[alsa-devel] Compressed Audio Playback/Capture through ALSA framework

Clemens Ladisch clemens at ladisch.de
Thu Mar 17 08:39:33 CET 2011

Patrick Lai wrote:
> Where can I find user-space code snippet to see how ALSA is configured 
> for IEC958 playback?

Use the ALSA device name "iec958" (or its alias "spdif").
For another than the default sound card, use "iec958:x".

For compressed formats, you have to set the non-audio bit.
Thise device has four parameters AES0..3 for the four bytes
of S/PDIF metainformation.  The non-audio bit can be set by
adding the parameter "AES0=6"; the complete device name then
looks like "spdif:AES0=6" or "spdif:other=parameters,AES0=6"
or "spdif:{ other-parameters ... AES0=6 }".

The try_open_device function of mplayer tries to do this:


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