/**
* A depacketizer from VP8. See {@link "http://tools.ietf.org/html/draft-ietf-payload-vp8-11"}
*
* @author Boris Grozev
* @author George Politis
*/
public class DePacketizer extends AbstractCodec2 {
/**
* The <tt>Logger</tt> used by the <tt>DePacketizer</tt> class and its instances for logging
* output.
*/
private static final Logger logger = Logger.getLogger(DePacketizer.class);
/** Whether trace logging is enabled. */
private static final boolean TRACE = logger.isTraceEnabled();
/**
* A <tt>Comparator</tt> implementation for RTP sequence numbers. Compares <tt>a</tt> and
* <tt>b</tt>, taking into account the wrap at 2^16.
*
* <p>IMPORTANT: This is a valid <tt>Comparator</tt> implementation only if used for subsets of
* [0, 2^16) which don't span more than 2^15 elements.
*
* <p>E.g. it works for: [0, 2^15-1] and ([50000, 2^16) u [0, 10000]) Doesn't work for: [0, 2^15]
* and ([0, 2^15-1] u {2^16-1}) and [0, 2^16)
*
* <p>NOTE: An identical implementation for Integers can be found in the class SeqNumComparator.
* Sequence numbers are 16 bits and unsigned, so an Integer should be sufficient to hold that.
*/
private static final Comparator<? super Long> seqNumComparator =
new Comparator<Long>() {
@Override
public int compare(Long a, Long b) {
if (a.equals(b)) return 0;
else if (a > b) {
if (a - b < 32768) return 1;
else return -1;
} else // a < b
{
if (b - a < 32768) return -1;
else return 1;
}
}
};
/**
* Stores the RTP payloads (VP8 payload descriptor stripped) from RTP packets belonging to a
* single VP8 compressed frame.
*/
private SortedMap<Long, Container> data = new TreeMap<Long, Container>(seqNumComparator);
/** Stores unused <tt>Container</tt>'s. */
private Queue<Container> free = new ArrayBlockingQueue<Container>(100);
/**
* Stores the first (earliest) sequence number stored in <tt>data</tt>, or -1 if <tt>data</tt> is
* empty.
*/
private long firstSeq = -1;
/**
* Stores the last (latest) sequence number stored in <tt>data</tt>, or -1 if <tt>data</tt> is
* empty.
*/
private long lastSeq = -1;
/**
* Stores the value of the <tt>PictureID</tt> field for the VP8 compressed frame, parts of which
* are currently stored in <tt>data</tt>, or -1 if the <tt>PictureID</tt> field is not in use or
* <tt>data</tt> is empty.
*/
private int pictureId = -1;
/**
* Stores the RTP timestamp of the packets stored in <tt>data</tt>, or -1 if they don't have a
* timestamp set.
*/
private long timestamp = -1;
/** Whether we have stored any packets in <tt>data</tt>. Equivalent to <tt>data.isEmpty()</tt>. */
private boolean empty = true;
/**
* Whether we have stored in <tt>data</tt> the last RTP packet of the VP8 compressed frame, parts
* of which are currently stored in <tt>data</tt>.
*/
private boolean haveEnd = false;
/**
* Whether we have stored in <tt>data</tt> the first RTP packet of the VP8 compressed frame, parts
* of which are currently stored in <tt>data</tt>.
*/
private boolean haveStart = false;
/**
* Stores the sum of the lengths of the data stored in <tt>data</tt>, that is the total length of
* the VP8 compressed frame to be constructed.
*/
private int frameLength = 0;
/** The sequence number of the last RTP packet, which was included in the output. */
private long lastSentSeq = -1;
/** Initializes a new <tt>JNIEncoder</tt> instance. */
public DePacketizer() {
super(
"VP8 RTP DePacketizer",
VideoFormat.class,
new VideoFormat[] {new VideoFormat(Constants.VP8)});
inputFormats = new VideoFormat[] {new VideoFormat(Constants.VP8_RTP)};
}
/** {@inheritDoc} */
@Override
protected void doClose() {}
/** {@inheritDoc} */
@Override
protected void doOpen() throws ResourceUnavailableException {
if (logger.isInfoEnabled()) logger.info("Opened VP8 depacketizer");
}
/**
* Re-initializes the fields which store information about the currently held data. Empties
* <tt>data</tt>.
*/
private void reinit() {
firstSeq = lastSeq = timestamp = -1;
pictureId = -1;
empty = true;
haveEnd = haveStart = false;
frameLength = 0;
Iterator<Map.Entry<Long, Container>> it = data.entrySet().iterator();
Map.Entry<Long, Container> e;
while (it.hasNext()) {
e = it.next();
free.offer(e.getValue());
it.remove();
}
}
/**
* Checks whether the currently held VP8 compressed frame is complete (e.g all its packets are
* stored in <tt>data</tt>).
*
* @return <tt>true</tt> if the currently help VP8 compressed frame is complete, <tt>false</tt>
* otherwise.
*/
private boolean frameComplete() {
return haveStart && haveEnd && !haveMissing();
}
/**
* Checks whether there are packets with sequence numbers between <tt>firstSeq</tt> and
* <tt>lastSeq</tt> which are *not* stored in <tt>data</tt>.
*
* @return <tt>true</tt> if there are packets with sequence numbers between <tt>firstSeq</tt> and
* <tt>lastSeq</tt> which are *not* stored in <tt>data</tt>.
*/
private boolean haveMissing() {
Set<Long> seqs = data.keySet();
long s = firstSeq;
while (s != lastSeq) {
if (!seqs.contains(s)) return true;
s = (s + 1) % (1 << 16);
}
return false;
}
/** {@inheritDoc} */
@Override
protected int doProcess(Buffer inBuffer, Buffer outBuffer) {
byte[] inData = (byte[]) inBuffer.getData();
int inOffset = inBuffer.getOffset();
if (!VP8PayloadDescriptor.isValid(inData, inOffset)) {
logger.warn("Invalid RTP/VP8 packet discarded.");
outBuffer.setDiscard(true);
return BUFFER_PROCESSED_FAILED; // XXX: FAILED or OK?
}
long inSeq = inBuffer.getSequenceNumber();
long inRtpTimestamp = inBuffer.getRtpTimeStamp();
int inPictureId = VP8PayloadDescriptor.getPictureId(inData, inOffset);
boolean inMarker = (inBuffer.getFlags() & Buffer.FLAG_RTP_MARKER) != 0;
boolean inIsStartOfFrame = VP8PayloadDescriptor.isStartOfFrame(inData, inOffset);
int inLength = inBuffer.getLength();
int inPdSize = VP8PayloadDescriptor.getSize(inData, inOffset);
int inPayloadLength = inLength - inPdSize;
if (empty && lastSentSeq != -1 && seqNumComparator.compare(inSeq, lastSentSeq) != 1) {
if (logger.isInfoEnabled()) logger.info("Discarding old packet (while empty) " + inSeq);
outBuffer.setDiscard(true);
return BUFFER_PROCESSED_OK;
}
if (!empty) {
// if the incoming packet has a different PictureID or timestamp
// than those of the current frame, then it belongs to a different
// frame.
if ((inPictureId != -1 && pictureId != -1 && inPictureId != pictureId)
| (timestamp != -1 && inRtpTimestamp != -1 && inRtpTimestamp != timestamp)) {
if (seqNumComparator.compare(inSeq, firstSeq) != 1) // inSeq <= firstSeq
{
// the packet belongs to a previous frame. discard it
if (logger.isInfoEnabled()) logger.info("Discarding old packet " + inSeq);
outBuffer.setDiscard(true);
return BUFFER_PROCESSED_OK;
} else // inSeq > firstSeq (and also presumably isSeq > lastSeq)
{
// the packet belongs to a subsequent frame (to the one
// currently being held). Drop the current frame.
if (logger.isInfoEnabled())
logger.info(
"Discarding saved packets on arrival of"
+ " a packet for a subsequent frame: "
+ inSeq);
// TODO: this would be the place to complain about the
// not-well-received PictureID by sending a RTCP SLI or NACK.
reinit();
}
}
}
// a whole frame in a single packet. avoid the extra copy to
// this.data and output it immediately.
if (empty && inMarker && inIsStartOfFrame) {
byte[] outData = validateByteArraySize(outBuffer, inPayloadLength, false);
System.arraycopy(inData, inOffset + inPdSize, outData, 0, inPayloadLength);
outBuffer.setOffset(0);
outBuffer.setLength(inPayloadLength);
outBuffer.setRtpTimeStamp(inBuffer.getRtpTimeStamp());
if (TRACE) logger.trace("Out PictureID=" + inPictureId);
lastSentSeq = inSeq;
return BUFFER_PROCESSED_OK;
}
// add to this.data
Container container = free.poll();
if (container == null) container = new Container();
if (container.buf == null || container.buf.length < inPayloadLength)
container.buf = new byte[inPayloadLength];
if (data.get(inSeq) != null) {
if (logger.isInfoEnabled())
logger.info("(Probable) duplicate packet detected, discarding " + inSeq);
outBuffer.setDiscard(true);
return BUFFER_PROCESSED_OK;
}
System.arraycopy(inData, inOffset + inPdSize, container.buf, 0, inPayloadLength);
container.len = inPayloadLength;
data.put(inSeq, container);
// update fields
frameLength += inPayloadLength;
if (firstSeq == -1 || (seqNumComparator.compare(firstSeq, inSeq) == 1)) firstSeq = inSeq;
if (lastSeq == -1 || (seqNumComparator.compare(inSeq, lastSeq) == 1)) lastSeq = inSeq;
if (empty) {
// the first received packet for the current frame was just added
empty = false;
timestamp = inRtpTimestamp;
pictureId = inPictureId;
}
if (inMarker) haveEnd = true;
if (inIsStartOfFrame) haveStart = true;
// check if we have a full frame
if (frameComplete()) {
byte[] outData = validateByteArraySize(outBuffer, frameLength, false);
int ptr = 0;
Container b;
for (Map.Entry<Long, Container> entry : data.entrySet()) {
b = entry.getValue();
System.arraycopy(b.buf, 0, outData, ptr, b.len);
ptr += b.len;
}
outBuffer.setOffset(0);
outBuffer.setLength(frameLength);
outBuffer.setRtpTimeStamp(inBuffer.getRtpTimeStamp());
if (TRACE) logger.trace("Out PictureID=" + inPictureId);
lastSentSeq = lastSeq;
// prepare for the next frame
reinit();
return BUFFER_PROCESSED_OK;
} else {
// frame not complete yet
outBuffer.setDiscard(true);
return OUTPUT_BUFFER_NOT_FILLED;
}
}
/**
* Returns true if the buffer contains a VP8 key frame at offset <tt>offset</tt>.
*
* @param buff the byte buffer to check
* @param off the offset in the byte buffer where the actual data starts
* @param len the length of the data in the byte buffer
* @return true if the buffer contains a VP8 key frame at offset <tt>offset</tt>.
*/
public static boolean isKeyFrame(byte[] buff, int off, int len) {
if (buff == null || buff.length < off + len || len < RawPacket.FIXED_HEADER_SIZE) {
return false;
}
// Check if this is the start of a VP8 partition in the payload
// descriptor.
if (!DePacketizer.VP8PayloadDescriptor.isValid(buff, off)) {
return false;
}
if (!DePacketizer.VP8PayloadDescriptor.isStartOfFrame(buff, off)) {
return false;
}
int szVP8PayloadDescriptor = DePacketizer.VP8PayloadDescriptor.getSize(buff, off);
return DePacketizer.VP8PayloadHeader.isKeyFrame(buff, off + szVP8PayloadDescriptor);
}
/**
* A class that represents the VP8 Payload Descriptor structure defined in {@link
* "http://tools.ietf.org/html/draft-ietf-payload-vp8-10"}
*/
public static class VP8PayloadDescriptor {
/** I bit from the X byte of the Payload Descriptor. */
private static final byte I_BIT = (byte) 0x80;
/** K bit from the X byte of the Payload Descriptor. */
private static final byte K_BIT = (byte) 0x10;
/** L bit from the X byte of the Payload Descriptor. */
private static final byte L_BIT = (byte) 0x40;
/** I bit from the I byte of the Payload Descriptor. */
private static final byte M_BIT = (byte) 0x80;
/** Maximum length of a VP8 Payload Descriptor. */
public static final int MAX_LENGTH = 6;
/** S bit from the first byte of the Payload Descriptor. */
private static final byte S_BIT = (byte) 0x10;
/** T bit from the X byte of the Payload Descriptor. */
private static final byte T_BIT = (byte) 0x20;
/** X bit from the first byte of the Payload Descriptor. */
private static final byte X_BIT = (byte) 0x80;
/**
* Gets the temporal layer index (TID), if that's set.
*
* @param buf the byte buffer that holds the VP8 packet.
* @param off the offset in the byte buffer where the VP8 packet starts.
* @param len the length of the VP8 packet.
* @return the temporal layer index (TID), if that's set, -1 otherwise.
*/
public static int getTemporalLayerIndex(byte[] buf, int off, int len) {
if (buf == null || buf.length < off + len || len < 2) {
return -1;
}
if ((buf[off] & X_BIT) == 0 || (buf[off + 1] & T_BIT) == 0) {
return -1;
}
int sz = getSize(buf, off);
if (buf.length < off + sz || sz < 1) {
return -1;
}
return (buf[off + sz - 1] & 0xc0) >> 6;
}
/**
* Returns a simple Payload Descriptor, with PartID = 0, the 'start of partition' bit set
* according to <tt>startOfPartition</tt>, and all other bits set to 0.
*
* @param startOfPartition whether to 'start of partition' bit should be set
* @return a simple Payload Descriptor, with PartID = 0, the 'start of partition' bit set
* according to <tt>startOfPartition</tt>, and all other bits set to 0.
*/
public static byte[] create(boolean startOfPartition) {
byte[] pd = new byte[1];
pd[0] = startOfPartition ? (byte) 0x10 : 0;
return pd;
}
/**
* The size in bytes of the Payload Descriptor at offset <tt>offset</tt> in <tt>input</tt>. The
* size is between 1 and 6.
*
* @param input input
* @param offset offset
* @return The size in bytes of the Payload Descriptor at offset <tt>offset</tt> in
* <tt>input</tt>, or -1 if the input is not a valid VP8 Payload Descriptor. The size is
* between 1 and 6.
*/
public static int getSize(byte[] input, int offset) {
if (!isValid(input, offset)) return -1;
if ((input[offset] & X_BIT) == 0) return 1;
int size = 2;
if ((input[offset + 1] & I_BIT) != 0) {
size++;
if ((input[offset + 2] & M_BIT) != 0) size++;
}
if ((input[offset + 1] & L_BIT) != 0) size++;
if ((input[offset + 1] & (T_BIT | K_BIT)) != 0) size++;
return size;
}
/**
* Gets the value of the PictureID field of a VP8 Payload Descriptor.
*
* @param input
* @param offset
* @return the value of the PictureID field of a VP8 Payload Descriptor, or -1 if the fields is
* not present.
*/
private static int getPictureId(byte[] input, int offset) {
if (!isValid(input, offset)) return -1;
if ((input[offset] & X_BIT) == 0 || (input[offset + 1] & I_BIT) == 0) return -1;
boolean isLong = (input[offset + 2] & M_BIT) != 0;
if (isLong) return (input[offset + 2] & 0x7f) << 8 | (input[offset + 3] & 0xff);
else return input[offset + 2] & 0x7f;
}
public static boolean isValid(byte[] input, int offset) {
return true;
}
/**
* Checks whether the '<tt>start of partition</tt>' bit is set in the VP8 Payload Descriptor at
* offset <tt>offset</tt> in <tt>input</tt>.
*
* @param input input
* @param offset offset
* @return <tt>true</tt> if the '<tt>start of partition</tt>' bit is set, <tt>false</tt>
* otherwise.
*/
public static boolean isStartOfPartition(byte[] input, int offset) {
return (input[offset] & S_BIT) != 0;
}
/**
* Returns <tt>true</tt> if both the '<tt>start of partition</tt>' bit is set and the
* <tt>PID</tt> fields has value 0 in the VP8 Payload Descriptor at offset <tt>offset</tt> in
* <tt>input</tt>.
*
* @param input
* @param offset
* @return <tt>true</tt> if both the '<tt>start of partition</tt>' bit is set and the
* <tt>PID</tt> fields has value 0 in the VP8 Payload Descriptor at offset <tt>offset</tt>
* in <tt>input</tt>.
*/
public static boolean isStartOfFrame(byte[] input, int offset) {
return isStartOfPartition(input, offset) && getPartitionId(input, offset) == 0;
}
/**
* Returns the value of the <tt>PID</tt> (partition ID) field of the VP8 Payload Descriptor at
* offset <tt>offset</tt> in <tt>input</tt>.
*
* @param input
* @param offset
* @return the value of the <tt>PID</tt> (partition ID) field of the VP8 Payload Descriptor at
* offset <tt>offset</tt> in <tt>input</tt>.
*/
public static int getPartitionId(byte[] input, int offset) {
return input[offset] & 0x07;
}
}
/**
* A class that represents the VP8 Payload Header structure defined in {@link
* "http://tools.ietf.org/html/draft-ietf-payload-vp8-10"}
*/
public static class VP8PayloadHeader {
/** S bit of the Payload Descriptor. */
private static final byte S_BIT = (byte) 0x01;
/**
* Returns true if the <tt>P</tt> (inverse key frame flag) field of the VP8 Payload Header at
* offset <tt>offset</tt> in <tt>input</tt> is 0.
*
* @return true if the <tt>P</tt> (inverse key frame flag) field of the VP8 Payload Header at
* offset <tt>offset</tt> in <tt>input</tt> is 0, false otherwise.
*/
public static boolean isKeyFrame(byte[] input, int offset) {
// When set to 0 the current frame is a key frame. When set to 1
// the current frame is an interframe. Defined in [RFC6386]
return (input[offset] & S_BIT) == 0;
}
}
/** A simple container for a <tt>byte[]</tt> and an integer. */
private static class Container {
/** This <tt>Container</tt>'s data. */
private byte[] buf;
/** Length used. */
private int len = 0;
}
}
