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List:       linux-sound
Subject:    Re: compression tools
From:       "Eric B. Mitchell" <emitchell () altaira ! com>
Date:       1998-09-22 22:49:57
[Download RAW message or body]

There is an implementation of the adpcm algorithms available in the
Speak Freely package:  	http://www.fourmilab.ch/speakfree/

Off topic: Although, I'm wonder if anyone has implemented the adaptive 
audio compression algorithms from Dr. Dobbs a few months ago...

Chris Bagwell wrote:
> 
> I can only speak from the point of view of *free*.  Best quality is only
> going to come with buying something from the likes of RealAudio.
> 
> Besides that, I've had good luck with various ADPCM formats.  Both IMA
> ADPCM and Microsoft ADPCM can convert 16-bit audio into 4-bit audio
> which results in a considerable compression.  Plus realtime
> compression/decompression is easy on even limited machines (even 386s).
> Sound quality holds up remarkably well.  Right now its probably easiest
> to convert your samples into .wav files under windows as it includes
> codecs for both of those versions.
> 
> I've implemented the decoder portion into sox but haven't gotten around
> to adding the encoder (although the algorithms are readily available).
> You could use that to listen to the streaming audio.  IMA ADPCM was
> designed to support streaming (recovery from lost blocks of data)
> although I haven't seen any decoders take advantage of this.  You can
> grab a copy of sox with this support from:
> 
> http://home.sprynet.com/sprynet/cbagwell/projects.html
> 
> There is also a RAW IMA ADPCM encoder/decoder available on the net that
> compiles under most versions of unix.  Do a search for adpcm.shar.
> 
> Hope it helps,
> Chris
> 
> Florin Andrei wrote:
> >
> > I need some real-time compression tools, wich can provide a reasonable
> > sound quality and a good compression ratio.
[snip]
> >         Any suggestions?
> >                                         Florin Andrei
> 
> --
>           Chris Bagwell              |  Fujitsu Network Communications
>  mailto:cbagwell@tddtx.fujitsu.com   |         Richardson, Texas

-- 
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| Eric B. Mitchell         mailto:ericmit@ix.netcom.com |
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