[asterisk-dev] RTP Native Bridge Codec Change Handling - Appears to compare immediately after setting equal

[Dave WOOLLEY]

Joshua Colp  wrote:
> 
> David WOOLLEY wrote:
> > David Woolley wrote:

> >> To me this seems me to make it very difficult for a codec change to
> >> actually be detected, as when you unroll the loop, the unconditional
> >> set precedes the test for changes!
> 
> I *think* you are correct and I believe this stems from the
> UPDATE_RTP_PEER frame. It is used to indicate explicitly that the remote
> peer has changed. Removing the code that you mention I think should do it...
> although I think this really shows another issue which is, the code doesn't
> handle codecs changing to a non-joint situation so a joint check should also
> probably be added in.

That was probably going to be the rider!  The actual scenario was that we were about to apply a back port of the fix for https://issues.asterisk.org/jira/browse/ASTERISK-16153 to deal with a case where one side was both A-Law and Mu-Law, and the other just A-Law, and they had selected the opposite choices,  but then noted that the side with both only gave Mu-Law in response to the re-invite, but that wasn't being forwarded, and nor was it tearing down the native bridge, even though there was some attempt to cope with changes.  I think the former is basically the problem I originally raised, and the latter the one you have added.

In that case, just applying the back port would either force them both to A-Law or cause the Mu-Law one to  go not acceptable, which is a case that I need to check further.  Where a joint test would certainly help is if both had offered both G.711 variants, but had reneged on different ones during the re-invite.

Unfortunately, this has become sufficiently complex, that, in the short term, we are probably going to try and configure so that only once codec is possible, and only try for a general solution in the longer term.

-- 
David Woolley
BTS Holdings Plc
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