RTP VoIP - each Packet being compressed and in ROHC pcap twice?

Asked by Jim Wheeler on 2012-05-03

I'm using Main build 304. When looking at ROHC output samples provided for RTP, each compressed packet appears twice (visible by Sequence Number and payload being the same. The source pcap does not repeat packets. I also ran the test_non_regression script against the source pcap and the output shows each packet being compressed/decompressed twice and the ROHC output pcap has each packet there twice just as the sample provided. I don't know enough about ROHC or your implementation yet to know if this is intentional or not, so hesitate to report it as a bug. So I'm posting it as a question. Is this normal/expected behavior?

Thanks,

Jim W.

Question information

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Status:
Solved
For:
rohc Edit question
Assignee:
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Solved by:
Didier Barvaux
Solved:
2012-05-04
Last query:
2012-05-04
Last reply:
2012-05-04

Hello Jim,

This is the expected behaviour. The non-regression tests are run in bidirectional mode. The source.pcap packets are compressed/decompressed through Compressor 1 / Decompressor 1 and Compressor 2 / Decompressor 2 as described on the figure in the header of the source code (http://bazaar.launchpad.net/~didier-barvaux/rohc/main/view/head:/test/non_regression/test_non_regression.c). So, there are twice more packets in the rohc.pcap capture than in the source.pcap one.

Regards,
Didier

Jim Wheeler (jim-wheeler) said : #2

Thanks Didier Barvaux, that solved my question.