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New csa2 FAQs: F002s1SOUND
Apple II Sound Manual I
Csa2 FAQs-on-Ground file: Fxxxs1Sound.txt
This material maintained by the Ground Apple II site, 1997.
It may be freely distributed.
Note: This is a pure Text file which includes no Font, Color, etc.
formatting. To correctly view tables and diagrams on a super-res
display, use a mono-spaced Font such as CoPilot or PCMononspaced.
____________________________
Apple II Sound & Music
Version: Version 1.5 (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 Extension 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.
HyperStudio 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 Extension 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
fundamental
sound-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 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;
boneheaded
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...
Computer or Card Wavetable voices WT bits FM voices Stereo?
Digitize?
-----------------------------------------------------------------------------
Apple IIgs 32 8 None Yes(4) Yes 8
Soundblaster 1 8 11 No Yes
8(4)
Soundblaster Pro 2 8 20 Yes Yes 8
Soundblaster 16 2 16 20 Yes Yes
16
Soundblaster 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)
Gravis UltraSound Max 32 8/16 None(2) Yes Yes
16
Gravis 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 Mac Infinite(1) 8/16(10) Infinite(1) Yes Yes
16
PowerPC Mac 2 16 None Yes Yes
16
AV PowerPC Mac Infinite(9) 8/16(10) Infinite(9) Yes Yes
16
Game Machine
Wavetable voices WT bits FM voices Other 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) 1993-94 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!!!