[mythtv-users] ALSA, SPDIF, 5.1 output

[John Poet]

I am using a pcHDTV card.  In general MythTV and this card work pretty
well.

The most annoying problem I have right now, is my ABC station.  It
generally broadcasts in ac3 5.1.  All the other stations seem to
broadcast in ac3 2.0.

If the ABC station is the FIRST station I view after starting
mythfrontend, I get sound, but it is messed up -- I only get audio out
of the right front channel.  In this state, my pre-amp states that it is
running in prologic mode.  This indicates to me that I don't have the
ac3 pass-through configured correctly.  

I am using a SoundBlaster Live! card.  I have "Audio output device" set
to "ALSA:default".  I do NOT have the "Enable AC3 to SPDIF passthrough"
checked, because that just causes static to come out of the speakers --
no matter what channel I am tuned to.

If I try and tune to the ABC station after viewing another channel, I
don't get any sound at all.  Mythfrontend reports these errors:

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~~~
QDateTime::fromString: Parameter out of range
QDateTime::fromString: Parameter out of range
Video has changed: 1280 720 from: 1920 1088
Audio has changed: 48000hz stereo
ALSA lib pcm_hw.c:347:(snd_pcm_hw_hw_free) SNDRV_PCM_IOCTL_HW_FREE
failed: File descriptor in bad state
ALSA lib pcm_hw.c:324:(snd_pcm_hw_hw_params) SNDRV_PCM_IOCTL_HW_PARAMS
failed: File descriptor in bad state
Unable to set hw params for playback: File descriptor in bad state
Error setting audio params: File descriptor in bad state
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~~~

If I tune back to any other station, the audio plays just fine.  This
indicates to me that the file descriptor does not stay in a bad state,
it is only in a bad state for the ABC channel, with it's 5.1 format.

If I check the "Enable AC3 to SPDIF passthrough", then I get static out
the speakers, but I can change to/from the ABC channel without getting
the above error messages.  I have tried setting "Audio output device" to
/dev/adsp, but that just results in mythfrontend spitting out:

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~~~
Error opening audio device (/dev/adsp):
/dev/adsp: No such device
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~~~

Can anyone who is using the pcHDTV card and "AC3 to SPDIF passthrough"
via ALSA, tell me how they have it configured?

Thanks,

John