Re: [GnomeMeeting-devel-list] Speex

[Damien Sandras <dsandras seconix com>]

Hi!

Le vendredi 10 mars 2006 à 23:29 +0100, Olaf Conradi a écrit :
> Hello,
> 
> I am testing Ekiga with the latest Debian snapshot (march 8th) to see
> how it works with my Speex plugin for Yate.
> 
> I noticed Ekiga was the first softphone I came across which sets the
> SDP payload type to "SPEEX" and not "speex". Digging into the RFCs of
> AVT payloads [1] it does say:
> 
> "Note that the payload format (encoding) names defined in the RTP
> Profile are commonly shown in upper case.  Media subtype names are
> commonly shown in lower case.  These names are case-insensitive in
> both places."
> 

Yes it is case-insensitive.

> But the latest speex RFC [2] says:
> 
> "When conveying information by SDP [4], the encoding name MUST be set
> to "speex"."

I will change it to lower case, but still, it is case-insensitive.

> 
> Thought you might want to know. Maybe you want to change this (just as
> iLBC is shown as "iLBC" by Ekiga in SDP payloads).
> 
> I did some testing between my codec and Ekiga and noticed Ekiga advertises this:
> 
> m=audio 5018 RTP/AVP 101 110
> a=rtpmap:101 telephone-event/8000
> a=fmtp:101 0-15
> a=rtpmap:110 SPEEX/8000
> 
> If I respond with:
> 
> m=audio 17002 RTP/AVP 110 101
> a=rtpmap:110 speex/8000
> a=fmtp:110 mode=5
> a=fmtp:110 ebw=narrow
> a=rtpmap:101 telephone-event/8000
> 
> Then Ekiga does not pickup that the other side wants to use mode 5
> (speex-nb-15k), not mode 3 (speex-nb-8k). The connection succeeds and
> all Ekiga hears is garbage as speex decodes in the wrong mode.
> 
> Why does Ekiga not request mode 3 if it does not cope with other modes
> or accept other modes? The Speex RFC [2] does state mode 3 is default,
> but both parties still have to agree.

Ekiga doesn't support specifying modes for codecs. The SPEEX draft (it
is not an RFC yet) is severely limited in that regard. The iLBC RFC
tells for example that : the default mode has to be used except if both
parties agree to use another mode. In this case, if you respond to my
offer, you shouldn't try to use another mode than the one Ekiga
requested (which is the default mode). So from my point of view, your
answer is not correct...


> 
> 
> Cheers
>  -Olaf
> 
> [1] http://www.ietf.org/internet-drafts/draft-ietf-avt-rfc3555bis-02.txt
> [2] http://www.ietf.org/internet-drafts/draft-ietf-avt-rtp-speex-00.txt
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-- 
 _      Damien Sandras
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