/**
* 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;
}
/**
* 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;
}
/**
* 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);
}
