public void write(AVStream av, AVPacket frame) throws IOException {
    tryWriteHeader(av);

    Format vf = frame.getFormat();
    if (Constants.H264.equalsIgnoreCase(vf.getEncoding())) {
      writeH264WithStartCode(frame);
      return;
    } else if (Constants.AAC.equalsIgnoreCase(vf.getEncoding())) {
      writeAAC(frame);
      return;
    }

    logger.warn("unsupported format {}", frame.getFormat());
  }
  private void writeAAC(AVPacket frame) throws IOException {
    ByteBuffer data = frame.getByteBuffer();
    int dataSize = 2 + data.remaining();

    ChannelBuffer aac = ChannelBuffers.buffer(11 + dataSize + 4);
    aac.writeByte(0x08);
    aac.writeMedium(dataSize);

    // timestamp
    long timestamp = frame.getTimestamp(AVTimeUnit.MILLISECONDS);
    aac.writeMedium((int) (0xFFFFFF & timestamp));
    aac.writeByte((int) (0xFF & (timestamp >> 24)));

    aac.writeMedium(0);

    aac.writeByte(0xAF); // aac, 44100, 2 channels, stereo
    aac.writeByte(0x01); // aac data
    aac.writeBytes(data);

    aac.writeInt(aac.readableBytes()); // pre tag size
    aac.readBytes(out, aac.readableBytes());
  }
  private void writeH264WithStartCode(AVPacket frame) throws IOException {
    ByteBuffer data = frame.getByteBuffer();
    if (data.remaining() > 4 && 1 != data.getInt(data.position())) {
      logger.warn("H264 Not Start With 0x00 00 00 01");
      return;
    }
    List<ByteBuffer> segs = H264Utils.splitFrame(data);

    int dataSize = 5 + 4 * segs.size();
    for (ByteBuffer seg : segs) {
      dataSize += seg.remaining();
    }

    ChannelBuffer avc = ChannelBuffers.buffer(11 + dataSize + 4 + 4 + 5);
    avc.writeByte(0x09); // video type
    avc.writeMedium(dataSize); // tag data size

    // timestamp
    long timestamp = frame.getTimestamp(AVTimeUnit.MILLISECONDS);
    avc.writeMedium((int) (0xFFFFFF & timestamp));
    avc.writeByte((int) (0xFF & (timestamp >> 24)));

    avc.writeMedium(0x0); // stream id

    avc.writeByte(frame.isKeyFrame() ? 0x17 : 0x27); // key frame + avc
    avc.writeByte(0x01); // avc NAL
    avc.writeMedium(
        (int) frame.getCompositionTime(AVTimeUnit.MILLISECONDS)); // Composition time offset

    // data
    for (ByteBuffer seg : segs) {
      avc.writeInt(seg.remaining());
      avc.writeBytes(seg);
    }

    avc.writeInt(avc.readableBytes()); // pre tag size

    avc.readBytes(out, avc.readableBytes());
  }