/**
* 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;
}
protected void build(ByteBuffer data) throws UnsupportedEncodingException {
// Data actually contains a 'Data' Box so process data using this
Mp4BoxHeader header = new Mp4BoxHeader(data);
Mp4DataBox databox = new Mp4DataBox(header, data);
dataSize = header.getDataLength();
numbers = databox.getNumbers();
// Disc number always hold four values, we can discard the first one and last one, the second
// one is the disc no
// and the third is the total no of discs so only use if not zero
StringBuffer sb = new StringBuffer();
sb.append(numbers.get(DISC_NO_INDEX));
if (numbers.get(DISC_TOTAL_INDEX) > 0) {
sb.append("/" + numbers.get(DISC_TOTAL_INDEX));
}
content = sb.toString();
}
/**
* @param header parentHeader info
* @param dataBuffer data of box (doesnt include parentHeader data)
*/
public Mp4NameBox(Mp4BoxHeader header, ByteBuffer dataBuffer) {
this.header = header;
// Double check
if (!header.getId().equals(IDENTIFIER)) {
throw new RuntimeException(
"Unable to process name box because identifier is:" + header.getId());
}
// Make slice so operations here don't effect position of main buffer
this.dataBuffer = dataBuffer.slice();
// issuer
this.name =
Utils.getString(
this.dataBuffer,
PRE_DATA_LENGTH,
header.getDataLength() - PRE_DATA_LENGTH,
header.getEncoding());
}
/**
* @param header parentHeader info
* @param dataBuffer data of box (doesnt include parentHeader data)
*/
public Mp4DataBox(Mp4BoxHeader header, ByteBuffer dataBuffer) {
this.header = header;
// Double check
if (!header.getId().equals(IDENTIFIER)) {
throw new RuntimeException(
"Unable to process data box because identifier is:" + header.getId());
}
// Make slice so operations here don't effect position of main buffer
this.dataBuffer = dataBuffer.slice();
// Type
type =
Utils.getIntBE(
this.dataBuffer, Mp4DataBox.TYPE_POS, Mp4DataBox.TYPE_POS + Mp4DataBox.TYPE_LENGTH - 1);
if (type == Mp4FieldType.TEXT.getFileClassId()) {
content =
Utils.getString(
this.dataBuffer,
PRE_DATA_LENGTH,
header.getDataLength() - PRE_DATA_LENGTH,
header.getEncoding());
} else if (type == Mp4FieldType.NUMERIC.getFileClassId()) {
numbers = new ArrayList<Short>();
for (int i = 0; i < ((header.getDataLength() - PRE_DATA_LENGTH) / NUMBER_LENGTH); i++) {
short number =
Utils.getShortBE(
this.dataBuffer,
PRE_DATA_LENGTH + (i * NUMBER_LENGTH),
PRE_DATA_LENGTH + (i * NUMBER_LENGTH) + (NUMBER_LENGTH - 1));
numbers.add(number);
}
// Make String representation (separate values with slash)
StringBuffer sb = new StringBuffer();
ListIterator<Short> iterator = numbers.listIterator();
while (iterator.hasNext()) {
sb.append(iterator.next());
if (iterator.hasNext()) {
sb.append("/");
}
}
content = sb.toString();
} else if (type == Mp4FieldType.BYTE.getFileClassId()) {
// TODO byte data length seems to be 1 for pgap and cpil but 2 for tmpo ?
// Create String representation for display
content = Utils.getIntBE(this.dataBuffer, PRE_DATA_LENGTH, header.getDataLength() - 1) + "";
// But store data for safer writng back to file
bytedata = new byte[header.getDataLength() - PRE_DATA_LENGTH];
int pos = dataBuffer.position();
dataBuffer.position(pos + PRE_DATA_LENGTH);
dataBuffer.get(bytedata);
dataBuffer.position(pos);
} else if (type == Mp4FieldType.COVERART_JPEG.getFileClassId()) {
content =
Utils.getString(
this.dataBuffer,
PRE_DATA_LENGTH,
header.getDataLength() - PRE_DATA_LENGTH,
header.getEncoding());
}
}