[alsa-devel] iec958 switch uneffective while playing ac3 stream (was: SPDIF/IEC958 sample rate on HDA/ALC882)

[Dominique Dumont]

Dag Lem <dag at nimrod.no> writes:

> 1. Turn off IEC958 (e.g. in alsamixer).
> 2. Start playing a 44.1kHz sound file with aplay (no sound is output,
>    of course).
> 3. Interrupt aplay.
> 4. Turn on IEC958.
> 5. Play an AC3/DTS file from DVD (mplayer dvd:// -ao alsa -ac hwdts,hwac3,)

I've an interesting weirdness :

If I switch iec958 in alsamixer while playing PCM , I can see when
switching on:
  * verb sent to switch iec958 on :
     snd_hda_codec_write: nid 6 direct 0 verb 70d parm 81
     snd_hda_codec_write: nid 6 direct 0 verb 300 parm b000
  * my amp 'digital source' going on with 48KHz

When switching off :
  *  verb sent to switch iec958 off :
    snd_hda_codec_write: nid 6 direct 0 verb 70d parm 80
    snd_hda_codec_write: nid 6 direct 0 verb 300 parm b080
  * my amp 'digital source' going on with 48KHz

But while playing ac3 with ac3dec, nothing happens. No verb is sent to
the codec, and the 'digital source' indicator on my amp stays on.

Still digging...

HTH