Add MP4 extraction of Dolby TrueHD samples

Extract 16 access units per readSample call to align
with what's done in MKV extraction.

Signed-off-by: glass <glass@dolby.com>

library/common/src/main/java/com/google/android/exoplayer2/audio/MlpUtil.java

@@ -0,0 +1,104 @@
+/*
+ * Copyright (C) 2021 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 androidx.annotation.Nullable;
+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.ParsableByteArray;
+
+/** Utility methods for parsing MLP frames, which are access units in MLP bitstreams. */
+public final class MlpUtil {
+
+  /** a MLP stream can carry simultaneously multiple representations of the same audio :
+   * stereo as well as multichannel and object based immersive audio,
+   * so just consider stereo by default */
+  private static final int CHANNEL_COUNT_2 = 2;
+
+  /**
+   * Returns the MLP format given {@code data} containing the MLPSpecificBox according to
+   * dolbytruehdbitstreamswithintheisobasemediafileformat.pdf
+   * The reading position of {@code data} will be modified.
+   *
+   * @param data The MLPSpecificBox to parse.
+   * @param trackId The track identifier to set on the format.
+   * @param sampleRate The sample rate to be included in the format.
+   * @param language The language to set on the format.
+   * @param drmInitData {@link DrmInitData} to be included in the format.
+   * @return The MLP format parsed from data in the header.
+   */
+  public static Format parseMlpFormat(
+      ParsableByteArray data, String trackId, int sampleRate,
+      String language, @Nullable DrmInitData drmInitData) {
+
+    return new Format.Builder()
+        .setId(trackId)
+        .setSampleMimeType(MimeTypes.AUDIO_TRUEHD)
+        .setChannelCount(CHANNEL_COUNT_2)
+        .setSampleRate(sampleRate)
+        .setDrmInitData(drmInitData)
+        .setLanguage(language)
+        .build();
+  }
+
+  private MlpUtil() {}
+
+  /**
+   * The number of samples to store in each output chunk when rechunking TrueHD streams. The number
+   * of samples extracted from the container corresponding to one syncframe must be an integer
+   * multiple of this value.
+   */
+  public static final int TRUEHD_RECHUNK_SAMPLE_COUNT = 16;
+
+  /**
+   * Rechunks TrueHD sample data into groups of {@link #TRUEHD_RECHUNK_SAMPLE_COUNT} samples.
+   */
+  public static class TrueHdSampleRechunker {
+
+    private int sampleCount;
+    public long timeUs;
+    public @C.BufferFlags int flags;
+    public int sampleSize;
+
+    public TrueHdSampleRechunker() {
+      reset();
+    }
+
+    public void reset() {
+      sampleCount = 0;
+      sampleSize = 0;
+    }
+
+    /** Returns true when enough samples have been appended. */
+    public boolean appendSampleMetadata(long timeUs, @C.BufferFlags int flags, int size) {
+
+      if (sampleCount++ == 0) {
+        // This is the first sample in the chunk.
+        this.timeUs = timeUs;
+        this.flags = flags;
+        this.sampleSize = 0;
+      }
+      this.sampleSize += size;
+      if (sampleCount >= TRUEHD_RECHUNK_SAMPLE_COUNT) {
+        sampleCount = 0;
+        return true;
+      }
+      return false;
+    }
+  }
+}

library/extractor/src/main/java/com/google/android/exoplayer2/extractor/mp4/Atom.java

@@ -152,6 +152,12 @@ import java.util.List;
   @SuppressWarnings("ConstantCaseForConstants")
   public static final int TYPE_dac4 = 0x64616334;
 
+  @SuppressWarnings("ConstantCaseForConstants")
+  public static final int TYPE_mlpa = 0x6d6c7061;
+
+  @SuppressWarnings("ConstantCaseForConstants")
+  public static final int TYPE_dmlp = 0x646d6c70;
+
   @SuppressWarnings("ConstantCaseForConstants")
   public static final int TYPE_dtsc = 0x64747363;
 

library/extractor/src/main/java/com/google/android/exoplayer2/extractor/mp4/AtomParsers.java

@@ -28,6 +28,7 @@ import com.google.android.exoplayer2.ParserException;
 import com.google.android.exoplayer2.audio.AacUtil;
 import com.google.android.exoplayer2.audio.Ac3Util;
 import com.google.android.exoplayer2.audio.Ac4Util;
+import com.google.android.exoplayer2.audio.MlpUtil;
 import com.google.android.exoplayer2.audio.OpusUtil;
 import com.google.android.exoplayer2.drm.DrmInitData;
 import com.google.android.exoplayer2.extractor.ExtractorUtil;
@@ -962,6 +963,7 @@ import org.checkerframework.checker.nullness.compatqual.NullableType;
           || childAtomType == Atom.TYPE_ac_3
           || childAtomType == Atom.TYPE_ec_3
           || childAtomType == Atom.TYPE_ac_4
+          || childAtomType == Atom.TYPE_mlpa
           || childAtomType == Atom.TYPE_dtsc
           || childAtomType == Atom.TYPE_dtse
           || childAtomType == Atom.TYPE_dtsh
@@ -1314,12 +1316,18 @@ import org.checkerframework.checker.nullness.compatqual.NullableType;
 
     int  channelCount;
     int  sampleRate;
+    int  sampleRate32 = 0;
     @C.PcmEncoding int pcmEncoding = Format.NO_VALUE;
     @Nullable String codecs = null;
 
     if (quickTimeSoundDescriptionVersion == 0 || quickTimeSoundDescriptionVersion == 1) {
       channelCount = parent.readUnsignedShort();
       parent.skipBytes(6);  // sampleSize, compressionId, packetSize.
+
+      int pos = parent.getPosition();
+      sampleRate32 = (int) parent.readUnsignedInt();
+
+      parent.setPosition(pos);
       sampleRate = parent.readUnsignedFixedPoint1616();
 
       if (quickTimeSoundDescriptionVersion == 1) {
@@ -1401,6 +1409,8 @@ import org.checkerframework.checker.nullness.compatqual.NullableType;
       mimeType = MimeTypes.AUDIO_OPUS;
     } else if (atomType == Atom.TYPE_fLaC) {
       mimeType = MimeTypes.AUDIO_FLAC;
+    } else if (atomType == Atom.TYPE_mlpa) {
+      mimeType = MimeTypes.AUDIO_TRUEHD;
     }
 
     @Nullable List<byte[]> initializationData = null;
@@ -1442,6 +1452,10 @@ import org.checkerframework.checker.nullness.compatqual.NullableType;
             initializationData = ImmutableList.of(initializationDataBytes);
           }
         }
+      } else if (childAtomType == Atom.TYPE_dmlp) {
+        parent.setPosition(Atom.HEADER_SIZE + childPosition);
+        out.format = MlpUtil.parseMlpFormat(parent, Integer.toString(trackId),
+            sampleRate32, language, drmInitData);
       } else if (childAtomType == Atom.TYPE_dac3) {
         parent.setPosition(Atom.HEADER_SIZE + childPosition);
         out.format =

library/extractor/src/main/java/com/google/android/exoplayer2/extractor/mp4/Mp4Extractor.java

@@ -30,6 +30,7 @@ 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.audio.MlpUtil;
 import com.google.android.exoplayer2.extractor.Extractor;
 import com.google.android.exoplayer2.extractor.ExtractorInput;
 import com.google.android.exoplayer2.extractor.ExtractorOutput;
@@ -501,11 +502,17 @@ public final class Mp4Extractor implements Extractor, SeekMap {
           track.durationUs != C.TIME_UNSET ? track.durationUs : trackSampleTable.durationUs;
       durationUs = max(durationUs, trackDurationUs);
       Mp4Track mp4Track =
-          new Mp4Track(track, trackSampleTable, extractorOutput.track(i, track.type));
+          new Mp4Track(track, trackSampleTable, extractorOutput.track(i, track.type), track.format.sampleMimeType);
 
       // Each sample has up to three bytes of overhead for the start code that replaces its length.
       // Allow ten source samples per output sample, like the platform extractor.
       int maxInputSize = trackSampleTable.maximumSize + 3 * 10;
+
+      if ((track.format.sampleMimeType != null) && (track.format.sampleMimeType.equals(MimeTypes.AUDIO_TRUEHD))) {
+        // TrueHD collates 16 source samples per output
+        maxInputSize = trackSampleTable.maximumSize * MlpUtil.TRUEHD_RECHUNK_SAMPLE_COUNT;
+      }
+
       Format.Builder formatBuilder = track.format.buildUpon();
       formatBuilder.setMaxInputSize(maxInputSize);
       if (track.type == C.TRACK_TYPE_VIDEO
@@ -540,7 +547,8 @@ public final class Mp4Extractor implements Extractor, SeekMap {
   }
 
   /**
-   * Attempts to extract the next sample in the current mdat atom for the specified track.
+   * Attempts to extract the next sample or the next 16 samples in case of Dolby TrueHD audio
+   * in the current mdat atom for the specified track.
    *
    * <p>Returns {@link #RESULT_SEEK} if the source should be reloaded from the position in {@code
    * positionHolder}.
@@ -632,12 +640,9 @@ public final class Mp4Extractor implements Extractor, SeekMap {
         sampleCurrentNalBytesRemaining -= writtenBytes;
       }
     }
-    trackOutput.sampleMetadata(
+
-        track.sampleTable.timestampsUs[sampleIndex],
+    track.sampleMetadata(sampleIndex, sampleSize, 0, null);
-        track.sampleTable.flags[sampleIndex],
+
-        sampleSize,
-        0,
-        null);
     track.sampleIndex++;
     sampleTrackIndex = C.INDEX_UNSET;
     sampleBytesRead = 0;
@@ -904,11 +909,40 @@ public final class Mp4Extractor implements Extractor, SeekMap {
     public final TrackOutput trackOutput;
 
     public int sampleIndex;
+    @Nullable public MlpUtil.TrueHdSampleRechunker trueHdSampleRechunker;
 
-    public Mp4Track(Track track, TrackSampleTable sampleTable, TrackOutput trackOutput) {
+    public Mp4Track(Track track, TrackSampleTable sampleTable, TrackOutput trackOutput, @Nullable String mimeType) {
       this.track = track;
       this.sampleTable = sampleTable;
       this.trackOutput = trackOutput;
+      this.trueHdSampleRechunker = null;
+
+      if ((mimeType != null) && mimeType.equals(MimeTypes.AUDIO_TRUEHD)) {
+        this.trueHdSampleRechunker = new MlpUtil.TrueHdSampleRechunker();
+      }
+    }
+
+    public void sampleMetadata( int sampleIndex, int sampleSize, int offset,
+        @Nullable TrackOutput.CryptoData cryptoData) {
+
+      long timeUs = sampleTable.timestampsUs[sampleIndex];
+      @C.BufferFlags int flags = sampleTable.flags[sampleIndex];
+
+      if (trueHdSampleRechunker != null) {
+        boolean fullChunk = trueHdSampleRechunker.appendSampleMetadata(timeUs,flags,sampleSize);
+
+        if (fullChunk || (sampleIndex+1 == sampleTable.sampleCount)) {
+          timeUs = trueHdSampleRechunker.timeUs;
+          flags = trueHdSampleRechunker.flags;
+          sampleSize = trueHdSampleRechunker.sampleSize;
+
+          trackOutput.sampleMetadata( timeUs, flags, sampleSize, offset, cryptoData);
+          trueHdSampleRechunker.reset();
+        }
+      } else {
+        trackOutput.sampleMetadata( timeUs, flags, sampleSize, offset, cryptoData);
       }
     }
   }
+
+}