Java Code Examples for com.google.android.exoplayer2.extractor.ExtractorInput#peekFully()

private int peekId3Header(ExtractorInput input) throws IOException, InterruptedException {
  int firstFramePosition = 0;
  while (true) {
    input.peekFully(scratch.data, /* offset= */ 0, ID3_HEADER_LENGTH);
    scratch.setPosition(0);
    if (scratch.readUnsignedInt24() != ID3_TAG) {
      break;
    }
    scratch.skipBytes(3);
    int length = scratch.readSynchSafeInt();
    firstFramePosition += ID3_HEADER_LENGTH + length;
    input.advancePeekPosition(length);
  }
  input.resetPeekPosition();
  input.advancePeekPosition(firstFramePosition);
  if (this.firstFramePosition == C.POSITION_UNSET) {
    this.firstFramePosition = firstFramePosition;
  }
  return firstFramePosition;
}
 

/**
 * Peeks a variable-length unsigned EBML integer from the input.
 */
private long readUint(ExtractorInput input) throws IOException, InterruptedException {
  input.peekFully(scratch.data, 0, 1);
  int value = scratch.data[0] & 0xFF;
  if (value == 0) {
    return Long.MIN_VALUE;
  }
  int mask = 0x80;
  int length = 0;
  while ((value & mask) == 0) {
    mask >>= 1;
    length++;
  }
  value &= ~mask;
  input.peekFully(scratch.data, 1, length);
  for (int i = 0; i < length; i++) {
    value <<= 8;
    value += scratch.data[i + 1] & 0xFF;
  }
  peekLength += length + 1;
  return value;
}
 

private int readLastScrValue(ExtractorInput input, PositionHolder seekPositionHolder)
    throws IOException, InterruptedException {
  int bytesToRead = (int) Math.min(DURATION_READ_BYTES, input.getLength());
  long bufferStartStreamPosition = input.getLength() - bytesToRead;
  if (input.getPosition() != bufferStartStreamPosition) {
    seekPositionHolder.position = bufferStartStreamPosition;
    return Extractor.RESULT_SEEK;
  }

  input.resetPeekPosition();
  input.peekFully(packetBuffer.data, /* offset= */ 0, bytesToRead);
  packetBuffer.setPosition(0);
  packetBuffer.setLimit(bytesToRead);

  lastScrValue = readLastScrValueFromBuffer(packetBuffer);
  isLastScrValueRead = true;
  return Extractor.RESULT_CONTINUE;
}
 

private int readLastPcrValue(ExtractorInput input, PositionHolder seekPositionHolder, int pcrPid)
    throws IOException, InterruptedException {
  long inputLength = input.getLength();
  int bytesToSearch = (int) Math.min(TIMESTAMP_SEARCH_BYTES, inputLength);
  long searchStartPosition = inputLength - bytesToSearch;
  if (input.getPosition() != searchStartPosition) {
    seekPositionHolder.position = searchStartPosition;
    return Extractor.RESULT_SEEK;
  }

  packetBuffer.reset(bytesToSearch);
  input.resetPeekPosition();
  input.peekFully(packetBuffer.data, /* offset= */ 0, bytesToSearch);

  lastPcrValue = readLastPcrValueFromBuffer(packetBuffer, pcrPid);
  isLastPcrValueRead = true;
  return Extractor.RESULT_CONTINUE;
}
 

/**
 * Does a byte by byte search to try and find the next level 1 element. This method is called if
 * some invalid data is encountered in the parser.
 *
 * @param input The {@link ExtractorInput} from which data has to be read.
 * @return id of the next level 1 element that has been found.
 * @throws EOFException If the end of input was encountered when searching for the next level 1
 *     element.
 * @throws IOException If an error occurs reading from the input.
 * @throws InterruptedException If the thread is interrupted.
 */
private long maybeResyncToNextLevel1Element(ExtractorInput input) throws IOException,
    InterruptedException {
  input.resetPeekPosition();
  while (true) {
    input.peekFully(scratch, 0, MAX_ID_BYTES);
    int varintLength = VarintReader.parseUnsignedVarintLength(scratch[0]);
    if (varintLength != C.LENGTH_UNSET && varintLength <= MAX_ID_BYTES) {
      int potentialId = (int) VarintReader.assembleVarint(scratch, varintLength, false);
      if (output.isLevel1Element(potentialId)) {
        input.skipFully(varintLength);
        return potentialId;
      }
    }
    input.skipFully(1);
  }
}
 

private int readFirstPcrValue(ExtractorInput input, PositionHolder seekPositionHolder, int pcrPid)
    throws IOException, InterruptedException {
  if (input.getPosition() != 0) {
    seekPositionHolder.position = 0;
    return Extractor.RESULT_SEEK;
  }

  int bytesToRead = (int) Math.min(DURATION_READ_BYTES, input.getLength());
  input.resetPeekPosition();
  input.peekFully(packetBuffer.data, /* offset= */ 0, bytesToRead);
  packetBuffer.setPosition(0);
  packetBuffer.setLimit(bytesToRead);

  firstPcrValue = readFirstPcrValueFromBuffer(packetBuffer, pcrPid);
  isFirstPcrValueRead = true;
  return Extractor.RESULT_CONTINUE;
}
 

@Override
public boolean sniff(ExtractorInput input) throws IOException, InterruptedException {
  byte[] buffer = tsPacketBuffer.data;
  input.peekFully(buffer, 0, TS_PACKET_SIZE * SNIFF_TS_PACKET_COUNT);
  for (int startPosCandidate = 0; startPosCandidate < TS_PACKET_SIZE; startPosCandidate++) {
    // Try to identify at least SNIFF_TS_PACKET_COUNT packets starting with TS_SYNC_BYTE.
    boolean isSyncBytePatternCorrect = true;
    for (int i = 0; i < SNIFF_TS_PACKET_COUNT; i++) {
      if (buffer[startPosCandidate + i * TS_PACKET_SIZE] != TS_SYNC_BYTE) {
        isSyncBytePatternCorrect = false;
        break;
      }
    }
    if (isSyncBytePatternCorrect) {
      input.skipFully(startPosCandidate);
      return true;
    }
  }
  return false;
}
 

/**
 * Peeks a variable-length unsigned EBML integer from the input.
 */
private long readUint(ExtractorInput input) throws IOException, InterruptedException {
  input.peekFully(scratch.data, 0, 1);
  int value = scratch.data[0] & 0xFF;
  if (value == 0) {
    return Long.MIN_VALUE;
  }
  int mask = 0x80;
  int length = 0;
  while ((value & mask) == 0) {
    mask >>= 1;
    length++;
  }
  value &= ~mask;
  input.peekFully(scratch.data, 1, length);
  for (int i = 0; i < length; i++) {
    value <<= 8;
    value += scratch.data[i + 1] & 0xFF;
  }
  peekLength += length + 1;
  return value;
}
 

/**
 * Does a byte by byte search to try and find the next level 1 element. This method is called if
 * some invalid data is encountered in the parser.
 *
 * @param input The {@link ExtractorInput} from which data has to be read.
 * @return id of the next level 1 element that has been found.
 * @throws EOFException If the end of input was encountered when searching for the next level 1
 *     element.
 * @throws IOException If an error occurs reading from the input.
 * @throws InterruptedException If the thread is interrupted.
 */
private long maybeResyncToNextLevel1Element(ExtractorInput input) throws IOException,
    InterruptedException {
  input.resetPeekPosition();
  while (true) {
    input.peekFully(scratch, 0, MAX_ID_BYTES);
    int varintLength = VarintReader.parseUnsignedVarintLength(scratch[0]);
    if (varintLength != C.LENGTH_UNSET && varintLength <= MAX_ID_BYTES) {
      int potentialId = (int) VarintReader.assembleVarint(scratch, varintLength, false);
      if (processor.isLevel1Element(potentialId)) {
        input.skipFully(varintLength);
        return potentialId;
      }
    }
    input.skipFully(1);
  }
}
 

private boolean sniffInternal(ExtractorInput input) throws IOException, InterruptedException {
  OggPageHeader header = new OggPageHeader();
  if (!header.populate(input, true) || (header.type & 0x02) != 0x02) {
    return false;
  }

  int length = Math.min(header.bodySize, MAX_VERIFICATION_BYTES);
  ParsableByteArray scratch = new ParsableByteArray(length);
  input.peekFully(scratch.data, 0, length);

  if (FlacReader.verifyBitstreamType(resetPosition(scratch))) {
    streamReader = new FlacReader();
  } else if (VorbisReader.verifyBitstreamType(resetPosition(scratch))) {
    streamReader = new VorbisReader();
  } else if (OpusReader.verifyBitstreamType(resetPosition(scratch))) {
    streamReader = new OpusReader();
  } else {
    return false;
  }
  return true;
}
 

/**
 * Consumes the next frame from the {@code input} if it contains VBRI or Xing seeking metadata,
 * returning a {@link Seeker} if the metadata was present and valid, or {@code null} otherwise.
 * After this method returns, the input position is the start of the first frame of audio.
 *
 * @param input The {@link ExtractorInput} from which to read.
 * @return A {@link Seeker} if seeking metadata was present and valid, or {@code null} otherwise.
 * @throws IOException Thrown if there was an error reading from the stream. Not expected if the
 *     next two frames were already peeked during synchronization.
 * @throws InterruptedException Thrown if reading from the stream was interrupted. Not expected if
 *     the next two frames were already peeked during synchronization.
 */
private Seeker maybeReadSeekFrame(ExtractorInput input) throws IOException, InterruptedException {
  ParsableByteArray frame = new ParsableByteArray(synchronizedHeader.frameSize);
  input.peekFully(frame.data, 0, synchronizedHeader.frameSize);
  int xingBase = (synchronizedHeader.version & 1) != 0
      ? (synchronizedHeader.channels != 1 ? 36 : 21) // MPEG 1
      : (synchronizedHeader.channels != 1 ? 21 : 13); // MPEG 2 or 2.5
  int seekHeader = getSeekFrameHeader(frame, xingBase);
  Seeker seeker;
  if (seekHeader == SEEK_HEADER_XING || seekHeader == SEEK_HEADER_INFO) {
    seeker = XingSeeker.create(input.getLength(), input.getPosition(), synchronizedHeader, frame);
    if (seeker != null && !gaplessInfoHolder.hasGaplessInfo()) {
      // If there is a Xing header, read gapless playback metadata at a fixed offset.
      input.resetPeekPosition();
      input.advancePeekPosition(xingBase + 141);
      input.peekFully(scratch.data, 0, 3);
      scratch.setPosition(0);
      gaplessInfoHolder.setFromXingHeaderValue(scratch.readUnsignedInt24());
    }
    input.skipFully(synchronizedHeader.frameSize);
    if (seeker != null && !seeker.isSeekable() && seekHeader == SEEK_HEADER_INFO) {
      // Fall back to constant bitrate seeking for Info headers missing a table of contents.
      return getConstantBitrateSeeker(input);
    }
  } else if (seekHeader == SEEK_HEADER_VBRI) {
    seeker = VbriSeeker.create(input.getLength(), input.getPosition(), synchronizedHeader, frame);
    input.skipFully(synchronizedHeader.frameSize);
  } else { // seekerHeader == SEEK_HEADER_UNSET
    // This frame doesn't contain seeking information, so reset the peek position.
    seeker = null;
    input.resetPeekPosition();
  }
  return seeker;
}
 

/**
 * Consumes the next frame from the {@code input} if it contains VBRI or Xing seeking metadata,
 * returning a {@link Seeker} if the metadata was present and valid, or {@code null} otherwise.
 * After this method returns, the input position is the start of the first frame of audio.
 *
 * @param input The {@link ExtractorInput} from which to read.
 * @return A {@link Seeker} if seeking metadata was present and valid, or {@code null} otherwise.
 * @throws IOException Thrown if there was an error reading from the stream. Not expected if the
 *     next two frames were already peeked during synchronization.
 * @throws InterruptedException Thrown if reading from the stream was interrupted. Not expected if
 *     the next two frames were already peeked during synchronization.
 */
private Seeker maybeReadSeekFrame(ExtractorInput input) throws IOException, InterruptedException {
  ParsableByteArray frame = new ParsableByteArray(synchronizedHeader.frameSize);
  input.peekFully(frame.data, 0, synchronizedHeader.frameSize);
  int xingBase = (synchronizedHeader.version & 1) != 0
      ? (synchronizedHeader.channels != 1 ? 36 : 21) // MPEG 1
      : (synchronizedHeader.channels != 1 ? 21 : 13); // MPEG 2 or 2.5
  int seekHeader = getSeekFrameHeader(frame, xingBase);
  Seeker seeker;
  if (seekHeader == SEEK_HEADER_XING || seekHeader == SEEK_HEADER_INFO) {
    seeker = XingSeeker.create(input.getLength(), input.getPosition(), synchronizedHeader, frame);
    if (seeker != null && !gaplessInfoHolder.hasGaplessInfo()) {
      // If there is a Xing header, read gapless playback metadata at a fixed offset.
      input.resetPeekPosition();
      input.advancePeekPosition(xingBase + 141);
      input.peekFully(scratch.data, 0, 3);
      scratch.setPosition(0);
      gaplessInfoHolder.setFromXingHeaderValue(scratch.readUnsignedInt24());
    }
    input.skipFully(synchronizedHeader.frameSize);
    if (seeker != null && !seeker.isSeekable() && seekHeader == SEEK_HEADER_INFO) {
      // Fall back to constant bitrate seeking for Info headers missing a table of contents.
      return getConstantBitrateSeeker(input);
    }
  } else if (seekHeader == SEEK_HEADER_VBRI) {
    seeker = VbriSeeker.create(input.getLength(), input.getPosition(), synchronizedHeader, frame);
    input.skipFully(synchronizedHeader.frameSize);
  } else { // seekerHeader == SEEK_HEADER_UNSET
    // This frame doesn't contain seeking information, so reset the peek position.
    seeker = null;
    input.resetPeekPosition();
  }
  return seeker;
}
 

public void startSample(ExtractorInput input) throws IOException, InterruptedException {
  if (foundSyncframe) {
    return;
  }
  input.peekFully(syncframePrefix, 0, Ac3Util.TRUEHD_SYNCFRAME_PREFIX_LENGTH);
  input.resetPeekPosition();
  if (Ac3Util.parseTrueHdSyncframeAudioSampleCount(syncframePrefix) == 0) {
    return;
  }
  foundSyncframe = true;
}
 

private static boolean sniffInternal(ExtractorInput input, boolean fragmented)
    throws IOException, InterruptedException {
  long inputLength = input.getLength();
  int bytesToSearch = (int) (inputLength == C.LENGTH_UNSET || inputLength > SEARCH_LENGTH
      ? SEARCH_LENGTH : inputLength);

  ParsableByteArray buffer = new ParsableByteArray(64);
  int bytesSearched = 0;
  boolean foundGoodFileType = false;
  boolean isFragmented = false;
  while (bytesSearched < bytesToSearch) {
    // Read an atom header.
    int headerSize = Atom.HEADER_SIZE;
    buffer.reset(headerSize);
    input.peekFully(buffer.data, 0, headerSize);
    long atomSize = buffer.readUnsignedInt();
    int atomType = buffer.readInt();
    if (atomSize == Atom.DEFINES_LARGE_SIZE) {
      // Read the large atom size.
      headerSize = Atom.LONG_HEADER_SIZE;
      input.peekFully(buffer.data, Atom.HEADER_SIZE, Atom.LONG_HEADER_SIZE - Atom.HEADER_SIZE);
      buffer.setLimit(Atom.LONG_HEADER_SIZE);
      atomSize = buffer.readLong();
    } else if (atomSize == Atom.EXTENDS_TO_END_SIZE) {
      // The atom extends to the end of the file.
      long fileEndPosition = input.getLength();
      if (fileEndPosition != C.LENGTH_UNSET) {
        atomSize = fileEndPosition - input.getPeekPosition() + headerSize;
      }
    }

    if (atomSize < headerSize) {
      // The file is invalid because the atom size is too small for its header.
      return false;
    }
    bytesSearched += headerSize;

    if (atomType == Atom.TYPE_moov) {
      // We have seen the moov atom. We increase the search size to make sure we don't miss an
      // mvex atom because the moov's size exceeds the search length.
      bytesToSearch += (int) atomSize;
      if (inputLength != C.LENGTH_UNSET && bytesToSearch > inputLength) {
        // Make sure we don't exceed the file size.
        bytesToSearch = (int) inputLength;
      }
      // Check for an mvex atom inside the moov atom to identify whether the file is fragmented.
      continue;
    }

    if (atomType == Atom.TYPE_moof || atomType == Atom.TYPE_mvex) {
      // The movie is fragmented. Stop searching as we must have read any ftyp atom already.
      isFragmented = true;
      break;
    }

    if (bytesSearched + atomSize - headerSize >= bytesToSearch) {
      // Stop searching as peeking this atom would exceed the search limit.
      break;
    }

    int atomDataSize = (int) (atomSize - headerSize);
    bytesSearched += atomDataSize;
    if (atomType == Atom.TYPE_ftyp) {
      // Parse the atom and check the file type/brand is compatible with the extractors.
      if (atomDataSize < 8) {
        return false;
      }
      buffer.reset(atomDataSize);
      input.peekFully(buffer.data, 0, atomDataSize);
      int brandsCount = atomDataSize / 4;
      for (int i = 0; i < brandsCount; i++) {
        if (i == 1) {
          // This index refers to the minorVersion, not a brand, so skip it.
          buffer.skipBytes(4);
        } else if (isCompatibleBrand(buffer.readInt())) {
          foundGoodFileType = true;
          break;
        }
      }
      if (!foundGoodFileType) {
        // The types were not compatible and there is only one ftyp atom, so reject the file.
        return false;
      }
    } else if (atomDataSize != 0) {
      // Skip the atom.
      input.advancePeekPosition(atomDataSize);
    }
  }
  return foundGoodFileType && fragmented == isFragmented;
}
 

@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); // version, flags
    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, 6);
    scratch.setPosition(0);
    int syncBytes = scratch.readUnsignedShort();
    if (syncBytes != AC3_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 = Ac3Util.parseAc3SyncframeSize(scratch.data);
      if (frameSize == C.LENGTH_UNSET) {
        return false;
      }
      input.advancePeekPosition(frameSize - 6);
    }
  }
}
 

/**
 * @see com.google.android.exoplayer2.extractor.Extractor#sniff(ExtractorInput)
 */
public boolean sniff(ExtractorInput input) throws IOException, InterruptedException {
  long inputLength = input.getLength();
  int bytesToSearch = (int) (inputLength == C.LENGTH_UNSET || inputLength > SEARCH_LENGTH
      ? SEARCH_LENGTH : inputLength);
  // Find four bytes equal to ID_EBML near the start of the input.
  input.peekFully(scratch.data, 0, 4);
  long tag = scratch.readUnsignedInt();
  peekLength = 4;
  while (tag != ID_EBML) {
    if (++peekLength == bytesToSearch) {
      return false;
    }
    input.peekFully(scratch.data, 0, 1);
    tag = (tag << 8) & 0xFFFFFF00;
    tag |= scratch.data[0] & 0xFF;
  }

  // Read the size of the EBML header and make sure it is within the stream.
  long headerSize = readUint(input);
  long headerStart = peekLength;
  if (headerSize == Long.MIN_VALUE
      || (inputLength != C.LENGTH_UNSET && headerStart + headerSize >= inputLength)) {
    return false;
  }

  // Read the payload elements in the EBML header.
  while (peekLength < headerStart + headerSize) {
    long id = readUint(input);
    if (id == Long.MIN_VALUE) {
      return false;
    }
    long size = readUint(input);
    if (size < 0 || size > Integer.MAX_VALUE) {
      return false;
    }
    if (size != 0) {
      int sizeInt = (int) size;
      input.advancePeekPosition(sizeInt);
      peekLength += sizeInt;
    }
  }
  return peekLength == headerStart + headerSize;
}
 

/**
 * Peeks and returns a {@code WavHeader}.
 *
 * @param input Input stream to peek the WAV header from.
 * @throws ParserException If the input file is an incorrect RIFF WAV.
 * @throws IOException If peeking from the input fails.
 * @throws InterruptedException If interrupted while peeking from input.
 * @return A new {@code WavHeader} peeked from {@code input}, or null if the input is not a
 *     supported WAV format.
 */
public static WavHeader peek(ExtractorInput input) throws IOException, InterruptedException {
  Assertions.checkNotNull(input);

  // Allocate a scratch buffer large enough to store the format chunk.
  ParsableByteArray scratch = new ParsableByteArray(16);

  // Attempt to read the RIFF chunk.
  ChunkHeader chunkHeader = ChunkHeader.peek(input, scratch);
  if (chunkHeader.id != WavUtil.RIFF_FOURCC) {
    return null;
  }

  input.peekFully(scratch.data, 0, 4);
  scratch.setPosition(0);
  int riffFormat = scratch.readInt();
  if (riffFormat != WavUtil.WAVE_FOURCC) {
    Log.e(TAG, "Unsupported RIFF format: " + riffFormat);
    return null;
  }

  // Skip chunks until we find the format chunk.
  chunkHeader = ChunkHeader.peek(input, scratch);
  while (chunkHeader.id != WavUtil.FMT_FOURCC) {
    input.advancePeekPosition((int) chunkHeader.size);
    chunkHeader = ChunkHeader.peek(input, scratch);
  }

  Assertions.checkState(chunkHeader.size >= 16);
  input.peekFully(scratch.data, 0, 16);
  scratch.setPosition(0);
  int type = scratch.readLittleEndianUnsignedShort();
  int numChannels = scratch.readLittleEndianUnsignedShort();
  int sampleRateHz = scratch.readLittleEndianUnsignedIntToInt();
  int averageBytesPerSecond = scratch.readLittleEndianUnsignedIntToInt();
  int blockAlignment = scratch.readLittleEndianUnsignedShort();
  int bitsPerSample = scratch.readLittleEndianUnsignedShort();

  int expectedBlockAlignment = numChannels * bitsPerSample / 8;
  if (blockAlignment != expectedBlockAlignment) {
    throw new ParserException("Expected block alignment: " + expectedBlockAlignment + "; got: "
        + blockAlignment);
  }

  @C.PcmEncoding int encoding = WavUtil.getEncodingForType(type, bitsPerSample);
  if (encoding == C.ENCODING_INVALID) {
    Log.e(TAG, "Unsupported WAV format: " + bitsPerSample + " bit/sample, type " + type);
    return null;
  }

  // If present, skip extensionSize, validBitsPerSample, channelMask, subFormatGuid, ...
  input.advancePeekPosition((int) chunkHeader.size - 16);

  return new WavHeader(
      numChannels, sampleRateHz, averageBytesPerSecond, blockAlignment, bitsPerSample, encoding);
}
 

/**
 * Returns a {@link Seeker} to seek using metadata read from {@code input}, which should provide
 * data from the start of the first frame in the stream. On returning, the input's position will
 * be set to the start of the first frame of audio.
 *
 * @param input The {@link ExtractorInput} from which to read.
 * @throws IOException Thrown if there was an error reading from the stream. Not expected if the
 *     next two frames were already peeked during synchronization.
 * @throws InterruptedException Thrown if reading from the stream was interrupted. Not expected if
 *     the next two frames were already peeked during synchronization.
 * @return a {@link Seeker}.
 */
private Seeker setupSeeker(ExtractorInput input) throws IOException, InterruptedException {
  // Read the first frame which may contain a Xing or VBRI header with seeking metadata.
  ParsableByteArray frame = new ParsableByteArray(synchronizedHeader.frameSize);
  input.peekFully(frame.data, 0, synchronizedHeader.frameSize);

  long position = input.getPosition();
  long length = input.getLength();
  int headerData = 0;
  Seeker seeker = null;

  // Check if there is a Xing header.
  int xingBase = (synchronizedHeader.version & 1) != 0
      ? (synchronizedHeader.channels != 1 ? 36 : 21) // MPEG 1
      : (synchronizedHeader.channels != 1 ? 21 : 13); // MPEG 2 or 2.5
  if (frame.limit() >= xingBase + 4) {
    frame.setPosition(xingBase);
    headerData = frame.readInt();
  }
  if (headerData == XING_HEADER || headerData == INFO_HEADER) {
    seeker = XingSeeker.create(synchronizedHeader, frame, position, length);
    if (seeker != null && !gaplessInfoHolder.hasGaplessInfo()) {
      // If there is a Xing header, read gapless playback metadata at a fixed offset.
      input.resetPeekPosition();
      input.advancePeekPosition(xingBase + 141);
      input.peekFully(scratch.data, 0, 3);
      scratch.setPosition(0);
      gaplessInfoHolder.setFromXingHeaderValue(scratch.readUnsignedInt24());
    }
    input.skipFully(synchronizedHeader.frameSize);
  } else if (frame.limit() >= 40) {
    // Check if there is a VBRI header.
    frame.setPosition(36); // MPEG audio header (4 bytes) + 32 bytes.
    headerData = frame.readInt();
    if (headerData == VBRI_HEADER) {
      seeker = VbriSeeker.create(synchronizedHeader, frame, position, length);
      input.skipFully(synchronizedHeader.frameSize);
    }
  }

  if (seeker == null || (!seeker.isSeekable()
      && (flags & FLAG_ENABLE_CONSTANT_BITRATE_SEEKING) != 0)) {
    // Repopulate the synchronized header in case we had to skip an invalid seeking header, which
    // would give an invalid CBR bitrate.
    input.resetPeekPosition();
    input.peekFully(scratch.data, 0, 4);
    scratch.setPosition(0);
    MpegAudioHeader.populateHeader(scratch.readInt(), synchronizedHeader);
    seeker = new ConstantBitrateSeeker(input.getPosition(), synchronizedHeader.bitrate, length);
  }

  return seeker;
}
 

/**
 * Peeks an Ogg page header and updates this {@link OggPageHeader}.
 *
 * @param input The {@link ExtractorInput} to read from.
 * @param quiet Whether to return {@code false} rather than throwing an exception if the header
 *     cannot be populated.
 * @return Whether the read was successful. The read fails if the end of the input is encountered
 *     without reading data.
 * @throws IOException If reading data fails or the stream is invalid.
 * @throws InterruptedException If the thread is interrupted.
 */
public boolean populate(ExtractorInput input, boolean quiet)
    throws IOException, InterruptedException {
  scratch.reset();
  reset();
  boolean hasEnoughBytes = input.getLength() == C.LENGTH_UNSET
      || input.getLength() - input.getPeekPosition() >= EMPTY_PAGE_HEADER_SIZE;
  if (!hasEnoughBytes || !input.peekFully(scratch.data, 0, EMPTY_PAGE_HEADER_SIZE, true)) {
    if (quiet) {
      return false;
    } else {
      throw new EOFException();
    }
  }
  if (scratch.readUnsignedInt() != TYPE_OGGS) {
    if (quiet) {
      return false;
    } else {
      throw new ParserException("expected OggS capture pattern at begin of page");
    }
  }

  revision = scratch.readUnsignedByte();
  if (revision != 0x00) {
    if (quiet) {
      return false;
    } else {
      throw new ParserException("unsupported bit stream revision");
    }
  }
  type = scratch.readUnsignedByte();

  granulePosition = scratch.readLittleEndianLong();
  streamSerialNumber = scratch.readLittleEndianUnsignedInt();
  pageSequenceNumber = scratch.readLittleEndianUnsignedInt();
  pageChecksum = scratch.readLittleEndianUnsignedInt();
  pageSegmentCount = scratch.readUnsignedByte();
  headerSize = EMPTY_PAGE_HEADER_SIZE + pageSegmentCount;

  // calculate total size of header including laces
  scratch.reset();
  input.peekFully(scratch.data, 0, pageSegmentCount);
  for (int i = 0; i < pageSegmentCount; i++) {
    laces[i] = scratch.readUnsignedByte();
    bodySize += laces[i];
  }

  return true;
}
 

@Override
public boolean sniff(ExtractorInput input) throws IOException, InterruptedException {
  // Skip any ID3 headers.
  ParsableByteArray scratch = new ParsableByteArray(10);
  ParsableBitArray scratchBits = new ParsableBitArray(scratch.data);
  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);

  // Try to find four or more consecutive AAC audio frames, exceeding the MPEG TS packet size.
  int headerPosition = startPosition;
  int validFramesSize = 0;
  int validFramesCount = 0;
  while (true) {
    input.peekFully(scratch.data, 0, 2);
    scratch.setPosition(0);
    int syncBytes = scratch.readUnsignedShort();
    if ((syncBytes & 0xFFF6) != 0xFFF0) {
      validFramesCount = 0;
      validFramesSize = 0;
      input.resetPeekPosition();
      if (++headerPosition - startPosition >= MAX_SNIFF_BYTES) {
        return false;
      }
      input.advancePeekPosition(headerPosition);
    } else {
      if (++validFramesCount >= 4 && validFramesSize > 188) {
        return true;
      }

      // Skip the frame.
      input.peekFully(scratch.data, 0, 4);
      scratchBits.setPosition(14);
      int frameSize = scratchBits.readBits(13);
      // Either the stream is malformed OR we're not parsing an ADTS stream.
      if (frameSize <= 6) {
        return false;
      }
      input.advancePeekPosition(frameSize - 6);
      validFramesSize += frameSize;
    }
  }
}