[asterisk-dev] how does a channel driver know the result of codec negotiation ?

[Olle E Johansson]

16 okt 2007 kl. 11.01 skrev Luigi Rizzo:

> On Tue, Oct 16, 2007 at 08:12:48AM +0200, Olle E Johansson wrote:
>>
>> 14 okt 2007 kl. 21.47 skrev Luigi Rizzo:
> ...
>>> Anyways, what would be wrong with the obvious solution of notify
>>> the caller's channel driver once the remote party reports supported
>>> formats ?  I don't know exactly if we already have a suitable
>>> callback in struct ast_channel_tech but given the abundance of
>>> entries there i suppose one more wouldn't harm too much.
>>
>> This is one of the issues we discussed at AstriDevCon in Atlanta
>> and we do have a proposal in Videocaps. Please look into
>> that branch. It might not be the proper one, but at least it
>> works.
>
> can you or someone who knows summarize the strategy used there ?
>
> i tried to look at the diff in that branch but it is huge,
> and so is the code itself in chan_sip, so i couldn't really
> figure out the bits related to this part.
>
> surely whoever implemented that thing can give us a short
> summary on the approach followed ?

Ok, I'll repeat it. It must surely be in the archives since I've sent
out quite a lot of information about it.

For video, it's imperative to know what the callee responds at
session setup. It's often also important for audio, but the failure
aren't as dramatic.

John has in video caps added a function that simply sends a
message at answer time, AST_CONTROL something, with
the capabilities on the answering side.

I don't think this is optimal, we should have an attachment to
the answer message instead. This was agreed upon at
AstriDevCon, but I haven't seen any follow-ups.

I've asked Digium for assistance and review of videocaps for
a long time, but haven't got any replies. I hope that they do
understand how important this is for Asterisk.

Cheers from Sweden :-)

/O