From ae40208d92b19535d12d81ebb38f95fe90ba155c Mon Sep 17 00:00:00 2001
From: ybai001 <ybai@dolby.com>
Date: Mon, 24 Dec 2018 09:38:52 +0800
Subject: [PATCH 1/6] Add AC-4 format support

 * Add AC-4 MIME type definition
 * Add AC-4 format support in Mp4Extractor and TsExtractor
 * Add AC-4 Extractor
 * Add AC-4 playback support in MPEG-4, MPEG-DASH, TS and HLS
---
 .../java/com/google/android/exoplayer2/C.java |   9 +-
 .../android/exoplayer2/audio/Ac4Util.java     | 269 ++++++++++++++++++
 .../exoplayer2/audio/DefaultAudioSink.java    |   4 +
 .../audio/MediaCodecAudioRenderer.java        |   5 +
 .../extractor/DefaultExtractorsFactory.java   |   6 +-
 .../exoplayer2/extractor/mp4/Atom.java        |   2 +
 .../exoplayer2/extractor/mp4/AtomParsers.java |   8 +
 .../extractor/mp4/FragmentedMp4Extractor.java |   8 +
 .../extractor/mp4/Mp4Extractor.java           |   9 +
 .../exoplayer2/extractor/ts/Ac4Extractor.java | 162 +++++++++++
 .../exoplayer2/extractor/ts/Ac4Reader.java    | 215 ++++++++++++++
 .../ts/DefaultTsPayloadReaderFactory.java     |   2 +
 .../exoplayer2/extractor/ts/TsExtractor.java  |  14 +
 .../android/exoplayer2/util/MimeTypes.java    |   7 +
 .../hls/DefaultHlsExtractorFactory.java       |  14 +
 15 files changed, 729 insertions(+), 5 deletions(-)
 create mode 100644 library/core/src/main/java/com/google/android/exoplayer2/audio/Ac4Util.java
 create mode 100644 library/core/src/main/java/com/google/android/exoplayer2/extractor/ts/Ac4Extractor.java
 create mode 100644 library/core/src/main/java/com/google/android/exoplayer2/extractor/ts/Ac4Reader.java

diff --git a/library/core/src/main/java/com/google/android/exoplayer2/C.java b/library/core/src/main/java/com/google/android/exoplayer2/C.java
index fac9818d9ec..315551fa62a 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/C.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/C.java
@@ -143,8 +143,8 @@ private C() {}
    * {@link #ENCODING_INVALID}, {@link #ENCODING_PCM_8BIT}, {@link #ENCODING_PCM_16BIT}, {@link
    * #ENCODING_PCM_24BIT}, {@link #ENCODING_PCM_32BIT}, {@link #ENCODING_PCM_FLOAT}, {@link
    * #ENCODING_PCM_MU_LAW}, {@link #ENCODING_PCM_A_LAW}, {@link #ENCODING_AC3}, {@link
-   * #ENCODING_E_AC3}, {@link #ENCODING_DTS}, {@link #ENCODING_DTS_HD} or {@link
-   * #ENCODING_DOLBY_TRUEHD}.
+   * #ENCODING_E_AC3}, {@link #ENCODING_DTS}, {@link #ENCODING_DTS_HD}, {@link
+   * #ENCODING_DOLBY_TRUEHD} or {@link #ENCODING_AC4}.
    */
   @Documented
   @Retention(RetentionPolicy.SOURCE)
@@ -162,7 +162,8 @@ private C() {}
     ENCODING_E_AC3,
     ENCODING_DTS,
     ENCODING_DTS_HD,
-    ENCODING_DOLBY_TRUEHD
+    ENCODING_DOLBY_TRUEHD,
+    ENCODING_AC4
   })
   public @interface Encoding {}
 
@@ -212,6 +213,8 @@ private C() {}
   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#ENCODING_AC4 */
+  public static final int ENCODING_AC4 = AudioFormat.ENCODING_AC4;
 
   /**
    * Stream types for an {@link android.media.AudioTrack}. One of {@link #STREAM_TYPE_ALARM}, {@link
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/audio/Ac4Util.java b/library/core/src/main/java/com/google/android/exoplayer2/audio/Ac4Util.java
new file mode 100644
index 00000000000..9b845a14d43
--- /dev/null
+++ b/library/core/src/main/java/com/google/android/exoplayer2/audio/Ac4Util.java
@@ -0,0 +1,269 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.google.android.exoplayer2.audio;
+
+import com.google.android.exoplayer2.C;
+import com.google.android.exoplayer2.Format;
+import com.google.android.exoplayer2.drm.DrmInitData;
+import com.google.android.exoplayer2.util.MimeTypes;
+import com.google.android.exoplayer2.util.ParsableBitArray;
+import com.google.android.exoplayer2.util.ParsableByteArray;
+import java.nio.ByteBuffer;
+
+/**
+ * Utility methods for parsing AC-4 frames, which are access units in AC-4 bitstreams.
+ */
+public final class Ac4Util {
+
+  /**
+   * Holds sample format information as presented by a syncframe header.
+   */
+  public static final class SyncFrameInfo {
+
+    /**
+     * The sample mime type of the bitstream is {@link MimeTypes#AUDIO_AC4}.
+     */
+    public final String mimeType;
+    /**
+     * The bitstream version.
+     */
+    public final int bitstreamVersion;
+    /**
+     * The audio sampling rate in Hz.
+     */
+    public final int sampleRate;
+    /**
+     * The number of audio channels
+     */
+    public final int channelCount;
+    /**
+     * The size of the frame.
+     */
+    public final int frameSize;
+    /**
+     * Number of audio samples in the frame.
+     */
+    public final int sampleCount;
+
+    private SyncFrameInfo(
+        String mimeType,
+        int bitstreamVersion,
+        int channelCount,
+        int sampleRate,
+        int frameSize,
+        int sampleCount) {
+      this.mimeType = mimeType;
+      this.bitstreamVersion = bitstreamVersion;
+      this.channelCount = channelCount;
+      this.sampleRate = sampleRate;
+      this.frameSize = frameSize;
+      this.sampleCount = sampleCount;
+    }
+  }
+
+  /**
+   * The channel count of AC-4 stream.
+   */
+  // TODO: Parse AC-4 stream channel count.
+  public static final int CHANNEL_COUNT_2 = 2;
+  /**
+   * The header size for AC-4 parser. Only needs to be as big as we need to read, not the full
+   * header size.
+   */
+  public static final int HEADER_SIZE_FOR_PARSER = 16;
+  /**
+   * Number of audio samples in the frame. Defined in IEC61937-14:2017 table 5 and 6. This table
+   * provides the number of samples per frame at the playback sampling frequency of 48kHz. For
+   * 44.1kHz, only frame_rate_index(13) is valid and corresponding sample count is 2048.
+   */
+  private static final int[] SAMPLE_COUNT = new int[] {
+      /* [ 0]  23.976 fps */ 2002,
+      /* [ 1]  24     fps */ 2000,
+      /* [ 2]  25     fps */ 1920,
+      /* [ 3]  29.97  fps */ 1601,  // 1601 | 1602 | 1601 | 1602 | 1602
+      /* [ 4]  30     fps */ 1600,
+      /* [ 5]  47.95  fps */ 1001,
+      /* [ 6]  48     fps */ 1000,
+      /* [ 7]  50     fps */  960,
+      /* [ 8]  59.94  fps */  800,  //  800 |  801 |  801 |  801 |  801
+      /* [ 9]  60     fps */  800,
+      /* [10] 100     fps */  480,
+      /* [11] 119.88  fps */  400,  //  400 |  400 |  401 |  400 |  401
+      /* [12] 120     fps */  400,
+      /* [13]  23.438 fps */ 2048
+  };
+
+  /**
+   * Returns the AC-4 format given {@code data} containing the AC4SpecificBox according to ETSI TS
+   * 103 190-1 Annex E. The reading position of {@code data} will be modified.
+   *
+   * @param data The AC4SpecificBox to parse.
+   * @param trackId The track identifier to set on the format.
+   * @param language The language to set on the format.
+   * @param drmInitData {@link DrmInitData} to be included in the format.
+   * @return The AC-4 format parsed from data in the header.
+   */
+  public static Format parseAc4AnnexEFormat(
+      ParsableByteArray data, String trackId, String language, DrmInitData drmInitData) {
+    data.skipBytes(1);
+    int sampleRate = ((data.readUnsignedByte() & 0x20) >> 5 == 1) ? 48000 : 44100;
+    return Format.createAudioSampleFormat(
+        trackId,
+        MimeTypes.AUDIO_AC4,
+        null,
+        Format.NO_VALUE,
+        Format.NO_VALUE,
+        CHANNEL_COUNT_2,
+        sampleRate,
+        null,
+        drmInitData,
+        0,
+        language);
+  }
+
+  private static int readVariableBits(ParsableBitArray data, int nbits) {
+    int value = 0;
+    while (true) {
+      int moreBits;
+      value += data.readBits(nbits);
+      moreBits = data.readBits(1);
+      if (moreBits == 0)
+        break;
+      value++;
+      value <<= nbits;
+    }
+    return value;
+  }
+
+  /**
+   * Returns AC-4 format information given {@code data} containing a syncframe. The reading
+   * position of {@code data} will be modified.
+   *
+   * @param data The data to parse, positioned at the start of the syncframe.
+   * @return The AC-4 format data parsed from the header.
+   */
+  public static SyncFrameInfo parseAc4SyncframeInfo(ParsableBitArray data) {
+    int headerSize = 0;
+    int syncWord  = data.readBits(16);
+    headerSize += 2;
+    int frameSize = data.readBits(16);
+    headerSize += 2;
+    if (frameSize == 0xFFFF) {
+      frameSize = data.readBits(24);
+      headerSize += 3;
+    }
+    frameSize += headerSize;
+    if (syncWord == 0xAC41) {
+      frameSize += 2;
+    }
+    int bitstreamVersion = data.readBits(2);
+    if (bitstreamVersion == 3){
+      bitstreamVersion += readVariableBits(data, 2);
+    }
+    int sequenceCounter = data.readBits(10);
+    if (data.readBits(1) == 1) {
+      if (data.readBits(3) > 0){
+        data.skipBits(2);
+      }
+    }
+    int sampleRate = (data.readBits(1) == 1) ? 48000 : 44100;
+    int frameRateIndex = data.readBits(4);
+    int sampleCount = 0;
+    if (sampleRate == 44100 && frameRateIndex == 13) {
+      sampleCount = SAMPLE_COUNT[frameRateIndex];
+    } else if (sampleRate == 48000 && frameRateIndex < SAMPLE_COUNT.length) {
+      sampleCount = SAMPLE_COUNT[frameRateIndex];
+      switch (sequenceCounter % 5) {
+        case 1:
+        case 3:
+          if (frameRateIndex == 3 || frameRateIndex == 8) {
+            sampleCount++;
+          }
+          break;
+        case 2:
+          if (frameRateIndex == 8 || frameRateIndex == 11) {
+            sampleCount++;
+          }
+          break;
+        case 4:
+          if (frameRateIndex == 3 || frameRateIndex == 8 || frameRateIndex == 11) {
+            sampleCount++;
+          }
+          break;
+        default:
+          break;
+      }
+    }
+    return new SyncFrameInfo(
+        MimeTypes.AUDIO_AC4, bitstreamVersion, CHANNEL_COUNT_2, sampleRate, frameSize, sampleCount);
+  }
+
+  /**
+   * Returns the size in bytes of the given AC-4 syncframe.
+   *
+   * @param data The syncframe to parse.
+   * @return The syncframe size in bytes. {@link C#LENGTH_UNSET} if the input is invalid.
+   */
+  public static int parseAc4SyncframeSize(byte[] data, int syncBytes) {
+    if (data.length < 7) {
+      return C.LENGTH_UNSET;
+    }
+    int headerSize = 2; // syncword
+    int frameSize = ((data[2] & 0xFF) << 8) | (data[3] & 0xFF);
+    headerSize += 2;
+    if (frameSize == 0xFFFF) {
+      frameSize = ((data[4] & 0xFF) << 16) | ((data[5] & 0xFF) << 8) | (data[6] & 0xFF);
+      headerSize += 3;
+    }
+    if (syncBytes == 0xAC41) {
+      headerSize += 2;
+    }
+    frameSize += headerSize;
+    return frameSize;
+  }
+
+  /**
+   * Reads the number of audio samples represented by the given AC-4 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 parseAc4SyncframeAudioSampleCount(ByteBuffer buffer) {
+    byte[] bufferBytes = new byte[HEADER_SIZE_FOR_PARSER];
+    buffer.get(bufferBytes);
+    ParsableBitArray data = new ParsableBitArray(bufferBytes);
+    SyncFrameInfo ac4SyncframeInfo = parseAc4SyncframeInfo(data);
+    return ac4SyncframeInfo.sampleCount;
+  }
+
+  /**
+   * Create AC-4 sample header, which includes AC-4 syncword and frame size.
+   *
+   * @param sampleSize The size of AC-4 sample.
+   * @return The AC-4 sample header byte array.
+   */
+  public static ParsableByteArray getAc4SampleHeader(int sampleSize) {
+    // Add AC-4 Syncword 0xAC40 and frame size to create AC-4 syncframe
+    // ETSI TS 103 190-1 V1.3.1, Annex G
+    byte[] ac4SampleHeader  = new byte[] {(byte)0xAC, 0x40, (byte)0xFF, (byte)0xFF,
+        (byte)(sampleSize >> 16 & 0xFF), (byte)(sampleSize >> 8 & 0xFF), (byte)(sampleSize & 0xFF)};
+    return new ParsableByteArray(ac4SampleHeader);
+  }
+
+  private Ac4Util() {}
+
+}
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/audio/DefaultAudioSink.java b/library/core/src/main/java/com/google/android/exoplayer2/audio/DefaultAudioSink.java
index fc515dbdb34..686e2365fd0 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/audio/DefaultAudioSink.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/audio/DefaultAudioSink.java
@@ -1202,6 +1202,8 @@ private static int getMaximumEncodedRateBytesPerSecond(@C.Encoding int encoding)
         return 18000 * 1000 / 8;
       case C.ENCODING_DOLBY_TRUEHD:
         return 24500 * 1000 / 8;
+      case C.ENCODING_AC4:
+        return 2688 * 1000 / 8;
       case C.ENCODING_INVALID:
       case C.ENCODING_PCM_16BIT:
       case C.ENCODING_PCM_24BIT:
@@ -1229,6 +1231,8 @@ private static int getFramesPerEncodedSample(@C.Encoding int encoding, ByteBuffe
           ? 0
           : (Ac3Util.parseTrueHdSyncframeAudioSampleCount(buffer, syncframeOffset)
               * Ac3Util.TRUEHD_RECHUNK_SAMPLE_COUNT);
+    } else if (encoding == C.ENCODING_AC4) {
+      return Ac4Util.parseAc4SyncframeAudioSampleCount(buffer);
     } else {
       throw new IllegalStateException("Unexpected audio encoding: " + encoding);
     }
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/audio/MediaCodecAudioRenderer.java b/library/core/src/main/java/com/google/android/exoplayer2/audio/MediaCodecAudioRenderer.java
index 49c391c4cc8..f9749450c3c 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/audio/MediaCodecAudioRenderer.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/audio/MediaCodecAudioRenderer.java
@@ -787,6 +787,11 @@ protected MediaFormat getMediaFormat(
         mediaFormat.setFloat(MediaFormat.KEY_OPERATING_RATE, codecOperatingRate);
       }
     }
+    if (MimeTypes.AUDIO_AC4.equals(format.sampleMimeType)) {
+      // Some devices handle AC-4 raw frame by default.
+      // Need to notify the codec to handle AC-4 sync frame.
+      mediaFormat.setInteger("ac4-is-sync", 1);
+    }
     return mediaFormat;
   }
 
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/extractor/DefaultExtractorsFactory.java b/library/core/src/main/java/com/google/android/exoplayer2/extractor/DefaultExtractorsFactory.java
index 54bb617c58c..14db0b2ae1b 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/extractor/DefaultExtractorsFactory.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/extractor/DefaultExtractorsFactory.java
@@ -23,6 +23,7 @@
 import com.google.android.exoplayer2.extractor.mp4.Mp4Extractor;
 import com.google.android.exoplayer2.extractor.ogg.OggExtractor;
 import com.google.android.exoplayer2.extractor.ts.Ac3Extractor;
+import com.google.android.exoplayer2.extractor.ts.Ac4Extractor;
 import com.google.android.exoplayer2.extractor.ts.AdtsExtractor;
 import com.google.android.exoplayer2.extractor.ts.DefaultTsPayloadReaderFactory;
 import com.google.android.exoplayer2.extractor.ts.PsExtractor;
@@ -206,7 +207,7 @@ public synchronized DefaultExtractorsFactory setTsExtractorFlags(
 
   @Override
   public synchronized Extractor[] createExtractors() {
-    Extractor[] extractors = new Extractor[FLAC_EXTRACTOR_CONSTRUCTOR == null ? 12 : 13];
+    Extractor[] extractors = new Extractor[FLAC_EXTRACTOR_CONSTRUCTOR == null ? 13 : 14];
     extractors[0] = new MatroskaExtractor(matroskaFlags);
     extractors[1] = new FragmentedMp4Extractor(fragmentedMp4Flags);
     extractors[2] = new Mp4Extractor(mp4Flags);
@@ -235,9 +236,10 @@ public synchronized Extractor[] createExtractors() {
                 | (constantBitrateSeekingEnabled
                     ? AmrExtractor.FLAG_ENABLE_CONSTANT_BITRATE_SEEKING
                     : 0));
+    extractors[12] = new Ac4Extractor();
     if (FLAC_EXTRACTOR_CONSTRUCTOR != null) {
       try {
-        extractors[12] = FLAC_EXTRACTOR_CONSTRUCTOR.newInstance();
+        extractors[13] = FLAC_EXTRACTOR_CONSTRUCTOR.newInstance();
       } catch (Exception e) {
         // Should never happen.
         throw new IllegalStateException("Unexpected error creating FLAC extractor", e);
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/extractor/mp4/Atom.java b/library/core/src/main/java/com/google/android/exoplayer2/extractor/mp4/Atom.java
index 440e577c7d8..5f1cf7ecb87 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/extractor/mp4/Atom.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/extractor/mp4/Atom.java
@@ -67,6 +67,8 @@
   public static final int TYPE_dac3 = Util.getIntegerCodeForString("dac3");
   public static final int TYPE_ec_3 = Util.getIntegerCodeForString("ec-3");
   public static final int TYPE_dec3 = Util.getIntegerCodeForString("dec3");
+  public static final int TYPE_ac_4 = Util.getIntegerCodeForString("ac-4");
+  public static final int TYPE_dac4 = Util.getIntegerCodeForString("dac4");
   public static final int TYPE_dtsc = Util.getIntegerCodeForString("dtsc");
   public static final int TYPE_dtsh = Util.getIntegerCodeForString("dtsh");
   public static final int TYPE_dtsl = Util.getIntegerCodeForString("dtsl");
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/extractor/mp4/AtomParsers.java b/library/core/src/main/java/com/google/android/exoplayer2/extractor/mp4/AtomParsers.java
index d085156f2bf..24b24d50117 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/extractor/mp4/AtomParsers.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/extractor/mp4/AtomParsers.java
@@ -22,6 +22,7 @@
 import com.google.android.exoplayer2.Format;
 import com.google.android.exoplayer2.ParserException;
 import com.google.android.exoplayer2.audio.Ac3Util;
+import com.google.android.exoplayer2.audio.Ac4Util;
 import com.google.android.exoplayer2.drm.DrmInitData;
 import com.google.android.exoplayer2.extractor.GaplessInfoHolder;
 import com.google.android.exoplayer2.metadata.Metadata;
@@ -684,6 +685,7 @@ private static StsdData parseStsd(ParsableByteArray stsd, int trackId, int rotat
           || childAtomType == Atom.TYPE_enca
           || childAtomType == Atom.TYPE_ac_3
           || childAtomType == Atom.TYPE_ec_3
+          || childAtomType == Atom.TYPE_ac_4
           || childAtomType == Atom.TYPE_dtsc
           || childAtomType == Atom.TYPE_dtse
           || childAtomType == Atom.TYPE_dtsh
@@ -974,6 +976,8 @@ private static void parseAudioSampleEntry(ParsableByteArray parent, int atomType
       mimeType = MimeTypes.AUDIO_AC3;
     } else if (atomType == Atom.TYPE_ec_3) {
       mimeType = MimeTypes.AUDIO_E_AC3;
+    } else if (atomType == Atom.TYPE_ac_4) {
+      mimeType = MimeTypes.AUDIO_AC4;
     } else if (atomType == Atom.TYPE_dtsc) {
       mimeType = MimeTypes.AUDIO_DTS;
     } else if (atomType == Atom.TYPE_dtsh || atomType == Atom.TYPE_dtsl) {
@@ -1031,6 +1035,10 @@ private static void parseAudioSampleEntry(ParsableByteArray parent, int atomType
         parent.setPosition(Atom.HEADER_SIZE + childPosition);
         out.format = Ac3Util.parseEAc3AnnexFFormat(parent, Integer.toString(trackId), language,
             drmInitData);
+      } else if (childAtomType == Atom.TYPE_dac4) {
+        parent.setPosition(Atom.HEADER_SIZE + childPosition);
+        out.format = Ac4Util.parseAc4AnnexEFormat(parent, Integer.toString(trackId), language,
+            drmInitData);
       } else if (childAtomType == Atom.TYPE_ddts) {
         out.format = Format.createAudioSampleFormat(Integer.toString(trackId), mimeType, null,
             Format.NO_VALUE, Format.NO_VALUE, channelCount, sampleRate, null, drmInitData, 0,
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/extractor/mp4/FragmentedMp4Extractor.java b/library/core/src/main/java/com/google/android/exoplayer2/extractor/mp4/FragmentedMp4Extractor.java
index 72bcaa9fe28..1d458546471 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/extractor/mp4/FragmentedMp4Extractor.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/extractor/mp4/FragmentedMp4Extractor.java
@@ -22,6 +22,7 @@
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.Format;
 import com.google.android.exoplayer2.ParserException;
+import com.google.android.exoplayer2.audio.Ac4Util;
 import com.google.android.exoplayer2.drm.DrmInitData;
 import com.google.android.exoplayer2.drm.DrmInitData.SchemeData;
 import com.google.android.exoplayer2.extractor.ChunkIndex;
@@ -1276,10 +1277,17 @@ private boolean readSample(ExtractorInput input) throws IOException, Interrupted
         }
       }
     } else {
+      int sampleHeaderSize = 0;
+      if (MimeTypes.AUDIO_AC4.equals(track.format.sampleMimeType)) {
+        ParsableByteArray ac4SampleHeaderData = Ac4Util.getAc4SampleHeader(sampleSize);
+        output.sampleData(ac4SampleHeaderData, ac4SampleHeaderData.capacity());
+        sampleHeaderSize = ac4SampleHeaderData.capacity();
+      }
       while (sampleBytesWritten < sampleSize) {
         int writtenBytes = output.sampleData(input, sampleSize - sampleBytesWritten, false);
         sampleBytesWritten += writtenBytes;
       }
+      sampleSize += sampleHeaderSize;
     }
 
     @C.BufferFlags int sampleFlags = fragment.sampleIsSyncFrameTable[sampleIndex]
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/extractor/mp4/Mp4Extractor.java b/library/core/src/main/java/com/google/android/exoplayer2/extractor/mp4/Mp4Extractor.java
index ec24bed9649..7c9fe2a1879 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/extractor/mp4/Mp4Extractor.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/extractor/mp4/Mp4Extractor.java
@@ -19,6 +19,7 @@
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.Format;
 import com.google.android.exoplayer2.ParserException;
+import com.google.android.exoplayer2.audio.Ac4Util;
 import com.google.android.exoplayer2.extractor.Extractor;
 import com.google.android.exoplayer2.extractor.ExtractorInput;
 import com.google.android.exoplayer2.extractor.ExtractorOutput;
@@ -31,6 +32,7 @@
 import com.google.android.exoplayer2.extractor.mp4.Atom.ContainerAtom;
 import com.google.android.exoplayer2.metadata.Metadata;
 import com.google.android.exoplayer2.util.Assertions;
+import com.google.android.exoplayer2.util.MimeTypes;
 import com.google.android.exoplayer2.util.NalUnitUtil;
 import com.google.android.exoplayer2.util.ParsableByteArray;
 import com.google.android.exoplayer2.util.Util;
@@ -536,11 +538,18 @@ private int readSample(ExtractorInput input, PositionHolder positionHolder)
         }
       }
     } else {
+      int sampleHeaderSize = 0;
+      if (MimeTypes.AUDIO_AC4.equals(track.track.format.sampleMimeType)) {
+        ParsableByteArray ac4SampleHeaderData = Ac4Util.getAc4SampleHeader(sampleSize);
+        trackOutput.sampleData(ac4SampleHeaderData, ac4SampleHeaderData.capacity());
+        sampleHeaderSize = ac4SampleHeaderData.capacity();
+      }
       while (sampleBytesWritten < sampleSize) {
         int writtenBytes = trackOutput.sampleData(input, sampleSize - sampleBytesWritten, false);
         sampleBytesWritten += writtenBytes;
         sampleCurrentNalBytesRemaining -= writtenBytes;
       }
+      sampleSize += sampleHeaderSize;
     }
     trackOutput.sampleMetadata(track.sampleTable.timestampsUs[sampleIndex],
         track.sampleTable.flags[sampleIndex], sampleSize, 0, null);
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/extractor/ts/Ac4Extractor.java b/library/core/src/main/java/com/google/android/exoplayer2/extractor/ts/Ac4Extractor.java
new file mode 100644
index 00000000000..87b106de426
--- /dev/null
+++ b/library/core/src/main/java/com/google/android/exoplayer2/extractor/ts/Ac4Extractor.java
@@ -0,0 +1,162 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.google.android.exoplayer2.extractor.ts;
+
+import static com.google.android.exoplayer2.extractor.ts.TsPayloadReader.FLAG_DATA_ALIGNMENT_INDICATOR;
+
+import com.google.android.exoplayer2.C;
+import com.google.android.exoplayer2.audio.Ac4Util;
+import com.google.android.exoplayer2.extractor.Extractor;
+import com.google.android.exoplayer2.extractor.ExtractorInput;
+import com.google.android.exoplayer2.extractor.ExtractorOutput;
+import com.google.android.exoplayer2.extractor.ExtractorsFactory;
+import com.google.android.exoplayer2.extractor.PositionHolder;
+import com.google.android.exoplayer2.extractor.SeekMap;
+import com.google.android.exoplayer2.extractor.ts.TsPayloadReader.TrackIdGenerator;
+import com.google.android.exoplayer2.util.ParsableByteArray;
+import com.google.android.exoplayer2.util.Util;
+
+import java.io.IOException;
+
+/**
+ * Extracts data from AC-4 bitstreams.
+ */
+public final class Ac4Extractor implements Extractor {
+
+  /**
+   * Factory for {@link Ac4Extractor} instances.
+   */
+  public static final ExtractorsFactory FACTORY = () -> new Extractor[] {new Ac4Extractor()};
+
+  /**
+   * The maximum number of bytes to search when sniffing, excluding ID3 information, before giving
+   * up.
+   */
+  private static final int MAX_SNIFF_BYTES = 8 * 1024;
+  private static final int AC40_SYNC_WORD = 0xAC40;
+  private static final int AC41_SYNC_WORD = 0xAC41;
+  /**
+   * Typical AC-4 frame size (in bytes)
+   * The value 16 kB is determined by the maximum frame size used in broadcast applications.
+   */
+  private static final int FRAMELEN_TYPICAL = 16384;  /* in bytes (16 kB) */
+  private static final int ID3_TAG = Util.getIntegerCodeForString("ID3");
+
+  private final long firstSampleTimestampUs;
+  private final Ac4Reader reader;
+  private final ParsableByteArray sampleData;
+
+  private boolean startedPacket;
+
+  public Ac4Extractor() {
+    this(0);
+  }
+
+  public Ac4Extractor(long firstSampleTimestampUs) {
+    this.firstSampleTimestampUs = firstSampleTimestampUs;
+    reader = new Ac4Reader();
+    sampleData = new ParsableByteArray(FRAMELEN_TYPICAL);
+  }
+
+  // Extractor implementation.
+
+  @Override
+  public boolean sniff(ExtractorInput input) throws IOException, InterruptedException {
+    // Skip any ID3 headers.
+    ParsableByteArray scratch = new ParsableByteArray(10);
+    int startPosition = 0;
+    while (true) {
+      input.peekFully(scratch.data, 0, 10);
+      scratch.setPosition(0);
+      if (scratch.readUnsignedInt24() != ID3_TAG) {
+        break;
+      }
+      scratch.skipBytes(3);
+      int length = scratch.readSynchSafeInt();
+      startPosition += 10 + length;
+      input.advancePeekPosition(length);
+    }
+    input.resetPeekPosition();
+    input.advancePeekPosition(startPosition);
+
+    int headerPosition = startPosition;
+    int validFramesCount = 0;
+    while (true) {
+      input.peekFully(scratch.data, 0, 7);
+      scratch.setPosition(0);
+      int syncBytes = scratch.readUnsignedShort();
+      if (syncBytes != AC40_SYNC_WORD && syncBytes != AC41_SYNC_WORD) {
+        validFramesCount = 0;
+        input.resetPeekPosition();
+        if (++headerPosition - startPosition >= MAX_SNIFF_BYTES) {
+          return false;
+        }
+        input.advancePeekPosition(headerPosition);
+      } else {
+        if (++validFramesCount >= 4) {
+          return true;
+        }
+        int frameSize = Ac4Util.parseAc4SyncframeSize(scratch.data, syncBytes);
+        if (frameSize == C.LENGTH_UNSET) {
+          return false;
+        }
+        input.advancePeekPosition(frameSize - 7);
+      }
+    }
+  }
+
+  @Override
+  public void init(ExtractorOutput output) {
+    reader.createTracks(output, new TrackIdGenerator(0, 1));
+    output.endTracks();
+    output.seekMap(new SeekMap.Unseekable(C.TIME_UNSET));
+  }
+
+  @Override
+  public void seek(long position, long timeUs) {
+    startedPacket = false;
+    reader.seek();
+  }
+
+  @Override
+  public void release() {
+    // Do nothing.
+  }
+
+  @Override
+  public int read(ExtractorInput input, PositionHolder seekPosition) throws IOException,
+      InterruptedException {
+    int bytesRead = input.read(sampleData.data, 0, FRAMELEN_TYPICAL);
+    if (bytesRead == C.RESULT_END_OF_INPUT) {
+      return RESULT_END_OF_INPUT;
+    }
+
+    // Feed whatever data we have to the reader, regardless of whether the read finished or not.
+    sampleData.setPosition(0);
+    sampleData.setLimit(bytesRead);
+
+    if (!startedPacket) {
+      // Pass data to the reader as though it's contained within a single infinitely long packet.
+      reader.packetStarted(firstSampleTimestampUs, FLAG_DATA_ALIGNMENT_INDICATOR);
+      startedPacket = true;
+    }
+    // TODO: Make it possible for the reader to consume the dataSource directly, so that it becomes
+    // unnecessary to copy the data through packetBuffer.
+    reader.consume(sampleData);
+    return RESULT_CONTINUE;
+  }
+
+}
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/extractor/ts/Ac4Reader.java b/library/core/src/main/java/com/google/android/exoplayer2/extractor/ts/Ac4Reader.java
new file mode 100644
index 00000000000..f5d50cde92b
--- /dev/null
+++ b/library/core/src/main/java/com/google/android/exoplayer2/extractor/ts/Ac4Reader.java
@@ -0,0 +1,215 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.google.android.exoplayer2.extractor.ts;
+
+import android.support.annotation.IntDef;
+import com.google.android.exoplayer2.C;
+import com.google.android.exoplayer2.Format;
+import com.google.android.exoplayer2.audio.Ac4Util;
+import com.google.android.exoplayer2.audio.Ac4Util.SyncFrameInfo;
+import com.google.android.exoplayer2.extractor.ExtractorOutput;
+import com.google.android.exoplayer2.extractor.TrackOutput;
+import com.google.android.exoplayer2.extractor.ts.TsPayloadReader.TrackIdGenerator;
+import com.google.android.exoplayer2.util.ParsableBitArray;
+import com.google.android.exoplayer2.util.ParsableByteArray;
+import java.lang.annotation.Documented;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+
+/**
+ * Parses a continuous AC-4 byte stream and extracts individual samples.
+ */
+public final class Ac4Reader implements ElementaryStreamReader {
+
+  @Documented
+  @Retention(RetentionPolicy.SOURCE)
+  @IntDef({STATE_FINDING_SYNC, STATE_READING_HEADER, STATE_READING_SAMPLE})
+  private @interface State {}
+
+  private static final int STATE_FINDING_SYNC = 0;
+  private static final int STATE_READING_HEADER = 1;
+  private static final int STATE_READING_SAMPLE = 2;
+
+  private final ParsableBitArray headerScratchBits;
+  private final ParsableByteArray headerScratchBytes;
+  private final String language;
+
+  private String trackFormatId;
+  private TrackOutput output;
+
+  @State private int state;
+  private int bytesRead;
+
+  // Used to find the header.
+  private boolean lastByteWasAC;
+  private boolean hasCRC;
+
+  // Used when parsing the header.
+  private long sampleDurationUs;
+  private Format format;
+  private int sampleSize;
+
+  // Used when reading the samples.
+  private long timeUs;
+
+  /**
+   * Constructs a new reader for AC-4 elementary streams.
+   */
+  public Ac4Reader() {
+    this(null);
+  }
+
+  /**
+   * Constructs a new reader for AC-4 elementary streams.
+   *
+   * @param language Track language.
+   */
+  public Ac4Reader(String language) {
+    headerScratchBits = new ParsableBitArray(new byte[Ac4Util.HEADER_SIZE_FOR_PARSER]);
+    headerScratchBytes = new ParsableByteArray(headerScratchBits.data);
+    state = STATE_FINDING_SYNC;
+    bytesRead = 0;
+    lastByteWasAC = false;
+    hasCRC = false;
+    this.language = language;
+  }
+
+  @Override
+  public void seek() {
+    state = STATE_FINDING_SYNC;
+    bytesRead = 0;
+    lastByteWasAC = false;
+    hasCRC = false;
+  }
+
+  @Override
+  public void createTracks(ExtractorOutput extractorOutput, TrackIdGenerator generator) {
+    generator.generateNewId();
+    trackFormatId = generator.getFormatId();
+    output = extractorOutput.track(generator.getTrackId(), C.TRACK_TYPE_AUDIO);
+  }
+
+  @Override
+  public void packetStarted(long pesTimeUs, @TsPayloadReader.Flags int flags) {
+    timeUs = pesTimeUs;
+  }
+
+  @Override
+  public void consume(ParsableByteArray data) {
+    while (data.bytesLeft() > 0) {
+      switch (state) {
+        case STATE_FINDING_SYNC:
+          if (skipToNextSync(data)) {
+            state = STATE_READING_HEADER;
+            headerScratchBytes.data[0] = (byte)0xAC;
+            headerScratchBytes.data[1] = 0x40;
+            if (hasCRC)
+              headerScratchBytes.data[1] = 0x41;
+            bytesRead = 2;
+          }
+          break;
+        case STATE_READING_HEADER:
+          if (continueRead(data, headerScratchBytes.data, Ac4Util.HEADER_SIZE_FOR_PARSER)) {
+            parseHeader();
+            headerScratchBytes.setPosition(0);
+            output.sampleData(headerScratchBytes, Ac4Util.HEADER_SIZE_FOR_PARSER);
+            state = STATE_READING_SAMPLE;
+          }
+          break;
+        case STATE_READING_SAMPLE:
+          int bytesToRead = Math.min(data.bytesLeft(), sampleSize - bytesRead);
+          output.sampleData(data, bytesToRead);
+          bytesRead += bytesToRead;
+          if (bytesRead == sampleSize) {
+            output.sampleMetadata(timeUs, C.BUFFER_FLAG_KEY_FRAME, sampleSize, 0, null);
+            timeUs += sampleDurationUs;
+            state = STATE_FINDING_SYNC;
+          }
+          break;
+        default:
+          break;
+      }
+    }
+  }
+
+  @Override
+  public void packetFinished() {
+    // Do nothing.
+  }
+
+  /**
+   * Continues a read from the provided {@code source} into a given {@code target}. It's assumed
+   * that the data should be written into {@code target} starting from an offset of zero.
+   *
+   * @param source The source from which to read.
+   * @param target The target into which data is to be read.
+   * @param targetLength The target length of the read.
+   * @return Whether the target length was reached.
+   */
+  private boolean continueRead(ParsableByteArray source, byte[] target, int targetLength) {
+    int bytesToRead = Math.min(source.bytesLeft(), targetLength - bytesRead);
+    source.readBytes(target, bytesRead, bytesToRead);
+    bytesRead += bytesToRead;
+    return bytesRead == targetLength;
+  }
+
+  /**
+   * Locates the next syncword, advancing the position to the byte that immediately follows it. If a
+   * syncword was not located, the position is advanced to the limit.
+   *
+   * @param pesBuffer The buffer whose position should be advanced.
+   * @return Whether a syncword position was found.
+   */
+  private boolean skipToNextSync(ParsableByteArray pesBuffer) {
+    while (pesBuffer.bytesLeft() > 0) {
+      if (!lastByteWasAC) {
+        lastByteWasAC = (pesBuffer.readUnsignedByte() == 0xAC);
+        continue;
+      }
+      int secondByte = pesBuffer.readUnsignedByte();
+      if (secondByte == 0x40 || secondByte == 0x41) {
+        lastByteWasAC = false;
+        hasCRC = (secondByte == 0x41);
+        return true;
+      } else {
+        lastByteWasAC = (secondByte == 0xAC);
+      }
+    }
+    return false;
+  }
+
+  /**
+   * Parses the sample header.
+   */
+  @SuppressWarnings("ReferenceEquality")
+  private void parseHeader() {
+    headerScratchBits.setPosition(0);
+    SyncFrameInfo frameInfo = Ac4Util.parseAc4SyncframeInfo(headerScratchBits);
+    if (format == null || frameInfo.channelCount != format.channelCount
+        || frameInfo.sampleRate != format.sampleRate
+        || frameInfo.mimeType != format.sampleMimeType) {
+      format = Format.createAudioSampleFormat(trackFormatId, frameInfo.mimeType, null,
+          Format.NO_VALUE, Format.NO_VALUE, frameInfo.channelCount, frameInfo.sampleRate, null,
+          null, 0, language);
+      output.format(format);
+    }
+    sampleSize = frameInfo.frameSize;
+    // In this class a sample is an AC-4 sync frame, but the MediaFormat sample rate specifies the
+    // number of PCM audio samples per second.
+    sampleDurationUs = C.MICROS_PER_SECOND * frameInfo.sampleCount / format.sampleRate;
+  }
+
+}
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/extractor/ts/DefaultTsPayloadReaderFactory.java b/library/core/src/main/java/com/google/android/exoplayer2/extractor/ts/DefaultTsPayloadReaderFactory.java
index a5506e2cfbe..488480d10e3 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/extractor/ts/DefaultTsPayloadReaderFactory.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/extractor/ts/DefaultTsPayloadReaderFactory.java
@@ -142,6 +142,8 @@ public TsPayloadReader createPayloadReader(int streamType, EsInfo esInfo) {
       case TsExtractor.TS_STREAM_TYPE_AC3:
       case TsExtractor.TS_STREAM_TYPE_E_AC3:
         return new PesReader(new Ac3Reader(esInfo.language));
+      case TsExtractor.TS_STREAM_TYPE_AC4:
+        return new PesReader(new Ac4Reader(esInfo.language));
       case TsExtractor.TS_STREAM_TYPE_DTS:
       case TsExtractor.TS_STREAM_TYPE_HDMV_DTS:
         return new PesReader(new DtsReader(esInfo.language));
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/extractor/ts/TsExtractor.java b/library/core/src/main/java/com/google/android/exoplayer2/extractor/ts/TsExtractor.java
index f47a481d7e0..21dec0d1111 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/extractor/ts/TsExtractor.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/extractor/ts/TsExtractor.java
@@ -85,6 +85,7 @@ public final class TsExtractor implements Extractor {
   public static final int TS_STREAM_TYPE_DTS = 0x8A;
   public static final int TS_STREAM_TYPE_HDMV_DTS = 0x82;
   public static final int TS_STREAM_TYPE_E_AC3 = 0x87;
+  public static final int TS_STREAM_TYPE_AC4 = 0xAC;  /* DVB/ATSC AC-4 Descriptor */
   public static final int TS_STREAM_TYPE_H262 = 0x02;
   public static final int TS_STREAM_TYPE_H264 = 0x1B;
   public static final int TS_STREAM_TYPE_H265 = 0x24;
@@ -100,6 +101,7 @@ public final class TsExtractor implements Extractor {
 
   private static final long AC3_FORMAT_IDENTIFIER = Util.getIntegerCodeForString("AC-3");
   private static final long E_AC3_FORMAT_IDENTIFIER = Util.getIntegerCodeForString("EAC3");
+  private static final long AC4_FORMAT_IDENTIFIER = Util.getIntegerCodeForString("AC-4");
   private static final long HEVC_FORMAT_IDENTIFIER = Util.getIntegerCodeForString("HEVC");
 
   private static final int BUFFER_SIZE = TS_PACKET_SIZE * 50;
@@ -484,8 +486,11 @@ private class PmtReader implements SectionPayloadReader {
     private static final int TS_PMT_DESC_AC3 = 0x6A;
     private static final int TS_PMT_DESC_EAC3 = 0x7A;
     private static final int TS_PMT_DESC_DTS = 0x7B;
+    private static final int TS_PMT_DESC_DVB_EXT = 0x7F;
     private static final int TS_PMT_DESC_DVBSUBS = 0x59;
 
+    private static final int TS_PMT_DESC_DVB_EXT_AC4 = 0x15;
+
     private final ParsableBitArray pmtScratch;
     private final SparseArray<TsPayloadReader> trackIdToReaderScratch;
     private final SparseIntArray trackIdToPidScratch;
@@ -638,6 +643,8 @@ private EsInfo readEsInfo(ParsableByteArray data, int length) {
             streamType = TS_STREAM_TYPE_AC3;
           } else if (formatIdentifier == E_AC3_FORMAT_IDENTIFIER) {
             streamType = TS_STREAM_TYPE_E_AC3;
+          } else if (formatIdentifier == AC4_FORMAT_IDENTIFIER) {
+            streamType = TS_STREAM_TYPE_AC4;
           } else if (formatIdentifier == HEVC_FORMAT_IDENTIFIER) {
             streamType = TS_STREAM_TYPE_H265;
           }
@@ -645,6 +652,13 @@ private EsInfo readEsInfo(ParsableByteArray data, int length) {
           streamType = TS_STREAM_TYPE_AC3;
         } else if (descriptorTag == TS_PMT_DESC_EAC3) { // enhanced_AC-3_descriptor
           streamType = TS_STREAM_TYPE_E_AC3;
+        } else if (descriptorTag == TS_PMT_DESC_DVB_EXT) {
+          // extension descriptor in DVB (ETSI EN 300 468)
+          int descriptorTagExt = data.readUnsignedByte();
+          if (descriptorTagExt == TS_PMT_DESC_DVB_EXT_AC4) {
+            // AC-4_descriptor in DVB (ETSI EN 300 468)
+            streamType = TS_STREAM_TYPE_AC4;
+          }
         } else if (descriptorTag == TS_PMT_DESC_DTS) { // DTS_descriptor
           streamType = TS_STREAM_TYPE_DTS;
         } else if (descriptorTag == TS_PMT_DESC_ISO639_LANG) {
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/util/MimeTypes.java b/library/core/src/main/java/com/google/android/exoplayer2/util/MimeTypes.java
index e506ae1b19b..e6cf5ed95ee 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/util/MimeTypes.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/util/MimeTypes.java
@@ -55,6 +55,7 @@ public final class MimeTypes {
   public static final String AUDIO_AC3 = BASE_TYPE_AUDIO + "/ac3";
   public static final String AUDIO_E_AC3 = BASE_TYPE_AUDIO + "/eac3";
   public static final String AUDIO_E_AC3_JOC = BASE_TYPE_AUDIO + "/eac3-joc";
+  public static final String AUDIO_AC4 = BASE_TYPE_AUDIO + "/ac4";
   public static final String AUDIO_TRUEHD = BASE_TYPE_AUDIO + "/true-hd";
   public static final String AUDIO_DTS = BASE_TYPE_AUDIO + "/vnd.dts";
   public static final String AUDIO_DTS_HD = BASE_TYPE_AUDIO + "/vnd.dts.hd";
@@ -237,6 +238,8 @@ public static boolean isApplication(@Nullable String mimeType) {
       return MimeTypes.AUDIO_E_AC3;
     } else if (codec.startsWith("ec+3")) {
       return MimeTypes.AUDIO_E_AC3_JOC;
+    } else if (codec.startsWith("ac-4") || codec.startsWith("dac4")) {
+      return MimeTypes.AUDIO_AC4;
     } else if (codec.startsWith("dtsc") || codec.startsWith("dtse")) {
       return MimeTypes.AUDIO_DTS;
     } else if (codec.startsWith("dtsh") || codec.startsWith("dtsl")) {
@@ -301,6 +304,8 @@ public static String getMimeTypeFromMp4ObjectType(int objectType) {
         return MimeTypes.AUDIO_DTS_HD;
       case 0xAD:
         return MimeTypes.AUDIO_OPUS;
+      case 0xAE:
+        return MimeTypes.AUDIO_AC4;
       default:
         return null;
     }
@@ -354,6 +359,8 @@ public static int getTrackType(@Nullable String mimeType) {
       case MimeTypes.AUDIO_E_AC3:
       case MimeTypes.AUDIO_E_AC3_JOC:
         return C.ENCODING_E_AC3;
+      case MimeTypes.AUDIO_AC4:
+        return C.ENCODING_AC4;
       case MimeTypes.AUDIO_DTS:
         return C.ENCODING_DTS;
       case MimeTypes.AUDIO_DTS_HD:
diff --git a/library/hls/src/main/java/com/google/android/exoplayer2/source/hls/DefaultHlsExtractorFactory.java b/library/hls/src/main/java/com/google/android/exoplayer2/source/hls/DefaultHlsExtractorFactory.java
index 8a403c37592..b1e78c22f27 100644
--- a/library/hls/src/main/java/com/google/android/exoplayer2/source/hls/DefaultHlsExtractorFactory.java
+++ b/library/hls/src/main/java/com/google/android/exoplayer2/source/hls/DefaultHlsExtractorFactory.java
@@ -25,6 +25,7 @@
 import com.google.android.exoplayer2.extractor.mp3.Mp3Extractor;
 import com.google.android.exoplayer2.extractor.mp4.FragmentedMp4Extractor;
 import com.google.android.exoplayer2.extractor.ts.Ac3Extractor;
+import com.google.android.exoplayer2.extractor.ts.Ac4Extractor;
 import com.google.android.exoplayer2.extractor.ts.AdtsExtractor;
 import com.google.android.exoplayer2.extractor.ts.DefaultTsPayloadReaderFactory;
 import com.google.android.exoplayer2.extractor.ts.TsExtractor;
@@ -43,6 +44,7 @@ public final class DefaultHlsExtractorFactory implements HlsExtractorFactory {
 
   public static final String AAC_FILE_EXTENSION = ".aac";
   public static final String AC3_FILE_EXTENSION = ".ac3";
+  public static final String AC4_FILE_EXTENSION = ".ac4";
   public static final String EC3_FILE_EXTENSION = ".ec3";
   public static final String MP3_FILE_EXTENSION = ".mp3";
   public static final String MP4_FILE_EXTENSION = ".mp4";
@@ -94,6 +96,8 @@ public Pair<Extractor, Boolean> createExtractor(
         return buildResult(new AdtsExtractor());
       } else if (previousExtractor instanceof Ac3Extractor) {
         return buildResult(new Ac3Extractor());
+      } else if (previousExtractor instanceof Ac4Extractor) {
+        return buildResult(new Ac4Extractor());
       } else if (previousExtractor instanceof Mp3Extractor) {
         return buildResult(new Mp3Extractor());
       } else {
@@ -135,6 +139,13 @@ public Pair<Extractor, Boolean> createExtractor(
       }
     }
 
+    if (!(extractorByFileExtension instanceof Ac4Extractor)) {
+      Ac4Extractor ac4Extractor = new Ac4Extractor();
+      if (sniffQuietly(ac4Extractor, extractorInput)) {
+        return buildResult(ac4Extractor);
+      }
+    }
+
     if (!(extractorByFileExtension instanceof Mp3Extractor)) {
       Mp3Extractor mp3Extractor =
           new Mp3Extractor(/* flags= */ 0, /* forcedFirstSampleTimestampUs= */ 0);
@@ -188,6 +199,8 @@ private Extractor createExtractorByFileExtension(
     } else if (lastPathSegment.endsWith(AC3_FILE_EXTENSION)
         || lastPathSegment.endsWith(EC3_FILE_EXTENSION)) {
       return new Ac3Extractor();
+    } else if (lastPathSegment.endsWith(AC4_FILE_EXTENSION)) {
+      return new Ac4Extractor();
     } else if (lastPathSegment.endsWith(MP3_FILE_EXTENSION)) {
       return new Mp3Extractor(/* flags= */ 0, /* forcedFirstSampleTimestampUs= */ 0);
     } else if (lastPathSegment.endsWith(MP4_FILE_EXTENSION)
@@ -254,6 +267,7 @@ private static Pair<Extractor, Boolean> buildResult(Extractor extractor) {
         extractor,
         extractor instanceof AdtsExtractor
             || extractor instanceof Ac3Extractor
+            || extractor instanceof Ac4Extractor
             || extractor instanceof Mp3Extractor);
   }
 

From 460f57614230837eab74b1f6bcd200bb3e3da15f Mon Sep 17 00:00:00 2001
From: ybai001 <ybai@dolby.com>
Date: Mon, 24 Dec 2018 09:38:52 +0800
Subject: [PATCH 2/6] Add AC-4 format support

 * Add AC-4 MIME type definition
 * Add AC-4 format support in Mp4Extractor and TsExtractor
 * Add AC-4 Extractor
 * Add AC-4 playback support in MPEG-4, MPEG-DASH, TS and HLS
---
 .../extractor/DefaultExtractorsFactory.java   |   1 +
 .../extractor/mp4/FragmentedMp4Extractor.java |  16 ++-
 .../extractor/mp4/Mp4Extractor.java           |  16 ++-
 .../exoplayer2/extractor/ts/Ac4Reader.java    |   4 +-
 library/core/src/test/assets/ts/sample.ac4    | Bin 0 -> 7594 bytes
 .../core/src/test/assets/ts/sample.ac4.0.dump | 106 ++++++++++++++++++
 .../DefaultExtractorsFactoryTest.java         |   4 +-
 .../extractor/ts/Ac4ExtractorTest.java        |  32 ++++++
 8 files changed, 167 insertions(+), 12 deletions(-)
 create mode 100644 library/core/src/test/assets/ts/sample.ac4
 create mode 100644 library/core/src/test/assets/ts/sample.ac4.0.dump
 create mode 100644 library/core/src/test/java/com/google/android/exoplayer2/extractor/ts/Ac4ExtractorTest.java

diff --git a/library/core/src/main/java/com/google/android/exoplayer2/extractor/DefaultExtractorsFactory.java b/library/core/src/main/java/com/google/android/exoplayer2/extractor/DefaultExtractorsFactory.java
index 14db0b2ae1b..e2f8887b5c7 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/extractor/DefaultExtractorsFactory.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/extractor/DefaultExtractorsFactory.java
@@ -49,6 +49,7 @@
  *   <li>WAV ({@link WavExtractor})
  *   <li>AC3 ({@link Ac3Extractor})
  *   <li>AMR ({@link AmrExtractor})
+ *   <li>AC4 ({@link Ac4Extractor})
  *   <li>FLAC (only available if the FLAC extension is built and included)
  * </ul>
  */
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/extractor/mp4/FragmentedMp4Extractor.java b/library/core/src/main/java/com/google/android/exoplayer2/extractor/mp4/FragmentedMp4Extractor.java
index 1d458546471..b1b598d6ef3 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/extractor/mp4/FragmentedMp4Extractor.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/extractor/mp4/FragmentedMp4Extractor.java
@@ -161,6 +161,8 @@ public class FragmentedMp4Extractor implements Extractor {
   private int sampleBytesWritten;
   private int sampleCurrentNalBytesRemaining;
   private boolean processSeiNalUnitPayload;
+  private boolean isAc4HeaderAdded;
+  private int ac4SampleHeaderSize;
 
   // Extractor output.
   private ExtractorOutput extractorOutput;
@@ -262,6 +264,8 @@ public FragmentedMp4Extractor(
     durationUs = C.TIME_UNSET;
     pendingSeekTimeUs = C.TIME_UNSET;
     segmentIndexEarliestPresentationTimeUs = C.TIME_UNSET;
+    isAc4HeaderAdded = false;
+    ac4SampleHeaderSize = 0;
     enterReadingAtomHeaderState();
   }
 
@@ -1217,6 +1221,7 @@ private boolean readSample(ExtractorInput input) throws IOException, Interrupted
       sampleSize += sampleBytesWritten;
       parserState = STATE_READING_SAMPLE_CONTINUE;
       sampleCurrentNalBytesRemaining = 0;
+      isAc4HeaderAdded = false;
     }
 
     TrackFragment fragment = currentTrackBundle.fragment;
@@ -1277,17 +1282,20 @@ private boolean readSample(ExtractorInput input) throws IOException, Interrupted
         }
       }
     } else {
-      int sampleHeaderSize = 0;
-      if (MimeTypes.AUDIO_AC4.equals(track.format.sampleMimeType)) {
+      if (MimeTypes.AUDIO_AC4.equals(track.format.sampleMimeType) && !isAc4HeaderAdded) {
         ParsableByteArray ac4SampleHeaderData = Ac4Util.getAc4SampleHeader(sampleSize);
         output.sampleData(ac4SampleHeaderData, ac4SampleHeaderData.capacity());
-        sampleHeaderSize = ac4SampleHeaderData.capacity();
+        ac4SampleHeaderSize = ac4SampleHeaderData.capacity();
+        isAc4HeaderAdded = true;
       }
       while (sampleBytesWritten < sampleSize) {
         int writtenBytes = output.sampleData(input, sampleSize - sampleBytesWritten, false);
         sampleBytesWritten += writtenBytes;
       }
-      sampleSize += sampleHeaderSize;
+      if (MimeTypes.AUDIO_AC4.equals(track.format.sampleMimeType)) {
+        sampleSize += ac4SampleHeaderSize;
+        isAc4HeaderAdded = false;
+      }
     }
 
     @C.BufferFlags int sampleFlags = fragment.sampleIsSyncFrameTable[sampleIndex]
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/extractor/mp4/Mp4Extractor.java b/library/core/src/main/java/com/google/android/exoplayer2/extractor/mp4/Mp4Extractor.java
index 7c9fe2a1879..49f5fac7a4b 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/extractor/mp4/Mp4Extractor.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/extractor/mp4/Mp4Extractor.java
@@ -118,6 +118,8 @@ public final class Mp4Extractor implements Extractor, SeekMap {
   private int firstVideoTrackIndex;
   private long durationUs;
   private boolean isQuickTime;
+  private boolean isAc4HeaderAdded;
+  private int ac4SampleHeaderSize;
 
   /**
    * Creates a new extractor for unfragmented MP4 streams.
@@ -139,6 +141,8 @@ public Mp4Extractor(@Flags int flags) {
     nalStartCode = new ParsableByteArray(NalUnitUtil.NAL_START_CODE);
     nalLength = new ParsableByteArray(4);
     sampleTrackIndex = C.INDEX_UNSET;
+    isAc4HeaderAdded = false;
+    ac4SampleHeaderSize = 0;
   }
 
   @Override
@@ -489,6 +493,7 @@ private int readSample(ExtractorInput input, PositionHolder positionHolder)
       if (sampleTrackIndex == C.INDEX_UNSET) {
         return RESULT_END_OF_INPUT;
       }
+      isAc4HeaderAdded = false;
     }
     Mp4Track track = tracks[sampleTrackIndex];
     TrackOutput trackOutput = track.trackOutput;
@@ -538,18 +543,21 @@ private int readSample(ExtractorInput input, PositionHolder positionHolder)
         }
       }
     } else {
-      int sampleHeaderSize = 0;
-      if (MimeTypes.AUDIO_AC4.equals(track.track.format.sampleMimeType)) {
+      if (MimeTypes.AUDIO_AC4.equals(track.track.format.sampleMimeType) && !isAc4HeaderAdded) {
         ParsableByteArray ac4SampleHeaderData = Ac4Util.getAc4SampleHeader(sampleSize);
         trackOutput.sampleData(ac4SampleHeaderData, ac4SampleHeaderData.capacity());
-        sampleHeaderSize = ac4SampleHeaderData.capacity();
+        ac4SampleHeaderSize = ac4SampleHeaderData.capacity();
+        isAc4HeaderAdded = true;
       }
       while (sampleBytesWritten < sampleSize) {
         int writtenBytes = trackOutput.sampleData(input, sampleSize - sampleBytesWritten, false);
         sampleBytesWritten += writtenBytes;
         sampleCurrentNalBytesRemaining -= writtenBytes;
       }
-      sampleSize += sampleHeaderSize;
+      if (MimeTypes.AUDIO_AC4.equals(track.track.format.sampleMimeType)) {
+        sampleSize += ac4SampleHeaderSize;
+        isAc4HeaderAdded = false;
+      }
     }
     trackOutput.sampleMetadata(track.sampleTable.timestampsUs[sampleIndex],
         track.sampleTable.flags[sampleIndex], sampleSize, 0, null);
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/extractor/ts/Ac4Reader.java b/library/core/src/main/java/com/google/android/exoplayer2/extractor/ts/Ac4Reader.java
index f5d50cde92b..2486ab54002 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/extractor/ts/Ac4Reader.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/extractor/ts/Ac4Reader.java
@@ -115,9 +115,7 @@ public void consume(ParsableByteArray data) {
           if (skipToNextSync(data)) {
             state = STATE_READING_HEADER;
             headerScratchBytes.data[0] = (byte)0xAC;
-            headerScratchBytes.data[1] = 0x40;
-            if (hasCRC)
-              headerScratchBytes.data[1] = 0x41;
+            headerScratchBytes.data[1] = headerScratchBytes.data[1] = (byte)(hasCRC ? 0x41 : 0x40);
             bytesRead = 2;
           }
           break;
diff --git a/library/core/src/test/assets/ts/sample.ac4 b/library/core/src/test/assets/ts/sample.ac4
new file mode 100644
index 0000000000000000000000000000000000000000..721f53cdd7f844f2459a014047a6e3d1d87c892a
GIT binary patch
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diff --git a/library/core/src/test/assets/ts/sample.ac4.0.dump b/library/core/src/test/assets/ts/sample.ac4.0.dump
new file mode 100644
index 00000000000..03ae07707a2
--- /dev/null
+++ b/library/core/src/test/assets/ts/sample.ac4.0.dump
@@ -0,0 +1,106 @@
+seekMap:
+  isSeekable = false
+  duration = UNSET TIME
+  getPosition(0) = [[timeUs=0, position=0]]
+numberOfTracks = 1
+track 0:
+  format:
+    bitrate = -1
+    id = 0
+    containerMimeType = null
+    sampleMimeType = audio/ac4
+    maxInputSize = -1
+    width = -1
+    height = -1
+    frameRate = -1.0
+    rotationDegrees = 0
+    pixelWidthHeightRatio = 1.0
+    channelCount = 2
+    sampleRate = 48000
+    pcmEncoding = -1
+    encoderDelay = 0
+    encoderPadding = 0
+    subsampleOffsetUs = 9223372036854775807
+    selectionFlags = 0
+    language = null
+    drmInitData = -
+    initializationData:
+  total output bytes = 7594
+  sample count = 19
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 366, hash B4277F9E
+  sample 1:
+    time = 40000
+    flags = 1
+    data = length 366, hash E8E0A142
+  sample 2:
+    time = 80000
+    flags = 1
+    data = length 366, hash 2E5073D0
+  sample 3:
+    time = 120000
+    flags = 1
+    data = length 366, hash 850E71D8
+  sample 4:
+    time = 160000
+    flags = 1
+    data = length 366, hash 69CD444E
+  sample 5:
+    time = 200000
+    flags = 1
+    data = length 366, hash BD24F36D
+  sample 6:
+    time = 240000
+    flags = 1
+    data = length 366, hash E24F2490
+  sample 7:
+    time = 280000
+    flags = 1
+    data = length 366, hash EE6F1F06
+  sample 8:
+    time = 320000
+    flags = 1
+    data = length 366, hash 2DAB000F
+  sample 9:
+    time = 360000
+    flags = 1
+    data = length 366, hash 8102B7EC
+  sample 10:
+    time = 400000
+    flags = 1
+    data = length 366, hash 55BF59AC
+  sample 11:
+    time = 440000
+    flags = 1
+    data = length 494, hash CBC2E09F
+  sample 12:
+    time = 480000
+    flags = 1
+    data = length 519, hash 9DAF56E9
+  sample 13:
+    time = 520000
+    flags = 1
+    data = length 598, hash 8169EE2
+  sample 14:
+    time = 560000
+    flags = 1
+    data = length 435, hash 28C21246
+  sample 15:
+    time = 600000
+    flags = 1
+    data = length 365, hash FF14716D
+  sample 16:
+    time = 640000
+    flags = 1
+    data = length 392, hash 4CC96B29
+  sample 17:
+    time = 680000
+    flags = 1
+    data = length 373, hash D7AC6D4E
+  sample 18:
+    time = 720000
+    flags = 1
+    data = length 392, hash 99F2511F
+tracksEnded = true
diff --git a/library/core/src/test/java/com/google/android/exoplayer2/extractor/DefaultExtractorsFactoryTest.java b/library/core/src/test/java/com/google/android/exoplayer2/extractor/DefaultExtractorsFactoryTest.java
index 148e04ca77a..bbe7985568e 100644
--- a/library/core/src/test/java/com/google/android/exoplayer2/extractor/DefaultExtractorsFactoryTest.java
+++ b/library/core/src/test/java/com/google/android/exoplayer2/extractor/DefaultExtractorsFactoryTest.java
@@ -25,6 +25,7 @@
 import com.google.android.exoplayer2.extractor.mp4.Mp4Extractor;
 import com.google.android.exoplayer2.extractor.ogg.OggExtractor;
 import com.google.android.exoplayer2.extractor.ts.Ac3Extractor;
+import com.google.android.exoplayer2.extractor.ts.Ac4Extractor;
 import com.google.android.exoplayer2.extractor.ts.AdtsExtractor;
 import com.google.android.exoplayer2.extractor.ts.PsExtractor;
 import com.google.android.exoplayer2.extractor.ts.TsExtractor;
@@ -62,7 +63,8 @@ public void testCreateExtractors_returnExpectedClasses() {
           OggExtractor.class,
           PsExtractor.class,
           WavExtractor.class,
-          AmrExtractor.class
+          AmrExtractor.class,
+          Ac4Extractor.class
         };
 
     assertThat(listCreatedExtractorClasses).containsNoDuplicates();
diff --git a/library/core/src/test/java/com/google/android/exoplayer2/extractor/ts/Ac4ExtractorTest.java b/library/core/src/test/java/com/google/android/exoplayer2/extractor/ts/Ac4ExtractorTest.java
new file mode 100644
index 00000000000..782956dee7b
--- /dev/null
+++ b/library/core/src/test/java/com/google/android/exoplayer2/extractor/ts/Ac4ExtractorTest.java
@@ -0,0 +1,32 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.google.android.exoplayer2.extractor.ts;
+
+import com.google.android.exoplayer2.testutil.ExtractorAsserts;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.robolectric.RobolectricTestRunner;
+
+/** Unit test for {@link Ac4Extractor}. */
+@RunWith(RobolectricTestRunner.class)
+public final class Ac4ExtractorTest {
+
+  @Test
+  public void testAc4Sample() throws Exception {
+    ExtractorAsserts.assertBehavior(Ac4Extractor::new, "ts/sample.ac4");
+  }
+}
+

From e462c6aab7dc5cab47c3daae5298626612d352be Mon Sep 17 00:00:00 2001
From: ybai001 <ybai@dolby.com>
Date: Mon, 24 Dec 2018 09:38:52 +0800
Subject: [PATCH 3/6] Add AC-4 format support

 * Add AC-4 MIME type definition
 * Add AC-4 format support in Mp4Extractor and TsExtractor
 * Add AC-4 Extractor
 * Add AC-4 playback support in MPEG-4, MPEG-DASH, TS and HLS
---
 .../extractor/DefaultExtractorsFactory.java   |   1 +
 .../extractor/mp4/FragmentedMp4Extractor.java |  16 ++-
 .../extractor/mp4/Mp4Extractor.java           |  16 ++-
 .../exoplayer2/extractor/ts/Ac4Reader.java    |   4 +-
 library/core/src/test/assets/ts/sample.ac4    | Bin 0 -> 7594 bytes
 .../core/src/test/assets/ts/sample.ac4.0.dump | 106 ++++++++++++++++++
 .../DefaultExtractorsFactoryTest.java         |   4 +-
 .../extractor/ts/Ac4ExtractorTest.java        |  32 ++++++
 8 files changed, 167 insertions(+), 12 deletions(-)
 create mode 100644 library/core/src/test/assets/ts/sample.ac4
 create mode 100644 library/core/src/test/assets/ts/sample.ac4.0.dump
 create mode 100644 library/core/src/test/java/com/google/android/exoplayer2/extractor/ts/Ac4ExtractorTest.java

diff --git a/library/core/src/main/java/com/google/android/exoplayer2/extractor/DefaultExtractorsFactory.java b/library/core/src/main/java/com/google/android/exoplayer2/extractor/DefaultExtractorsFactory.java
index 14db0b2ae1b..e2f8887b5c7 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/extractor/DefaultExtractorsFactory.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/extractor/DefaultExtractorsFactory.java
@@ -49,6 +49,7 @@
  *   <li>WAV ({@link WavExtractor})
  *   <li>AC3 ({@link Ac3Extractor})
  *   <li>AMR ({@link AmrExtractor})
+ *   <li>AC4 ({@link Ac4Extractor})
  *   <li>FLAC (only available if the FLAC extension is built and included)
  * </ul>
  */
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/extractor/mp4/FragmentedMp4Extractor.java b/library/core/src/main/java/com/google/android/exoplayer2/extractor/mp4/FragmentedMp4Extractor.java
index 1d458546471..b1b598d6ef3 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/extractor/mp4/FragmentedMp4Extractor.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/extractor/mp4/FragmentedMp4Extractor.java
@@ -161,6 +161,8 @@ public class FragmentedMp4Extractor implements Extractor {
   private int sampleBytesWritten;
   private int sampleCurrentNalBytesRemaining;
   private boolean processSeiNalUnitPayload;
+  private boolean isAc4HeaderAdded;
+  private int ac4SampleHeaderSize;
 
   // Extractor output.
   private ExtractorOutput extractorOutput;
@@ -262,6 +264,8 @@ public FragmentedMp4Extractor(
     durationUs = C.TIME_UNSET;
     pendingSeekTimeUs = C.TIME_UNSET;
     segmentIndexEarliestPresentationTimeUs = C.TIME_UNSET;
+    isAc4HeaderAdded = false;
+    ac4SampleHeaderSize = 0;
     enterReadingAtomHeaderState();
   }
 
@@ -1217,6 +1221,7 @@ private boolean readSample(ExtractorInput input) throws IOException, Interrupted
       sampleSize += sampleBytesWritten;
       parserState = STATE_READING_SAMPLE_CONTINUE;
       sampleCurrentNalBytesRemaining = 0;
+      isAc4HeaderAdded = false;
     }
 
     TrackFragment fragment = currentTrackBundle.fragment;
@@ -1277,17 +1282,20 @@ private boolean readSample(ExtractorInput input) throws IOException, Interrupted
         }
       }
     } else {
-      int sampleHeaderSize = 0;
-      if (MimeTypes.AUDIO_AC4.equals(track.format.sampleMimeType)) {
+      if (MimeTypes.AUDIO_AC4.equals(track.format.sampleMimeType) && !isAc4HeaderAdded) {
         ParsableByteArray ac4SampleHeaderData = Ac4Util.getAc4SampleHeader(sampleSize);
         output.sampleData(ac4SampleHeaderData, ac4SampleHeaderData.capacity());
-        sampleHeaderSize = ac4SampleHeaderData.capacity();
+        ac4SampleHeaderSize = ac4SampleHeaderData.capacity();
+        isAc4HeaderAdded = true;
       }
       while (sampleBytesWritten < sampleSize) {
         int writtenBytes = output.sampleData(input, sampleSize - sampleBytesWritten, false);
         sampleBytesWritten += writtenBytes;
       }
-      sampleSize += sampleHeaderSize;
+      if (MimeTypes.AUDIO_AC4.equals(track.format.sampleMimeType)) {
+        sampleSize += ac4SampleHeaderSize;
+        isAc4HeaderAdded = false;
+      }
     }
 
     @C.BufferFlags int sampleFlags = fragment.sampleIsSyncFrameTable[sampleIndex]
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/extractor/mp4/Mp4Extractor.java b/library/core/src/main/java/com/google/android/exoplayer2/extractor/mp4/Mp4Extractor.java
index 7c9fe2a1879..49f5fac7a4b 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/extractor/mp4/Mp4Extractor.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/extractor/mp4/Mp4Extractor.java
@@ -118,6 +118,8 @@ public final class Mp4Extractor implements Extractor, SeekMap {
   private int firstVideoTrackIndex;
   private long durationUs;
   private boolean isQuickTime;
+  private boolean isAc4HeaderAdded;
+  private int ac4SampleHeaderSize;
 
   /**
    * Creates a new extractor for unfragmented MP4 streams.
@@ -139,6 +141,8 @@ public Mp4Extractor(@Flags int flags) {
     nalStartCode = new ParsableByteArray(NalUnitUtil.NAL_START_CODE);
     nalLength = new ParsableByteArray(4);
     sampleTrackIndex = C.INDEX_UNSET;
+    isAc4HeaderAdded = false;
+    ac4SampleHeaderSize = 0;
   }
 
   @Override
@@ -489,6 +493,7 @@ private int readSample(ExtractorInput input, PositionHolder positionHolder)
       if (sampleTrackIndex == C.INDEX_UNSET) {
         return RESULT_END_OF_INPUT;
       }
+      isAc4HeaderAdded = false;
     }
     Mp4Track track = tracks[sampleTrackIndex];
     TrackOutput trackOutput = track.trackOutput;
@@ -538,18 +543,21 @@ private int readSample(ExtractorInput input, PositionHolder positionHolder)
         }
       }
     } else {
-      int sampleHeaderSize = 0;
-      if (MimeTypes.AUDIO_AC4.equals(track.track.format.sampleMimeType)) {
+      if (MimeTypes.AUDIO_AC4.equals(track.track.format.sampleMimeType) && !isAc4HeaderAdded) {
         ParsableByteArray ac4SampleHeaderData = Ac4Util.getAc4SampleHeader(sampleSize);
         trackOutput.sampleData(ac4SampleHeaderData, ac4SampleHeaderData.capacity());
-        sampleHeaderSize = ac4SampleHeaderData.capacity();
+        ac4SampleHeaderSize = ac4SampleHeaderData.capacity();
+        isAc4HeaderAdded = true;
       }
       while (sampleBytesWritten < sampleSize) {
         int writtenBytes = trackOutput.sampleData(input, sampleSize - sampleBytesWritten, false);
         sampleBytesWritten += writtenBytes;
         sampleCurrentNalBytesRemaining -= writtenBytes;
       }
-      sampleSize += sampleHeaderSize;
+      if (MimeTypes.AUDIO_AC4.equals(track.track.format.sampleMimeType)) {
+        sampleSize += ac4SampleHeaderSize;
+        isAc4HeaderAdded = false;
+      }
     }
     trackOutput.sampleMetadata(track.sampleTable.timestampsUs[sampleIndex],
         track.sampleTable.flags[sampleIndex], sampleSize, 0, null);
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/extractor/ts/Ac4Reader.java b/library/core/src/main/java/com/google/android/exoplayer2/extractor/ts/Ac4Reader.java
index f5d50cde92b..a1e5e51e9d9 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/extractor/ts/Ac4Reader.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/extractor/ts/Ac4Reader.java
@@ -115,9 +115,7 @@ public void consume(ParsableByteArray data) {
           if (skipToNextSync(data)) {
             state = STATE_READING_HEADER;
             headerScratchBytes.data[0] = (byte)0xAC;
-            headerScratchBytes.data[1] = 0x40;
-            if (hasCRC)
-              headerScratchBytes.data[1] = 0x41;
+            headerScratchBytes.data[1] = (byte)(hasCRC ? 0x41 : 0x40);
             bytesRead = 2;
           }
           break;
diff --git a/library/core/src/test/assets/ts/sample.ac4 b/library/core/src/test/assets/ts/sample.ac4
new file mode 100644
index 0000000000000000000000000000000000000000..721f53cdd7f844f2459a014047a6e3d1d87c892a
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zY@7cY=TKH(oiJ>StR!1}TlLI`<ac8n^xf4Nf|cG~FmPAt?M7?MR2AQiycY!HZP)Op
zZqQZZ!4`1`#Kkx09fjriP_y3j5bpXD{qJ$wm*3@v@e`CnE%ZW@>%N%uSr#$4%bv*g
zo+m*MlH-(Gq4e+HR}2Hn+p8$>DRTgc9pJkZN5KErwvOz}JsrHR@KSYv{LrD6szVvd
zVe_9l96PI~#hPLy&izyaVjJao>2wk5%O{E7+D~tkEV^v*2(rYDmG@j}80H@HQeF?u
z&@q@*S|KW#nBe0%jT(JJDYbaZEs;9iuZf<Copvaf@ml;&`}F8rzWP=HrhuJ#OKwfH
zP02}UN?*T6PeO~|sp$>N#A>vUY+A#1s^5#nj~g8L%k7#&!|Hh+_nNN>r-Pa20(Vw%
zAQA{y1=k`tPZe1J1_JrT7|aFZ1V0GFu#mpz7uTH}ubaD_r!Oi?PraJ^q<rTRUv{dT
zXn~@4t%PWoRS7Fkx*5#?i+||;y8>}FOFkTR9e<>agCIQ4^F#Mik=1+?ah=b#-Pz+r
zmvPPPFueYPft=q-IRwXp=Rq2`SNI&8_gg6Az-qcjLs$la&X$LH!_izfHm>TlGGB6V
z&^?gYnI}<dta)fRlAI)3*_sdR@XH5}P|eTI`OW+i)Z%dV2lRiL-^o#rDaC-h!603P
z^#pN{Z|3+!G=)y}Y;R=Tv?s6ZKy}#lm1c|xn7lHfmw3{D+D!7IdJZHi|Avp-!<a87
zR+O~oOjQV6DjH|DbX}BKSHn4y7+ap8T{wzXeDdsAy~Dx)V@~4(Voj*#MPb!1x(->N
zfVah+LM7l4hlJ|$5l&eucNUr!LT<}uoQKPs!5=TDLp4o!J4(X_QyP>W9<=uK=OTmP
zfTBiU1QCF7>d3S7iMea5*|G6I{JOER_=on5)z=ka4Cs||UoG+zAsbS2vd^=qEhsBS
zYhuBTFoxCSvuZcGny%s{F%mxpme<U{&}Rf6w^?^$s>r9050fmf=Ap($U|F5XsH61N
zhJ7PwOpTIQD+<wO5+59`G8`O0Nn^~;Q^wbdo@$>@3ykN1Yd?N2_sp%;i&;u$mN1-z
a8_0ekcO;V@pg-E8wD*(rzw|VFT>b$mUG&rd

literal 0
HcmV?d00001

diff --git a/library/core/src/test/assets/ts/sample.ac4.0.dump b/library/core/src/test/assets/ts/sample.ac4.0.dump
new file mode 100644
index 00000000000..03ae07707a2
--- /dev/null
+++ b/library/core/src/test/assets/ts/sample.ac4.0.dump
@@ -0,0 +1,106 @@
+seekMap:
+  isSeekable = false
+  duration = UNSET TIME
+  getPosition(0) = [[timeUs=0, position=0]]
+numberOfTracks = 1
+track 0:
+  format:
+    bitrate = -1
+    id = 0
+    containerMimeType = null
+    sampleMimeType = audio/ac4
+    maxInputSize = -1
+    width = -1
+    height = -1
+    frameRate = -1.0
+    rotationDegrees = 0
+    pixelWidthHeightRatio = 1.0
+    channelCount = 2
+    sampleRate = 48000
+    pcmEncoding = -1
+    encoderDelay = 0
+    encoderPadding = 0
+    subsampleOffsetUs = 9223372036854775807
+    selectionFlags = 0
+    language = null
+    drmInitData = -
+    initializationData:
+  total output bytes = 7594
+  sample count = 19
+  sample 0:
+    time = 0
+    flags = 1
+    data = length 366, hash B4277F9E
+  sample 1:
+    time = 40000
+    flags = 1
+    data = length 366, hash E8E0A142
+  sample 2:
+    time = 80000
+    flags = 1
+    data = length 366, hash 2E5073D0
+  sample 3:
+    time = 120000
+    flags = 1
+    data = length 366, hash 850E71D8
+  sample 4:
+    time = 160000
+    flags = 1
+    data = length 366, hash 69CD444E
+  sample 5:
+    time = 200000
+    flags = 1
+    data = length 366, hash BD24F36D
+  sample 6:
+    time = 240000
+    flags = 1
+    data = length 366, hash E24F2490
+  sample 7:
+    time = 280000
+    flags = 1
+    data = length 366, hash EE6F1F06
+  sample 8:
+    time = 320000
+    flags = 1
+    data = length 366, hash 2DAB000F
+  sample 9:
+    time = 360000
+    flags = 1
+    data = length 366, hash 8102B7EC
+  sample 10:
+    time = 400000
+    flags = 1
+    data = length 366, hash 55BF59AC
+  sample 11:
+    time = 440000
+    flags = 1
+    data = length 494, hash CBC2E09F
+  sample 12:
+    time = 480000
+    flags = 1
+    data = length 519, hash 9DAF56E9
+  sample 13:
+    time = 520000
+    flags = 1
+    data = length 598, hash 8169EE2
+  sample 14:
+    time = 560000
+    flags = 1
+    data = length 435, hash 28C21246
+  sample 15:
+    time = 600000
+    flags = 1
+    data = length 365, hash FF14716D
+  sample 16:
+    time = 640000
+    flags = 1
+    data = length 392, hash 4CC96B29
+  sample 17:
+    time = 680000
+    flags = 1
+    data = length 373, hash D7AC6D4E
+  sample 18:
+    time = 720000
+    flags = 1
+    data = length 392, hash 99F2511F
+tracksEnded = true
diff --git a/library/core/src/test/java/com/google/android/exoplayer2/extractor/DefaultExtractorsFactoryTest.java b/library/core/src/test/java/com/google/android/exoplayer2/extractor/DefaultExtractorsFactoryTest.java
index 148e04ca77a..bbe7985568e 100644
--- a/library/core/src/test/java/com/google/android/exoplayer2/extractor/DefaultExtractorsFactoryTest.java
+++ b/library/core/src/test/java/com/google/android/exoplayer2/extractor/DefaultExtractorsFactoryTest.java
@@ -25,6 +25,7 @@
 import com.google.android.exoplayer2.extractor.mp4.Mp4Extractor;
 import com.google.android.exoplayer2.extractor.ogg.OggExtractor;
 import com.google.android.exoplayer2.extractor.ts.Ac3Extractor;
+import com.google.android.exoplayer2.extractor.ts.Ac4Extractor;
 import com.google.android.exoplayer2.extractor.ts.AdtsExtractor;
 import com.google.android.exoplayer2.extractor.ts.PsExtractor;
 import com.google.android.exoplayer2.extractor.ts.TsExtractor;
@@ -62,7 +63,8 @@ public void testCreateExtractors_returnExpectedClasses() {
           OggExtractor.class,
           PsExtractor.class,
           WavExtractor.class,
-          AmrExtractor.class
+          AmrExtractor.class,
+          Ac4Extractor.class
         };
 
     assertThat(listCreatedExtractorClasses).containsNoDuplicates();
diff --git a/library/core/src/test/java/com/google/android/exoplayer2/extractor/ts/Ac4ExtractorTest.java b/library/core/src/test/java/com/google/android/exoplayer2/extractor/ts/Ac4ExtractorTest.java
new file mode 100644
index 00000000000..782956dee7b
--- /dev/null
+++ b/library/core/src/test/java/com/google/android/exoplayer2/extractor/ts/Ac4ExtractorTest.java
@@ -0,0 +1,32 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.google.android.exoplayer2.extractor.ts;
+
+import com.google.android.exoplayer2.testutil.ExtractorAsserts;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.robolectric.RobolectricTestRunner;
+
+/** Unit test for {@link Ac4Extractor}. */
+@RunWith(RobolectricTestRunner.class)
+public final class Ac4ExtractorTest {
+
+  @Test
+  public void testAc4Sample() throws Exception {
+    ExtractorAsserts.assertBehavior(Ac4Extractor::new, "ts/sample.ac4");
+  }
+}
+

From 51632f027d09a1c1d456c184cf3b2ea79fc1330f Mon Sep 17 00:00:00 2001
From: BAI Yanning <30304609+ybai001@users.noreply.github.com>
Date: Fri, 25 Jan 2019 16:49:43 +0800
Subject: [PATCH 4/6] Update Ac4Reader.java

---
 .../com/google/android/exoplayer2/extractor/ts/Ac4Reader.java   | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/library/core/src/main/java/com/google/android/exoplayer2/extractor/ts/Ac4Reader.java b/library/core/src/main/java/com/google/android/exoplayer2/extractor/ts/Ac4Reader.java
index 2486ab54002..a1e5e51e9d9 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/extractor/ts/Ac4Reader.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/extractor/ts/Ac4Reader.java
@@ -115,7 +115,7 @@ public void consume(ParsableByteArray data) {
           if (skipToNextSync(data)) {
             state = STATE_READING_HEADER;
             headerScratchBytes.data[0] = (byte)0xAC;
-            headerScratchBytes.data[1] = headerScratchBytes.data[1] = (byte)(hasCRC ? 0x41 : 0x40);
+            headerScratchBytes.data[1] = (byte)(hasCRC ? 0x41 : 0x40);
             bytesRead = 2;
           }
           break;

From 8f32c29cc6691536255d6d93bfd6537f1e245a5f Mon Sep 17 00:00:00 2001
From: ybai001 <ybai@dolby.com>
Date: Thu, 31 Jan 2019 11:31:19 +0800
Subject: [PATCH 5/6] Update code based on code review result

 * remove field mimeType in Ac4Util.java
 * change constant CHANNEL_COUNT_2 to private in Ac4Util.java
---
 .../com/google/android/exoplayer2/audio/Ac4Util.java  | 11 ++---------
 .../android/exoplayer2/extractor/ts/Ac4Reader.java    |  5 +++--
 2 files changed, 5 insertions(+), 11 deletions(-)

diff --git a/library/core/src/main/java/com/google/android/exoplayer2/audio/Ac4Util.java b/library/core/src/main/java/com/google/android/exoplayer2/audio/Ac4Util.java
index 9b845a14d43..fc4c8efb855 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/audio/Ac4Util.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/audio/Ac4Util.java
@@ -33,10 +33,6 @@ public final class Ac4Util {
    */
   public static final class SyncFrameInfo {
 
-    /**
-     * The sample mime type of the bitstream is {@link MimeTypes#AUDIO_AC4}.
-     */
-    public final String mimeType;
     /**
      * The bitstream version.
      */
@@ -59,13 +55,11 @@ public static final class SyncFrameInfo {
     public final int sampleCount;
 
     private SyncFrameInfo(
-        String mimeType,
         int bitstreamVersion,
         int channelCount,
         int sampleRate,
         int frameSize,
         int sampleCount) {
-      this.mimeType = mimeType;
       this.bitstreamVersion = bitstreamVersion;
       this.channelCount = channelCount;
       this.sampleRate = sampleRate;
@@ -78,7 +72,7 @@ private SyncFrameInfo(
    * The channel count of AC-4 stream.
    */
   // TODO: Parse AC-4 stream channel count.
-  public static final int CHANNEL_COUNT_2 = 2;
+  private static final int CHANNEL_COUNT_2 = 2;
   /**
    * The header size for AC-4 parser. Only needs to be as big as we need to read, not the full
    * header size.
@@ -207,8 +201,7 @@ public static SyncFrameInfo parseAc4SyncframeInfo(ParsableBitArray data) {
           break;
       }
     }
-    return new SyncFrameInfo(
-        MimeTypes.AUDIO_AC4, bitstreamVersion, CHANNEL_COUNT_2, sampleRate, frameSize, sampleCount);
+    return new SyncFrameInfo(bitstreamVersion, CHANNEL_COUNT_2, sampleRate, frameSize, sampleCount);
   }
 
   /**
diff --git a/library/core/src/main/java/com/google/android/exoplayer2/extractor/ts/Ac4Reader.java b/library/core/src/main/java/com/google/android/exoplayer2/extractor/ts/Ac4Reader.java
index a1e5e51e9d9..fd1a2bae442 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/extractor/ts/Ac4Reader.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/extractor/ts/Ac4Reader.java
@@ -23,6 +23,7 @@
 import com.google.android.exoplayer2.extractor.ExtractorOutput;
 import com.google.android.exoplayer2.extractor.TrackOutput;
 import com.google.android.exoplayer2.extractor.ts.TsPayloadReader.TrackIdGenerator;
+import com.google.android.exoplayer2.util.MimeTypes;
 import com.google.android.exoplayer2.util.ParsableBitArray;
 import com.google.android.exoplayer2.util.ParsableByteArray;
 import java.lang.annotation.Documented;
@@ -198,8 +199,8 @@ private void parseHeader() {
     SyncFrameInfo frameInfo = Ac4Util.parseAc4SyncframeInfo(headerScratchBits);
     if (format == null || frameInfo.channelCount != format.channelCount
         || frameInfo.sampleRate != format.sampleRate
-        || frameInfo.mimeType != format.sampleMimeType) {
-      format = Format.createAudioSampleFormat(trackFormatId, frameInfo.mimeType, null,
+        || !MimeTypes.AUDIO_AC4.equals(format.sampleMimeType)) {
+      format = Format.createAudioSampleFormat(trackFormatId, MimeTypes.AUDIO_AC4, null,
           Format.NO_VALUE, Format.NO_VALUE, frameInfo.channelCount, frameInfo.sampleRate, null,
           null, 0, language);
       output.format(format);

From 55ed5cfac665a563f6369056b387453223e7b223 Mon Sep 17 00:00:00 2001
From: ybai001 <ybai@dolby.com>
Date: Fri, 1 Feb 2019 09:03:40 +0800
Subject: [PATCH 6/6] Set ac4-is sync only if SDK_INT <= 28

---
 .../android/exoplayer2/audio/MediaCodecAudioRenderer.java       | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/library/core/src/main/java/com/google/android/exoplayer2/audio/MediaCodecAudioRenderer.java b/library/core/src/main/java/com/google/android/exoplayer2/audio/MediaCodecAudioRenderer.java
index f9749450c3c..381a2ad682b 100644
--- a/library/core/src/main/java/com/google/android/exoplayer2/audio/MediaCodecAudioRenderer.java
+++ b/library/core/src/main/java/com/google/android/exoplayer2/audio/MediaCodecAudioRenderer.java
@@ -787,7 +787,7 @@ protected MediaFormat getMediaFormat(
         mediaFormat.setFloat(MediaFormat.KEY_OPERATING_RATE, codecOperatingRate);
       }
     }
-    if (MimeTypes.AUDIO_AC4.equals(format.sampleMimeType)) {
+    if (Util.SDK_INT <= 28 && MimeTypes.AUDIO_AC4.equals(format.sampleMimeType)) {
       // Some devices handle AC-4 raw frame by default.
       // Need to notify the codec to handle AC-4 sync frame.
       mediaFormat.setInteger("ac4-is-sync", 1);