This document contains information relevant to the AV Macs,
especially in relation to the use and programming of their DSP chip.
It is the product of my own experience and many helpful responses I
have received to posts I have made. I have taken slight liberties in
editing responses, so what you see below are not always the exact
words of the contributors to the FAQ. It is structured in the
typical FAQ format of question and answer with the questions listed
at the beginning. Please write me with any additions to or comments
about this document. The most recent changes occur in questions 5
and 7.
Ben Denckla
Manager
Harvard University Electronic Music Studio
1. Are modem/fax software and the GeoPort telecom adapter included?
2. Does audio output from the CD have an extra stage of A/D & D/A?
3. Is there an included utility which allows digital recording of
part of an audio CD to an AIFF file?
4. Is there an included utility which will allow me to play/record
16-bit, 44.1KHz stereo AIFF files?
5. Is there any digital audio software available for the 660AV?
6. Is there any digital audio interfacing hardware available?
(AES/EBU <--> DAV or AES/EBU <--> GeoPort)
7. What is needed to do DSP programming?
8. Where can I get example code for programs that use the AV's DSP?
9. Where can I get information about the DSP chip?
10. BugLite only supports 32-bit floating point data. Do I really
want to use this data type?
11. Can I use Think C to write the Macintosh part of DSP
applications?
12. What happens to DSP modules I have written when the hardware
platform changes (to PowerPC, for instance)?
.c.1. Are modem/fax software and the GeoPort telecom adapter
included?
The Geoport adapter must be bought separately for about $125.
It comes with the modem driver software and a complete, user-level
fax software package. So you still need to own a separate modem
communications program. Contrary to what some documentation says,
the modem will do 14.4 Kbaud, not just 9600 baud.
As an aside, I would like to point out that though the AV does
speech generation and recognition right out of the box, it can't do
modem/fax out of the box. Frankly I cannot believe that the number
of users needing speech functions even approaches the number who need
modem/fax. A clear case of "Gee-whiz! Bells & whistles! Screw the
user!" marketing. Not that the $125 for the GeoPort even compares
the the $995 for the ARTA toolkit (see below).
.c.2. Does audio output from the CD have an extra stage of A/D & D/A?
Yes. Evidence of this appears on p. 39 of Apple Developer Note
#5, where the L & R outputs of the CD enter a block labelled "analog
front end" before entering the Singer block.
John Turpin confirms this and notes that the
digital audio output from the CD is not compatible with the Singer
serial data bus.
.c.3. Is there an included utility which allows digital recording of
part of an audio CD to an AIFF file?
No. In order to to this, you need to open a QuickTime-aware
application and select the audio "file" from the mounted CD using the
File Open menu item. You'll then get a dialog asking for conversion
confirmation. Then you will have a QuickTime movie with 16-bit audio
which still needs to be converted to an AIFF file. This can be done
using the ftp-available utility "snd-converter-pro-20.hqx" or
"soundtrack.cpt.hqx". "movie2snd1.01.sit.hqx" is said to "extract
soundtracks from QuickTime movies" but I have not personally tried it
so I don't know to what format it extracts.
Matt Warner
James Wang , and
(No Name)
contributed to the answer of this question.
.c.4. Is there an included utility which will allow me to play/record
16-bit, 44.1KHz stereo AIFF files?
No. The bundled version of FusionRecorder does allow you to
record this kind of audio into QuickTime movies, though. A utility
called "Zounds" that comes with the ARTA toolkit (see below) does
just this.
.c.5. Is there any digital audio software available for the 660AV?
slansky_doug@macmail2.rtsg.mot.com (Doug Slansky) replies:
The company OSC (800-343-3325, 415-252-0460) makes Deck II, 4-
track sound recording program that was originally written for
Digidesign hardware but has now been ported to work on the 3210 in
the AV's as well. It features include QuickTime synchronization and
SMPTE support.
Ben Denckla replies:
Alaska Software (800-500-3320, 408-738-3320) makes DigiTrax, a
6-track sound recording program written specifically (from the ground
up) for use on the AV's. The program will be released in the 3rd
week of February '94. It has a suggested retail price of $349 but is
available during February for only $199. Its features include
realtime parametric EQ, QuickTime synchronization, and a live video
window.
.c.6. Is there any digital audio interfacing hardware available?
(AES/EBU <--> DAV or AES/EBU <--> GeoPort)
Open question.
.c.7. What is needed to do DSP programming?
warnergt@cbnewsi.cb.att.com (george.t.warner) replies:
Tools for DSP development under the Apple Real Time
Architecture (ARTA) on AV Macs are available for $995 from:
Spectral Innovations
1885 Lundy Avenue, Suite 208
San Jose, CA 95131
408/955-0366
macdsp@applelink.apple.com
You will need MPW to use these tools. The tools include the
AT&T DSP3210 assembler, linker/loader, simulator, Macsbug D Commands,
Apple Snoopy browser/debugger, and Apple BugLite graphical DSP module
installer. It does not include the C Compiler but as you may have
already read, the compiler is not very good. Fortunately, DSP3210
assembly programming (unlike other DSPs) is very C-like, so getting
up to speed is not too difficult. The main part is getting used to
the latencies involved with the pipelined architecture.
Additionally, the AT&T Application Library includes many (about
100?) useful DSP algorithms (FFTs, FIR and IIR filters) with complete
source code. It should sell for about $100.
walter_horat@rasterops.com (Walter Horat) replies:
Apple got the 3210 tools from AT&T, which were written to use
VCOS (AT&Ts 3210 realtime O/S). Apple modified the tools somewhat
for use on the Mac, and began shipping them to developers. When
Apple realized that it might cost money to actually *support* the
tools, they foisted the tools off on a company called Spectral
Innovations (actually not a bad choice since Spectral has been doing
programming for AT&T DSPs for over five years).
BTW, the 'C' compiler is a complete piece of shit. It produces
some of the worst code I have ever seen (trying to do a matrix
multiply in 3210 'C' ran 5 times slower than the host 68k on a Quadra
700 - rewriting the same in assembler ran 7-8 times *faster*). If
you do any serious 3210 programming, you will need to learn 3210
assembler.
Ben Denckla replies:
Here are some of my comments on the ARTA toolkit.
I. Cost
The cost is amazingly prohibitive. If you look at the price of
APDA developer's toolkits for things like Telephone Manager, Sound
Manager, or MIDI Manager, they are less than one tenth the price
($75, $50, and $35 respectively). I thought my 660AV was going to be
a real steal for $1820 + whatever development tools were needed.
Well I had no clue that that "whatever" would be $995, more than half
of the price of the computer itself. So the 660AV makes a lot of
sense: it does speech generation and recognition (two capabilites
that are really only needed for people with disabilities) right out
of the box, but you have to pay $995 to actually be able to program
the thing. Does the price of such DSP development software reflect
the fact that DSP programming is an esoteric activity, or does it
_cause_ DSP programming to remain esoteric? I thought the 660AV was
a revolution in bringing DSP programming onto the personal desktop.
I was wrong, because the cost of the development software shattered
the illusion of the bargain.
II. Documentation
The documentation comes in two parts:
A. A big stack of 3-hole punched looseleaf paper, containing
about 10 different sections, only two of which are separated from
each other in any manner (you have to hunt through and separate out
the documents). No overall table of contents, not even an overall
list of contents.
B. A spiral bound, bad photocopy of the AT&T DSP3210 manual.
The photocopy is blurry and has at least one page out of order (the
first page of the table of contents, actually). It's unclear why
they don't just get some from AT&T since AT&T is willing to send out
the real thing for free (see below).
A large portion of the documentation is almost identical to
that found it Apple Developer Notes #5.
III. Code Examples
There are only 3 tiny examples of realtime DSP modules
included, and only 1 timeshare example. The examples are not
extensively documented.
IV. Software
Although BugLite crashes often, it does under consistent and
non-critical circumstances. This is annoying, but does not seriously
compromise its usefulness. Although one cannot use the sound input
and output (mike & speaker) icons at the same time, you can do
realtime processing of sound by hooking up a sound input or output by
itself and putting the Mac in Playthrough mode (this is done by
clicking on "Options" on the "Sound In" part of the Sound Control
Panel). This Playthrough mode provides the "phantom" microphone or
speaker icon, conceptually speaking.
Zounds works, but will crash if you try to open a mono AIFF
file with it. This is no big deal, but this should be handled with
an error message dialog, not a crash.
There is a bug in the assembler. Statements of the form N*nop may
cause errors inside do { } blocks due to incorrect counting of the
number of instructions. The way around this is to use the form of do
which requires the user to count up the number of instructions in the
loop or explicitly write "nop; nop; nop;" instead of "3*nop". I assume
that any instruction of the form N*instr could cause the miscounting
error; I have used the nop instruction as an example because this
syntax is probably most often used in conjunction with nop.
.c.8. Where can I get example code for programs that use the AV's
DSP?
See question #7 for description of DSP module examples that
come with the ARTA toolkit.
Author: George Warner
Name: ARTAbrot 1.1
Description: Mandelbrot program
Source Code: Mac (C) & DSP
Location: sumex-aim.stanford.edu
archive.umich.edu
AmericaOnLine
AppleLink (Developer Code Submissions area)
Author: Malcolm Slaney :
Name: VUMeters
Description: simulates analog VU meters
Source Code: Mac (Think C) & DSP
Location: ears.atg.apple.com
.c.9. Where can I get information about the DSP chip?
Call AT&T Microelectronics (1-800-372-2447) and ask for the
"AT&T DSP3210 Digital Signal Processor Information Manual". They
sent it out to me quickly & for free.
.c.10. BugLite only supports 32-bit floating point data. Do I really
want to use this data type?
walter_horat@rasterops.com (Walter Horat) replies:
I used to think the same way before programming on the 3210 (I
don't need floats, so I'll just program in integer arithmetic). Once
you get into the architecture of the chip and the instruction set,
you realize that it really was designed *only* to manipulate floating
point data types. The integer operations which the chip supports are
not very robust, for instance there is no integer multiply. But, you
can effectively convert a 8 or 16 bit integer (in signed, unsigned,
u-law or a-law format) to a dsp-floating point number in a single
instruction cycle. The reverse conversion is just as fast. And you
can convert from dsp/ieee and ieee/dsp format in a single instruction
(an instruction takes four cycles to process, but the 3210 has a
four-stage pipeline, so instructions effectively complete in 1 cycle)
.c.11. Can I use Think C to write the Macintosh part of DSP
applications?
Malcolm Slaney replies:
YES! The VUMeters application [see question #8] was done this
way. Only the DSP code needs to be compiled under MPW. The ARTA
Toolkit does include a good DSP simulator which definitely makes
code development easier.
.c.12. What happens to DSP modules I have written when the hardware
platform changes (to PowerPC, for instance)?
warnergt@cbnewsi.cb.att.com (george.t.warner) replies:
The DSP3210 will not go away when the PowerPCs come out. While
Apple has not yet announced what their plans are, I can say that it
is very likely that third parties will make plug-in DSP3210 boards
for PowerPCs not equipped with a DSP.