[alsa-devel] iec958 switch uneffective while playing ac3 stream

Dag Lem dag at nimrod.no
Wed Mar 28 14:46:08 CEST 2007

Dominique Dumont <domi.dumont at free.fr> writes:

> I've also used iecset to switch the audio/non-audio bit while playing
> an AC3 stream with 'ac3dec -C -D hw:0,1'.
> With 'iecset audio mode true', I can hear the typical shuf-shuf-shuf
> of an ac3 stream played "raw" and the 48KHz Frame rate is shown by my
> amplifier.
> With 'iecset audio mode true', the sound shuts off and the 48KHz
> indicator is removed from my amp display.

Did you try my workaround cookbook?

1. Turn off IEC958 in alsamixer.
2. Play and interrupt a 44.1kHz PCM with aplay.
3. Turn on IEC958 in alsamixer.
4. Play AC3 stream.

I have also read while googling that the "WAV volume" in Windows
drivers must be set to max in order for S/PDIF output to work. I
assume this is the same as PCM volume in ALSA.

Best regards,

Dag Lem

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