Add AC-4 format support

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

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() {}
+
+}

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);
     }

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;
   }
 

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);

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");