[Members] XSF roadmap

Justin Karneges justin at affinix.com
Sat Nov 20 13:12:08 CST 2010


On Saturday 20 November 2010 03:39:41 jehan at zemarmot.net wrote:
> Hi again,
> 
> I answer myself below
> 
> On Sat, 20 Nov 2010 20:13:30 +0900, <jehan at zemarmot.net> wrote:
> > On Sat, 20 Nov 2010 11:47:22 +0100, Alexander Gnauck
> 
> [...]
> 
> >> Most people use Skype because it A) just works and B) has excellent
> >> voice quality. We can fix A with interop testing, but I don't know how
> >> we can fix B. Is somebody on the list which has experience with free
> >> codecs?
> > 
> > Yes I was only worried about A) but B) is very true as well.
> 
> [...]
> 
> > As for the codec, I think to remember discussions (in IETF probably?)
> > were going on about having a new codec derived from the current existing
> > ones because speex or others would not be that efficient for voip (or so
> > I think to remember being told, I have no knowledge on the matter). What
> > about this point?
> 
> After a few research, I found CELT, developed by Xiph.org:
> http://www.celt-codec.org/ and
> https://datatracker.ietf.org/doc/draft-valin-celt-codec/
> 
> And I also found info about a Opus codec which is developed by Skype,
> is apparently some container, I guess (because it says it uses SILK
> which is apparently also an audio codec developed by Skype, and CELT as
> well. Yes it gets complicated) and also proposed as an IETF draft. Yet
> whereas CELT is completely royalty free, Opus would have some patent
> issues (held by Skype of course) and may require some license fee:
> https://datatracker.ietf.org/ipr/1297/
> If you read the license declaration in the page, Skype really keeps a
> lot of possibilities to suddenly turn on Opus users. So I hope we won't
> be using such technology. I thought that any standard proposed to IETF
> had to release its right to the IETF?!
> 
> Anyway is there other codecs I miss? IS CELT the state of the
> art/future (for now) of voip?

For the future, I believe so.  However, Speex is still very good.  I doubt 
most peoples' ears would be able to notice the difference between Speex, CELT, 
and SILK, given typical bandwidth (not saying these other codecs aren't 
better, just that they are only marginally better.  think Vorbis vs MP3).  I 
consider audio a solved problem, thanks to Speex.

If audio on your Jingle call was bad, then it is probably due to the 
implementations (GStreamer-based voip apps have had problems in the past with 
choppiness or "talking through a fan" effects, though I think by now this 
shouldn't be happening) or you were not using the Speex codec at all (both 
GTalk and Pidgin support PCMA/U out of the box, and you often need to coerce 
Pidgin to use Speex).  Make sure you are on the latest versions and confirm 
your codecs if possible.

-Justin


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