[Speex-dev] Speex and bandwidth usage on Asterisk's IAX

[Jean-Marc Valin]

Hi Stephen,

Thanks for posting these results. Just curious, what VBR_QUALITY did you
set for VBR?

	Jean-Marc

Le vendredi 05 mai 2006 à 18:36 +0200, Stephen Davies a écrit :
> Hi,
> 
> I've just joined the list.  Thanks Jean-Marc and other contributors
> for your efforts with Speex.
> 
> Anyway - I've been hired by a local firm to investigate,
> write-code-as-required and generally help them get the maximum
> bang-for-the-byte for VOIP traffic on the hyperexpensive Internet
> bandwidth going out of South Africa.
> 
> I started the process by doing some methodical measurements and just
> wanted to post the results to the list.
> 
> My test hookup was two Asterisk boxes, connected with private 100Mb
> ethernet for an IAX trunk.  I used Asterisk SVN - so far I've tested
> the branch-1.2; I will test the trunk too.
> 
> My customer moves a decent volume of calls, so I tested the various
> codecs and configs with 5 concurrent calls, 10, 15, 20, 25 and 30.  I
> used recordings of real conversations - playing the one side from
> machine A to machine B, the other from B -> A (in other words, just
> like real calls).
> 
> The reported results are all with IAX trunking in use (trunk
> timestamps also enabled).
> (IAX trunking makes a huge difference for total bandwidth usage - for
> example for an 8k codec like g.729 (or speex quality=3) trunking
> reduces bandwidth usage nearly in half).
> 
> I'm probably being a bit optimistic about my accuracy in quoting
> results with the decimal place!
> 
> Here are some results for codecs other than Speex:
> 
> G.711a:
>     5 concurrent calls: 67.8kbps/call
>     30 concurrent calls: 66.2kbps/call
> 
> G.729:
>     5 concurrent calls: 13.1kbps/call
>     30 concurrent calls: 10.8kbps/call
> 
> iLBC:
>     5 concurrent calls: 16.6kbps/call
>     30 concurrent calls: 15.2kbps/call
> 
> Speex is very versatile, so I started testing Speex with all the fancy
> stuff off.  Quality was set to 3.  I am using an SVN checkout of
> Speex.
> 
> Speex "basic":
>     5 concurrent calls: 13.5kbps/call
>     30 concurrent calls: 11.2kbps/call
> 
> Next, started turning on the nice features:
> 
> Speex "vad":
>     5 concurrent calls: 12.2kbps/call
>     30 concurrent calls: 9.6kbps/call
> 
> Speex "vbr":
>     5 concurrent calls: 11.2kbps/call
>     30 concurrent calls: 8.95kbps/call
> 
> Speex "vbr". preprocessor on and doing denoise, agc and pp_vad:
>     5 concurrent calls: 7.0kbps/call
>     30 concurrent calls: 6.9kbps/call
> 
> So I think that that final result is pretty amazing.  That's 35% less
> bandwidth usage than G.729.  Even without the preprocessors help you
> do 17% better.
> 
> Regards,
> Steve Davies
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