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Amiga Format CD 42
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Amiga Format AFCD42 (Issue 126, Aug 1999).iso
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rescale.readme
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Short: Anti-alias resampling for RAW 8SVX sound v1.11
Uploader: Björn Östberg <JetRacer@Hem.Passagen.se>
Author: Björn Östberg <JetRacer@Hem.Passagen.se>
Type: mus/edit
Version: 1.11
Rescale Version 1.11 Copyright ©1999 Björn Ösberg
Usage: Rescale <SourceFile> <DestFile> SourceRate DestRate ReplayRate
Or: Rescale <SourceFile> <DestFile> SourceRate DestRate SourceRate
Programming: Björn Östberg (JetRacer@Hem.Passagen.se)
Additional Code By: Fredrik Rambris (Fredrik.Rambris@Amiga.nu)
HomePage: www.Amiga.nu
Rescale v1.11 68020 and 68020/68882 versions are included in this archive.
---------------------------------------------------------------------------
Disclaimer: The programmer can't be held responsible for any damages caused
by this program - use it at your own risc!
No distribution fee whatsoever can be charged for the archive nor it's
contense (Aminet have exclusive right to distribute this archive and charge
whatever fee they seem suitable). The archive must be distributed in it's
original shape without any modifications.
---------------------------------------------------------------------------
Rescale is a resample utility (SHELL only) which resamples standard 8SVX raw
sounds. The resample method used in the Rescale utility is vector based
scaling -similar to the one used in sizeable fonts but with antialias
features.
Running Rescale without any statements or faulty syntax will make it type
out some instructions aswell as copyright and version info. There are no
restrictions when it comes to setting the samplerate so be carefull. A
nice side-effect of the previus is that you can specify the relation between
source/dest in any way you like:
Downsample relative 1:2 with 44.1KHz with replay rate
Rescale <SourceFile> <DestFile> 1 2 44100
Downsample period 127 to period 254 -no replay rate
Rescale <SourceFile> <DestFile> 127 254 127
Etc.
Rescale can actually be used to rescale any signed 8-bit raw datafile at
all. -Usefull for programmers who wants to rescale sinus tables, etc. with
very high quality.
In practic
¯¯¯¯¯¯¯¯¯¯
-That sounds nice but what does it all mean?
Well, f.ex. that you can resample finetune without any hearable quality
loss (Unlike X-Tracker, OctaMED X, AudioMaster X, etc.). You can also
downsample with insane rates as 1:4 or below without jitter (with
reservations for the 8-bit format itself) or a totall loss of treble (no
digital filters).
Quality loss
¯¯¯¯¯¯¯¯¯¯¯¯
If you have resampled chords in protracker (or whatever) you know that it
sound crappy. What most people don't know is why:
With probably no exceptions the sample editors/converters and composer
programs of today all use the classic integer-based skip/duplicate or
skip/mix resample methods. The quality loss that these produce is very high
due to the fact that the quantization timing error increase drasticly.
Or in laymans terms: it produces transient noise and static tuning errors.
About the programmer
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯
I (Björn Östberg) created the Rescale utility as an exersize learning
ANSII-C. Have no fear -An experienced programmer and friend of mine (Fredrik
Rambris) had a peek at the source before I released it and he had no
objections whatsoever. He also helped me out with the AmigaOS filehandling
(since ANSII-C filehandling sucks!) and memory allocation using Exec. The
rescaling rutine is small enough to be rather harmless so that rules out
most error sources. I also have extencive experience with the programming
language Basic aswell so I'm no real freshman programmer.
In the near future (before Y2K -hopefully):
·IFF 8SVX support -Have to hunt some specs.
·AIFF support -Within months
·AIFF-C support -Same here. Hate Apple for not releasing (de)compression
code -not everybody can use Soundmanager you know.
·Wav/RIFF support -Within months
·Boopsi GUI -Have to learn some more...
·Multichannel support -Stereo within months, multi Y2K or never.
·8/16/24/32-bit support -Within months
History:
v1.11 99-05-05 (Current) First release. Small bugfix: Minor UI errors...
Major Aminet upload problems due to lack of initiative =)
v1.1 99-04-09 Bugfix: Fixed a defect statement
causing the help text to be typed no matter if the user syntax was
correct or not. Fixed minor bugs; some spell errors, etc. Wrote ReadMe
files, compressed AmiNet LHA Archive, and such. The utility was created
and converted within six days.
v1.0ß 99-04-08 Added the help text to the main.
v0.9 99-04-08 Completed Basic convertion. Got some help with AmigaOS
filehandling & arguments parsing, aswell as memory allocation using Exec.
v0.8 99-04-07 Did most Basic convertion, compiles just fine -the program
doesn't do anything usefull yet though.
v0.7 99-04-05 Re-arranged the scaling routine written in Basic to a
procedure, added requesters and simple error handling.
v0.6 99-04-03 Wrote a scaling routine in Basic within 10 minutes. Was in a
state of shock the rest of the day since the routine worked at the first
try (almost) and only produced a guru once ;-)
For those of you with CD-R:
I'm also working on an ultra qualitative Protracker mod-to-sample music
rendering program -using this very scaling routine and other cool stuff.
Much can be done to improve the quality of non-realtime protracker
rendering. Floatingpoint everywhere (almost). Floatingpoint volume slide
routines -updates the amplitude for every single sample, etc. I'm a reverb
nut so I think I'll just throw in my reverb routine aswell (4-256 channels
highly qualitative reverb). Natually I will support AIFF, AIFF-C, WAV &
RAW signed/unsigned 8/16/24/32-bit - aswell as a stereo surround audiomode
(reverb). Note: This one is still vaporware.
For musicians and nirds:
Ontop of the previus I'm co-working on a sample editor/creator/sampler/
mixer/ etc. program called Soundfactory®. REAL cool stuff. Advanced
synthetics, advanced reverb, digital equalizer, advanced proffesional
editing tools, professional multichannel editing and mixing, direct HDD edit
with disk cache, HDD recording through AHI, maybe even a full tracker
composer, all within a single program. Really advanced programming style:
main executable is hosting external processing/gui/functionallity modules.
Fault tolerant design, etc.
On what platform? AmigaOS!
When? Our goal is before Y2K, but we will probably break that deadline.
This one is NOT vaporware - development in progress...
Björn Östberg <JetRacer@Hem.Passagen.se>
SpEEd Productions Site: http://www.Amiga.nu -Soundfactory® Development News