Inferno Audio Device

Inferno fully implements audio on the Windows 95/NT and Solaris platforms. Other platforms will be supported in the near future.

You can use the Inferno Audio device to:

Use a microphone attached to your computer to hear the sound through your speakers or save the sound in a file
Use a microphone attached to one computer to hear the sound through speakers on a machine across the network
Play a sound file (such as .WAV or .SND files on Windows 95/NT)

The following are examples of how to use the Audio device within the Inferno emulator.

Playing a sound file from the Emu control console
The basic way to hear a sound file is to use the following commands from the Emu control console:

     bind -a '#A' /dev
     cat soundfile > /dev/audio

The first command binds the audio device, #A, to the device directory, by convention /dev. The second command directs the sound file through the audio device, /dev/audio.

The soundfile can be a .WAV or .SND file The Inferno Audio device uses the format and attributes specified in the audioctl file. This control file is in the directory where the Audio device is bound; by convention, /dev, as in the bind command above. For more information, see audio - interface to audio device in the Inferno Reference Manual.

To view the current settings in the control file, enter the following from the Emu control console prompt (using the /dev convention):

     cat /dev/audioctl

The default control file is:

     indev mic line
     outdev spkr hdph line
     enc pcm ulaw alaw
     rate 8000 11025 22050 44100
     bits 16 8
     chans 2 1
     left 100 0 100
     right 100 0 100
     buf 100 0 100
     count 0

Each line represents an individual characteristic and all possible values. The second field in each line is the current setting.

To change a setting to match a particular sound file (the launch.wav file uses the defaults), you use the echo command. For example, to change the sample rate, enter the following at the control console prompt:

     echo rate=11025 > /dev/audioctl

Playing a sound file from within Limbo programs
Below are links to three Limbo files that demonstrate programming for the Inferno audio device. Click on the link and then use your browser's Save As... option to save the file to an Inferno directory, such as <inferno_root>/usr/inferno.

To compile these into executable .dis files, use the Limbo compiler. For example, to compile play.b, enter the following command at the control console prompt:

     limbo play.b

You can experiment with these Limbo modules and recompile them to learn more about programming for the Inferno audio device.