[Freeswitch-users] G729

[Steven Ayre]

On 8 February 2011 17:23, Steve Underwood <steveu at coppice.org> wrote:

> On 02/09/2011 12:09 AM, Steven Ayre wrote:
> > Annex A is just an alternative way of encoding the data, using less
> > processing power but at poorer quality. They generate compatible data
> > - decoders both with and without annex a support decode both G729 and
> > G729A encoded data. The difference is purely in the implementation of
> > the encoder/decoder. If your device uses G729A in the SDP, it's broken.
> This is correct, but there are still quite a few things around that have
> broken SDP that says g729a. The last time I looked, Freeswitch had a
> fudge in the source code to tolerate that.
>

Cool, didn't realise that. So no modifications should be needed then.


> >
> > Annex B uses the same PT & name. It does work in passthrough mode, as
> > does plain G729.
> There is supplementary info in the SDP to say whether AnnexB is enabled,
> like so:
>
> a=fmtp:18 annexb=yes
>

Which is I believe passed to the other leg. Is that correct?


>
>
> > -Steve
> >
> >
> > On 8 February 2011 15:31, curriegrad2004 <curriegrad2004 at gmail.com
> > <mailto:curriegrad2004 at gmail.com>> wrote:
> >
> >     G729 only. No A's or AB.
> >
> >     If you want to pass through other variants of G.729, you can simply
> >     modify mod_g729.c to include additional variants of G729
> >
> >     Which by the way, I've pasted the area of the code you might want to
> >     modify. I've done this on mine and it worked fine as pass through.
> >
> >     00217         SWITCH_ADD_CODEC(codec_interface, "G.729A");
> >     00218         for (count = 12; count > 0; count--) {
> >     00219                 switch_core_codec_add_implementation(pool,
> >     codec_interface,
> >     00220
> >                            SWITCH_CODEC_TYPE_AUDIO, 18, "G729A", NULL,
> >     8000, 8000, 8000,
> >     00221
> >                            mpf * count, spf * count, bpf * count, ebpf *
> >     count, 1, count * 10,
> >     00222
> >                            switch_g729_init, switch_g729_encode,
> >     switch_g729_decode, switch_g729_destroy);
> >     00223         }
> >
> >
> >     On Tue, Feb 8, 2011 at 7:02 AM, Sam <u2nsam at gmail.com
> >     <mailto:u2nsam at gmail.com>> wrote:
> >     > Hi,
> >     >
> >     > Which type of  G.729 codec does freeswitch uses in passthrough
> >     mode ?
> >     > Is it g729a or g729b or g729ab .
> >     >
> >     > Regards
> >     > Sam
> >
> Steve
>
>
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