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Atari Mega Archive 1
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sam_seq.lzh
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READ_ME.DOC
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1994-08-27
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STE ONLY - STE ONLY - STE ONLY - STE ONLY - STE ONLY - STE ONLY
!!!!! THIS WILL NOT WORK ON AN STFM !!!!!
**************************************************************
If you don't want to read this text please at least read the last bit,
especially if you have a HARD DISK !!! (under Hints)
STEreo Sampled Sound Sequencing System.
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By Ian Hancock. PHAZE Shifters.
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© NOVEMBER:1992.
IT HELPS IF YOU READ THIS IN
AT LEAST MEDIUM RESOLUTION.
A bit of a manual for the sequencer !!
Introduction:
What started out as a simple method of playing one sample
after another for my own benefit turned, into a reasonably well
featured (but still simple enough) Sound Sample Sequencer. I must add
at this point the sequencer and BASIC code blocks ONLY WORK ON THE
ATARI STE this is because the STFM does not have the 2-channel stereo,
Direct Memory Access, Digital to Analog Convertor which is present in
the STE.
But sequencers already exist, so why make another ?
Well since the Atari STE is very poorly supported (but it's
improving I'm pleased to see) I decided to have a go at using some of
its extra custom hardware; Typically its DMA Stereo sound. Having
previously owned MASTER SOUND™ and seen its primitive sequencing
system I though there was scope for a bigger and better version. I
present SSSSS (conveniently alliterated).
SO WHAT ?!
The major advantage of my system is not immediately visible to
the user since the editor doesn't make use of it. However when
incorporating the sequences you have created with BASIC it will
become obvious. Ever wanted a nice bit of sampled music in a
program you have written ? NO - well skip this bit then.
YES - read on.
And have you wanted it to be played in the background, while you
program is working ?
Look no further ! Not only is it easy (because I've done all
the hard work) but while your music is playing there is next to no
drain on the processor at all.
{ For those who know what's what:
The routine which plays the sample sequence takes advantage of
the Vertical Blank Interrupt. Counting interrupts between samples,
and starting each new sample after an elapsed time. Since it uses
the DMA sound chip there is no processor time taken up by playing
each sample, with the result that the processor only really gets
called upon when a different sample has to be played and even then it
probably doesn't notice ! }
(You can carry on reading now if you left me earlier !)
I will write any comments which I think may be useful to some, but on
the whole are NOT necessary for those who just want to use the package
in { } curly braces. I hope this helps cater for a wider audience.
How to use it and what you need.
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In order to make use of the sequencer you will :
NOT need:- a midi instrument.
It's not that kind of sequencer.
NEED:- An Atari STE - it will crash on an STFM !!
- A sound sampler, or access to sound samples.
- to know what type of sample files your sound sampler
creates.
Ie. Are they AVR files (Audio Visual Research) or raw (not
headed).
The sequencer will read AVR files directly.
It will also read raw files - provided you use the 'head'
function first and supply the file details. The head
function will also alter the attributes of an existing AVR
file.
- sound samples that are either 6khz, 12khz, 25khz or 50khz.
Approximately - these are the only frequencies the STE
will play. Other frequencies will be played at the wrong
speed !
- some patience and imagination.
The Screen Layout.
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At the top is the title and version details. Below this is a
large box which initially contains nothing. This is the main display
window. The buttons to the right of this control the display window.
There are two modes which the display window can be in : -
Samples - mode. or
Sequence - mode.
The current display mode is highlighted with an inverse video
button.
Irrespective of mode, the main display contains two arrows. These
arrows are the cursor arrows and they point to one item in the display
(or none if there are no items in the display). It is THIS ITEM which
will have (individual item operations) operations performed on it.
Below the main window to the left is the sequence control button
set. These are used to edit and manipulate your sequence. To the right
of this are the file handling controls and on the extreme right is the
info and exit buttons.
A Detailed Run-down.
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FILE HANDLING CONTROLS:
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SEQ - SEQUENCE FILES.
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These are the files used by the program to store the samples and
mixes.
A 'MIX AND SAMPLES' or 'ALL' file contains all of the sample data and
the mix information. When you save your finished work you should save
it using the 'ALL' option, as this contains all of the data required.
A 'MIX' file just contains the data for a mix. If you wish to make
alternative mixes of a 'MIX AND SAMPLES' file then you can do this and
just save the 'MIX ONLY'. A 'MIX ONLY' file is much smaller than a
'MIX AND SAMPLES' file because it only holds the sample-play-order (or
key press) information for a mix. However a 'MIX ONLY' file canNOT
replace a 'MIX AND SAMPLES' file. And it should be noted that 'MIX
ONLY' files require the SAME 'MIX AND SAMPLES' file they were created
with to be of any use.
* LOAD - This gives the option to load an 'ALL' or 'MIX' file.
NOTE a mix file cannot be loaded if there are no samples present ie.
the 'MIX AND SAMPLES' file for the mix is not loaded in already.
Loading a 'MIX AND SAMPLES' file clears everything currently in
memory!!
Loading a 'MIX ONLY' file clears only the mix, leaving the samples
intact!!
* SAVE - This gives the same options as load.
Saving a 'MIX AND SAMPLES' file can ONLY be done if you have made a
mix - ie. there must be at least ONE item in the SEQUENCE listing (at
least one item displayed when the sequencer is in SEQUENCE mode).
Saving a 'MIX ONLY' - remember this does NOT save your samples, and so
is ONLY any use if you have a corresponding 'MIX AND SAMPLES' file !!!
SAM - SAMPLE FILES.
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The sample files which can be loaded using the SAMple LOAD option MUST
be in AUDIO VISUAL RESEARCH format !!! These files are usually created
with a *.AVR extension. If you are not sure whether your files are in
AVR format then simply try to load them - if it doesn't work then they
are not AVR samples !!
If you have RAW samples, that is ones without any header (most
samplers can save these !) then these can be loaded provided you
follow the instructions on how to HEAD a file first.
{ NOTE there are two types of raw sample - signed and unsigned. This
status refers to whether the bytes in the sample go from 0 to 256 for
unsigned samples. Or -128 to 127 for signed samples. The STE can only
play signed samples, and so when an unsigned sample is loaded, it is
automatically signed. }
* LOAD - Shows a file selector to allow you to load your samples.
Load will load any AVR file (signed or unsigned) - if the frequency of
the file is not recognized then your sample will be played at the
wrong frequency. The frequency of a file can be changed, if it is not
correct, by using the HEAD facility.
* SAVE - Shows a file selector to allow you to save your samples.
The sequencer ONLY saves files in SIGNED AVR format.
The sample which is saved is the one pointed to by the cursor-arrows,
when in SAMPLE mode.
{ This can be useful if you have unsigned RAW or AVR files and you
wish to convert them to signed. The process can also be reversed if
you re-head a signed sample and say it is unsigned, lo