better handling of input format change for non-adaptive codecs

* this fixes a bug when switching from HE-AAC 22050Hz to AAC 44100Hz (the AudioTrack was not reset and we were trying to send a bad number of bytes, triggering a "AudioTrack.write() called with invalid size" error)
* this also improves quality switches, making it almost seamless

library/src/main/java/com/google/android/exoplayer/MediaCodecTrackRenderer.java

@@ -135,6 +135,25 @@ public abstract class MediaCodecTrackRenderer extends TrackRenderer {
    */
   private static final int RECONFIGURATION_STATE_QUEUE_PENDING = 2;
 
+  /**
+   * No reinit is needed
+   */
+  private static final int REINIT_STATE_NONE = 0;
+  /**
+   * The input format has just changed. Signal an end of stream to the codec so that we can
+   * retrieve the very last decoded samples from the previous format.
+   */
+  private static final int REINIT_STATE_SIGNAL_END_OF_STREAM = 1;
+  /**
+   * The end of stream has been sent, wait for the codec to acknowledge it.
+   */
+  private static final int REINIT_STATE_WAIT_END_OF_STREAM = 2;
+  /**
+   * The last sample has been processed, we can safely reinit now.
+   */
+  private static final int REINIT_STATE_DO_REINIT_NOW = 3;
+
+
   public final CodecCounters codecCounters;
 
   private final DrmSessionManager drmSessionManager;
@@ -159,6 +178,7 @@ public abstract class MediaCodecTrackRenderer extends TrackRenderer {
   private boolean openedDrmSession;
   private boolean codecReconfigured;
   private int codecReconfigurationState;
+  private int codecReinitState;
 
   private int trackIndex;
   private int sourceState;
@@ -166,6 +186,7 @@ public abstract class MediaCodecTrackRenderer extends TrackRenderer {
   private boolean outputStreamEnded;
   private boolean waitingForKeys;
   private boolean waitingForFirstSyncFrame;
+  private boolean hasQueuedOneInputBuffer;
   private long currentPositionUs;
 
   /**
@@ -194,6 +215,7 @@ public abstract class MediaCodecTrackRenderer extends TrackRenderer {
     formatHolder = new MediaFormatHolder();
     decodeOnlyPresentationTimestamps = new ArrayList<Long>();
     outputBufferInfo = new MediaCodec.BufferInfo();
+    codecReinitState = REINIT_STATE_NONE;
   }
 
   @Override
@@ -302,6 +324,7 @@ public abstract class MediaCodecTrackRenderer extends TrackRenderer {
     inputIndex = -1;
     outputIndex = -1;
     waitingForFirstSyncFrame = true;
+    hasQueuedOneInputBuffer = false;
     codecCounters.codecInitCount++;
   }
 
@@ -346,6 +369,7 @@ public abstract class MediaCodecTrackRenderer extends TrackRenderer {
       codecReconfigured = false;
       codecIsAdaptive = false;
       codecReconfigurationState = RECONFIGURATION_STATE_NONE;
+      codecReinitState = REINIT_STATE_NONE;
       codecCounters.codecReleaseCount++;
       try {
         codec.stop();
@@ -493,6 +517,13 @@ public abstract class MediaCodecTrackRenderer extends TrackRenderer {
     if (inputStreamEnded) {
       return false;
     }
+
+    if (codecReinitState == REINIT_STATE_DO_REINIT_NOW) {
+      releaseCodec();
+      maybeInitCodec();
+      return false;
+    }
+
     if (inputIndex < 0) {
       inputIndex = codec.dequeueInputBuffer(0);
       if (inputIndex < 0) {
@@ -502,6 +533,16 @@ public abstract class MediaCodecTrackRenderer extends TrackRenderer {
       sampleHolder.data.clear();
     }
 
+    if (codecReinitState == REINIT_STATE_SIGNAL_END_OF_STREAM) {
+      codec.queueInputBuffer(inputIndex, 0, 0, 0, MediaCodec.BUFFER_FLAG_END_OF_STREAM);
+      inputIndex = -1;
+      codecReinitState = REINIT_STATE_WAIT_END_OF_STREAM;
+      return false;
+    } else if (codecReinitState != REINIT_STATE_NONE) {
+      // we are still waiting for the last samples to be output
+      return false;
+    }
+
     int result;
     if (waitingForKeys) {
       // We've already read an encrypted sample into sampleHolder, and are waiting for keys.
@@ -591,6 +632,7 @@ public abstract class MediaCodecTrackRenderer extends TrackRenderer {
         codec.queueInputBuffer(inputIndex, 0 , bufferSize, presentationTimeUs, 0);
       }
       inputIndex = -1;
+      hasQueuedOneInputBuffer = true;
       codecReconfigurationState = RECONFIGURATION_STATE_NONE;
     } catch (CryptoException e) {
       notifyCryptoError(e);
@@ -644,8 +686,12 @@ public abstract class MediaCodecTrackRenderer extends TrackRenderer {
       codecReconfigured = true;
       codecReconfigurationState = RECONFIGURATION_STATE_WRITE_PENDING;
     } else {
-      releaseCodec();
+      if (!hasQueuedOneInputBuffer) {
-      maybeInitCodec();
+        // no need to signal end of stream if nothing has been queued, we can just reinit asap
+        codecReinitState = REINIT_STATE_DO_REINIT_NOW;
+      } else {
+        codecReinitState = REINIT_STATE_SIGNAL_END_OF_STREAM;
+      }
     }
   }
 
@@ -733,7 +779,12 @@ public abstract class MediaCodecTrackRenderer extends TrackRenderer {
     }
 
     if ((outputBufferInfo.flags & MediaCodec.BUFFER_FLAG_END_OF_STREAM) != 0) {
-      outputStreamEnded = true;
+      if (codecReinitState == REINIT_STATE_WAIT_END_OF_STREAM) {
+        codecReinitState = REINIT_STATE_DO_REINIT_NOW;
+      } else {
+        outputStreamEnded = true;
+      }
+
       return false;
     }