Re: [AVT] T.38 over RTP: RTP Sequence Number

Vladimir Ulybin wrote:
> 
> I think we may use for RTP sequence number the same rules of
> incrementing as for T.38 UDPTL SN, i.e. increment SN per every new
> primary IFP packet and do not increment SN if a fax packet is repeated.
> 

There exist at least two possible ways of performing this without 
screwing up the RTCP statistics and fulfilling your other requirements:

The first one is to use FEC to provide the packet repetition. I would 
suggest that you use RFC 2733 to provide repetition in a smarter way. 
This way one FEC packet can cover a few RTP packets. If this is done 
using RFC 2198 packetization then you don't even need to run two RTP 
sessions.

The second is actually to use that Retransmission RTP payload format for 
repetitions. The payload format is really for repetitions and the spec 
provides with necessary information on bind and sync. Simple skip the 
NACK process.

Cheers

Magnus Westerlund

Multimedia Technologies, Ericsson Research EAB/TVA/A
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