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EnigmA Amiga Run 1997 July
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EnigmA AMIGA RUN 20 (1997)(G.R. Edizioni)(IT)[!][issue 1997-07 & 08][EAR-CD IV].iso
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MPEGAPlayer.doc
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-------------------------------------------------------------------------------
MPEGAPlayer 1.4 (28-Dec-1996)
-------------------------------------------------------------------------------
Distribution Conditions
-----------------------
This program is copyright (c) 1995-96 by Stephane TAVENARD.
It may be distributed freely under the condition that no profit is
gained from its distribution, nor from any other program distributed
in the same package.
Permission is granted to distribute this package by Bulletin Board
systems or network sites, under the condition that no fee is charged
on downloading it.
All files that are part of this package have to be distributed
together and none of them may be changed in any way other than
archiving or crunching. The only exception to this rule are the
icons, including the tooltypes, which may be changed to accommodate
them to the rest of the disk it is distributed on.
This program is distibuted as freeware.
Disclamer
---------
This package is provided "as is" without warranty of any kind.
The author assumes no responsibility or liability whatsoever
for any damage or dataloss caused by using this package.
Introduction
------------
What is MPEG audio ?
It's a very efficient audio compression standard. Actually, there are 3 methods
of compression named Layer I, II & III. Layer III is more efficient than
Layer II and layer II is more efficient than layer I :) .
Layer III is not implemented yet in this player because Layer III is more
difficult to decode and it is not used by professionals.
MPEG audio allow to compress a 16-bits PCM sound file from 1.2 to 32 times.
Why is it so hard to make a real time MPEG audio decoder ?
MPEG audio decoding requires a lot of arithmetic calculation, so a lot of CPU
power is required. Normally, MPEG audio decoding is made with help of a DSP.
History
-------
V1.0 11-Jun-1995 First release (not public)
V1.1 19-Jun-1995 Corrected minor bug in audio signal allocation
V1.11 09-Jul-1995 Asynchronous Config window & Screen locking bug corrected
V1.2 10-Sep-1995 Added mixing frequency for audio output
07-Feb-1996 68060 version not optimized
V1.3 01-Jul-1996 Fixed a bug in the check routine
Corrected old bug that kill my prog
V1.4 28-Dec-1996 Correct bug in Config save ! (very old bug...)
Now supports MPEG-2 Layer1&2
Now Scopes Genies works !
Added Volume/Balance/Faster/Slower/Prev/Next
Use Christian Buchner 14-bit calibrated audio
Description
-----------
This is a player for DeliTracker program (thanks to Peter Kunath and
Frank Riffel for this marvellous soundplayer). You need at least a
68020 CPU to use it ! This player can decode and play standard
MPEG audio bitstreams, layers I & II. Audio output can be either in
8 bits or in 16 bits (14 bits audio, really).
NOTA: the 68060 can't directly execute 64 bit divisions and multiplications.
so the '060 version doesn't use the 64 bit instructions.
How to use it ?
First, get a version of DeliTracker (best: get the latest version).
Then, copy the player file ('MPEGAPlayer.020' for 68020 - 68040 CPUs,
'MPEGAPlayer.060' for 68060 CPUs) in the DeliPlayer directory.
Last, start DeliTracker and try to load the MPEG file in this package
('FRIENDLY.MP2' is a 1:22 compressed file).
You don't hear anything:
-> there's a bug ?
You hear a some sound broken with blanks:
-> Your CPU is not enough faster for the current options.
You hear a countinous sound (10 sec):
-> Ok, you've got a good CPU, try to find long MPEG file now.
How to change options ?
In the player option window of DeliTracker, select Config button.
Then you can configure the MPEG decoder for mono and stereo files
separately (why ? because decoding time of stereo files is approx.
2x decoding time of mono files). Config. options are:
Quality: High, Medium, Low
-> defines the decoding quality, and also the decoding speed. Slow CPU users,
select Low quality ...
Frequency: Normal, 1/2, 1/4
-> defines the output decoding frequency. 1/4 is the most optimized
decoding algorithm, but a 44100Hz original sampling file will be play
at 11025Hz only ! (usefull for low CPU, too). You can only use Normal
mode if you have a screen mode >15kHz and a fast CPU !
Output: 8 bits, 16 bits
-> in 8 bits mode, play 8-bit audio samples (strange, no ?)
-> in 16 bits mode, play 14-bit audio samples (better...)
For stereo files, it's possible to play them in mono (save a lot of CPU time)
when selecting 'Force Mono'
Mixing Enabled: if selected, the audio output is played at the rate specified by
'Mixing frequency'
Ok, everything is clear ? try it now !
Thanks to my friend, AMIGA, the best computer ever made.
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Stéphane TAVENARD (ANGERS/France)
E-Mail: tavenard@xiii.univ-angers.fr
Note: It's the Email of my brother Raphaël (I'm not connected yet !) ;-(