示例#1
0
  /**
   * Seek for box with the specified id starting from the current location of filepointer,
   *
   * <p>Note it won't find the box if it is contained with a level below the current level, nor if
   * we are at a parent atom that also contains data and we havent yet processed the data. It will
   * work if we are at the start of a child box even if it not the required box as long as the box
   * we are looking for is the same level (or the level above in some cases).
   *
   * @param data
   * @param id
   * @throws java.io.IOException
   */
  public static Mp4BoxHeader seekWithinLevel(ByteBuffer data, String id) throws IOException {
    logger.finer("Started searching for:" + id + " in bytebuffer at" + data.position());

    Mp4BoxHeader boxHeader = new Mp4BoxHeader();
    if (data.remaining() >= Mp4BoxHeader.HEADER_LENGTH) {
      boxHeader.update(data);
    } else {
      return null;
    }
    while (!boxHeader.getId().equals(id)) {
      logger.finer(
          "Found"
              + boxHeader.getId()
              + "Still searching for:"
              + id
              + " in bytebuffer at"
              + data.position());
      // Something gone wrong probably not at the start of an atom so return null;
      if (boxHeader.getLength() < Mp4BoxHeader.HEADER_LENGTH) {
        return null;
      }
      data.position(data.position() + (boxHeader.getLength() - HEADER_LENGTH));
      if (data.remaining() >= Mp4BoxHeader.HEADER_LENGTH) {
        boxHeader.update(data);
      } else {
        return null;
      }
    }
    return boxHeader;
  }
示例#2
0
  /**
   * Seek for box with the specified id starting from the current location of filepointer,
   *
   * <p>Note it wont find the box if it is contained with a level below the current level, nor if we
   * are at a parent atom that also contains data and we havent yet processed the data. It will work
   * if we are at the start of a child box even if it not the required box as long as the box we are
   * looking for is the same level (or the level above in some cases).
   *
   * @param raf
   * @param id
   * @throws java.io.IOException
   */
  public static Mp4BoxHeader seekWithinLevel(RandomAccessFile raf, String id) throws IOException {
    logger.finer("Started searching for:" + id + " in file at:" + raf.getChannel().position());

    Mp4BoxHeader boxHeader = new Mp4BoxHeader();
    ByteBuffer headerBuffer = ByteBuffer.allocate(HEADER_LENGTH);
    int bytesRead = raf.getChannel().read(headerBuffer);
    if (bytesRead != HEADER_LENGTH) {
      return null;
    }
    headerBuffer.rewind();
    boxHeader.update(headerBuffer);
    while (!boxHeader.getId().equals(id)) {
      logger.finer("Still searching for:" + id + " in file at:" + raf.getChannel().position());

      // Something gone wrong probably not at the start of an atom so return null;
      if (boxHeader.getLength() < Mp4BoxHeader.HEADER_LENGTH) {
        return null;
      }
      int noOfBytesSkipped = raf.skipBytes(boxHeader.getDataLength());
      logger.finer("Skipped:" + noOfBytesSkipped);
      if (noOfBytesSkipped < boxHeader.getDataLength()) {
        return null;
      }
      headerBuffer.rewind();
      bytesRead = raf.getChannel().read(headerBuffer);
      logger.finer("Header Bytes Read:" + bytesRead);
      headerBuffer.rewind();
      if (bytesRead == Mp4BoxHeader.HEADER_LENGTH) {
        boxHeader.update(headerBuffer);
      } else {
        return null;
      }
    }
    return boxHeader;
  }
示例#3
0
 /**
  * Construct header
  *
  * <p>Create header using headerdata, expected to find header at headerdata current position
  *
  * <p>Note after processing adjusts position to immediately after header
  *
  * @param headerData
  */
 public Mp4BoxHeader(ByteBuffer headerData) {
   update(headerData);
 }