From: Mark Phillips <umphill5 AT cs DOT umanitoba DOT ca>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: audio samples for allegro
Date: Tue, 29 Jun 1999 10:35:43 -0500
Organization: The University of Manitoba
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> I don't know about the Allegro audio format but to convert
> signed to unsigned is not difficult: add an offset to all
> samples so that the most negative sample becomes 0.
> 
> Example:
> Signed input in [-128,+127], add 127 to each sample and you
> will get unsigned samples in [0..255].
> 

Or you could just toggle the most significant bit:

for(long i=0; i<bytes_in_buffer; i++)
   byte_buffer[i] ^= 0x80;

But as I remember the original poster asked for 16 bit data so that would
be:

for(long i=0; i<words_in_buffer; i++)
   word_buffer[i] ^= 0x8000;

Mark