..
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Apple II Sound & Music
Version 1.51 (2-JAN-97)
Written by Ian Schmidt (irsman@iag.net)
Thanks for corrections and updates to Joe
Walters, Dave Lyons, Dave
Huang, Mitchell Spector, and Scott Gentry.
Send additional questions/comments/blatent
error reports to
irsman@iag.net.
A quickie what's new:
* Added to the Other Systems table.
* Various additional info and editing.
* Started the 8-bit section
I know some of you emailed me info on the Phasor,
Mockingboard, etc, a
while ago but I can't find it now, so please e-mail anything you've
got to
irsman@iag.net. Also, additional info (like the name) on the program
which
plays GS sampled sounds on 8-bit IIs would be a good thing.
Table of Contents
* An introduction to music and sound
* 8-bit music and sound
* Types of sound files used on the IIgs
* How to digitize sounds
* How to edit sounds
* Types of music files
* An overview of SoundSmith-style editors
* An overview of MIDI
* Technical specifications for the IIgs Ensoniq chip
* About IIgs stereo cards
* What about them other machines? And video games?
_________________________________________________________________
An introduction to music and sound on computers
Music and sound have been a computerized
pursuit since at least the
1960s, when enterprising hackers discovered that by programming
the large
mainframes of the time to do different operations, different tones
could be
generated on a common AM radio from the interference (this
is still a
problem today :-).
Early synthesizers developed at the time
(known as Mellotrons)
consisted of a huge bank of tape loops, with each key playing a
different
tape. Primitive analog tone generators were also in use. These
early
synthesizers first got wide industry exposure via Walter aka Wendy
(never
mind) Carlos' "Switched-On Bach" album.
At this time (mid to late 60s), Robert
Moog developed the direct
ancestors of today's synthesizer. Moog's synthesizers were programmed
via
'patch bays', wherein the user would connect a series of jacks
in a specific
configuration via patch cords to get a certain tone. This use of
the word
'patch' for a sound setting on a synthesizer persists, despite
that today a
'patch' is usually a data file stored on disk or in ROM.
The Moog's debut in a Top 40 song was Del
Shannon's "Runaway". A Moog
was used along with a tube-based analog synthesizer called a theremin
in the
Beach Boys' classic "Good Vibrations". The possibilities of synthesizers
weren't really exploited until the onslaught of 70s 'art-rock'
bands such as
the Who, Supertramp, ELP (Emerson, Lake, and Palmer), Genesis,
Yes, Pink
Floyd and Rush.
Synthesizers have continued to advance
to the point where they are now
the only instrument needed to make a typical Top 40 or rap album.
This was
foreseen somewhat by Boston, who included a "No Keyboards!" logo
on one of
their early albums despite the obvious inclusion of a Hammond
organ on
several songs. Computer control of music developed somewhat later,
however.
Several companies in the early 1980s had competing systems
for allowing
electronic synthesizers to interface to computers and each other,
Roland's
"CV-Gate" system being among the most popular.
Around 1983 or so, a group of companies
developed the now ubiqitous
MIDI (Musical Instrument Digital Interface) standard. It
is now very
difficult to find a synthesizer without MIDI capabilities, and
all popular
computers can be interfaced to MIDI instruments, including the
Apple II.
The first development after MIDI was introduced
was the "sequencer"
program, a program which allowed the recording and playback of
MIDI data
streams, as well as sophisticated editing functions. This allowed
perfect
playback of songs every time, as well as more advanced functionality
such
as the ability to synchronize MIDI data with SMPTE (Society
of Motion
Picture and Television Engineers) time code, a fact which
made it very
simple to add MIDI-based music to television shows and theatrical
films and
synchronize to a resolution finer than 1 frame. SMPTE and MIDI
were used
heavily in the production of the soundtrack for the recent
blockbuster
"Jurassic Park" for example.
At about the same time as the first sequencers
were arriving,
computers began to get sound chips with some semi-decent capabilities.
Machines such as the TI-99/4A and Atari 800 had chips capable of
playing at
least 3 independent tones at any one time. However, the tones were
preset,
usually to a square wave, which has very little musical interest.
This went to the next step when a young
engineer developed the SID
sound chip for the Commodore 64 computer. The SID chip could play
3 tones at
once [plus 1 channel devoted to 'white noise' percussive
sounds], and each
of the tones could be selected from a range of several waveforms.
In
addition, advanced effects such as "ring modulation" were avalible
on this
chip. The C=64 soon allowed many to compose some amazing
tunes, but the
best was yet to come.
The engineer who designed the SID went
on to join a company called
Ensoniq, where he designed the DOC (Digital Oscillator Chip) which
powered
the company's now legendary Mirage synthesizer. The Mirage was
unique in
that it was the first major synthesizer to offer sampling, wherein
you could
digitally record any sound you wanted, from trumpets to snare drums
to water
dripping, and use it as an instrument. Best of all, the DOC chip
could play
up to 32 samples at any one time, making it useful to emulate a
whole
orchestra with one Mirage. The DOC chip also powered Ensoniq's
ESQ-1 and
SQ-80 synthesizers.
Now, to get some Apple II-ish relevance.
During the design of the
Cortland (aka IIgs), Apple was planning on using a chip not unlike
the one
on the Mac II series. This chip played 4 samples at once, but was
limited
in it's stereo capabilities (you got 2 samples on the left,
and 2 on the
right, and that's it) as well as overall flexibility (it's
limited to 1
fixed sampling rate of 22,052 Hz).
Luckily, Ensoniq sent a sample of the DOC
chip to Apple, and it ended
up in the hands of a music enthusiast working on the IIgs project.
This
engineer fought with management until they decided to use the DOC
chip for
the IIgs. However, up until nearly the last minute, the DOC
and it's 64k
of RAM were to be an extra-cost feature, which would have killed
the GS
music software market dead. Luckily, price drops on components
allowed the
DOC to be standard, so all IIgs owners could hear great sound.
Back to generalized things, the next development
was to combine
sampling and sequencing software on capable computers. This resulted
in the
*Tracker genre on the Amiga, as well as Music Construction Set,
Music
Studio, and other programs on many platforms. These programs typically
had a
sequence file and a series of sample files used as instruments,
with some
notable exceptions (the *Tracker series on the Amiga had
all-in-one
'modular' files, hence the name MOD).
_________________________________________________________________
8-bit music and sound
The 8-bit IIs are quite underpowered in
the sound department compared
to the IIgs. However, anyone who's played Dung Beetles or Sea Dragon
knows
that some pretty sophisticated stuff is still possible. The
8-bit sound
normally consists simply of an ability for programs to make the
speaker
click.
If a program toggles the speaker very fast,
tones are generated. And
using other techniques beyond the scope of this FAQ, you can even
play
digitized samples on the speaker, although the quality isn't very
good. This
capability is best known from it's use in some of the classic Apple
II
games, but there is also a program available that allows
you to play any
arbitrary IIgs-style sampled sound on any Apple II.
_________________________________________________________________
Types of sound files found on the IIgs
Several types of sample files are used. Here are the most
common.
Name Ext. FType
Description
---------------------------------------------------
Raw no std. BIN
Contains only raw sample data. The
auxtype is normally the sample rate
divided by 51. (See section CA for
more on why this is).
ACE .ACE $CD
Contains raw sample data compressed with
ACE, Apple's Tool029 sound compressor.
ASIF no std. $D8
Contains sample data plus additional data.
Notable due to its use by SoundSmith.
AIFF .AIFF $D8
Interchange format popular on the
Macintosh. Not used much on the IIgs.
Hyper
Studio no std. $D8 Contains
raw or ACE compressed data plus
additional information.
rSound no std. $D8 Resource
fork contains one or more rSound
and rResName resources. Used by HyperCard
IIgs and the Sound CDev.
_________________________________________________________________
An introduction to sampling
Sampling is conceptually simple; an incoming
analog sound signal is
converted to a digital number (0-255 on the IIgs). Getting good
samples
depends on a number of factors:
* Sampling rate. This is how often in samples per second the
incoming signal is actually noticed and saved. In general,
you
want to have a sampling rate of twice the frequency of the
highest
pitch sound you intend to sample. (The reasoning behind
this is
known as the Nyquist Sampling Theorem). Compact discs sample
at
44,100 Hz, which means they can accurately track signals
up to
22,050 Hz, beyond the range of human hearing. Long-distance
telephone calls are sampled at 8,000 Hz, since the characteristic
part of human voices is generally from 1000-3000 Hz.
* Stereo card quality and shielding (the Audio Animator makes the
best samples of any card I've tried, by far).
* Input signal level (the higher the better, except that there
is a
threshold known as the 'clipping level' above which the
sampler
will be unable to track the signal. Analog tape recorders
do
something very similar).
Once a sample is made, it can be manipulated
in a variety of ways via
mathematics. Because this processing is digital, no degradation
of the
signal can occur, unlike with analog processing. Some effects which
can be
done include:
* Cut and pasting parts of the sample around.
* Mixing/overlaying two samples.
* Flanger/Chorus effects.
* Amplification and deamplification.
* Echoing
* Filtering and equilization
and much more...check out a modern rack-mounted guitar digital signal
processor for all the things possible :)
To digitize a sound (I'll use AudioZap
as the example, others are
similar):
* Hook everything up.
* Check the oscilloscope. The wave should be barely touching the
top
and bottom of the 'scope. Any higher and the sound is clipping;
any lower and you'll get a poor quality recording. Adjustment
methods vary by card; for the Sonic Blaster card AZ can
adjust it
in software. Otherwise, consult your card's manual.
* Select a recording rate (lower numbers on AZ = faster).
* Click Record and cue up your tape or CD.
* Select Ok and then start the tape or CD.
* Click the mouse and stop the tape or CD when you are done.
You've just made a sample! congratulations!
Experiment...you can't hurt
anything, but may discover fun/neat things to do!
_________________________________________________________________
Some basics on editing sounds.
(This section attempts to be program-independent, but
in some cases
specific refrences to AudioZap may sneak in :-)
I'll assume you now have a sound loaded
up, and whatever program is
showing you a nice wave graph. Now, you can pick out portions of
the wave by
simply clicking and dragging the mouse over a part of the wave,
and letting
go when you have as much as you want. If you now try to Play, you'll
only
hear the portion you have selected. If you need to adjust your
selection
range, many programs allow you to shift or apple-click and extend
the
endpoints instead of just starting over with a new range.
Once you have an area selected, you can
cut/copy/paste/clear just like
you would text in a word processor. When pasting a waveform, you
simply
click once where you'd like, and select Paste. The program inserts
the
previously cut or copied piece of wave and moves the wave over
to make room,
just like with a word processor.
For more specific information, consult
the documentation for the
program you use.
_________________________________________________________________
AE Types of music files
Name Ext. FType Description
---------------------------------------------------
MCS None MUS Music
Construction Set tune.
TMS .SNG BIN Music
Studio song.
SS None MUS
SoundSmith song.
NTMOD None INT NoiseTracker
GS module
NTSNG None BIN NoiseTracker
GS song.
MOD None $F4 Amiga
ProTracker module ($F4 is temporary).
MIDI .MID MDI Standard
MIDI file.
_______________________________________________________________
A Brief Overview of SoundSmith Style Editors
SoundSmith (and all other MOD derived editors)
use a very simplistic
way to representing music, to wit:
0 C5 1000 --- 0000
1 --- 0000 --- 0000 ... additional tracks here
2 G5 33FF G5 53FF
3 --- 0000 --- 0000
4 C5 1000 --- 0000
This is often known as a 'spreadsheet'
format since there are rows and
columns much like a spreadsheet. Let's take a look at an individual
cell:
Number of cell
| Instrument number
| | Effect data
| | /|
2 G5 33FF
/\ |
|| Effect number
||
Note and octave
For this note, it's #2 of 63 in the pattern,
it's a G in octave 5,
using instrument number 3, effect 3, and data FF. What effect 3
actually
means depends on the tracker in question. On SoundSmith and derivatives,
it
means "Set the volume to --", in this case set it to $FF (255)
which is the
maximum.
Now, into a larger structure. 64 lines
of cells m akes up a block, or
pattern as it is sometimes called. (MED on the Amiga allows blocks
of
varying lengths, but we won't consider those here). You can terminate
a
block early with a special effect. On the Amiga, an actual effect
number is
used. On SoundSmith, entering the note/octave as NXT makes that
line of
cells the last line played in that block.
Now that we've covered cells and blocks,
we can get into the
large-scale structure of things. To make a complete song, we can
give the
player a 'block list' which tells it to play a specific sequence
of blocks
in a specific order. For instance, we could have it play block
4, then block
0, then block 1, then block 2, then block 2. An entry in the block
list is
known as a 'position'. MOD-derived formats typically allow 128
positions,
and 64 (MOD) or 71 (SoundSmith) blocks.
A Practical Example:
Crank up MODZap 0.9 or later and a favorite
tune. Set it to the
"Classic Player". Now, remember those numbers you never understood
before,
off to the left of the scrolling cells? Here's what they mean,
in terms of
what you just learned: *grin*
This is the # of entries in the block list
> 35 --- 0000
This is the current block list entry playing
> 04 --- 0000
This is the block # currently playing
> 01 --- 0000
This is the current cell # in the current block > 36
A#4 0384
As you watch, the current cell # will normally
(barring certain
effects) smoothly go from 00 to 63. When it hits 63, it will go
to 00 again
and the current block list entry number will increment by 1. When
it does,
the current block number will change if needed (remember, a block
can appear
multiple places in the block list).
_________________________________________________________________
An Overview of MIDI
MIDI is a specification developed to allow
computers and electronic
musical instruments to communicate with each other. Physical MIDI
hookups
can get rather complicated; here is a brief primer:
MIDI hookups are a lot like your stereo,
in that each device has IN and
OUT ports. However, MIDI devices also have a port known as THRU,
which
retransmits information from the In port (more on why this is a
Good Thing
later). MIDI devices are thus connected in a modfified daisy-chain
arrangement, with the Out of the master (usually a computer) connected
to
the In of Slave #1, and Slave #1's Thru connected to Slave #2's
In, and so
on. The Outs of all devices go to the In of the master.
Here is a diagram of a simple hookup:
-----------------------------------
| ----------------
|
| | ___________ |
----- |
| | |
| | | | |
In In Out
In Out Thru In Out Thru
Computer
Synth Drum Machine
(Master)
(Slave #1) (Slave #2)
MIDI is based on 16 'channels'. Each channel
is typically assigned to
one specific device you have connected in your chain. In the example
above,
you might have the synth set to listen to channels 1-9, and the
drum machine
set to listen to channel 10 (this is a typical assignment).
With this setup, when the computer transmits
a note on channel 10, it
will first go to the IN of the synth, which will simultaneously
retransmit
it via it's THRU port and note that it doesn't want to use the
data. The
note will then appear on the drum machine's IN port. The drum machine
will
transmit it on it's THRU port (to which nothing is connected in
the example)
and start the note.
This allows flexibility; if for instance
you wanted you could connect a
second drum machine with different sounds, set it to channel 10
also, and
have a unique mix :)
I will not cover MIDI recording and editing
here, to avoid getting too
technical :)
_________________________________________________________________
Technical Specs for the GS Ensoniq chip
The 5503 Ensoniq Digital Oscillator Chip
(DOC) contains 32
fundamentalsound-generator units, known as 'oscillators'. Each
oscillator is
capable of either making an independent tone by itself, or of being
paired
up cooperatively with it's neighbor in a pairing known as a 'generator'.
The
generator arrangement is used by most programs, for it allows more
flexibility and a thicker, lusher sound.
The DOC plays 8-bit waveforms, with the
centerline at $80 (128
decimal). $00 (0 decimal too) is reserved for 'stop'. If a sample
value of 0
is encounter.cgied by a DOC oscillator, the oscillator will immediately
halt
and not produce any more sound. The DOC additionally has an 8-bit
volume
register for each oscillator, with a linear slope. The dynamic
range of the
DOC (the 'space' between the softest and loudest sounds it can
produce) is
approximately 42 dB, or about on par with an average cassette tape.
Each oscillator has it's own 16 bit frequency
register, ranging from 0
to 65535. In a normal DOC configuration, each step of the frequency
register
increases the play rate by 51 Hz, and computing the maximum theoretical
play
rate is left as an exercise for the student. :)
When oscillators are paired to create generators,
there are 4 possible
modes:
* Free-run: the oscillator simply plays the waveform and stops.
No
interaction with it's 'twin' occurs.
* Swap: Only one oscillator of the pair is active at a time. When
one stops, the other immediately starts.
* Loop: The oscillator simply plays the waveform and if it hits
the
end without encounter.cgiing a zero, it starts over at the
beginning.
* Sync/AM: One oscillator of the pair modulates the volume of the
other with the waveform it's playing. Not commonly used.
Oscillators play waves stored in up to
128k of DRAM. The Ensoniq has
it's own memory refresh system. Note that Apple only supplies 64k
of
DRAM for the DOC (this is known as the DOC RAM).
The output of an oscillator can be directed
to any one of 16 possible
channels. Apple only makes 8 channels avalible via the 3 bits on
the sound
expansion molex connector, and all current stereo cards limit this
to 1 bit,
or two channels.
_________________________________________________________________
About IIgs Stereo Cards
Mfr
Name
Notes
---
----
-----
MDIdeas SuperSonic
First IIgs stereo card. Not very well
constructed, but sounds nice.
Digitizer option is pretty good.
MDIdeas Digitizer Pro Daughterboard
for SuperSonic, but also
takes up another slot in your GS. Pretty
good, but very few were sold.
Applied GStereo
I've never used one; included for
Ingenuity
completeness.
Applied FutureSound
Most advanced card made. Includes
Visions
sophisticated noise reduction,
coprocessor, and timing generator for
ultimate control of sampling rates.
Applied Sonic Blaster Generally
poor to average card; bad
Engineering
decision to use non-shielded ribbon
cable results in hissier than average
output and digitizing.
Applied Audio Animator The one they
got right. Has digitizing
Engineering
circuitry external to the GS itself to
avoid noise, plus a MIDI interface.
Econ Tech. SoundMeister Generally above
average quality. Nothing
much to say. Pro version with direct-to-
harddisk recording cancelled.
_________________________________________________________________
What about them other machines?
Here's a rundown of sound on other computers...
Wavetable
Computer/Card voices
WT bits FM voices Stereo? Digitize?
--------------------------------------------------------------------
Apple IIgs 32
8 None
Yes(4) Yes 8
Soundblaster 1
8 11
No Yes 8(4)
Pro
2 8
20 Yes
Yes 8
16
2 16
20 Yes
Yes 16
16 AWE32
32 16
20 Yes
Yes 16
Pro Audio
Spectrum 16 2
16 20
Yes Yes 16
Gravis
UltraSound 32
8/16 None(2)
Yes Yes 16(4)
UltraSound Max 32
8/16 None(2)
Yes Yes 16
UltraSound PnP 32
8/16 None(2)
Yes Yes 16(11)
Logitech
SoundMan Wave 20
16 22
Yes Yes 16
Commodore
Amiga (all) 4
8 None
Yes Yes 8(4)
Mac
non AV, 0x0 4
8 None
Yes(3) Yes 8(4)
AV 0x0 Infinite(1)
8/16(10) Infinite(1) Yes Yes 16
PowerPC
2 16
None Yes Yes
16
AV PowerPC Infinite(9) 8/16(10)
Infinite(9) Yes Yes 16
Wavetable
Other
Game Machine voices
WT bits FM voices voices Stereo?
--------------------------------------------------------------------
Atari 2600 0
0 0
2 No
Intellivision 0
0 0
4(8) No
Nintendo Ent.
System
1(5) 8
4 0
No
Sega Genesis 1(5)
8 6
0 Yes
Sega CD
3(7) 8/16(7)
6 0
Yes
Super NES
8 12(6)
0 0
Yes
Sega Saturn 32(12)
8/16 32(12)
0 Yes
Notes:
"Wavetable" as used here means "a channel capable of playing back
a
digitized waveform". This is NOT the generally musically accepted
meaning of
the term, but it IS how it is commonly used when referring to computer
sound
boards.
"8/16" for WT playback bits means the chip is capable of directly
processing
8-bit or 16-bit samples without conversion (the GUS's GF1 chip
and the AV
Mac's DSP chip obviously fit these criteria).
1- The AV Mac's DSP chip can theoretically mix an infinite number
of
wavetable voices or synthesize an infinite number of FM voices.
However,
this is limited in practice by the speed of the chip and any other
things
you have it doing (voice recognition, modem replacement, etc).
2- The Gravis UltraSound can emulate FM synthesis in software.
3- Macs before the Mac II were mono-only.
4- This requires additional hardware.
5- The Genesis and NES's wavetable channel is pretty hackish, and
not very
high quality; nonetheless it works for speech.
6- The SNES's sound chip accepts 12 bit samples which have been
ADPCM
compressed (the same type method as ACE on the GS).
7- The Sega CD has two channels of 44.1khz stereo 16-bit CD audio
in
addition to the capabilities of the Genesis.
8- The Intellivision uses the General Instruments AY-3-8192 chip
found on
Apple II boards such as the Phasor and Mockingboard. This
provides three
tones and one percussive noise at once.
9- The PowerPC AV Macs have no dedicated DSP chip; they use the
main CPU,
which can cause application performance degradation (see also note
1).
10-AV Macs of both CPU types have a 2-channel 16-bit CODEC to actually
reproduce the audio, but the DSP or 60x chip are capable of conversion.
11-The Gravis UltraSound PnP specs also apply to other AMD InterWave-chip
based boards such as the Reveal WavExtreme 32.
12-The Saturn's 32 voices can each be set to either waveform playback
or FM.
FM is not limited to sine waves as on older chips, however.
__________________________________________________________________________
Copyright (c) 1993-97 Ian Schmidt and Cygnix Development. Contents
may be
freely distributed as long as no editing occurs without permission,
and no
money is exchanged. Exceptions are hereby explicitly provided
for Joe
Kohn's Shareware Solutions II, the services America Online, GEnie,
and
Delphi, and for user groups everywhere. The Apple II: It
just keeps going
and going and going....
Oh, and for the benefit of Marc:
-30-
Ian Schmidt / irsman@iastate.edu / irsman@cs.iastate.edu / BAZ IS RIGHT!!!