Path: utzoo!utgpu!news-server.csri.toronto.edu!bonnie.concordia.ca!uunet!fernwood!decwrl!elroy.jpl.nasa.gov!swrinde!cs.utexas.edu!rice!uupsi!mpoint!dave
From: dave@msb.com (Dave Lockwood)
Newsgroups: comp.sys.atari.st
Subject: Re: Converting Sparcstation .au files to Mac/Atari format
Keywords: digitized samples .au
Message-ID: <1991May12.173027.10784@msb.com>
Date: 12 May 91 17:30:27 GMT
References: <1991May8.055008.2758@isc.rit.edu> <1991May9.154204.18726@wam.umd.edu>
Organization: Meetpoint Station BBS
Lines: 24

Converting the .au samples is a snap.  According to the audio man page on my
system, the Sun audio data is 8 bit signed volume values.  The high order bit
is a sign bit.  If set, the volume is positive (1's compliment), and if the
sign bit is 0, the value is a negative volume (also 1's compliment).

In a C program reading the Sun audio data, stick this code in the middle of
the conversion loop:

if(value & 128)
  value = 128 + (127 - (value & 127));

See...baby food.  If the sign bit isn't set, no conversion need be done.  The
resulting output is a volume level from 0 to 255 with 128 being the zero
crossing.  Multiply the result by a fraction if you want to change the volume
before output.

I'll leave the headers up to you.  I never monkeyed with that (the man page is
rather cryptic about this), and besides, you wouldn't want me to take ALL the
fun out of it, would you? ;-)
-- 
A tool that isn't sharp enough to cut    | dave@msb.com (Dave Lockwood)
you badly isn't sharp enough to use.     | UUCP: ...!uupsi!mpoint!dave
However, the sharp edges should *NOT* be | Sysop of Meetpoint Station BBS
on the handle.                           | cat flames | mail santa@north.pole