Java Ac3Util类代码示例

import com.google.android.exoplayer.util.Ac3Util; //导入依赖的package包/类
/**
 * Parses the sample header.
 */
private void parseHeader() {
  if (mediaFormat == null) {
    mediaFormat = isEac3
        ? Ac3Util.parseEac3SyncframeFormat(headerScratchBits, null, C.UNKNOWN_TIME_US, null)
        : Ac3Util.parseAc3SyncframeFormat(headerScratchBits, null, C.UNKNOWN_TIME_US, null);
    output.format(mediaFormat);
  }
  sampleSize = isEac3 ? Ac3Util.parseEAc3SyncframeSize(headerScratchBits.data)
      : Ac3Util.parseAc3SyncframeSize(headerScratchBits.data);
  int audioSamplesPerSyncframe = isEac3
      ? Ac3Util.parseEAc3SyncframeAudioSampleCount(headerScratchBits.data)
      : Ac3Util.getAc3SyncframeAudioSampleCount();
  // In this class a sample is an access unit (syncframe in AC-3), but the MediaFormat sample rate
  // specifies the number of PCM audio samples per second.
  sampleDurationUs =
      (int) (C.MICROS_PER_SECOND * audioSamplesPerSyncframe / mediaFormat.sampleRate);
}
 

import com.google.android.exoplayer.util.Ac3Util; //导入依赖的package包/类
/**
 * Parses the sample header.
 */
private void parseHeader() {
  headerScratchBits.setPosition(0);
  sampleSize = Ac3Util.parseFrameSize(headerScratchBits);
  if (mediaFormat == null) {
    headerScratchBits.setPosition(0);
    mediaFormat = Ac3Util.parseFrameAc3Format(headerScratchBits);
    output.format(mediaFormat);
    bitrate = Ac3Util.getBitrate(sampleSize, mediaFormat.sampleRate);
  }
  frameDurationUs = (int) (1000L * 8 * sampleSize / bitrate);
}
 

import com.google.android.exoplayer.util.Ac3Util; //导入依赖的package包/类
private static int getFramesPerEncodedSample(int encoding, ByteBuffer buffer) {
  if (encoding == C.ENCODING_DTS || encoding == C.ENCODING_DTS_HD) {
    return DtsUtil.parseDtsAudioSampleCount(buffer);
  } else if (encoding == C.ENCODING_AC3) {
    return Ac3Util.getAc3SyncframeAudioSampleCount();
  } else if (encoding == C.ENCODING_E_AC3) {
    return Ac3Util.parseEAc3SyncframeAudioSampleCount(buffer);
  } else {
    throw new IllegalStateException("Unexpected audio encoding: " + encoding);
  }
}
 

import com.google.android.exoplayer.util.Ac3Util; //导入依赖的package包/类
private static void parseAudioSampleEntry(ParsableByteArray parent, int atomType, int position,
    int size, long durationUs, StsdDataHolder out, int entryIndex) {
  parent.setPosition(position + Atom.HEADER_SIZE);
  parent.skipBytes(16);
  int channelCount = parent.readUnsignedShort();
  int sampleSize = parent.readUnsignedShort();
  parent.skipBytes(4);
  int sampleRate = parent.readUnsignedFixedPoint1616();

  // If the atom type determines a MIME type, set it immediately.
  String mimeType = null;
  if (atomType == Atom.TYPE_ac_3) {
    mimeType = MimeTypes.AUDIO_AC3;
  } else if (atomType == Atom.TYPE_ec_3) {
    mimeType = MimeTypes.AUDIO_EC3;
  }

  byte[] initializationData = null;
  int childPosition = parent.getPosition();
  while (childPosition - position < size) {
    parent.setPosition(childPosition);
    int childStartPosition = parent.getPosition();
    int childAtomSize = parent.readInt();
    Assertions.checkArgument(childAtomSize > 0, "childAtomSize should be positive");
    int childAtomType = parent.readInt();
    if (atomType == Atom.TYPE_mp4a || atomType == Atom.TYPE_enca) {
      if (childAtomType == Atom.TYPE_esds) {
        Pair<String, byte[]> mimeTypeAndInitializationData =
            parseEsdsFromParent(parent, childStartPosition);
        mimeType = mimeTypeAndInitializationData.first;
        initializationData = mimeTypeAndInitializationData.second;
        if (MimeTypes.AUDIO_AAC.equals(mimeType)) {
          // TODO: Do we really need to do this? See [Internal: b/10903778]
          // Update sampleRate and channelCount from the AudioSpecificConfig initialization data.
          Pair<Integer, Integer> audioSpecificConfig =
              CodecSpecificDataUtil.parseAacAudioSpecificConfig(initializationData);
          sampleRate = audioSpecificConfig.first;
          channelCount = audioSpecificConfig.second;
        }
      } else if (childAtomType == Atom.TYPE_sinf) {
        out.trackEncryptionBoxes[entryIndex] = parseSinfFromParent(parent, childStartPosition,
            childAtomSize);
      }
    } else if (atomType == Atom.TYPE_ac_3 && childAtomType == Atom.TYPE_dac3) {
      // TODO: Choose the right AC-3 track based on the contents of dac3/dec3.
      // TODO: Add support for encryption (by setting out.trackEncryptionBoxes).
      parent.setPosition(Atom.HEADER_SIZE + childStartPosition);
      out.mediaFormat = Ac3Util.parseAnnexFAc3Format(parent);
      return;
    } else if  (atomType == Atom.TYPE_ec_3 && childAtomType == Atom.TYPE_dec3) {
      parent.setPosition(Atom.HEADER_SIZE + childStartPosition);
      out.mediaFormat = Ac3Util.parseAnnexFEAc3Format(parent);
      return;
    }
    childPosition += childAtomSize;
  }

  // If the media type was not recognized, ignore the track.
  if (mimeType == null) {
    return;
  }

  out.mediaFormat = MediaFormat.createAudioFormat(mimeType, sampleSize, durationUs, channelCount,
      sampleRate,
      initializationData == null ? null : Collections.singletonList(initializationData));
}