/**
* Decodes packet header.
*
* @param in Input IoBuffer
* @param lastHeader Previous header
* @return Decoded header
*/
public static Header decodeHeader(IoBuffer in, Header lastHeader) {
if (log.isTraceEnabled()) {
log.trace("decodeHeader - lastHeader: {} buffer: {}", lastHeader, in);
}
byte headerByte = in.get();
int headerValue;
int byteCount = 1;
if ((headerByte & 0x3f) == 0) {
// Two byte header
headerValue = (headerByte & 0xff) << 8 | (in.get() & 0xff);
byteCount = 2;
} else if ((headerByte & 0x3f) == 1) {
// Three byte header
headerValue = (headerByte & 0xff) << 16 | (in.get() & 0xff) << 8 | (in.get() & 0xff);
byteCount = 3;
} else {
// Single byte header
headerValue = headerByte & 0xff;
byteCount = 1;
}
final int channelId = RTMPUtils.decodeChannelId(headerValue, byteCount);
final int headerSize = RTMPUtils.decodeHeaderSize(headerValue, byteCount);
Header header = new Header();
header.setChannelId(channelId);
if (headerSize != HEADER_NEW && lastHeader == null) {
log.error("Last header null not new, headerSize: {}, channelId {}", headerSize, channelId);
// this will trigger an error status, which in turn will disconnect the "offending" flash
// player
// preventing a memory leak and bringing the whole server to its knees
return null;
}
int timeValue;
switch (headerSize) {
case HEADER_NEW:
// an absolute time value
timeValue = RTMPUtils.readUnsignedMediumInt(in);
header.setSize(RTMPUtils.readUnsignedMediumInt(in));
header.setDataType(in.get());
header.setStreamId(RTMPUtils.readReverseInt(in));
if (timeValue == 0xffffff) {
timeValue = (int) (in.getUnsignedInt() & Integer.MAX_VALUE);
header.setExtendedTimestamp(timeValue);
}
header.setTimerBase(timeValue);
header.setTimerDelta(0);
break;
case HEADER_SAME_SOURCE:
// a delta time value
timeValue = RTMPUtils.readUnsignedMediumInt(in);
header.setSize(RTMPUtils.readUnsignedMediumInt(in));
header.setDataType(in.get());
header.setStreamId(lastHeader.getStreamId());
if (timeValue == 0xffffff) {
timeValue = (int) (in.getUnsignedInt() & Integer.MAX_VALUE);
header.setExtendedTimestamp(timeValue);
} else if (timeValue == 0 && header.getDataType() == TYPE_AUDIO_DATA) {
// header.setIsGarbage(true);
log.trace(
"Audio with zero delta; setting to garbage; ChannelId: {}; DataType: {}; HeaderSize: {}",
new Object[] {header.getChannelId(), header.getDataType(), headerSize});
}
header.setTimerBase(lastHeader.getTimerBase());
header.setTimerDelta(timeValue);
break;
case HEADER_TIMER_CHANGE:
// a delta time value
timeValue = RTMPUtils.readUnsignedMediumInt(in);
header.setSize(lastHeader.getSize());
header.setDataType(lastHeader.getDataType());
header.setStreamId(lastHeader.getStreamId());
if (timeValue == 0xffffff) {
timeValue = (int) (in.getUnsignedInt() & Integer.MAX_VALUE);
header.setExtendedTimestamp(timeValue);
} else if (timeValue == 0 && header.getDataType() == TYPE_AUDIO_DATA) {
// header.setIsGarbage(true);
log.trace(
"Audio with zero delta; setting to garbage; ChannelId: {}; DataType: {}; HeaderSize: {}",
new Object[] {header.getChannelId(), header.getDataType(), headerSize});
}
header.setTimerBase(lastHeader.getTimerBase());
header.setTimerDelta(timeValue);
break;
case HEADER_CONTINUE:
header.setSize(lastHeader.getSize());
header.setDataType(lastHeader.getDataType());
header.setStreamId(lastHeader.getStreamId());
header.setTimerBase(lastHeader.getTimerBase());
header.setTimerDelta(lastHeader.getTimerDelta());
if (lastHeader.getExtendedTimestamp() != 0) {
timeValue = (int) (in.getUnsignedInt() & Integer.MAX_VALUE);
header.setExtendedTimestamp(timeValue);
log.trace("HEADER_CONTINUE with extended timestamp: {}", timeValue);
}
break;
default:
log.error("Unexpected header size: {}", headerSize);
return null;
}
log.trace("CHUNK, D, {}, {}", header, headerSize);
return header;
}
