[Live-devel] Increasing UDP packet sizes for streaming MPEG video?

[Ross Finlayson]

>Grabbing an Ethernet trace of the data as it comes in shows the data 
>in UDP packets coming across the line with data payloads of 1328 
>bytes.  I am interested in increasing this to a few dozen kb at 
>least, in order to improve performance, but where should I look to 
>find the code that deals with this?

First, I'm assuming that your network MTU is large enough to 
accommodate larger UDP packets.  (If instead, your network MTU is 
something like the usual 1500 bytes, then you should not try to send 
larger UDP packets, otherwise you'll end up with IP-level 
fragmentation, and bad performance if packets get lost.)

If your network MTU is really large enough to accommodate larger 
packets, then you can do so by making the following two changes:
1/ In "MultiFramedRTPSink.cpp", change the call to "setPacketSizes()" 
on line 46.  (Alternatively, call "setPacketSizes()" with your new 
parameters after each "RTPSink" object is created.)
2/ In "MPEG2TransportFileServerMediaSubsession.cpp", change the 
definition of "TRANSPORT_PACKETS_PER_NETWORK_PACKET", so that
	12 + 188*TRANSPORT_PACKETS_PER_NETWORK_PACKET < your maximum 
UDP packet size
	(12 bytes is the size of the RTP header)
-- 

Ross Finlayson
Live Networks, Inc.
http://www.live555.com/
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