[OpenSIPS-Users] codec manipulation feature

[Bogdan-Andrei Iancu]

Hi Brett,

Brett Nemeroff wrote:
> my $0.02 here.. I'm not sure if this is what you guys had in mind.. 
> but I've had situations where this would be handy.. It'd need to have 
> some way of identifing the codec (by number?). I'm not sure if the 
> core really has anything that parses the SDP by RFC spec,
there is an SDP parser in the core :)
> so I'm not sure how you'd do things like "removing g729 codec 
> including the annex=b annotation".
but not sure if so complex :D (like relation between the SDP fields).
> But imaging that anything is possible:
>
what we had in mind was to add functions to:

1) test if a codec is advertised
2) remove codecs
3) change the priority between the existing codecs


Regards,
bogdan

> I imagine functions:
> reject_codec: reject a call if a codec matches
> remove_codec: remove an offered codec
> codec_present: returns true if codec specified is offered
>
> if (reject_codec('ulaw')) {
> sl_send_reply("488","ULAW Calls not allowed");
> exit;
> }
>
>
> if ((codec_present('ULAW')) && codec_present('G729a')) {
> remove_codec('ULAW');
> xlog("L_INFO","Removing bad codec: ULAW");
> }
>
> if (!codec_present('G729a')){
> sl_send_reply("488","Please send G729a calls");
> }
>
>
> On Mon, Jun 15, 2009 at 3:02 PM, Jeff Pyle <jpyle at fidelityvoice.com 
> <mailto:jpyle at fidelityvoice.com>> wrote:
>
>     Hi Bogdan,
>
>     It’s been a little while since we talked about this. I was
>     wondering if there was anything in the works to detect and/or
>     manipulate the codecs present in an SDP.
>
>
>
>     - Jeff
>
>
>
>
>     On 2/1/09 4:08 AM, "Steve Kurzeja" <steve.kurzeja at gmail.com
>     <http://steve.kurzeja@gmail.com>> wrote:
>
>         This idea is quite standard in SBCs, typically called codec
>         profiles, where you permit only certain codecs to be passed
>         through the SBC in an INVITE and all the rest are stripped out.
>
>         We use it to get around interop issues with certain codecs.
>         E.g. we have some end devices/customers that have issues using
>         g729a so we choose to remove this codec for these specific
>         endpoints.
>
>         The poor man's method to implementing this is just doing
>         header manipulations in the SDP but it would be nice to be
>         standardized.
>
>         Regards,
>         Steve
>
>
>         On Fri, Jan 30, 2009 at 2:20 AM, Jeff Pyle
>         <jpyle at fidelityvoice.com <http://jpyle@fidelityvoice.com>> wrote:
>
>             Hi Bogdan,
>
>             I'm looking for the ability to selectively remove codec
>             advertisements from
>             the SDP. For example, if my customer sends a call to me
>             for PSTN
>             termination he may advertise G711 and G729, with G711
>             preferred. By looking
>             at the number of existing dialogs I may know that he's
>             running low on
>             bandwidth, so I would like to suppress the G711
>             advertisement ultimately
>             causing a 200 OK from the carrier with G729.
>
>             Generically, in this application we're looking only to
>             suppress G711 at
>             certain times.
>
>             I understand normally codec selection is done completely
>             by the gateway
>             device. However, my gateway devices aren't smart enough to
>             take bandwidth
>             utilization into consideration when choosing which codecs
>             to advertise. I'm
>             hoping my proxy might be. :)
>
>             Does that make sense?
>
>
>
>             - Jeff
>
>
>
>             On 1/29/09 5:04 AM, "Bogdan-Andrei Iancu"
>             <bogdan at voice-system.ro <http://bogdan@voice-system.ro>>
>             wrote:
>
>             > Hi Jeff,
>             >
>             > right now there is only available some functionality to
>             check the codecs
>             > (to see what codecs are advertised in the SDP)... What
>             exactly are you
>             > looking for (like codec ops) ?
>             >
>             > Regards,
>             > Bogdan
>             >
>             > Jeff Pyle wrote:
>             >> Bogdan,
>             >>
>             >> Some months back you mentioned an upcoming feature that
>             would allow
>             >> Opensips to manipulate the codecs present in the SDP.
>             Just wondering
>             >> if there is anything available to test yet. This feature, in
>             >> combination with dialog contexts, will be of great use
>             to us to allow
>             >> us to take a guess at the bandwidth consumption for a
>             particular
>             >> customer and force the use of a compressed codec if
>             necessary.
>             >>
>             >>
>             >> Thanks,
>             >> Jeff
>             >
>
>
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