[vorbis] Low bitrate encoding

Olaf van der Spek Olaf at XCC.TMFWeb.NL
Tue Jan 9 02:49:09 PST 2001



----- Original Message -----
From: "jaromil" <jaromil at dyne.org>
To: <vorbis at xiph.org>
Sent: Tuesday, January 09, 2001 11:41 AM
Subject: Re: [vorbis] Low bitrate encoding

> On Tue, Jan 09, 2001 at 07:23:55PM +1100, Michael Smith wrote:
> >
> > >oggenc currently doesn't know how to downsample or lowpass.  If you
> > >feed it a lower sample rate file, you'll see down to ~ 16-20kbps right
> > >now.  It's not well tuned for it yet, so preecho (especially) will be
> > >annoying.
> >
> > By the way, downsampling is somewhere on my mental to-do list for
oggenc. I
> > probably won't get to it for a while, though. If there's high demand for
> > it, it might encourage me to find time for it sooner.
>
> i am currently working on down/upsampling routines for the next major
> release of muse (2:1/1:2, is that meant here?), as far as i get something
> useful i'll notice - next 2 weeks. found really useful to peek into the
> sourcecode of SDL (www.libsdl.org) src/audio/SDL_audiocvt.

Is downsampling (from 44100 hz to 22500 hz) something else then just taking
the average of two samples from the read buffer and putting that in the
write buffer?

>
> jrml
>
>
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