[Freeswitch-users] Codecs issue

[Steven Ayre]

It's part of the RTP/SDP standards. They're either static or dynamic
numbers.

Dynamic ones (96-127) are named by name in a=rtpmap lines.

Static numbers are reserved numbers and the a=rtpmap is allowed but optional
(although some devices incorrectly require it)
The list of reserved static numbers is:
http://www.iana.org/assignments/rtp-parameters

-Steve


On 16 January 2011 23:18, Diego Viola <diego.viola at gmail.com> wrote:

> How do you understand these RTP/AVP numbers?
>
>  m=audio 23344 RTP/AVP 3 18 98 99 9 0 8 101 13
>
> What does the numbers mean? I don't see that on the wiki.
>
> Any help appreciated.
>
> On Sun, Jan 16, 2011 at 7:48 PM, David Ponzone <david.ponzone at ipeva.fr>
> wrote:
> > That sounds like a bad reading of the trace.
> > The important line is the 239th:
> >  m=audio 23344 RTP/AVP 3 18 98 99 9 0 8 101 13
> > That means codec 3 is sent first (so GSM), then 18 (so G729).
> > I think you should read a little bit on early negotiation.
> > If leg A has GSM in 1st position, if your inbound codec list allows GSM,
> and
> > your outbound codec list is : G729, PCM, GSM, than your outbound INVITE
> to
> > leg B will have GSM in 1st position, because that was requested by leg A.
> > That's in the wiki, it's a part I rewrote myself some weeks ago, in the
> most
> > readable way I could.
> > David Ponzone  Direction Technique
> > email: david.ponzone at ipeva.fr
> > tel:      01 74 03 18 97
> > gsm:   06 66 98 76 34
> > Service Client IPeva
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> >
> >
> >
> > Le 16/01/2011 à 21:59, Diego Viola a écrit :
> >
> > Hello,
> >
> > I'm experiencing some strange issue with codecs. I have the following
> > in my vars.xml file:
> >
> >  <X-PRE-PROCESS cmd="set"
> > data="global_codec_prefs=G729,G7221 at 32000h,G7221 at 16000h
> ,G722,PCMU,PCMA,GSM"/>
> >  <X-PRE-PROCESS cmd="set"
> data="outbound_codec_prefs=G729,PCMU,PCMA,GSM"/>
> >
> > "inbound-late-negotiation" and "disable-transcoding" are commented in
> > my internal SIP profile. So I guess I'm in Early Negotiation (default
> > behavior) mode.
> >
> > However, when I send a call to my provider, and I look at the SIP
> > trace I see that FS is sending another codec, not G729 as I specified
> > in the global_codec_prefs / outbound_codec_prefs parameters.
> >
> > I'm sending calls like this:
> >
> >        <action application="bridge" data="sofia/internal/$1 at 38.102.93.70
> "/>
> >
> > Here is a SIP trace of a call:
> >
> > http://pastebin.freeswitch.org/15042
> >
> > I'm not understanding why FS is sending an INVITE with the G7221 codec
> > in line 240, if I'm telling it explicitly that I want G729 as the
> > priority when possible in the codec prefs options. But I see G729 in
> > the 200 OK in line 291.
> >
> > I've been told to use absolute_codec_string=G729 in my dialplan or
> > enable late negotiation, but why if I'm already telling it to use G729
> > in the codec prefs?
> >
> > my softphone IP: 190.23.80.10
> > provider IP: 38.102.93.70
> > FS IP: 77.92.65.126
> >
> > calls flow like this:
> >
> > softphone -> FS -> provider
> >
> > Any help appreciated.
> >
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>
>
>
> --
> Diego Viola
> Representative of Bridgecom LLC
> Phone: +595 971 320 520
> GTalk: diego.viola at gmail.com
> MSN: diegoev at msn.com
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>
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