Audio Capabilities

Each workstation is equipped with audio hardware on the motherboard. This should work in the normal way under Windows, and it should also work under FreeBSD (it did when we installed the systems, anyway).

To listen to audio output from the systems, you will need to supply your own headphones with a standard stereo mini-plug. It is probably necessary to plug in on the back of the system. We originally bought extension cables to lead the audio around the front, but the cables all got stolen.

Volume and Mixing Control

The various synthesized and external inputs are mixed together by the SoundBlaster and output on the SPKR OUT jack. Under FreeBSD, the mixing is under software control using the mixer program. For example: mixer vol 60:60 sets the output volume level to a more comfortable level. mixer mic 100:100 turns up the microphone gain to the maximum. The default setting of 16:16 has the microphone almost muted, in my experience. See the man page for mixer for more details.

Playing Audio Files

You can play Sun audio format (.au) files on the workstation in two different ways. Suppose you have an audio file sounds.au that you wish to hear. One way to do it is to play it over the PC speaker using the following command: cat sounds.au > /dev/pcaudio The other way to do it is to use the SoundBlaster 16 installed in the system. Plug a set of headphones into the black patch cord coming from the back of the workstation. Then execute the following command: cat sounds.au > /dev/audio You should hear the audio through the headphones. To control the volume, use the mixer command as describe above.

Using the CD-ROM Drive

The CD-ROM device is called /dev/mcd0. You can use it to play an audio CD using the cdplay command, for example: cdplay mcd0 See the man page for this command for further information. While an audio CD is playing, you can listen either by plugging headphones into the jack on the CD-ROM drive on the front of the workstation, or else by plugging headphones into the black patch cord coming from the back of the workstation. In the first case, the volume can be controlled with the volume dial on the CD-ROM drive. In the second case, the volume has to be software controlled using the mixer command as described above.

It is also possible to mount CD-ROMS containing data; this is described here.

Recording Audio

A simple way to record audio data is to either plug a microphone into the MIC IN jack on the back of the system, or a high-level source into the LINE IN jack, use the mixer program to set the appropriate gain level for the audio input, and then run: cat /dev/audio > stuff.au Use ^C to interrupt the recording when you are done. Note that the file stuff.au will grow at a rate of about 1MB/min while recording is going on. A recording can be played back as follows: cat stuff.au > /dev/audio I have found that although it is possible to play back a file recorded in this way, the file is missing various headers required by the Sun audio format, so this file may be rejected by sound editing programs looking for these headers.

Sound Tools

The nas (Network Audio System) provides general-purpose audio manipulation capabilities in a client/server model that works will with the X Window System. See the nas man page for more details. I have only tried this system briefly, and though a number of the tools seemed to work, I had trouble recording and there was some flakiness in the server. This may eventually get fixed -- faster if somebody looks into it and tells me what is wrong.

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