[vorbis-dev] Vocoders

[seanl at literati.org]

The DoD has a 2400 bps vocoder with quality similar to 4kbps CELP.  It's
called Mixed Excitation Linear Predictor.  I've played around with it and
it has excellent quality (though nowhere near GSM; you can still tell
you're using a vocoder) and handles background noise pretty well.  This is
definitely more recent than LPC-10.  GSM is 13 kbps, so I suppose it
depends on what sort of bitrate and quality you want.

http://www.plh.af.mil/ddvpc/index.html

This page has MELP, LPC, CELP, and CVSD.  I didn't see source code there,
so if you want source code for MELP, email me and I'll track it down (I
have it on a machine without Internet access right now).

On Wed, May 10, 2000 at 05:27:27PM -0700, Rage O Matic wrote:
> > > Vorbis looks real interesting. but I'm more interested in voice coders
> > > right now. I worked on some really nice stuff at around 4kbps in the
> > > early 90's. The trouble is any coder even remotely similar is surrounded
> > > by an impenetrable shield of IP. Does anyone know of any work in
> > > progress on good free low bit rate vocoders?
> >
> 
> I dont think any low bit rate vocoders are in progress now. LPC-10 was the
> last effort I've seen. Not much work on those algorithms. GSM seems to be
> the most recent, and most advanced coding. It's used int most cell phones.
> ADPCM is another group of compressions.
> 
> 
> --- >8 ----
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-- 
Sean R. Lynch <seanl at literati.org>         http://www.literati.org/seanl/
Finger for public key.  540F 19F2 C416 847F 4832  B346 9AF3 E455 6E73 B691



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