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RTPDePacketizer.javaAPI DocJMF 2.1.1e19486Mon May 12 12:20:46 BST 2003com.sun.media.codec.video.jpeg

RTPDePacketizer

public class RTPDePacketizer extends Object
This codec is a JPEG RTP depacketizer. It receives individual RTP buffers with a JPEG_RTP format. These buffers will be used to reconstruct a complete frame in the JPEG format. Once a frame is constructed, it is sent over to the next node i.e. a node capable of handling the JPEG format.

Fields Summary
private JPEGFrame
currentFrame
protected byte[]
frameBuffer
protected int
sequenceNumber
protected int
quality
protected int
type
byte[]
lastJFIFHeader
int
lastQuality
int
lastType
int
lastWidth
int
lastHeight
Constructors Summary
Methods Summary
public intgetFragOffset(byte[] data, int doff)

	// Fragment offset is the 2nd, 3rd & 4th byte of the JPEG Hdr.
	int foff = 0;
	foff |= (data[doff + 1] & 0xff) << 16;
	foff |= (data[doff + 2] & 0xff) << 8;
	foff |= (data[doff + 3] & 0xff);

	return foff;
public intgetQuality()


         

    
       
	return quality;
public intgetType()

	return type;
public intprocess(javax.media.Buffer inBuffer, javax.media.Buffer outBuffer)
This method will reconstruct a JPEG frame from individual RTP packets. The reconstruction process waits till all the packtes of a frame are received and send this over to the decoder only if all the frames were received. If a the first packet of a frame is not received, all other packets belonging to this frame are discarded.

	// If we've been decoding a frame and packets from another
	// frame has arrived, then we are missing the a few packets
	// for the current frame.  We'll discard the current frame. 
	if (currentFrame != null && 
	    inBuffer.getTimeStamp() != currentFrame.rtptimestamp) {
	    currentFrame = null;
	}

	// Check if this is the first packet from a new frame.
	// The first packet has a framgment offset of 0.
	if (getFragOffset((byte[])inBuffer.getData(), inBuffer.getOffset()) == 0) {
	    currentFrame = new JPEGFrame(this, inBuffer, (byte[])outBuffer.getData());
	} else if (currentFrame != null) {
	    // This is a new packet for the current frame.
	    currentFrame.add(inBuffer, 0);
	} else {
	    // If we don't have a current frame, then we are missing the
	    // first packet for this frame.  We'll discard the current packet.
	    return PlugIn.OUTPUT_BUFFER_NOT_FILLED;
	}

	// If this is the last packet from this frame, we'll need to
	// check if all the packets from this frame has been received.
        if ((inBuffer.getFlags() & Buffer.FLAG_RTP_MARKER) !=0) {
	    if (currentFrame.gotAllPackets(inBuffer.getSequenceNumber())) {
		currentFrame.completeTransfer(inBuffer, outBuffer);
	 	currentFrame = null;
		return PlugIn.BUFFER_PROCESSED_OK;
	    } else {
	 	currentFrame = null;
		return PlugIn.OUTPUT_BUFFER_NOT_FILLED;
	    }
	}

	return PlugIn.OUTPUT_BUFFER_NOT_FILLED;