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VOCPACK
Lossless sound file compressor
Copyright (C) 1993 Nicola Ferioli
File: VP.DOC
Version: 2.0
Date: 01 September 1993
===========================================================================
1 - INTRODUCTION
Vocpack is a compressor/decompressor for 8-bit and 16-bit digital sound
files using a lossless algorithm; it is useful to save disk space without
degrading sound quality.
Vocpack is available in two forms: a command-line version and a library of
functions which can be called from C programs (see LIB.DOC).
Any PCM sound can be compressed and it isn't necessary to strip file
headers before compressing since the method used is not lossy.
The typical compression ratio (compressed size / original size) with 8-bit
files goes from 0,8 for sounds sampled at 11 KHz to 0,4 for 44 Khz ones
(full-power sounds; low volume recordings and human voice give a better
ratio). The best results are obtained with 44 KHz sounds: general-purpose
archivers create files that can be twice longer than the output of Vocpack.
The compression ratio for 16-bit files varies from 0,9 to 0,6.
You can obtain smaller values using lossy compressors but if your goal is
to keep the sound quality unaltered you should use a lossless program like
Vocpack.
.MOD and .ST files are not compressed very well, since they contain a lot
of sequencing information and the sound is sampled at a low frequency; in
this case the files created by Vocpack could be slightly bigger than the
ones produced by general-purpose compression programs.
===========================================================================
2 - WHAT'S NEW IN VERSION 2.0
VOCPACK 2.0
- is faster: compresses and decompresses in less than 1/2 of the time
employed by version 1.0; with some files just 1/4 of that time;
- compression ratio is similar, often slightly better;
- compresses 16-bit sounds;
- uses 386 processor instructions for best performance;
- can detect automatically the kind of data contained in VOC and WAVE
files;
- the original file name is stored in the compressed file, so it can be
restored when expanding;
- the command-line version has a new interface, easier to use; it can run
in less than 30 Kb of free memory and if there is more memory it is used
for disk buffering;
- the new Library Version can be linked with C programs and it can do
realtime processing ( > 40 Kb per second on a 486DX/33 MHz); it requires
less than 8 Kb for code and data;
- is not compatible with version 1.0: to uncompress old methods 0 and 1 you
must use the included program UNVP10.EXE.
===========================================================================
3 - VERSION NUMBER & REGISTRATION
Vocpack is SHAREWARE software; you are free to copy and distribute
unregistered versions of this program on condition that all files are
included without any modification. No fee must be charged for such
distribution.
The copyright displayed by the program VP.EXE contains the version number
of Vocpack: '2.0 demo' for unregistered copies and '2.0' for registered
ones. The unregistered version is for evaluation purpose and can only
compress files; decompression is enabled when you register, so don't use
version '2.0 demo' to store important files since you won't be able to
extract them, unless you register. A warning message will be displayed
every time you compress a file with an unregistered copy. See REGISTER.DOC
for more information.
===========================================================================
4 - USAGE
The command line of Vocpack has the form
VP [-options] <inputfile> [outputfile]
You can run VP with no parameter to obtain a short summary of the available
options.
File names <inputfile> and [outputfile] can't contain wildcard characters,
but may include drive and/or path.
The choice between packing and unpacking depends on the content of
<inputfile>: if it's a file already compressed by Vocpack then it gets
expanded, otherwise it gets compressed.
If [outputfile] is given then the new file created will have this name; the
default output file name for compression, used if [outputname] is missing,
is the same of <inputfile> with the extension changed to '.vp'; when
unpacking the default is the original name of the file, stored in the
header of the compressed file.
For example,
VP SOUND.WAV packs sound.wav to sound.vp
VP SOUND.VP unpacks sound.vp back to sound.wav
'Options' can be one or more of the following:
i : display information about <inputfile>: compression method used,
original and compressed size, compression ratio;
o : overwrite output file if it already exists; if this switch is not
present, Vocpack asks for confirmation before overwriting;
q : quiet mode, don't display the progress indicator.
Options must be preceded by a '-' and can be placed anywhere on the command
line; they can be uppercase or lowercase and they can be combined ('-oq' is
the same of '-o -q').
When compressing, Vocpack needs to know the kind of data contained in the
file (8 or 16 bit, mono or stereo ...); if the file is in VOC or WAVE
format Vocpack tries to get such information from the file header,
otherwise the user must supply them through the following command-line
options:
u : unsigned data;
s : signed data;
2 : stereo data (default: mono);
6 : 16-bit data (default: 8-bit);
1 : odd alignment (default: even); this switch specifies whether the
lower byte of a 16-bit sample is placed at an even or odd offset
from the beginning of the file.
If one or more of these options is present, autodetection is disabled.
Remember that VOC files contain unsigned data; WAVE files use unsigned
8-bit samples and signed 16-bit samples with even alignment.
To decompress a file packed with Vocpack version 1.0 you must use the
program UNVP10.EXE contained in this package: version 2.0 doesn't handle
them to save memory (old methods used more than 100 Kbyte of data when
expanding).
===========================================================================
5 - ERROR CODES
When an error occurs, Vocpack returns one of the following error codes (DOS
errorlevel):
1 = bad command line; the help screen was displayed
2 = input file not found
3 = output file can't be created
4 = input file is not compressed with Vocpack (or bad version)
5 = user break
6 = out of memory (version 1.0 only)
7 = read error
8 = write error
===========================================================================
6 - MISCELLANEOUS THINGS
Vocpack 2.0 requires at least a 386 processor to run.
This software is provided 'as is' with no express or implied warranty. The
author is not liable for any loss of data or other damage caused by the use
of this software.
Bugs, suggestions, etc. can be e-mailed to the Internet address at the end
of this document.
This text contains trademarks registered by their respective owners.
===========================================================================
FERIOLI NICOLA Internet: ser1509@cdc835.cdc.polimi.it
VIA BOEZIO 6 (this might change during 1994)
21052 BUSTO ARSIZIO
ITALY