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

[Luigi Rizzo]

On Mon, Oct 15, 2007 at 02:49:12AM -0500, Tilghman Lesher wrote:
> On Sunday 14 October 2007 14:47:11 Luigi Rizzo wrote:
> > On Sat, Oct 13, 2007 at 09:37:20AM +0200, Kevin P. Fleming wrote:
> > > Luigi Rizzo wrote:
> > > > i know - didn't want to make the story too long :)
> > > > (i suppose it is also a problem to pass the information across
> > > > a chain of asterisks)
> > >
> > > Yes, that will be complicated to solve properly as well.
> > >
> > > > ok will keep in mind. Any idea of how other PBX address this issue ?
> > >
> > > I don't know of very many PBX products that support videophones, and
> >
> > but as you said the problem exists in general, even for audio-only
> > calls where the PBX is not in the media stream (and the two ends
> > use a different technology - e.g. probably chan_sip handles this
> > case already when connectiong two sip endpoints just because they
> > happen to talk the same language ?)
> >
> > 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.
> 
> As an alternative approach, why not create a frame type to notify
> all channels listening that the native media type has changed?  Those
> channels which wish to receive the data as non-transcoded could then
> request to change their native media types, thus saving the Asterisk
> server an amount of transcoding.  Other channels are free to ignore the
> notification, in which case Asterisk transcodes to the proper type for each
> receptive channel.  Everybody wins.

I am not sure this addresses my need.

The problem i have is telling the source what the receiver(s) can
handle - your proposal goes the other way around, tell receivers
what the source is sending.

cheers
luigi