Open Sound System driver for CMedia Electronics CMI8788 audio

CMI87xx device characteristics:

  • 8/16/24/32 bit playback/record

  • mono/stereo/4ch/5.1/7.1 playback

  • 8KHz to 192Khz sample rate.

The CMedia 8788 device provides 3 types of devices. The first devices is a Multichannel full duplex device. The second device provides Front Panel audio access and the SPDIF device provide SPDIF (Digital) audio I/O.


The CMedia chip provides some unique features that are set up by the Mixer chip. There are 3 mixer devices presented to the user.

Main Mixer Panel (/dev/mixer0)

  • Master Mixer panel is for controlling output volumes for each of the 8 channels.

  • Monitor buttons will allow you to monitor the input from the Rear Panel inputs, Front Panel Inputs and SPDIF IN.

  • Speaker-Spread function duplicates the front channel output on all 8 speakers.

  • SPDIF Loopback simply takes SPDIF Input and Plays it out the SPDIF Output. panel.

AC97 Input Mixer Panel (/dev/mixer1) This mixer panel is used to switch between the various inputs like line-in, mic, cd. When the Rear Panel Monitor button is check marked in the Main mixer panel, the IGAIN slider in this panel controls the level of the input that can be hear on the speakers.

AC97 Front Panel Mixer (/dev/mixer2) This mixer controls the front panel ac97 device. It can be used to control all the volumes and inputs as well as SPDIF output on the front panel device.




/etc/oss4/conf/oss_cmi878x.conf Device configuration file


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