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SGI audio Frequently Asked Questions (FAQ)


Archive-name: sgi/faq/audio
Last-modified: Wed Oct 20  1:00:04 CDT 1999
Posting-Frequency: Twice monthly
URL: http://www-viz.tamu.edu/~sgi-faq/

    SGI audio Frequently Asked Questions (FAQ)

This is one of the Silicon Graphics FAQ series, which consists of:

    SGI admin FAQ - IRIX system administration
    SGI apps FAQ - Applications and miscellaneous programming
    SGI audio FAQ - Audio applications and programming
    SGI diffs FAQ - Changes to the other FAQs since the last posting
    SGI graphics FAQ - Graphics and user environment customization
    SGI hardware FAQ - Hardware
    SGI impressario FAQ - IRIS Impressario
    SGI inventor FAQ - IRIS Inventor
    SGI misc FAQ - Introduction & miscellaneous information
    SGI movie FAQ - Movies
    SGI performer FAQ - IRIS Performer
    SGI pointer FAQ - Pointer to the other FAQs
    SGI security FAQ - IRIX security

Read the misc FAQ for information about the FAQs themselves. Each FAQ is
posted to comp.sys.sgi.misc and to the news.answers and comp.answers
newsgroups (whose purpose is to store FAQs) twice per month. If you
can't find one of the FAQs with your news program, you can get it from

    ftp://viz.tamu.edu/pub/sgi/faq/
    ftp://rtfm.mit.edu/pub/usenet/news.answers/sgi/faq/

(rtfm.mit.edu is home to many other FAQs and informational documents,
and is a good place to look if you can't find an answer here.) The FAQs
are on the World Wide Web at

    http://www-viz.tamu.edu/~sgi-faq/

If you can't use FTP or WWW, send mail to mail-server@rtfm.mit.edu with
the word 'help' on a line by itself in the text, and it will send you a
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command 'send usenet/news.answers/sgi/faq/misc' to get the SGI misc FAQ,
and similarly for the other FAQs. Send the command 'send
usenet/news.answers/internet-services/access-via-email' to get the
"Accessing the Internet by E-Mail FAQ".

You may distribute the SGI FAQs freely and we encourage you to do so.
However, you must keep them intact, including headers and this notice,
and you must not charge for or profit from them. Contact us for other
arrangements. We can't be responsible for copies of the SGI FAQs at
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are certain to be out of date. The contents are accurate as far as we
know, but the usual disclaimers apply. Send additions and changes to
sgi-faq@viz.tamu.edu.

Topics covered in this FAQ:
---------------------------
   -1- How do I program the Motorola 56000 DSP on the Indigo (R3K and
       R4K)?
   -2- How do I connect my stereo to my Ind{igo,igo2,y}?
   -3- How do I change the volume of the audio out the back of my
       machine?
   -4- Indigo2 speaker seems quieter than my Indigo. Am I imagining
       things?
   -5- I need to crank up the input gain on Indigo2 to use the
       microphone successfully. What's the scoop?
   -6- The glossy paper says that Indigo2 and Indy have 4-channel input
       and output. That sounds really cool. How do I use it?
   -7- Okay, so 4-channels of input and output is great, but I need
       more. Can I get more channels of audio for my machine?
   -8- Now that I have IRIX 5.2, I can't seem to find audio.h and
       libaudio.a in order to compile my audio code. What gives?
   -9- I like the boot tune, but it's just a bit too loud. How do I tone
       it down a bit?
  -10- How can I change the output speaker/headphone volume from a shell
       script?
  -11- What 3rd party audio solutions exist for Silicon Graphics
       machines?
  -12- I'd like to write my own audio programs. How do I get started?
  -13- How can I get the keyboard beep out line out/digital out on
       Indigo2?
  -14- How do I suppress the keyboard bell (which *does* come out the
       line out and digital output) on an Indy?
  -15- Why does /dev/audio not work on my Ind{y,igo2,igo}?
  -16- Where can I get a MOD player for SGI?
  -17- I need audio for my Onyx. What are the details?
  -18- Why does my floating point signal processing routine, when given
       certain inputs, run incredibly slowly and consume all of the CPU
       in _system_ or _interrupt_ time?
  -19- What are the audio features of SGI machines?

----------------------------------------------------------------------

Subject:    -1- How do I program the Motorola 56000 DSP on the Indigo
                (R3K and R4K)?
Date: 20 Aug 1994 00:00:01 EST

  Short answer: You don't.

  Long answer: The DSP on the Indigo is used exclusively by the audio
  system: whenever you are using the audio, you are using the DSP.

  In order to insure that audio processes are serviced, access to the DSP
  is limited to the audio device driver which performs all functions on
  behalf of application programs.

  Moreover, any code developed for the DSP on the Indigo may not work on
  other systems since the DSP is not guaranteed to be present. For
  instance, Indigo2 and Indy do not have a DSP. Audio is supported by a
  combination of code running on the CPU and a audio ASIC chip. SGI
  supports the Audio Library software inter- face as opposed to any
  particular hardware implementation of the audio system.

  Lastly, any signal processing code developed on the host CPU benefits
  from speed increases of the CPU (and this code is easier to write as
  well).

------------------------------

Subject:    -2- How do I connect my stereo to my Ind{igo,igo2,y}?
Date: 20 Aug 1994 00:00:01 EST

  The Line in and Line out levels have been designed to be directly
  connected to conventional stereo systems.

  One way to do it is to connect it up as if the computer was a tape
  recorder.  Line out on the computer connects to Rec in on the stereo
  and Line in connects to Rec out.

------------------------------

Subject:    -3- How do I change the volume of the audio out the back of
                my machine?
Date: 20 Aug 1994 00:00:01 EST

  The headphone and speaker volume is adjusted using apanel(1). The
  sliders under the 'Speaker' label control the output volume of the
  speaker and headphone. The line-level output voltage is not
  affected.

------------------------------

Subject:    -4- Indigo2 speaker seems quieter than my Indigo. Am I
                imagining things?
Date: 20 Aug 1994 00:00:01 EST

  No, this is not a figment of the imagination. There are two factors
  at work that make the Indigo2 quieter than Indigo: 1) the speaker amp
  is less powerful on Indigo2; 2) the system fan on Indigo2 is louder
  than the Indigo fan. These two things lead to a quiet speaker that
  seems even quieter. See the release notes for more information.

------------------------------

Subject:    -5- I need to crank up the input gain on Indigo2 to use the
                microphone successfully. What's the scoop?
Date: 20 Aug 1994 00:00:01 EST

  The Indigo2 and Indy both have less input gain than the Indigo and
  4D/35. However, all have plenty of gain to operate the microphone.
  On the Indigo2 and Indy, you have to set the input gain to a larger
  nominal level.

------------------------------

Subject:    -6- The glossy paper says that Indigo2 and Indy have 4-
                channel input and output. That sounds really cool. How
                do I use it?
Date: 20 Aug 1994 00:00:01 EST

  In order to enable 4-channel audio, you must choose "4-channel mode"
  from the 'Options' menu of apanel or make a call in your program to
  ALsetparams(3A). See the man page for ALsetparams(3A) for more infor-
  mation.

  Enabling the 4-channel mode will cause the electrical char-
  acteristics of your audio connections to change: the headphone jack
  will become a second line-level output (like the normal line-level
  output). The mic input will become a second line-level input *if* you
  have 'line' selected as your input source. If you have the input
  source set to 'mic', then the mic input will continue to behave as a
  microphone input.

  Lastly, when your machine is in 4-channel mode, the input and output
  sample rates will be locked together. Thus, changing the input or
  output rate in this mode will affect the output or input rate,
  respectively.

  You may also run 4-channel applications when the audio system in in
  2-channel mode, and vice versa (2-channel applications work when the
  system is in 4-channel mode).

------------------------------

Subject:    -7- Okay, so 4-channels of input and output is great, but I
                need more. Can I get more channels of audio for my
                machine?
Date: 20 Aug 1994 00:00:01 EST

  Sonic Solutions (San Raphael, CA) has announced that it is porting
  Sonic System to SGI platforms. See below.

------------------------------

Subject:    -8- Now that I have IRIX 5.2, I can't seem to find audio.h
                and libaudio.a in order to compile my audio code. What
                gives?
Date: 8 Mar 1997 00:00:01 EST

  The #include file audio.h and the library libaudio.a became a part of
  the "Digital Media Developement Option" (dmdev) in IRIX 5.X.  Dmdev
  contains more than just the audio development libraries, and it is
  available for an extra fee. If you are like many people and think
  this is a bogus situation, tell your salesperson.

  For IRIX 5.3 and later, the digital media libraries, including the
  audio development environment (audio.h and libaudio.a), are part of 
  the IRIS Development Option (IDO).  Thus, you need no additional 
  products (i.e. DMDEV) to develop software which utilizes the built-in 
  digital audio.

------------------------------

Subject:    -9- I like the boot tune, but it's just a bit too loud. How
                do I tone it down a bit?
Date: 20 Aug 1994 00:00:01 EST

  The boot tune volume is controlled by the 'volume' variable used by
  the system PROM. The value for 'volume' can be set in the range
  [0-255], where lower numbers represent a lower boot tune volume.  A
  'volume' value of 0 disables the boot tune, viz. the tune is not
  played at all.  The value of 'volume' can be set in the PROM monitor
  or using the nvram(1M) command.

------------------------------

Subject:   -10- How can I change the output speaker/headphone volume
                from a shell script?
Date: 20 Aug 1994 00:00:01 EST

  You can use two methods to do this: 1) apanel -nodisplay or volume.c
  program (this program can be found in ~4Dgifts/examples/ libaudio
  directory).

------------------------------

Subject:   -11- What 3rd party audio solutions exist for Silicon
                Graphics machines?
Date: Wed Sep 22 13:31:10 CDT 1999

  Doug Scott <dscott@sgi.com> maintains a list of "Audio Applications
  for Silicon Graphics Systems" which he posts to comp.sys.sgi.audio.
  A copy is at http://reality.sgi.com/dscott/audio.apps/.

------------------------------

Subject:   -12- I'd like to write my own audio programs. How do I get
                started?
Date: 26 Aug 1995 00:00:01 EST

  First, you need the IRIS Development Option (IDO). With IDO
  you get the Digital Media Development software (libraries for
  audio, video, compression, MIDI, and movie development).

  There is audio example code in the ~4Dgifts/examples/dmedia/audio
  directory. There you will find code demonstrating the use of
  libaudio and libaudiofile. You will also find a number
  of examples showing the combination of audio and graphical user
  interface (Motif) widgets.

  In the dmedia/cd+dat directory are example programs showing the
  use of libcdaudio and libdataudio.

  In the off chance that you are using IRIX 5.2 and cannot upgrade
  to 5.3, read the information below.

  Audio Development on IRIX 5.2 systems:

  First, for 5.2 systems you need the Digital Media Development
  Option.  From Michael Portuesi (portuesi@sgi.com):

  The Digital Media Development Option contains the Video, Audio, Audio
  File, MIDI, CD, DAT, Movie, and Compression Libraries for your
  digital media programming enjoyment.

  The part number for the Digital Media Development Option is
  SC4-DMDEV-2.0.   If you would like to develop applications which
  manipulate QuickTime files, you must also order the companion
  product, QuickTime 1.0 Compressor Library, part number SC4-QTCL-1.0.

  In the United States, you can order these products by calling Silicon
  Graphics toll-free at 1-800-800-SGI1 (1-800-800-7441).  If you live
  in a country other than the United States, contact your nearest
  Silicon Graphics office, or call one of these regional telephone
  numbers:

  Europe                  (41) 22-798.75.25       (Geneva, CH)
  North Pacific           (81) 3-5420.71.10
  South Pacific           (61) 2-879.95.00
  Latin America           1(415) 390.46.37
  Canada                  1(416) 625-4747

  For audio, example code is contained in ~4Dgifts/examples/libaudio.
  This example code comes with the DMDEV option. (For IRIX 5.3, the
  digital media libraries are part of the IRIS Development Option
  (IDO).)  Other code demonstrating the use of the CD and DAT audio
  libraries can be found in a 'tar' file at ftp.sgi.com:~ftp/sgi/dat.

------------------------------

Subject:   -13- How can I get the keyboard beep out line out/digital out
                on Indigo2?
Date: 10 Dec 1994 00:00:01 EST

  You can't. The keyboard beep is created by a chip on the Indigo2
  motherboard and the signal is mixed into the analog audio signal
  before going to the speaker (but after then D/A converter).

------------------------------

Subject:   -14- How do I suppress the keyboard bell (which *does* come
                out the line out and digital output) on an Indy?
Date: 10 Dec 1994 00:00:01 EST

  Turning the bell off:

  xset -b	OR	xset b off

  See the xset(1) man page for more details.

------------------------------

Subject:   -15- Why does /dev/audio not work on my Ind{y,igo2,igo}?
Date: 26 Aug 1995 00:00:01 EST

  The /dev/audio interface was created for the older 4D/20 platform
  with 8-bit audio. The actual file /dev/audio remains on
  Ind{y,igo2,igo}.

  The sole interface to audio on recent SGI machines is the Audio
  Library and the underlying driver(s).

  The program 'playulaw' in the 'radio' package (ftp.cwi.nl) will play
  u-law data piped from standard input. Also, the radio binaries are
  available at http://www.ibd.nrc.ca/~sgi. (Thanks to Walter Roberson
  <roberson@ibd.nrc.ca> for this information.)

------------------------------

Subject:   -16- Where can I get a MOD player for SGI?
Date: 15 Feb 1997 00:00:01 EST

  There is an older version of 'tracker' by Marc Espie that runs on SGI
  machines. It's called tracker-al and can be found at:

  ftp://viz.tamu.edu/pub/sgi/software/audio/tracker-al.tar.gz

  Also, Stefan Kanthak <kanthak@Plutonium.Informatik.RWTH-Aachen.DE> 
  has written a MOD player called 'mikmod' that supports SGI systems. It
  can be found at http://www2.eng.cam.ac.uk/~93sam/mikmod/ 

------------------------------

Subject:   -17- I need audio for my Onyx. What are the details?
Date: 26 Aug 1995 00:00:01 EST

  There are two options for audio in an Onyx:
  1. Audio/Serial Option from Silicon Graphics
  2. VigraSound board from Vigra

  1. Audio/Serial Option

  From Bill Warner (wtw@sgi.com):

  IRIS Audio Library now runs on Onyx/Challenge with the Audio/Serial
  Option (ASO).    The ASO is a HIO  card that installs on
  an IO4 board in an Onyx or Challenge.

  Supported platforms:
  -------------------

  o IP19 Onyx, Challenge, and RealityStation systems, running IRIX 5.3
  o IP21 Power Onyx and Power Challenge systems, running IRIX 6.0.1
  o current Audio Library software supports at most one ASO or VigraSound
    board per host

  Software:
  --------

  o The ASO audio software is binary compatible with Indigo2, Indy, Indigo,
    4D/35 audio, and VigraSound audio.

    Any SGI or 3rd party application which is linked with the IRIS Audio
    Library will be able to run on a system that supports the ASO.

  o Onyx/Challenge customers may install the standard IRIS sound
    and movie tools (e.g. Audio Control Panel, Soundeditor,
    Movieplayer) from the dmedia_eoe and dmedia_tools images which are
    bundled with IRIX 5.3 or IRIX 6.0.1.

  Hardware:
  --------
  o HIO card that installs on an IO4,
    3-space connector panels that install on the I/O door.

  o identical audio features as Indigo2 and Indy audio

  o 6 high-performance serial ports, each up to 115.2kbps.  Software
    selectable between RS-232 and RS-422 modes.  Non-STREAMS,
    shared-memory-based software interface provided, as well as standard
    STREAMS interface.

  Sales and support:
  -----------------
  The Audio/Serial Option is purchased from SGI.  It has a list price
  of $4995.

  2. VigraSound

  From Scott Porter (sporter@sgi.com):

  VigraSound version 1.0 now available from Vigra.

  IRIS Audio Library software now runs on Onyx/Challenge with
  VigraSound VME audio board.


  Supported platforms:
  -------------------

  o  IP19 Onyx and Challenge systems
  o  must be running IRIX 5.2
  o  current Audio Library software supports one VigraSound board per
     host


  Software:
  --------

  o  SGI and Vigra have developed an IRIS Audio Library driver module
     and microcode for Vigra's VigraSound (formerly "MMI-110") audio
     board.

  o  The VigraSound software is binary compatible with Indigo2, Indy,
     Indigo, 4D/35 audio.

     Any SGI or 3rd party application which is linked with the IRIS
     Audio Library will be able to run on an IP19 system after the
     VigraSound board and vigrasound software module are installed.

  o  Collaborative applications like InPerson, MediaMail, and the
     bundled IRIS media tools will now run with audio on an Onyx (no
     need to recompile or relink).

  o  Onyx/Challenge customers may install the standard IRIS sound
     and movie tools (e.g. Audio Control Panel, Soundeditor,
     Movieplayer) from the dmedia_eoe and dmedia_tools images which are
     bundled with IRIX 5.2.

  o  IP19 Onyx/Challenge developers may install the IRIS Audio Library
     from the dmedia_dev image which is included in the IRIS Media
     Libraries 2.0 software option product, along with the IRIS Media
     Libraries Programming Guide.


  Hardware:
  --------

  o  6U VME VigraSound audio board developed by Vigra (a division of
     VisiCom Laboratories, Inc.)

  o  same feature set as the Indigo/4D35 stereo audio subsystem

  o  inputs:
        stereo line-level,
        mono microphone (input level controlled through s/w),
        stereo AES/EBU digital port

  o  outputs:
        stereo line-level,
        stereo headphone (output level controlled through s/w),
        stereo AES/EBU digital port

  o  independent input and output sample rates

  o  input sample rates:   8, 11.025, 16, 22.05, 32, 44.1, 48 kHz
        (rate may also be slaved to AES digital input rate)

  o  output sample rates:  8, 11.025, 16, 22.05, 32, 44.1, 48 kHz
        (rate may also be slaved to AES digital input rate)


  Sales and support:
  -----------------

  o   SGI customers purchase the VigraSound hardware/software package
      (including a CD which contains the vigrasound eoe s/w module)
      directly from Vigra, Inc.

  o   List price for the VigraSound 1.0 hardware/software package:
      $3995

  o   Vigra contacts for the VigraSound audio product:

      Julie Wix		Product Manager (sales contact)
      Rusty Wise		VP, Sales and Marketing
      Tim Elsmore		Technical Director

      Vigra phone  	(619)  597-7080
      Vigra fax       	(619)  597-7094

      Vigra is a division of VisiCom Laboratories, Inc

  o   Customers obtain all other software (IRIX 5.2, IDO 5.2, IRIS
      Media Libraries 2.0, etc) from SGI.

  o   Vigra provides front-line support for customer issues related to
      the VigraSound audio product (hardware and software)  on IP19
      Onyx/Challenge:

      Vigra Customer Support Group
      6044A Cornerstone Court
      San Diego, CA  92121-4703

      email:  techsup@vigra.com

------------------------------

Subject:   -18- Why does my floating point signal processing routine,
                when given certain inputs, run incredibly slowly and
                consume all of the CPU in _system_ or _interrupt_ time?
Date: 03 Sep 1995 00:00:01 EST

  You may be experiencing an undesirable "floating point underflow"
  behavior of the floating point unit on R3k's and beyond. You'll need
  to add a workaround to your code and, on some machines, install a
  patch as well. A thorough writeup by Chris Pirazzi of SGI
  <cpirazzi@cp.esd.sgi.com> is at
  ftp://viz.tamu.edu/pub/sgi/software/programming/fp-underflow.

------------------------------

Subject:   -19- What are the audio features of SGI machines?
Date: 26 Aug 1995 00:00:01 EST

  Indigo (R3000 and R4000):
    - Stereo analog input (line input or mic (mono) input)
    - Stereo analog output (simultaneous speaker/headphone & line out)
    - Serial digital input (supports AES and S/PDIF encoding)
    - Serial digital output (supports AES and S/PDIF encoding)
    - Independent input and output sample rates including:
	8, 11.025, 16, 22.04, 32, 44.1, and 48.0 kHz
    - 3.5 mm connectors
    - microphone (mono) included
    - mono speaker

  Indigo2 & Indy & Audio/Serial Option:
    - Stereo analog input (line input or mic input)
    - Stereo analog output (simultaneous speaker/headphone & line out)
    - Stereo microphone support
    - 4-channel analog input and output using mic connector as second input
	pair and headphone connector as second output pair
    - Serial digital input (supports AES and S/PDIF encoding)
    - Serial digital output (supports AES and S/PDIF encoding)
    - Independent input and output sample rates including:
        8, 11.025, 16, 22.04, 32, 44.1, and 48.0 kHz
    - 3.5 mm connectors
    - microphone (mono) included
    - mono speaker

------------------------------

End of sgi/faq/audio Digest
******************************
-- 
The SGI FAQ group <sgi-faq@viz.tamu.edu>   http://www-viz.tamu.edu/~sgi-faq/
Finger us for info on the SGI FAQs, or look in ftp://viz.tamu.edu/pub/sgi/.



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