
             }
             mMediaCodec.flush();
@@ -516,7 +518,7 @@ class MediaCodecBridge {
     }
 
     @CalledByNative
-    private void playOutputBuffer(byte[] buf) {
+    private long playOutputBuffer(byte[] buf) {
         if (mAudioTrack != null) {
             if (AudioTrack.PLAYSTATE_PLAYING != mAudioTrack.getPlayState()) {
                 mAudioTrack.play();
@@ -526,7 +528,14 @@ class MediaCodecBridge {
                 Log.i(TAG, "Failed to send all data to audio output, expected size: " +
                         buf.length + ", actual size: " + size);
             }
+            // TODO(qinmin): return the head position allows us to estimate

[wolenetz, 2014/04/01 18:15:47]

nit:s/return/Returning/

[qinmin, 2014/04/01 20:42:34]

Done.

+            // the current presentation time in native code. However, it is
+            // better to use AudioTrack.getCurrentTimestamp() to get the last
+            // known time when a frame is played. However, we will need to
+            // convert the java nano time to C++ timestamp.

[wolenetz, 2014/04/01 18:15:47]

Why don't we do this?

Also, we should account for long-running streams: Per
http://developer.android.com/reference/android/media/AudioTrack.html#getPlayb...:
"It will wrap (overflow) periodically, for example approximately once every
27:03:11 hours:minutes:seconds at 44.1 kHz"

[qinmin, 2014/04/01 20:42:34]

This CL fixes the general AV sync issue in both JB and KitKat.
I will do a separate CL for kitkat to use getCurrentTimestamp().
Before this overlows, AudioTimeStampHelper would also overflow. 
Updated the TODO to mention both cases here, and filed bug 358801

On 2014/04/01 18:15:47, wolenetz wrote:

+            return mAudioTrack.getPlaybackHeadPosition();
         }
+        return 0;
     }
 
     @CalledByNative