Add support for Dolby TrueHD passthrough

Issue: #2147

-------------
Created by MOE: https:/google/moe
MOE_MIGRATED_REVID=180678595

RELEASENOTES.md

@@ -39,6 +39,8 @@
 * DefaultTrackSelector: Support disabling of individual text track selection
  flags.
 * New Cast extension: Simplifies toggling between local and Cast playbacks.
+* Audio: Support TrueHD passthrough for rechunked samples in Matroska files
+ ([#2147](https:/google/ExoPlayer/issues/2147)).
 
 ### 2.6.1 ###
 

library/core/src/main/java/com/google/android/exoplayer2/C.java

@@ -122,13 +122,22 @@ private C() {}
  */
  public static final int AUDIO_SESSION_ID_UNSET = AudioManager.AUDIO_SESSION_ID_GENERATE;
 
- /**
- * Represents an audio encoding, or an invalid or unset value.
- */
+ /** Represents an audio encoding, or an invalid or unset value. */
  @Retention(RetentionPolicy.SOURCE)
- @IntDef({Format.NO_VALUE, ENCODING_INVALID, ENCODING_PCM_8BIT, ENCODING_PCM_16BIT,
- ENCODING_PCM_24BIT, ENCODING_PCM_32BIT, ENCODING_PCM_FLOAT, ENCODING_AC3, ENCODING_E_AC3,
- ENCODING_DTS, ENCODING_DTS_HD})
+ @IntDef({
+ Format.NO_VALUE,
+ ENCODING_INVALID,
+ ENCODING_PCM_8BIT,
+ ENCODING_PCM_16BIT,
+ ENCODING_PCM_24BIT,
+ ENCODING_PCM_32BIT,
+ ENCODING_PCM_FLOAT,
+ ENCODING_AC3,
+ ENCODING_E_AC3,
+ ENCODING_DTS,
+ ENCODING_DTS_HD,
+ ENCODING_DOLBY_TRUEHD
+ })
  public @interface Encoding {}
 
  /**
@@ -138,46 +147,28 @@ private C() {}
  @IntDef({Format.NO_VALUE, ENCODING_INVALID, ENCODING_PCM_8BIT, ENCODING_PCM_16BIT,
  ENCODING_PCM_24BIT, ENCODING_PCM_32BIT, ENCODING_PCM_FLOAT})
  public @interface PcmEncoding {}
- /**
- * @see AudioFormat#ENCODING_INVALID
- */
+ /** @see AudioFormat#ENCODING_INVALID */
  public static final int ENCODING_INVALID = AudioFormat.ENCODING_INVALID;
- /**
- * @see AudioFormat#ENCODING_PCM_8BIT
- */
+ /** @see AudioFormat#ENCODING_PCM_8BIT */
  public static final int ENCODING_PCM_8BIT = AudioFormat.ENCODING_PCM_8BIT;
- /**
- * @see AudioFormat#ENCODING_PCM_16BIT
- */
+ /** @see AudioFormat#ENCODING_PCM_16BIT */
  public static final int ENCODING_PCM_16BIT = AudioFormat.ENCODING_PCM_16BIT;
- /**
- * PCM encoding with 24 bits per sample.
- */
+ /** PCM encoding with 24 bits per sample. */
  public static final int ENCODING_PCM_24BIT = 0x80000000;
- /**
- * PCM encoding with 32 bits per sample.
- */
+ /** PCM encoding with 32 bits per sample. */
  public static final int ENCODING_PCM_32BIT = 0x40000000;
- /**
- * @see AudioFormat#ENCODING_PCM_FLOAT
- */
+ /** @see AudioFormat#ENCODING_PCM_FLOAT */
  public static final int ENCODING_PCM_FLOAT = AudioFormat.ENCODING_PCM_FLOAT;
- /**
- * @see AudioFormat#ENCODING_AC3
- */
+ /** @see AudioFormat#ENCODING_AC3 */
  public static final int ENCODING_AC3 = AudioFormat.ENCODING_AC3;
- /**
- * @see AudioFormat#ENCODING_E_AC3
- */
+ /** @see AudioFormat#ENCODING_E_AC3 */
  public static final int ENCODING_E_AC3 = AudioFormat.ENCODING_E_AC3;
- /**
- * @see AudioFormat#ENCODING_DTS
- */
+ /** @see AudioFormat#ENCODING_DTS */
  public static final int ENCODING_DTS = AudioFormat.ENCODING_DTS;
- /**
- * @see AudioFormat#ENCODING_DTS_HD
- */
+ /** @see AudioFormat#ENCODING_DTS_HD */
  public static final int ENCODING_DTS_HD = AudioFormat.ENCODING_DTS_HD;
+ /** @see AudioFormat#ENCODING_DOLBY_TRUEHD */
+ public static final int ENCODING_DOLBY_TRUEHD = AudioFormat.ENCODING_DOLBY_TRUEHD;
 
  /**
  * @see AudioFormat#CHANNEL_OUT_7POINT1_SURROUND

library/core/src/main/java/com/google/android/exoplayer2/audio/Ac3Util.java

@@ -27,9 +27,7 @@
 import com.google.android.exoplayer2.util.ParsableByteArray;
 import java.nio.ByteBuffer;
 
-/**
- * Utility methods for parsing (E-)AC-3 syncframes, which are access units in (E-)AC-3 bitstreams.
- */
+/** Utility methods for parsing Dolby TrueHD and (E-)AC3 syncframes. */
 public final class Ac3Util {
 
  /**
@@ -93,6 +91,17 @@ private Ac3SyncFrameInfo(String mimeType, int streamType, int channelCount, int
 
  }
 
+ /**
+ * The number of samples to store in each output chunk when rechunking TrueHD streams. The number
+ * of samples extracted from the container corresponding to one syncframe must be an integer
+ * multiple of this value.
+ */
+ public static final int TRUEHD_RECHUNK_SAMPLE_COUNT = 8;
+ /**
+ * The number of bytes that must be parsed from a TrueHD syncframe to calculate the sample count.
+ */
+ public static final int TRUEHD_SYNCFRAME_PREFIX_LENGTH = 12;
+
  /**
  * The number of new samples per (E-)AC-3 audio block.
  */
@@ -441,6 +450,43 @@ public static int parseEAc3SyncframeAudioSampleCount(ByteBuffer buffer) {
  : BLOCKS_PER_SYNCFRAME_BY_NUMBLKSCOD[(buffer.get(buffer.position() + 4) & 0x30) >> 4]);
  }
 
+ /**
+ * Returns the number of audio samples represented by the given TrueHD syncframe, or 0 if the
+ * buffer is not the start of a syncframe.
+ *
+ * @param syncframe The bytes from which to read the syncframe. Must be at least {@link
+ * #TRUEHD_SYNCFRAME_PREFIX_LENGTH} bytes long.
+ * @return The number of audio samples represented by the syncframe, or 0 if the buffer doesn't
+ * contain the start of a syncframe.
+ */
+ public static int parseTrueHdSyncframeAudioSampleCount(byte[] syncframe) {
+ // TODO: Link to specification if available.
+ if (syncframe[4] != (byte) 0xF8
+ || syncframe[5] != (byte) 0x72
+ || syncframe[6] != (byte) 0x6F
+ || syncframe[7] != (byte) 0xBA) {
+ return 0;
+ }
+ return 40 << (syncframe[8] & 7);
+ }
+
+ /**
+ * Reads the number of audio samples represented by the given TrueHD syncframe, or 0 if the buffer
+ * is not the start of a syncframe. The buffer's position is not modified.
+ *
+ * @param buffer The {@link ByteBuffer} from which to read the syncframe. Must have at least
+ * {@link #TRUEHD_SYNCFRAME_PREFIX_LENGTH} bytes remaining.
+ * @return The number of audio samples represented by the syncframe, or 0 if the buffer is not the
+ * start of a syncframe.
+ */
+ public static int parseTrueHdSyncframeAudioSampleCount(ByteBuffer buffer) {
+ // TODO: Link to specification if available.
+ if (buffer.getInt(buffer.position() + 4) != 0xBA6F72F8) {
+ return 0;
+ }
+ return 40 << (buffer.get(buffer.position() + 8) & 0x07);
+ }
+
  private static int getAc3SyncframeSize(int fscod, int frmsizecod) {
  int halfFrmsizecod = frmsizecod / 2;
  if (fscod < 0 || fscod >= SAMPLE_RATE_BY_FSCOD.length || frmsizecod < 0

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

@@ -446,9 +446,12 @@ public void configure(@C.Encoding int inputEncoding, int inputChannelCount, int
  if (outputEncoding == C.ENCODING_AC3 || outputEncoding == C.ENCODING_E_AC3) {
  // AC-3 allows bitrates up to 640 kbit/s.
  bufferSize = (int) (PASSTHROUGH_BUFFER_DURATION_US * 80 * 1024 / C.MICROS_PER_SECOND);
- } else /* (outputEncoding == C.ENCODING_DTS || outputEncoding == C.ENCODING_DTS_HD */ {
+ } else if (outputEncoding == C.ENCODING_DTS) {
  // DTS allows an 'open' bitrate, but we assume the maximum listed value: 1536 kbit/s.
  bufferSize = (int) (PASSTHROUGH_BUFFER_DURATION_US * 192 * 1024 / C.MICROS_PER_SECOND);
+ } else /* outputEncoding == C.ENCODING_DTS_HD || outputEncoding == C.ENCODING_DOLBY_TRUEHD*/ {
+ // HD passthrough requires a larger buffer to avoid underrun.
+ bufferSize = (int) (PASSTHROUGH_BUFFER_DURATION_US * 192 * 6 * 1024 / C.MICROS_PER_SECOND);
  }
  }
  bufferSizeUs =
@@ -580,6 +583,13 @@ public boolean handleBuffer(ByteBuffer buffer, long presentationTimeUs)
  if (!isInputPcm && framesPerEncodedSample == 0) {
  // If this is the first encoded sample, calculate the sample size in frames.
  framesPerEncodedSample = getFramesPerEncodedSample(outputEncoding, buffer);
+ if (framesPerEncodedSample == 0) {
+ // We still don't know the number of frames per sample, so drop the buffer.
+ // For TrueHD this can occur after some seek operations, as not every sample starts with
+ // a syncframe header. If we chunked samples together so the extracted samples always
+ // started with a syncframe header, the chunks would be too large.
+ return true;
+ }
  }
 
  if (drainingPlaybackParameters != null) {
@@ -1225,6 +1235,9 @@ private static int getFramesPerEncodedSample(@C.Encoding int encoding, ByteBuffe
  return Ac3Util.getAc3SyncframeAudioSampleCount();
  } else if (encoding == C.ENCODING_E_AC3) {
  return Ac3Util.parseEAc3SyncframeAudioSampleCount(buffer);
+ } else if (encoding == C.ENCODING_DOLBY_TRUEHD) {
+ return Ac3Util.parseTrueHdSyncframeAudioSampleCount(buffer)
+ * Ac3Util.TRUEHD_RECHUNK_SAMPLE_COUNT;
  } else {
  throw new IllegalStateException("Unexpected audio encoding: " + encoding);
  }