[asterisk-users] sip ... codec conversion matrix

[Cesc Santa]

inline

On 8/10/07, Gordon Henderson <gordon+asterisk at drogon.net> wrote:
>
> On Fri, 10 Aug 2007, Cesc Santa wrote:
>
> >
> > I can use them ... but cannot do translation ... only "pass-through" ...
> it
> > complains that
> > there is no function to convert to internal codec (pcm?)
> >
> > G726 should also be compiled in as standard - it's supplied with
> asterisk.
> >
> > no license to use it needed?
>
> None at all.


ok ... i guess i will have to try harder ;)


> These may not be "free" enough for your Linux distribution, so that might
> >> be why you don't have them if you're running a binary installation. Eg.
> >> iLbc isn't "free" enough for standard Debian.
> >
> > well, i use debian, but not the asterisk binary distro ... i compiled
> myself
> > from 1.2.18 sources
>
> OK. This is what I do too!
>
> I have Debian Sarge on my development box.
>
> So it's strange you don't have iLBC and speex. There is a debian package
> for speex:
>
> On my development box:
>
> bob:~# dpkg -l | grep speex
> ii  libspeex-dev   1.1.6-2        The Speex Speech Codec
> ii  libspeex1      1.1.6-2        The Speex Speech Codec
> ii  speex          1.1.6-2        The Speex Speech Codec


this is probably one thing i am missing ... i will check


but I have no iLBC packages - they appear to be in the asterisk source...
>
> bob:~# asterisk -rx 'show translation'
>           Translation times between formats (in milliseconds)
>            Source Format (Rows) Destination Format(Columns)
>
>           g723   gsm  ulaw  alaw  g726 adpcm  slin lpc10  g729 speex  ilbc
>     g723     -     -     -     -     -     -     -     -     -     -     -
>      gsm     -     -     2     2     3     2     1     7     -    31    19
>     ulaw     -     4     -     1     3     2     1     7     -    31    19
>     alaw     -     4     1     -     3     2     1     7     -    31    19
>     g726     -     4     2     2     -     2     1     7     -    31    19
>    adpcm     -     4     2     2     3     -     1     7     -    31    19
>     slin     -     3     1     1     2     1     -     6     -    30    18
>    lpc10     -     5     3     3     4     3     2     -     -    32    20
>     g729     -     -     -     -     -     -     -     -     -     -     -
>    speex     -     5     3     3     4     3     2     8     -     -    20
>     ilbc     -     6     4     4     5     4     3     9     -    33     -
>
> so I get everything apart from g723 and g729. I didn't do anything special
> to the makefile, etc. (other than set the i586 flag as my target box needs
> it)


and this is definitely what I would expect to have ... knowing someone has
it ... i'll get to work :)


> G723 and G729 are patent encumbered and so you need licenses to run the
> >> software. You can get G729 licenses from Digium, but I don't know about
> >> G723...
> >
> > ok ... i will contact digium for g729 license ... anyone knows about
> g723?
>
> Do you actually need g729? I'd not spend the money on it unless you really
> needed it.
>
> I've not heard of anyone using or offering g723...
>
> And I have to say; you're not missing much by not having iLBC or speex.
> The CPU overhead is significant and the voice quality is somewhat
> "dubious" :) Unless you absolutely really desperately need to compress the
> data stream to squeeze out every ounch of bandwidth, then I'd really not
> use them.
>
> If you need to compress, start with G726, then move to GSM, and then if
> you need better audio quality, buy g729 licenses.
>
> Gordon


I agree with you ...  actually, I am interested in G729 (and I am definitely
getting a few licenses).
G723 I also got a customer who would like to see it working in my product
... so I'll check it out.
As for Speex and iLBC, it was some collateral "damage" ... I was looking at
the transcoding
and knowing these codecs were/are free, I found it strange that I could not
translate them ...
I'll fix that. Even it is just for the fun.

Many thanks!

Cesc
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