Java MpegAudioHeader.populateHeader方法代码示例

import com.google.android.exoplayer2.extractor.MpegAudioHeader; //导入方法依赖的package包/类
/**
 * Attempts to read the remaining two bytes of the frame header.
 * <p>
 * If a frame header is read in full then the state is changed to {@link #STATE_READING_FRAME},
 * the media format is output if this has not previously occurred, the four header bytes are
 * output as sample data, and the position of the source is advanced to the byte that immediately
 * follows the header.
 * <p>
 * If a frame header is read in full but cannot be parsed then the state is changed to
 * {@link #STATE_READING_HEADER}.
 * <p>
 * If a frame header is not read in full then the position of the source is advanced to the limit,
 * and the method should be called again with the next source to continue the read.
 *
 * @param source The source from which to read.
 */
private void readHeaderRemainder(ParsableByteArray source) {
  int bytesToRead = Math.min(source.bytesLeft(), HEADER_SIZE - frameBytesRead);
  source.readBytes(headerScratch.data, frameBytesRead, bytesToRead);
  frameBytesRead += bytesToRead;
  if (frameBytesRead < HEADER_SIZE) {
    // We haven't read the whole header yet.
    return;
  }

  headerScratch.setPosition(0);
  boolean parsedHeader = MpegAudioHeader.populateHeader(headerScratch.readInt(), header);
  if (!parsedHeader) {
    // We thought we'd located a frame header, but we hadn't.
    frameBytesRead = 0;
    state = STATE_READING_HEADER;
    return;
  }

  frameSize = header.frameSize;
  if (!hasOutputFormat) {
    frameDurationUs = (C.MICROS_PER_SECOND * header.samplesPerFrame) / header.sampleRate;
    Format format = Format.createAudioSampleFormat(formatId, header.mimeType, null,
        Format.NO_VALUE, MpegAudioHeader.MAX_FRAME_SIZE_BYTES, header.channels, header.sampleRate,
        null, null, 0, language);
    output.format(format);
    hasOutputFormat = true;
  }

  headerScratch.setPosition(0);
  output.sampleData(headerScratch, HEADER_SIZE);
  state = STATE_READING_FRAME;
}
 

import com.google.android.exoplayer2.extractor.MpegAudioHeader; //导入方法依赖的package包/类
private int readSample(ExtractorInput extractorInput) throws IOException, InterruptedException {
  if (sampleBytesRemaining == 0) {
    extractorInput.resetPeekPosition();
    if (!extractorInput.peekFully(scratch.data, 0, 4, true)) {
      return RESULT_END_OF_INPUT;
    }
    scratch.setPosition(0);
    int sampleHeaderData = scratch.readInt();
    if ((sampleHeaderData & HEADER_MASK) != (synchronizedHeaderData & HEADER_MASK)
        || MpegAudioHeader.getFrameSize(sampleHeaderData) == C.LENGTH_UNSET) {
      // We have lost synchronization, so attempt to resynchronize starting at the next byte.
      extractorInput.skipFully(1);
      synchronizedHeaderData = 0;
      return RESULT_CONTINUE;
    }
    MpegAudioHeader.populateHeader(sampleHeaderData, synchronizedHeader);
    if (basisTimeUs == C.TIME_UNSET) {
      basisTimeUs = seeker.getTimeUs(extractorInput.getPosition());
      if (forcedFirstSampleTimestampUs != C.TIME_UNSET) {
        long embeddedFirstSampleTimestampUs = seeker.getTimeUs(0);
        basisTimeUs += forcedFirstSampleTimestampUs - embeddedFirstSampleTimestampUs;
      }
    }
    sampleBytesRemaining = synchronizedHeader.frameSize;
  }
  int bytesAppended = trackOutput.sampleData(extractorInput, sampleBytesRemaining, true);
  if (bytesAppended == C.RESULT_END_OF_INPUT) {
    return RESULT_END_OF_INPUT;
  }
  sampleBytesRemaining -= bytesAppended;
  if (sampleBytesRemaining > 0) {
    return RESULT_CONTINUE;
  }
  long timeUs = basisTimeUs + (samplesRead * C.MICROS_PER_SECOND / synchronizedHeader.sampleRate);
  trackOutput.sampleMetadata(timeUs, C.BUFFER_FLAG_KEY_FRAME, synchronizedHeader.frameSize, 0,
      null);
  samplesRead += synchronizedHeader.samplesPerFrame;
  sampleBytesRemaining = 0;
  return RESULT_CONTINUE;
}
 

import com.google.android.exoplayer2.extractor.MpegAudioHeader; //导入方法依赖的package包/类
/**
 * Attempts to read the remaining two bytes of the frame header.
 * <p>
 * If a frame header is read in full then the state is changed to {@link #STATE_READING_FRAME},
 * the media format is output if this has not previously occurred, the four header bytes are
 * output as sample data, and the position of the source is advanced to the byte that immediately
 * follows the header.
 * <p>
 * If a frame header is read in full but cannot be parsed then the state is changed to
 * {@link #STATE_READING_HEADER}.
 * <p>
 * If a frame header is not read in full then the position of the source is advanced to the limit,
 * and the method should be called again with the next source to continue the read.
 *
 * @param source The source from which to read.
 */
private void readHeaderRemainder(ParsableByteArray source) {
  int bytesToRead = Math.min(source.bytesLeft(), HEADER_SIZE - frameBytesRead);
  source.readBytes(headerScratch.data, frameBytesRead, bytesToRead);
  frameBytesRead += bytesToRead;
  if (frameBytesRead < HEADER_SIZE) {
    // We haven't read the whole header yet.
    return;
  }

  headerScratch.setPosition(0);
  boolean parsedHeader = MpegAudioHeader.populateHeader(headerScratch.readInt(), header);
  if (!parsedHeader) {
    // We thought we'd located a frame header, but we hadn't.
    frameBytesRead = 0;
    state = STATE_READING_HEADER;
    return;
  }

  frameSize = header.frameSize;
  if (!hasOutputFormat) {
    frameDurationUs = (C.MICROS_PER_SECOND * header.samplesPerFrame) / header.sampleRate;
    Format format = Format.createAudioSampleFormat(null, header.mimeType, null, Format.NO_VALUE,
        MpegAudioHeader.MAX_FRAME_SIZE_BYTES, header.channels, header.sampleRate, null, null, 0,
        language);
    output.format(format);
    hasOutputFormat = true;
  }

  headerScratch.setPosition(0);
  output.sampleData(headerScratch, HEADER_SIZE);
  state = STATE_READING_FRAME;
}
 

import com.google.android.exoplayer2.extractor.MpegAudioHeader; //导入方法依赖的package包/类
@Override
public void setUp() throws Exception {
  MpegAudioHeader xingFrameHeader = new MpegAudioHeader();
  MpegAudioHeader.populateHeader(XING_FRAME_HEADER_DATA, xingFrameHeader);
  seeker = XingSeeker.create(xingFrameHeader, new ParsableByteArray(XING_FRAME_PAYLOAD),
      XING_FRAME_POSITION, C.LENGTH_UNSET);
  seekerWithInputLength = XingSeeker.create(xingFrameHeader,
      new ParsableByteArray(XING_FRAME_PAYLOAD), XING_FRAME_POSITION, INPUT_LENGTH);
  xingFrameSize = xingFrameHeader.frameSize;
}
 

import com.google.android.exoplayer2.extractor.MpegAudioHeader; //导入方法依赖的package包/类
private int readSample(ExtractorInput extractorInput) throws IOException, InterruptedException {
  if (sampleBytesRemaining == 0) {
    extractorInput.resetPeekPosition();
    if (!extractorInput.peekFully(scratch.data, 0, 4, true)) {
      return RESULT_END_OF_INPUT;
    }
    scratch.setPosition(0);
    int sampleHeaderData = scratch.readInt();
    if (!headersMatch(sampleHeaderData, synchronizedHeaderData)
        || MpegAudioHeader.getFrameSize(sampleHeaderData) == C.LENGTH_UNSET) {
      // We have lost synchronization, so attempt to resynchronize starting at the next byte.
      extractorInput.skipFully(1);
      synchronizedHeaderData = 0;
      return RESULT_CONTINUE;
    }
    MpegAudioHeader.populateHeader(sampleHeaderData, synchronizedHeader);
    if (basisTimeUs == C.TIME_UNSET) {
      basisTimeUs = seeker.getTimeUs(extractorInput.getPosition());
      if (forcedFirstSampleTimestampUs != C.TIME_UNSET) {
        long embeddedFirstSampleTimestampUs = seeker.getTimeUs(0);
        basisTimeUs += forcedFirstSampleTimestampUs - embeddedFirstSampleTimestampUs;
      }
    }
    sampleBytesRemaining = synchronizedHeader.frameSize;
  }
  int bytesAppended = trackOutput.sampleData(extractorInput, sampleBytesRemaining, true);
  if (bytesAppended == C.RESULT_END_OF_INPUT) {
    return RESULT_END_OF_INPUT;
  }
  sampleBytesRemaining -= bytesAppended;
  if (sampleBytesRemaining > 0) {
    return RESULT_CONTINUE;
  }
  long timeUs = basisTimeUs + (samplesRead * C.MICROS_PER_SECOND / synchronizedHeader.sampleRate);
  trackOutput.sampleMetadata(timeUs, C.BUFFER_FLAG_KEY_FRAME, synchronizedHeader.frameSize, 0,
      null);
  samplesRead += synchronizedHeader.samplesPerFrame;
  sampleBytesRemaining = 0;
  return RESULT_CONTINUE;
}
 

import com.google.android.exoplayer2.extractor.MpegAudioHeader; //导入方法依赖的package包/类
/**
 * Peeks the next frame and returns a {@link ConstantBitrateSeeker} based on its bitrate.
 */
private Seeker getConstantBitrateSeeker(ExtractorInput input)
    throws IOException, InterruptedException {
  input.peekFully(scratch.data, 0, 4);
  scratch.setPosition(0);
  MpegAudioHeader.populateHeader(scratch.readInt(), synchronizedHeader);
  return new ConstantBitrateSeeker(input.getLength(), input.getPosition(), synchronizedHeader);
}
 

import com.google.android.exoplayer2.extractor.MpegAudioHeader; //导入方法依赖的package包/类
@Before
public void setUp() throws Exception {
  MpegAudioHeader xingFrameHeader = new MpegAudioHeader();
  MpegAudioHeader.populateHeader(XING_FRAME_HEADER_DATA, xingFrameHeader);
  seeker = XingSeeker.create(C.LENGTH_UNSET, XING_FRAME_POSITION, xingFrameHeader,
      new ParsableByteArray(XING_FRAME_PAYLOAD));
  seekerWithInputLength = XingSeeker.create(STREAM_LENGTH,
      XING_FRAME_POSITION, xingFrameHeader, new ParsableByteArray(XING_FRAME_PAYLOAD));
  xingFrameSize = xingFrameHeader.frameSize;
}
 

import com.google.android.exoplayer2.extractor.MpegAudioHeader; //导入方法依赖的package包/类
private boolean synchronize(ExtractorInput input, boolean sniffing)
    throws IOException, InterruptedException {
  int validFrameCount = 0;
  int candidateSynchronizedHeaderData = 0;
  int peekedId3Bytes = 0;
  int searchedBytes = 0;
  int searchLimitBytes = sniffing ? MAX_SNIFF_BYTES : MAX_SYNC_BYTES;
  input.resetPeekPosition();
  if (input.getPosition() == 0) {
    peekId3Data(input);
    peekedId3Bytes = (int) input.getPeekPosition();
    if (!sniffing) {
      input.skipFully(peekedId3Bytes);
    }
  }
  while (true) {
    if (!input.peekFully(scratch.data, 0, 4, validFrameCount > 0)) {
      // We reached the end of the stream but found at least one valid frame.
      break;
    }
    scratch.setPosition(0);
    int headerData = scratch.readInt();
    int frameSize;
    if ((candidateSynchronizedHeaderData != 0
        && (headerData & HEADER_MASK) != (candidateSynchronizedHeaderData & HEADER_MASK))
        || (frameSize = MpegAudioHeader.getFrameSize(headerData)) == C.LENGTH_UNSET) {
      // The header doesn't match the candidate header or is invalid. Try the next byte offset.
      if (searchedBytes++ == searchLimitBytes) {
        if (!sniffing) {
          throw new ParserException("Searched too many bytes.");
        }
        return false;
      }
      validFrameCount = 0;
      candidateSynchronizedHeaderData = 0;
      if (sniffing) {
        input.resetPeekPosition();
        input.advancePeekPosition(peekedId3Bytes + searchedBytes);
      } else {
        input.skipFully(1);
      }
    } else {
      // The header matches the candidate header and/or is valid.
      validFrameCount++;
      if (validFrameCount == 1) {
        MpegAudioHeader.populateHeader(headerData, synchronizedHeader);
        candidateSynchronizedHeaderData = headerData;
      } else if (validFrameCount == 4) {
        break;
      }
      input.advancePeekPosition(frameSize - 4);
    }
  }
  // Prepare to read the synchronized frame.
  if (sniffing) {
    input.skipFully(peekedId3Bytes + searchedBytes);
  } else {
    input.resetPeekPosition();
  }
  synchronizedHeaderData = candidateSynchronizedHeaderData;
  return true;
}
 

import com.google.android.exoplayer2.extractor.MpegAudioHeader; //导入方法依赖的package包/类
/**
 * 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;
}
 

import com.google.android.exoplayer2.extractor.MpegAudioHeader; //导入方法依赖的package包/类
private boolean synchronize(ExtractorInput input, boolean sniffing)
    throws IOException, InterruptedException {
  int validFrameCount = 0;
  int candidateSynchronizedHeaderData = 0;
  int peekedId3Bytes = 0;
  int searchedBytes = 0;
  int searchLimitBytes = sniffing ? MAX_SNIFF_BYTES : MAX_SYNC_BYTES;
  input.resetPeekPosition();
  if (input.getPosition() == 0) {
    Id3Util.parseId3(input, gaplessInfoHolder);
    peekedId3Bytes = (int) input.getPeekPosition();
    if (!sniffing) {
      input.skipFully(peekedId3Bytes);
    }
  }
  while (true) {
    if (!input.peekFully(scratch.data, 0, 4, validFrameCount > 0)) {
      // We reached the end of the stream but found at least one valid frame.
      break;
    }
    scratch.setPosition(0);
    int headerData = scratch.readInt();
    int frameSize;
    if ((candidateSynchronizedHeaderData != 0
        && (headerData & HEADER_MASK) != (candidateSynchronizedHeaderData & HEADER_MASK))
        || (frameSize = MpegAudioHeader.getFrameSize(headerData)) == C.LENGTH_UNSET) {
      // The header doesn't match the candidate header or is invalid. Try the next byte offset.
      if (searchedBytes++ == searchLimitBytes) {
        if (!sniffing) {
          throw new ParserException("Searched too many bytes.");
        }
        return false;
      }
      validFrameCount = 0;
      candidateSynchronizedHeaderData = 0;
      if (sniffing) {
        input.resetPeekPosition();
        input.advancePeekPosition(peekedId3Bytes + searchedBytes);
      } else {
        input.skipFully(1);
      }
    } else {
      // The header matches the candidate header and/or is valid.
      validFrameCount++;
      if (validFrameCount == 1) {
        MpegAudioHeader.populateHeader(headerData, synchronizedHeader);
        candidateSynchronizedHeaderData = headerData;
      } else if (validFrameCount == 4) {
        break;
      }
      input.advancePeekPosition(frameSize - 4);
    }
  }
  // Prepare to read the synchronized frame.
  if (sniffing) {
    input.skipFully(peekedId3Bytes + searchedBytes);
  } else {
    input.resetPeekPosition();
  }
  synchronizedHeaderData = candidateSynchronizedHeaderData;
  return true;
}
 

import com.google.android.exoplayer2.extractor.MpegAudioHeader; //导入方法依赖的package包/类
/**
 * 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) {
    // 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;
}
 

import com.google.android.exoplayer2.extractor.MpegAudioHeader; //导入方法依赖的package包/类
private boolean synchronize(ExtractorInput input, boolean sniffing)
    throws IOException, InterruptedException {
  int validFrameCount = 0;
  int candidateSynchronizedHeaderData = 0;
  int peekedId3Bytes = 0;
  int searchedBytes = 0;
  int searchLimitBytes = sniffing ? MAX_SNIFF_BYTES : MAX_SYNC_BYTES;
  input.resetPeekPosition();
  if (input.getPosition() == 0) {
    peekId3Data(input);
    peekedId3Bytes = (int) input.getPeekPosition();
    if (!sniffing) {
      input.skipFully(peekedId3Bytes);
    }
  }
  while (true) {
    if (!input.peekFully(scratch.data, 0, 4, validFrameCount > 0)) {
      // We reached the end of the stream but found at least one valid frame.
      break;
    }
    scratch.setPosition(0);
    int headerData = scratch.readInt();
    int frameSize;
    if ((candidateSynchronizedHeaderData != 0
        && !headersMatch(headerData, candidateSynchronizedHeaderData))
        || (frameSize = MpegAudioHeader.getFrameSize(headerData)) == C.LENGTH_UNSET) {
      // The header doesn't match the candidate header or is invalid. Try the next byte offset.
      if (searchedBytes++ == searchLimitBytes) {
        if (!sniffing) {
          throw new ParserException("Searched too many bytes.");
        }
        return false;
      }
      validFrameCount = 0;
      candidateSynchronizedHeaderData = 0;
      if (sniffing) {
        input.resetPeekPosition();
        input.advancePeekPosition(peekedId3Bytes + searchedBytes);
      } else {
        input.skipFully(1);
      }
    } else {
      // The header matches the candidate header and/or is valid.
      validFrameCount++;
      if (validFrameCount == 1) {
        MpegAudioHeader.populateHeader(headerData, synchronizedHeader);
        candidateSynchronizedHeaderData = headerData;
      } else if (validFrameCount == 4) {
        break;
      }
      input.advancePeekPosition(frameSize - 4);
    }
  }
  // Prepare to read the synchronized frame.
  if (sniffing) {
    input.skipFully(peekedId3Bytes + searchedBytes);
  } else {
    input.resetPeekPosition();
  }
  synchronizedHeaderData = candidateSynchronizedHeaderData;
  return true;
}