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SGI audio Frequently Asked Questions (FAQ)

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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/

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    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

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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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