/**
* Gets the first RED block in the RED payload.
*
* @param buffer the byte buffer that contains the RED payload.
* @param offset the offset in the buffer where the RED payload begins.
* @param length the length of the RED payload.
* @return the primary RED block if it exists, null otherwise.
*/
public static REDBlock getPrimaryBlock(byte[] buffer, int offset, int length) {
// Chrome is typically sending RED packets with a single block carrying
// either VP8 or FEC. This is unusual, and probably wrong as it messes
// up the sequence numbers and packet loss computations but it's just
// the way it is. Here we detect this situation and avoid looping
// through the blocks if there is a single block.
if (isMultiBlock(buffer, offset, length)) {
REDBlock block = null;
REDBlockIterator redBlockIterator = new REDBlockIterator(buffer, offset, length);
while (redBlockIterator.hasNext()) {
block = redBlockIterator.next();
}
if (block == null) {
logger.warn("No primary block found.");
}
return block;
} else {
if (buffer == null || offset < 0 || length < 0 || buffer.length < offset + length) {
logger.warn(
"Prevented an array out of bounds exception: "
+ "buffer length: "
+ buffer.length
+ ", offset: "
+ offset
+ ", len: "
+ length);
return null;
}
byte blockPT = (byte) (buffer[offset] & 0x7f);
int blockOff = offset + 1; // + 1 for the primary block header.
int blockLen = length - blockOff;
if (buffer.length < blockOff + blockLen) {
logger.warn("Primary block doesn't fit in RED packet.");
return null;
}
return new REDBlock(buffer, blockOff, blockLen, blockPT);
}
}
/**
* Matches a RED block in the RED payload.
*
* @param predicate the predicate that is used to match the RED block.
* @param buffer the byte buffer that contains the RED payload.
* @param offset the offset in the buffer where the RED payload begins.
* @param length the length of the RED payload.
* @return the first RED block that matches the given predicate, null otherwise.
*/
public static REDBlock matchFirst(
Predicate<REDBlock> predicate, byte[] buffer, int offset, int length) {
if (isMultiBlock(buffer, offset, length)) {
REDBlockIterator it = new REDBlockIterator(buffer, offset, length);
while (it.hasNext()) {
REDBlock b = it.next();
if (b != null && predicate.test(b)) {
return b;
}
}
return null;
} else {
REDBlock b = getPrimaryBlock(buffer, offset, length);
if (b != null && predicate.test(b)) {
return b;
} else {
return null;
}
}
}