1 files changed, 209 insertions, 0 deletions
diff --git a/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/extractor/ts/Ac3Reader.java b/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/extractor/ts/Ac3Reader.java
new file mode 100644
index 0000000000..3a6eebbcd2
--- /dev/null
+++ b/mobile/android/exoplayer2/src/main/java/org/mozilla/thirdparty/com/google/android/exoplayer2/extractor/ts/Ac3Reader.java
@@ -0,0 +1,209 @@
+/*
+ * Copyright (C) 2016 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 org.mozilla.thirdparty.com.google.android.exoplayer2.extractor.ts;
+
+import androidx.annotation.IntDef;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.C;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.Format;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.audio.Ac3Util;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.audio.Ac3Util.SyncFrameInfo;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.extractor.ExtractorOutput;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.extractor.TrackOutput;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.extractor.ts.TsPayloadReader.TrackIdGenerator;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.util.ParsableBitArray;
+import org.mozilla.thirdparty.com.google.android.exoplayer2.util.ParsableByteArray;
+import java.lang.annotation.Documented;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+
+/**
+ * Parses a continuous (E-)AC-3 byte stream and extracts individual samples.
+ */
+public final class Ac3Reader 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 static final int HEADER_SIZE = 128;
+
+  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 lastByteWas0B;
+
+  // 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 (E-)AC-3 elementary streams.
+   */
+  public Ac3Reader() {
+    this(null);
+  }
+
+  /**
+   * Constructs a new reader for (E-)AC-3 elementary streams.
+   *
+   * @param language Track language.
+   */
+  public Ac3Reader(String language) {
+    headerScratchBits = new ParsableBitArray(new byte[HEADER_SIZE]);
+    headerScratchBytes = new ParsableByteArray(headerScratchBits.data);
+    state = STATE_FINDING_SYNC;
+    this.language = language;
+  }
+
+  @Override
+  public void seek() {
+    state = STATE_FINDING_SYNC;
+    bytesRead = 0;
+    lastByteWas0B = 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] = 0x0B;
+            headerScratchBytes.data[1] = 0x77;
+            bytesRead = 2;
+          }
+          break;
+        case STATE_READING_HEADER:
+          if (continueRead(data, headerScratchBytes.data, HEADER_SIZE)) {
+            parseHeader();
+            headerScratchBytes.setPosition(0);
+            output.sampleData(headerScratchBytes, HEADER_SIZE);
+            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 (!lastByteWas0B) {
+        lastByteWas0B = pesBuffer.readUnsignedByte() == 0x0B;
+        continue;
+      }
+      int secondByte = pesBuffer.readUnsignedByte();
+      if (secondByte == 0x77) {
+        lastByteWas0B = false;
+        return true;
+      } else {
+        lastByteWas0B = secondByte == 0x0B;
+      }
+    }
+    return false;
+  }
+
+  /**
+   * Parses the sample header.
+   */
+  @SuppressWarnings("ReferenceEquality")
+  private void parseHeader() {
+    headerScratchBits.setPosition(0);
+    SyncFrameInfo frameInfo = Ac3Util.parseAc3SyncframeInfo(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 access unit (syncframe in AC-3), but Format#sampleRate
+    // specifies the number of PCM audio samples per second.
+    sampleDurationUs = C.MICROS_PER_SECOND * frameInfo.sampleCount / format.sampleRate;
+  }
+
+}