[speex-dev] --dtx alone does nothing?

[David Willmore]

> All you say look normal to me.

Okay, clarification requires less code to be written than a bug. :)

> > Does that makes sense?  I would have thought that --dtx alone would have =
> doen it,
> > but maybe it needs perfect digital silence to work?  Or only uses the voi=
> ce activation
> > to know when there's silence?
> 
> DTX requires the VAD to know when there's silence, so it can't do
> anything without --vad. I'll add a warning for that.=20

Okay, my second guess was right.  I'm not completely insane today.

> > Another point I'd just like clarified is how to specify bit rates.  There=
>  seem to be=20
> > four different ways to do it:
> >=20
> > 1) --quality
> 
> Note that in narrowband mode, there are less than 11 different modes, so
> quality 1 and 2 are the same, the same for 3 and 4, 5 and 6, and 7 and
> 8.

Okay, I probably would have noticed that if I had stared at the data for too long.

> > 2) --bitrate  (CBR?)
> 
> yes, --bitrate is for CBR. Note there are only a few bit-rates available
> so the one chosen is the first mode with a bit-rate less or equal the
> the bit-rate specified.

Okay, so just --bitrate gives CBR.

> > 3) --bitrate with --vbr
> 
> With --vbr, you control the bit-rate with --quality (which is a float in
> vbr mode, but an int otherwise).

Okay, so for VBR, one sets a bit rate with quality which is a float.

> > 4) --abr
> 
> This is how can specify a bit-rate in vbr mode (no need to have --vbr
> too).

So for VBR you can use --abr as well to specify an average bit rate.

So there should be some equivalency between --abr values and --quality
values?  Or do they effect the rate in different ways.

> > Is that right?  Can someone point me to a description of what to expect f=
> rom each
> > of them?  Any chance of geting a histogram output like LAME has for it's =
> variable
> > bit rate encoding?  Heck, I'd be willing to code it. :)
> 
> That would be welcome. There could be a --histo switch or something like
> that.

Okay, I'll start on it. :)

I'm still confused as to all of the different ways to specify the bit rate/
quality of an encoding.  Could you enumerate the valid combinations of
switches?

Cheers,
David
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