adpcm.sh

ADPCM 4:1 coder and decoder

In article <23rhgd$[e-mail]> [e-mail] (Joel Plutchak) writes:
> In article <[e-mail]> [e-mail] (Jari Kaija) writes:
> >*>Does anyoune know details, how ADPCM-compressed data is calculated,
> >*>so that a soundblaster card can automatically decompress it?
> >
> >I need that conversion too, but FAX, what I get by Creative Labs
> >(Signapore) tells, they WON'T tell method of ADPCM. GRRRRR!

>    And I looked into the format, too, and never quite got something
> that gave me a clean recreation of the original sample.

If the Creative is doing standard ADPCM, then here's some source to work
with it.  This code was originally posted just over a year ago, but I
can't remember to what group(s).

Mark T. Price (sg)           [e-mail]
>plan 9 studios<             "Bite me, it's fun!" -- Crow, MST 3000

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#! /bin/sh
# This is a shell archive.  Remove anything before this line, then unpack
# it by saving it into a file and typing "sh file".  To overwrite existing
# files, type "sh file -c".  You can also feed this as standard input via
# unshar, or by typing "sh <file", e.g..  If this archive is complete, you
# will see the following message at the end:
#		"End of shell archive."
# Contents:  README adpcm.2 Makefile adpcm.h adpcm.c testc.c testd.c
# Wrapped by [e-mail] on Tue Jul  7 15:25:07 1992
PATH=/bin:/usr/bin:/usr/ucb ; export PATH
if test -f 'README' -a "${1}" != "-c" ; then 
  echo shar: Will not clobber existing file \"'README'\"
else
echo shar: Extracting \"'README'\" \(899 characters\)
sed "s/^X//" >'README' <<'END_OF_FILE'
XThis directory contains version 1.0 of a simple 16 bit PCM <-> 4 bit
XADPCM coder and decoder. See the source and the manpage for comments
Xon the algorithm.
X
XThe routines have been tested on an SGI Indigo running Irix 4.0.2 and
Xon a Sparcstation 1+ running SunOS 4.1.1.
X
XOn a Sun you should compile with -DNODIVMUL. The resulting code will
Xcompress at 250Ksample/sec and decompress at 300Ksample/sec.
X
XOn an SGI you should compile *without* -DNODIVMUL, and the compressor
Xruns at 350Ksample/sec and the decompressor at 700Ksample/sec.
X
XIf you use this package I would like to hear from you.
XI am especially interested in people who can test interoperability
Xwith proven Intel/DVI ADPCM coders. I have tried to get the algorithm
Xcorrect, but you never know....
X
X	Jack Jansen
X	Centre for Mathematics and Computer Science
X	Kruislaan 413
X	Amsterdam
X	the Netherlands
X
X	[phone]
X	[e-mail]
END_OF_FILE
if test 899 -ne `wc -c <'README'`; then
    echo shar: \"'README'\" unpacked with wrong size!
fi
# end of 'README'
fi
if test -f 'adpcm.2' -a "${1}" != "-c" ; then 
  echo shar: Will not clobber existing file \"'adpcm.2'\"
else
echo shar: Extracting \"'adpcm.2'\" \(1866 characters\)
sed "s/^X//" >'adpcm.2' <<'END_OF_FILE'
X.TH ADPCM 2 "7 June 1992"
X.SH NAME
Xadpcm - Adaptive delta compression for audio samples
X.B
X#include "adpcm.h"
X.br
Xadpcm_coder(short inbuf[], char outbuf[], int nsample,
X.br
X	struct adpcm_state *state);
X.br
Xadpcm_decoder(char inbuf[], short outbuf[], int nsample,
X.br
X	struct adpcm_state *state);
X.SH DESCRIPTION
XThese routine convert 16 bit linear PCM samples to 4 bit ADPCM code
Xand vice versa. The ADPCM code used is the Intel/DVI ADPCM code which
Xis being recommended by the IMA Digital Audio Technical Working Group.
X.PP
X\fIAdpcm_coder\fP converts \fInsample\fP 16 bit samples from
X\fIinbuf\fP and stores the 4 bit codes, packed two per byte, in
X\fIoutbuf\fP. \fIState\fP points to a structure containing the coder
Xstate information, a short and a char. It should be initialized to
Xzero before the first call. The coder updates the state record, and it
Xshould be passed to each subsequent call.
X.PP
X\fIAdpcm_decoder\fP converts \fInsample\fP 4 bit codes from
X\fIinbuf\fP to 16 bit samples and stores these in \fPoutbuf\fP.
X\fIState\fP is a state record similar to that used by the coder.
X.PP
XIf you compress audio to transmit it across a lossy network it is a
Xgood idea to send the compressor state along with each packet. (This
Xmust be the state as it was \fIbefore\fP the call to
X\fIadpcm_coder\fP, not the state after the return). This state record
Xcan then be fed to the decompressor. This way the decompressor can
Xtolerate packet loss.
X.SH NOTES
XThe routines have not been tested against an official Intel/DVI coder
Xyet, so incompatabilities might exist.
X.br
XThe state record is not byte-order-independent. Remember this when
Xtransmitting it across the network.
X.SH "SEE ALSO"
XProposal for Standardized Audio Interchange Formats, IMA compatability
Xproject proceedings, Vol 2, Issue 2, May 1992.
X.SH AUTHOR
XJack Jansen, CWI, Amsterdam
X.br
[e-mail]
END_OF_FILE
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X#
X# Makefile for adpcm and test programs
X#
X# For Suns, define -DNODIVMUL (to make code run 5 times faster)
X#CFLAGS=-DNODIVMUL -O
X#
X# For SGI's don't define -DNODIVMUL (it only makes things slower)
XCFLAGS=-O
X
XALLSRC=README adpcm.2 Makefile adpcm.h adpcm.c testc.c testd.c
X
Xall: testc testd adpcm.o
X
Xadpcm.o: adpcm.h
X
Xtestc: testc.o adpcm.o
X	cc testc.o adpcm.o -o testc
X
Xtestd: testd.o adpcm.o
X	cc testd.o adpcm.o -o testd
X
Xadpcm.shar: $(ALLSRC)
X	shar $(ALLSRC) > adpcm.shar
END_OF_FILE
if test 473 -ne `wc -c <'Makefile'`; then
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fi
# end of 'Makefile'
fi
if test -f 'adpcm.h' -a "${1}" != "-c" ; then 
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else
echo shar: Extracting \"'adpcm.h'\" \(411 characters\)
sed "s/^X//" >'adpcm.h' <<'END_OF_FILE'
X/*
X** adpcm.h - include file for adpcm coder.
X**
X** Version 1.0, 7-Jul-92.
X*/
X
Xstruct adpcm_state {
X    short	valprev;	/* Previous output value */
X    char	index;		/* Index into stepsize table */
X};
X
X#ifdef __STDC__
X#define ARGS(x) x
X#else
X#define ARGS(x) ()
X#endif
X
Xvoid adpcm_coder ARGS((short [], char [], int, struct adpcm_state *));
Xvoid adpcm_decoder ARGS((char [], short [], int, struct adpcm_state *));
END_OF_FILE
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fi
# end of 'adpcm.h'
fi
if test -f 'adpcm.c' -a "${1}" != "-c" ; then 
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else
echo shar: Extracting \"'adpcm.c'\" \(6342 characters\)
sed "s/^X//" >'adpcm.c' <<'END_OF_FILE'
X/***********************************************************
XCopyright 1992 by Stichting Mathematisch Centrum, Amsterdam, The
XNetherlands.
X
X                        All Rights Reserved
X
XPermission to use, copy, modify, and distribute this software and its 
Xdocumentation for any purpose and without fee is hereby granted, 
Xprovided that the above copyright notice appear in all copies and that
Xboth that copyright notice and this permission notice appear in 
Xsupporting documentation, and that the names of Stichting Mathematisch
XCentrum or CWI not be used in advertising or publicity pertaining to
Xdistribution of the software without specific, written prior permission.
X
XSTICHTING MATHEMATISCH CENTRUM DISCLAIMS ALL WARRANTIES WITH REGARD TO
XTHIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
XFITNESS, IN NO EVENT SHALL STICHTING MATHEMATISCH CENTRUM BE LIABLE
XFOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
XWHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
XACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
XOF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
X
X******************************************************************/
X
X/*
X** Intel/DVI ADPCM coder/decoder.
X**
X** The algorithm for this coder was taken from the IMA Compatability Project
X** proceedings, Vol 2, Number 2; May 1992.
X**
X** Version 1.0, 7-Jul-92.
X*/
X
X#include "adpcm.h"
X
X#ifndef __STDC__
X#define signed
X#endif
X
X/* Intel ADPCM step variation table */
Xstatic int indexTable[16] = {
X    -1, -1, -1, -1, 2, 4, 6, 8,
X    -1, -1, -1, -1, 2, 4, 6, 8,
X};
X
Xstatic int stepsizeTable[89] = {
X    7, 8, 9, 10, 11, 12, 13, 14, 16, 17,
X    19, 21, 23, 25, 28, 31, 34, 37, 41, 45,
X    50, 55, 60, 66, 73, 80, 88, 97, 107, 118,
X    130, 143, 157, 173, 190, 209, 230, 253, 279, 307,
X    337, 371, 408, 449, 494, 544, 598, 658, 724, 796,
X    876, 963, 1060, 1166, 1282, 1411, 1552, 1707, 1878, 2066,
X    2272, 2499, 2749, 3024, 3327, 3660, 4026, 4428, 4871, 5358,
X    5894, 6484, 7132, 7845, 8630, 9493, 10442, 11487, 12635, 13899,
X    15289, 16818, 18500, 20350, 22385, 24623, 27086, 29794, 32767
X};
X    
Xvoid
Xadpcm_coder(indata, outdata, len, state)
X    short indata[];
X    char outdata[];
X    int len;
X    struct adpcm_state *state;
X{
X    short *inp;			/* Input buffer pointer */
X    signed char *outp;		/* output buffer pointer */
X    int val;			/* Current input sample value */
X    int sign;			/* Current adpcm sign bit */
X    int delta;			/* Current adpcm output value */