AV Mac mini-FAQ esp. re: DSP
Benjamin Denckla
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 received to a post I made
containing various questions about the AV's. 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 or comments about this document.
Ben Denckla
Manager
Harvard University Electronic Music Studio
1. Are modem/fax software and the GeoPort telecom
adapter included?
2. Does the CD audio 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 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. Is there any example code included with the ARTA
toolkit?
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)?
1. Are modem/fax software and the GeoPort telecom adapter
included?
The Geoport adapter must be bought separately for about
$125. The adapter comes with the modem driver software and a
complete, user-level fax software package. So you still
need to buy a separate modem communications program.
Contrary to what some documentation says, you can do
14.4Kbaud, not just 9600 baud, with the modem.
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).
2. Does the CD audio have an extra stage of A/D & D/A?
What makes me suspicious of this is that on p. 39 of Apple
Developer Note #5, the the L & R outputs of the CD enter a
block labelled "analog front end" before entering the Singer
block.
John Turpin <tur...@apple.com> replies:
Yes. The connection from the internal CD to singer is
analog. I do not have a good explanation for this. I do not
know the details, but the digital audio output from the CD
is not compatible with the singer serial data bus.
3. Is there an included utility which allows digital
recording of part of an audio CD to an AIFF file?
walter...@rasterops.com (Walter Horat) replies:
Yes. QuickTime 1.6 in conjunction with an AppleCD 300 drive
can be used to mount audio CDs on the desktop; each track
appears as a file. Copying the "files" gives you 16-bit
stereo AIFF files on your mac; no a/d, no d/a, just data.
4. Is there an included utility which will allow me to
play/record 16-bit, 44.1KHz AIFF files?
No. The bundled version of FusionRecorder does allow you to
record 16/44.1 into QuickTime movies, though.
5. Is there any digital audio software available for the
660AV?
slansk...@macmail2.rtsg.mot.com (Doug Slansky) replies:
Contact OSC (800-343-3325) regarding Deck II, a sound
editing program being upgraded specifically to use the 3210
in the AVs. See MacWeek (10/4/93), page 24 for details.
6. Is there any digital audio interfacing hardware
available? (AES/EBU <--> DAV or AES/EBU <--> GeoPort)
Open question.
7. What is needed to do DSP programming?
warn...@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
mac...@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...@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).
Spectral also sells something called the AT&T DSP3210
Application Library, which is a collection of small routines
to do things like FFTs, matrix multiplies, etc...
BBTW, 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:
I now own the ARTA toolkit and have a few comments about it.
First of all, a few picky remarks about the documentation.
It 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).
There are only 3 tiny examples of realtime DSP modules
included, and I believe only 1 timeshare task example
exists. The examples are not well-documented.
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.
8. Is there any example code included with the ARTA toolkit?
warn...@cbnewsi.cb.att.com (george.t.warner) replies:
For sample source code, look for my posting, ARTAbrot.
ARTAbrot is an ARTA Mandelbrot program which uses the
DSP3210 in av Macs. It includes complete source code (even
for the DSP). You may be able to hack it to do what you want
to do without having to write a whole application.
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.
10. BugLite only supports 32-bit floating point data. Do I
really want to use this data type?
walter...@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)
11. Can I use Think C to write the Macintosh part of DSP
applications?
walter...@rasterops.com (Walter Horat) replies:
If you want to use Think C, you're pretty much f***ed; all
the tool support is in MPW. I suppose you could use Think C
6.0/Toolserver, but I've never tried it.
warn...@cbnewsi.cb.att.com (george.t.warner) replies:
I, too, would ultimately like to use Symantec C. I haven't
even attempted it yet. I'm so busy trying to get software
out the door that I'm simply using what I *know* currently
works: MPW. Even if you can use Symantec C, you will still
need MPW for the DSP tools (assembler, linker, simulator).
12. What happens to DSP modules I have written when the
hardware platform changes (to PowerPC, for instance)?
warn...@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.
Jon Wätte
>2. Does the CD audio have an extra stage of A/D & D/A?
>What makes me suspicious of this is that on p. 39 of Apple
>Developer Note #5, the the L & R outputs of the CD enter a
>block labelled "analog front end" before entering the Singer
>block.
>John Turpin <tur...@apple.com> replies:
>Yes. The connection from the internal CD to singer is
>analog. I do not have a good explanation for this. I do not
>know the details, but the digital audio output from the CD
>is not compatible with the singer serial data bus.
This is not the whole story. If you "import" audio from the
CD using QuickTime Audio CD Import, you will NOT go through
Singer, just through the SCSI bus and get a clone of the
digital audio image.
The "Singer" analog connection only affects the case where
you select "Internal CD" in the "Sound Input" control panel.
>3. Is there an included utility which allows digital
>recording of part of an audio CD to an AIFF file?
>walter...@rasterops.com (Walter Horat) replies:
>Yes. QuickTime 1.6 in conjunction with an AppleCD 300 drive
>can be used to mount audio CDs on the desktop; each track
>appears as a file. Copying the "files" gives you 16-bit
>stereo AIFF files on your mac; no a/d, no d/a, just data.
This is also wrong - you do not get 16bit AIFF files, you
get 16bit QuickTime movies which have to be converted to
AIFF using a separate utility (not included)
--
-- Jon W{tte, h...@nada.kth.se, Mac Hacker Deluxe --
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