How do I access the sound hardware?
Most linux sound devices are accessed using a device node named /dev/dsp found in the root file system. If your board has an AC97 codec or a UDA1341 chip then you can use /dev/dsp. Boards with a UCB1200 chip use the /dev/snd device node instead to access the audio capabilities of that chip. The Graphics Client Plus and Graphics Master have a UCB1200 chip. The Bitsy has USB1200 and UDA1341 chips. Our other boards have an AC97 codec.
If the deivce nodes are missing from your root file system, you can create them using
mknod /dev/dsp c 14 3
mknod /dev/snd c 42 0
Some of our ramdisk root file systems include the splay program for playing audio files using these chips. To play an mp3 file called my_song.mp3 on your board with /dev/snd use the command:
/root/splay -d /dev/snd /mnt/my_song.mp3
and with /dev/dsp (the default device node for sound) use the command:
/root/splay /mnt/my_song.mp3
If splay is not included in your root file system, you can download it here.
Prior to kernel version 2.4.9-ac10-rmk2-np1-ads4, the drivers for UDA1341 and AC97 were not included in the default configuration or built into the precompiled kernels. If you are using an older kernel and want to use these chips for audio, consider upgrading to a more recent kernel or recompile your kernel with the options for these drivers enabled.
31-Dec-2003: jlackey - update device information and provide link to splay
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Posted - 13 Jun 2002 : 16:48:58
