Fix handling of E-AC-3 streams with AC-3 frames

Issue: #6602
PiperOrigin-RevId: 287816831

RELEASENOTES.md

@@ -32,6 +32,8 @@
   ([#6733](https://github.com/google/ExoPlayer/issues/6733)). Incorrect handling
   could previously cause downloads to be paused when they should have been able
   to proceed.
+* Fix handling of E-AC-3 streams that contain AC-3 syncframes
+  ([#6602](https://github.com/google/ExoPlayer/issues/6602)).
 
 ### 2.11.1 (2019-12-20) ###
 

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

@@ -31,16 +31,16 @@
 
 /**
  * Utility methods for parsing Dolby TrueHD and (E-)AC-3 syncframes. (E-)AC-3 parsing follows the
- * definition in ETSI TS 102 366 V1.2.1.
+ * definition in ETSI TS 102 366 V1.4.1.
  */
 public final class Ac3Util {
 
   /** Holds sample format information as presented by a syncframe header. */
   public static final class SyncFrameInfo {
 
     /**
-     * AC3 stream types. See also ETSI TS 102 366 E.1.3.1.1. One of {@link #STREAM_TYPE_UNDEFINED},
-     * {@link #STREAM_TYPE_TYPE0}, {@link #STREAM_TYPE_TYPE1} or {@link #STREAM_TYPE_TYPE2}.
+     * AC3 stream types. See also E.1.3.1.1. One of {@link #STREAM_TYPE_UNDEFINED}, {@link
+     * #STREAM_TYPE_TYPE0}, {@link #STREAM_TYPE_TYPE1} or {@link #STREAM_TYPE_TYPE2}.
      */
     @Documented
     @Retention(RetentionPolicy.SOURCE)
@@ -114,9 +114,7 @@ private SyncFrameInfo(
    * The number of new samples per (E-)AC-3 audio block.
    */
   private static final int AUDIO_SAMPLES_PER_AUDIO_BLOCK = 256;
-  /**
-   * Each syncframe has 6 blocks that provide 256 new audio samples. See ETSI TS 102 366 4.1.
-   */
+  /** Each syncframe has 6 blocks that provide 256 new audio samples. See subsection 4.1. */
   private static final int AC3_SYNCFRAME_AUDIO_SAMPLE_COUNT = 6 * AUDIO_SAMPLES_PER_AUDIO_BLOCK;
   /**
    * Number of audio blocks per E-AC-3 syncframe, indexed by numblkscod.
@@ -134,20 +132,21 @@ private SyncFrameInfo(
    * Channel counts, indexed by acmod.
    */
   private static final int[] CHANNEL_COUNT_BY_ACMOD = new int[] {2, 1, 2, 3, 3, 4, 4, 5};
-  /**
-   * Nominal bitrates in kbps, indexed by frmsizecod / 2. (See ETSI TS 102 366 table 4.13.)
-   */
-  private static final int[] BITRATE_BY_HALF_FRMSIZECOD = new int[] {32, 40, 48, 56, 64, 80, 96,
-      112, 128, 160, 192, 224, 256, 320, 384, 448, 512, 576, 640};
-  /**
-   * 16-bit words per syncframe, indexed by frmsizecod / 2. (See ETSI TS 102 366 table 4.13.)
-   */
-  private static final int[] SYNCFRAME_SIZE_WORDS_BY_HALF_FRMSIZECOD_44_1 = new int[] {69, 87, 104,
-      121, 139, 174, 208, 243, 278, 348, 417, 487, 557, 696, 835, 975, 1114, 1253, 1393};
+  /** Nominal bitrates in kbps, indexed by frmsizecod / 2. (See table 4.13.) */
+  private static final int[] BITRATE_BY_HALF_FRMSIZECOD =
+      new int[] {
+        32, 40, 48, 56, 64, 80, 96, 112, 128, 160, 192, 224, 256, 320, 384, 448, 512, 576, 640
+      };
+  /** 16-bit words per syncframe, indexed by frmsizecod / 2. (See table 4.13.) */
+  private static final int[] SYNCFRAME_SIZE_WORDS_BY_HALF_FRMSIZECOD_44_1 =
+      new int[] {
+        69, 87, 104, 121, 139, 174, 208, 243, 278, 348, 417, 487, 557, 696, 835, 975, 1114, 1253,
+        1393
+      };
 
   /**
-   * Returns the AC-3 format given {@code data} containing the AC3SpecificBox according to ETSI TS
-   * 102 366 Annex F. The reading position of {@code data} will be modified.
+   * Returns the AC-3 format given {@code data} containing the AC3SpecificBox according to Annex F.
+   * The reading position of {@code data} will be modified.
    *
    * @param data The AC3SpecificBox to parse.
    * @param trackId The track identifier to set on the format.
@@ -179,8 +178,8 @@ public static Format parseAc3AnnexFFormat(
   }
 
   /**
-   * Returns the E-AC-3 format given {@code data} containing the EC3SpecificBox according to ETSI TS
-   * 102 366 Annex F. The reading position of {@code data} will be modified.
+   * Returns the E-AC-3 format given {@code data} containing the EC3SpecificBox according to Annex
+   * F. The reading position of {@code data} will be modified.
    *
    * @param data The EC3SpecificBox to parse.
    * @param trackId The track identifier to set on the format.
@@ -243,9 +242,10 @@ public static Format parseEAc3AnnexFFormat(
   public static SyncFrameInfo parseAc3SyncframeInfo(ParsableBitArray data) {
     int initialPosition = data.getPosition();
     data.skipBits(40);
-    boolean isEac3 = data.readBits(5) == 16; // See bsid in subsection E.1.3.1.6.
+    // Parse the bitstream ID for AC-3 and E-AC-3 (see subsections 4.3, E.1.2 and E.1.3.1.6).
+    boolean isEac3 = data.readBits(5) > 10;
     data.setPosition(initialPosition);
-    String mimeType;
+    @Nullable String mimeType;
     @StreamType int streamType = SyncFrameInfo.STREAM_TYPE_UNDEFINED;
     int sampleRate;
     int acmod;
@@ -254,7 +254,7 @@ public static SyncFrameInfo parseAc3SyncframeInfo(ParsableBitArray data) {
     boolean lfeon;
     int channelCount;
     if (isEac3) {
-      // Syntax from ETSI TS 102 366 V1.2.1 subsections E.1.2.1 and E.1.2.2.
+      // Subsection E.1.2.
       data.skipBits(16); // syncword
       switch (data.readBits(2)) { // strmtyp
         case 0:
@@ -472,7 +472,8 @@ public static int parseAc3SyncframeSize(byte[] data) {
     if (data.length < 6) {
       return C.LENGTH_UNSET;
     }
-    boolean isEac3 = ((data[5] & 0xFF) >> 3) == 16; // See bsid in subsection E.1.3.1.6.
+    // Parse the bitstream ID for AC-3 and E-AC-3 (see subsections 4.3, E.1.2 and E.1.3.1.6).
+    boolean isEac3 = ((data[5] & 0xF8) >> 3) > 10;
     if (isEac3) {
       int frmsiz = (data[2] & 0x07) << 8; // Most significant 3 bits.
       frmsiz |= data[3] & 0xFF; // Least significant 8 bits.
@@ -485,24 +486,22 @@ public static int parseAc3SyncframeSize(byte[] data) {
   }
 
   /**
-   * Returns the number of audio samples in an AC-3 syncframe.
-   */
-  public static int getAc3SyncframeAudioSampleCount() {
-    return AC3_SYNCFRAME_AUDIO_SAMPLE_COUNT;
-  }
-
-  /**
-   * Reads the number of audio samples represented by the given E-AC-3 syncframe. The buffer's
+   * Reads the number of audio samples represented by the given (E-)AC-3 syncframe. The buffer's
    * position is not modified.
    *
    * @param buffer The {@link ByteBuffer} from which to read the syncframe.
    * @return The number of audio samples represented by the syncframe.
    */
-  public static int parseEAc3SyncframeAudioSampleCount(ByteBuffer buffer) {
-    // See ETSI TS 102 366 subsection E.1.2.2.
-    int fscod = (buffer.get(buffer.position() + 4) & 0xC0) >> 6;
-    return AUDIO_SAMPLES_PER_AUDIO_BLOCK * (fscod == 0x03 ? 6
-        : BLOCKS_PER_SYNCFRAME_BY_NUMBLKSCOD[(buffer.get(buffer.position() + 4) & 0x30) >> 4]);
+  public static int parseAc3SyncframeAudioSampleCount(ByteBuffer buffer) {
+    // Parse the bitstream ID for AC-3 and E-AC-3 (see subsections 4.3, E.1.2 and E.1.3.1.6).
+    boolean isEac3 = ((buffer.get(buffer.position() + 5) & 0xF8) >> 3) > 10;
+    if (isEac3) {
+      int fscod = (buffer.get(buffer.position() + 4) & 0xC0) >> 6;
+      int numblkscod = fscod == 0x03 ? 3 : (buffer.get(buffer.position() + 4) & 0x30) >> 4;
+      return BLOCKS_PER_SYNCFRAME_BY_NUMBLKSCOD[numblkscod] * AUDIO_SAMPLES_PER_AUDIO_BLOCK;
+    } else {
+      return AC3_SYNCFRAME_AUDIO_SAMPLE_COUNT;
+    }
   }
 
   /**

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

@@ -1166,10 +1166,9 @@ private static int getFramesPerEncodedSample(@C.Encoding int encoding, ByteBuffe
       case C.ENCODING_DTS_HD:
         return DtsUtil.parseDtsAudioSampleCount(buffer);
       case C.ENCODING_AC3:
-        return Ac3Util.getAc3SyncframeAudioSampleCount();
       case C.ENCODING_E_AC3:
       case C.ENCODING_E_AC3_JOC:
-        return Ac3Util.parseEAc3SyncframeAudioSampleCount(buffer);
+        return Ac3Util.parseAc3SyncframeAudioSampleCount(buffer);
       case C.ENCODING_AC4:
         return Ac4Util.parseAc4SyncframeAudioSampleCount(buffer);
       case C.ENCODING_DOLBY_TRUEHD: