[linux-audio-user] Audio file format

Nick nicktsocanos at charter.net
Mon Mar 31 16:42:00 EST 2003

A WAV RIFF will have in it's header a tag that indicates there is a
compressor used, and maybe additional information for the compressor (called
a CB or compressor block) that follows the header. There are a lot of
different types of compressors it can use, you can find it in the Windows
header file somewhere (mmreg.h I think?). You need a CODEC to uncode most of

ADPCM means Adaptive Differential encoding. There is another type called
Mu-Law encoding. ADPCM works by storing differences between samples that
change. It doesn't lose any of the sound information. MP3 and OGG lose
information (well, I think they throw it away on purpose, which is why they
get better compression ratios). Once you lose that information though it is
gone forever. I don't think there is any way to get it back again. You can
notice it if you take an MP3 Rip and convert it to OGG. It will sound weird
and you will notice that information lost forever.

----- Original Message -----
From: "Jaakko Prattala" <Jaakko.Prattala at Helsinki.FI>
To: <linux-audio-user at music.columbia.edu>
Sent: Monday, March 31, 2003 10:40 PM
Subject: Re: [linux-audio-user] Audio file format

> On Monday 31 March 2003 13:16, Robert Epprecht wrote:
> > 1.wav: RIFF (little-endian) data, WAVE audio, Microsoft ADPCM, mono
> > Hz
> >
> >
> > I thought WAVE was a format without compression? The duration of the
> > (when played by 'play') shows that this is not possible. So what is it?
> ADPCM is a kind of a compression method.
> That's all (I think) I know. Google is your friend:
> 92800 hits for adpcm :-)
> --
> Jaakko Prättälä
> Jaakko.Prattala at Helsinki.FI

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