Allow audio position to jump on first input buffer

Allow the position to jump on receiving the first presentable input buffer,
if and only if the buffer timestamp differs significantly from what was
expected. This prevents a stuck buffering case for streams that are thought
to start at t=0, but actually start at t=large_value.

library/core/src/main/java/com/google/android/exoplayer2/audio/MediaCodecAudioRenderer.java

@@ -29,6 +29,7 @@ import com.google.android.exoplayer2.Format;
 import com.google.android.exoplayer2.PlaybackParameters;
 import com.google.android.exoplayer2.PlayerMessage.Target;
 import com.google.android.exoplayer2.audio.AudioRendererEventListener.EventDispatcher;
+import com.google.android.exoplayer2.decoder.DecoderInputBuffer;
 import com.google.android.exoplayer2.drm.DrmInitData;
 import com.google.android.exoplayer2.drm.DrmSessionManager;
 import com.google.android.exoplayer2.drm.FrameworkMediaCrypto;
@@ -70,6 +71,7 @@ public class MediaCodecAudioRenderer extends MediaCodecRenderer implements Media
   private int encoderDelay;
   private int encoderPadding;
   private long currentPositionUs;
+  private boolean allowFirstBufferPositionDiscontinuity;
   private boolean allowPositionDiscontinuity;
 
   /**
@@ -366,6 +368,7 @@ public class MediaCodecAudioRenderer extends MediaCodecRenderer implements Media
     super.onPositionReset(positionUs, joining);
     audioSink.reset();
     currentPositionUs = positionUs;
+    allowFirstBufferPositionDiscontinuity = true;
     allowPositionDiscontinuity = true;
   }
 
@@ -424,6 +427,19 @@ public class MediaCodecAudioRenderer extends MediaCodecRenderer implements Media
     return audioSink.getPlaybackParameters();
   }
 
+  @Override
+  protected void onQueueInputBuffer(DecoderInputBuffer buffer) {
+    if (allowFirstBufferPositionDiscontinuity && !buffer.isDecodeOnly()) {
+      // TODO: Remove this hack once we have a proper fix for [Internal: b/71876314].
+      // Allow the position to jump if the first presentable input buffer has a timestamp that
+      // differs significantly from what was expected.
+      if (Math.abs(buffer.timeUs - currentPositionUs) > 500000) {
+        currentPositionUs = buffer.timeUs;
+      }
+      allowFirstBufferPositionDiscontinuity = false;
+    }
+  }
+
   @Override
   protected boolean processOutputBuffer(long positionUs, long elapsedRealtimeUs, MediaCodec codec,
       ByteBuffer buffer, int bufferIndex, int bufferFlags, long bufferPresentationTimeUs,

library/core/src/main/java/com/google/android/exoplayer2/audio/SimpleDecoderAudioRenderer.java

@@ -105,6 +105,7 @@ public abstract class SimpleDecoderAudioRenderer extends BaseRenderer implements
   private boolean audioTrackNeedsConfigure;
 
   private long currentPositionUs;
+  private boolean allowFirstBufferPositionDiscontinuity;
   private boolean allowPositionDiscontinuity;
   private boolean inputStreamEnded;
   private boolean outputStreamEnded;
@@ -416,6 +417,7 @@ public abstract class SimpleDecoderAudioRenderer extends BaseRenderer implements
       return false;
     }
     inputBuffer.flip();
+    onQueueInputBuffer(inputBuffer);
     decoder.queueInputBuffer(inputBuffer);
     decoderReceivedBuffers = true;
     decoderCounters.inputBufferCount++;
@@ -504,6 +506,7 @@ public abstract class SimpleDecoderAudioRenderer extends BaseRenderer implements
   protected void onPositionReset(long positionUs, boolean joining) throws ExoPlaybackException {
     audioSink.reset();
     currentPositionUs = positionUs;
+    allowFirstBufferPositionDiscontinuity = true;
     allowPositionDiscontinuity = true;
     inputStreamEnded = false;
     outputStreamEnded = false;
@@ -654,6 +657,18 @@ public abstract class SimpleDecoderAudioRenderer extends BaseRenderer implements
     eventDispatcher.inputFormatChanged(newFormat);
   }
 
+  private void onQueueInputBuffer(DecoderInputBuffer buffer) {
+    if (allowFirstBufferPositionDiscontinuity && !buffer.isDecodeOnly()) {
+      // TODO: Remove this hack once we have a proper fix for [Internal: b/71876314].
+      // Allow the position to jump if the first presentable input buffer has a timestamp that
+      // differs significantly from what was expected.
+      if (Math.abs(buffer.timeUs - currentPositionUs) > 500000) {
+        currentPositionUs = buffer.timeUs;
+      }
+      allowFirstBufferPositionDiscontinuity = false;
+    }
+  }
+
   private void updateCurrentPosition() {
     long newCurrentPositionUs = audioSink.getCurrentPositionUs(isEnded());
     if (newCurrentPositionUs != AudioSink.CURRENT_POSITION_NOT_SET) {