Ffmpeg extension: Wait for channel count and sample rate

When playing TrueHD streams, it's possible that the first decoded
buffer is empty, and that the channel count and sample rate are
still unknown. To correct for this, defer determining the format
until a buffer that will actually be output from the decoder has
been obtained, and only then query the channel count and sample
rate.

Issue: #8616
#minor-release
PiperOrigin-RevId: 366246245

RELEASENOTES.md

@@ -138,6 +138,9 @@
         ([#8447](https://github.com/google/ExoPlayer/issues/8447)).
 *   Update instructions and publishing configuration for releasing to Google's
     Maven repository instead of bintray/JCenter.
+*   FFmpeg extension: Fix playback failure when switching to TrueHD tracks
+    during playback
+    ([#8616](https://github.com/google/ExoPlayer/issues/8616)).
 
 ### 2.13.2 (2021-02-25)
 

extensions/ffmpeg/src/main/java/com/google/android/exoplayer2/ext/ffmpeg/FfmpegAudioDecoder.java

@@ -110,14 +110,18 @@ protected FfmpegDecoderException createUnexpectedDecodeException(Throwable error
     int inputSize = inputData.limit();
     ByteBuffer outputData = outputBuffer.init(inputBuffer.timeUs, outputBufferSize);
     int result = ffmpegDecode(nativeContext, inputData, inputSize, outputData, outputBufferSize);
-    if (result == AUDIO_DECODER_ERROR_INVALID_DATA) {
+    if (result == AUDIO_DECODER_ERROR_OTHER) {
+      return new FfmpegDecoderException("Error decoding (see logcat).");
+    } else if (result == AUDIO_DECODER_ERROR_INVALID_DATA) {
       // Treat invalid data errors as non-fatal to match the behavior of MediaCodec. No output will
       // be produced for this buffer, so mark it as decode-only to ensure that the audio sink's
       // position is reset when more audio is produced.
       outputBuffer.setFlags(C.BUFFER_FLAG_DECODE_ONLY);
       return null;
-    } else if (result == AUDIO_DECODER_ERROR_OTHER) {
-      return new FfmpegDecoderException("Error decoding (see logcat).");
+    } else if (result == 0) {
+      // There's no need to output empty buffers.
+      outputBuffer.setFlags(C.BUFFER_FLAG_DECODE_ONLY);
+      return null;
     }
     if (!hasOutputFormat) {
       channelCount = ffmpegGetChannelCount(nativeContext);