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Re: [Question #229419]: What protocol number should be for RTP header compression

 

Question #229419 on rohc changed:
https://answers.launchpad.net/rohc/+question/229419

    Status: Open => Answered

Didier Barvaux proposed the following answer:
Wei,

> Yes, Didier, all packets are of the same stream. In my case, IP addresses,
> UDP ports, SSRC/CSRC don't change. Only a few fields like the SN change.
> [...]

> I just copy/paste the main function of the simple_rohc_program.c file here
> since there is no way to upload it.
> [...]

The program you copied/pasted compresses 30 times the same packet. All
of those packets belong to the same RTP stream (same IP addrs, same UDP
ports, same SSRC), but they also got the same RTP SN. That's not
expected for one RTP stream. That might well explain the low compression
efficiency that you got. Please change the SN in the for loop between 2
compressions. You should also change the RTP TimeStamp (TS): make it
increase of the same delta for every new packet (300, 600, 900, 1200..
for example).

Regards,
Didier

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