io.pkts.framer

Class RTPFramer

java.lang.Object

io.pkts.framer.RTPFramer

All Implemented Interfaces:

Framer<TransportPacket,RtpPacket>

public final class RTPFramer
extends Object
implements Framer<TransportPacket,RtpPacket>

Author:

jonas@jonasborjesson.com

Constructor Summary

Constructors

Constructor and Description
RTPFramer()

Method Summary

Modifier and Type	Method and Description
boolean	accept(Buffer data) There is no real good test to make sure that the data indeed is an RTP packet.
RtpPacket	frame(TransportPacket parent, Buffer buffer) Ask the framer to frame the buffer into a packet.
Protocol	getProtocol()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

RTPFramer

public RTPFramer()

Method Detail

getProtocol

public Protocol getProtocol()

Specified by:

getProtocol in interface Framer<TransportPacket,RtpPacket>

Returns:

the protocol this framer is capable of framing

accept

public boolean accept(Buffer data)
               throws IOException

There is no real good test to make sure that the data indeed is an RTP packet. Appendix 2 in RFC3550 describes one way of doing it but you really need a sequence of packets in order to be able to determine if this indeed is a RTP packet or not. The best is to analyze the session negotiation but here we are just looking at a single packet so can't do that. Also, RTP and RTCP packets are hard to distinguish from each other and you really need help from outside such as from the Session Description Protocol but until we connect things together we will do a simple check so that we do not pick up RTCP packets. Note, this check is not super safe, see RFC 5761. Check whether the supplied data could be framed into a frame of this type. Typically, a Framer will read a few bytes in an effort to figure out if the incoming data may be something it recognizes. E.g., a HTTP Framer could check if the first bytes match "GET", "POST", "PUT" and "DELETE" if if so assume that the payload indeed is HTTP and therefore return true. Of course, you may never really know until you actually have parsed the entire body but this method should return quick and if turns out that the data isn't what it thought, throw an exception and the framework will take care of it.

Specified by:

accept in interface Framer<TransportPacket,RtpPacket>

Parameters:

data - the data to check whether it could be a frame of this type

Returns:

true if the data indeed could be of this framer type, false if not

Throws:

IOException

frame

public RtpPacket frame(TransportPacket parent,
                       Buffer buffer)
                throws IOException

Description copied from interface: Framer

Ask the framer to frame the buffer into a packet. Note that the Packet has not been parsed, just framed.

Specified by:

frame in interface Framer<TransportPacket,RtpPacket>

Parameters:

parent - the parent frame or null if the frame doesn't have one.

buffer - the buffer containing all the raw data

Returns:

a new frame

Throws:

IOException - in case something goes wrong when reading data from the buffer