[speex-dev] Speex settings and jitter

Chris Flerackers cflerackers at androme.be
Fri May 23 00:33:21 PDT 2003



Hi Conrad,

Thanks a lot for the info. This is exactly what I needed.
We want to use speex in our IP telephony client and I was indeed trying to
put together
a GUI configuration screen.

Best regards,
Chris

> On Tue, May 20, 2003 at 06:04:39PM +0200, Chris Flerackers wrote:
>> Hi,
>>
>> Is there are document where the interaction between all the configuration
>> options of speex is explained?
>> Speex seems to have CBR, VBR and ABR. You can also use SPEEX_SET_QUALITY
>> (SPEEX_SET_VBR_QUALITY) and SPEEX_SET_BITRATE which I suppose can't be
set
>> at the same time. Is there a list of possible combinations somewhere?
>
> Hi Chris,
>
> not sure if there's a document describing this, I got the info from
> the mail archives and emails with Jean-Marc. This is pretty important
> for writing a GUI of course, so here's what I know (as implemented
> in Sweep).
>
> nb. this also takes into account DTX, which is basically optional on
> top of VAD (setting VBR implies VAD).
>
> As of 1.0, the following option combinations are valid:
>
>         CBR
>         CBR + VAD
>         CBR + VAD + DTX
>         VBR + VAD (or "VBR without DTX", added in speex-1.0rc3)
>         VBR + VAD + DTX (ie. normal VBR)
>
> Quality/bitrate:
>
>         for CBR: either SPEEX_SET_QUALITY (int) or SPEEX_SET_BITRATE
>
>         for VBR: either SPEEX_SET_VBR_QUALITY (float) or SPEEX_SET_ABR
>
> AFAIK setting BITRATE or ABR will _override_ QUALITY or VBR_QUALITY
> respectively.
>
> Conrad.

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