Speex dev - Oct 2006 - Does VAD/DTX work without VBR and Preprocessor

Hello,

I'm try to run speex on some ARM processor.
I'd like to cut away some speex features including VBR, ABR and preprocessor
while still supporting VAD/DTX.

But I've found some puzzles in the source code regarding VAD as below,

1) there are VAD related codes in the source file preprocess.c.
Will VAD still work If  I don't use the source file preprocess.c?

2)The speex manual says VAD can work without VBR enabled.
But I found it's not like that in the source code where VAD is just part of
the VBR.

Can the VBR/ABR/preprocess related souce codes be cut away if VAD and DTX
can work without VBR,ABR or preprocessor?

Regards,

Lianghu
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> 1) there are VAD related codes in the source file preprocess.c.
> Will VAD still work If  I don't use the source file preprocess.c?
Yes. The VAD in preprocess.c is an "external" (independent from the
encoder) VAD.
> 2)The speex manual says VAD can work without VBR enabled.
> But I found it's not like that in the source code where VAD is just
part
> of  the VBR.
This means that you can enable VAD and not VBR. However, the VAD code is
actually a special case of VBR.
> Can the VBR/ABR/preprocess related souce codes be cut away if VAD and
> DTX  can work without VBR,ABR or preprocessor?
If you remove the VBR code, you can't use the VAD anymore. I *think* you
can remove the ABR code, though. Of course, you can also remove
VAD/VBR/ABR/DTX altogether and the encoder will still work.

	Jean-Marc

Hi Marc,

Thanks for your quick response.

So if VAD is enabled then VBR will be enable although it's a special VBR.
How about take out the VAD code from the VBR and remove the code else?

Lianghu

On 10/24/06, Jean-Marc Valin <jean-marc.valin@usherbrooke.ca>
wrote:
>
> > 1) there are VAD related codes in the source file preprocess.c.
> > Will VAD still work If  I don't use the source file preprocess.c?
>
> Yes. The VAD in preprocess.c is an "external" (independent from
the
> encoder) VAD.
>
> > 2)The speex manual says VAD can work without VBR enabled.
> > But I found it's not like that in the source code where VAD is
just part
> > of  the VBR.
>
> This means that you can enable VAD and not VBR. However, the VAD code is
> actually a special case of VBR.
>
> > Can the VBR/ABR/preprocess related souce codes be cut away if VAD and
> > DTX  can work without VBR,ABR or preprocessor?
>
> If you remove the VBR code, you can't use the VAD anymore. I *think*
you
> can remove the ABR code, though. Of course, you can also remove
> VAD/VBR/ABR/DTX altogether and the encoder will still work.
>
>         Jean-Marc
>
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