Subject: Re: /dev/audio works, (SPARC)tracker not
To: Timothy Newsham <>
From: Geert Uytterhoeven <>
List: amiga
Date: 12/12/1994 10:12:45
> > Just a suggestion: Why not using 2 channels to play u-law encoded sound? 
> > That way you can use one channel for 8-bit samples and the other channel
> > to modulate the volume (6-bit) to achieve a net result of 14-bit (= full
> > u-law linear range).
> Strangely enough I was thinking about this and wondering if it was
> possible, and if so, how practical it was.  Using volume to modulate
> might not get you 12 bits.  There 8bit data and 6 bit volume but
> many of the combinations of A x B are repeats, and not all values

Oops, I forgot that. But it's definitely suited for u-law, since u-law
works that way (piecewise linear approximation) and so all required
values are possible.

> can be obtained with A x B.  (btw.  volume x data just takes one
> channel,  but the hardware does support modulating one channel with
> another I believe, that would give you 8 bits each right?)
> I guess its well suited to mu-law though since there are many
> 12-bit combinations that are not represented by 8bit mulaw codes.
> This might work nicely but it would eat up all four of your channels
> for stereo output.  I might look into this further later on as
> an optional setting.
> btw.  has anyone done this before?

There was a discussion about this on comp.sys.amiga.programmers some
weeks ago. I thin to remember there were some players on AmiNet that
use this trick.



| Geert Uytterhoeven -->> Wavelets, Amiga, MultiUser, Linux/68k,...  |
|                               |
| Dept. of Computer Science, Katholieke Universiteit Leuven, Belgium |