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[Didier Barvaux <question276107@xxxxxxxxxxxxxxxxxxxxx>]

Question #276107 on rohc changed:
https://answers.launchpad.net/rohc/+question/276107

    Status: Open => Needs information

Didier Barvaux requested more information:
Hello,

> Sorry my tunnel isn't aware of the stream ended. I don't think iprohc is able to
> detect the stream end.

You're right, the IP/ROHC application is not able to detect stream
beginning/end.

> At each tunnel end I'm using SIP softswitch( And SIPp) to test the streams. I think
> only way to detect the stream end by SIP Bye message right ?

Yes, SIP INVITE and BYE messages may be used to detect stream
beginning/end.

> But here streams have to be attached by same CID. I don't know if ROHC
does that.

Sorry, I don't understand what do you mean. Do you say that the SIP and RTP streams
have to share the same CID?

> It would be very much help full to have a such API which will detect the the unused
> CID and clean them for new use.

I think that the detection should not be part of the ROHC library itself. However, the
library can provide a new function rohc_comp_free_context() or the like in its API and 
the IP/ROHC application (or any other app using the ROHC library) can use it to indicate
that a stream ended. The application would be free to detect the end of a stream using
whatever mechanism. The IP/ROHC app might try to perform some DPI to detect SIP
INVITE and BYE messages.

> And also more CID can be added on the fly and it send the state to the remote
> decompressor to enlarge the CID at remote side too. So that way we can avoid the
> conflict the CID mismatch with remote tunnel.

It looks like a different problem than the "detect end of stream" problem, doesn't it? What
use case would you like to solve by adding new CIDs on the fly? Current versions of the
ROHC library let you define the maximum number of CIDs at initialization. Is it a limitation
for you?

Regards,
Didier

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