[mythtv-users] Myth/spdif no audio, mplayer works fine

John Patrick Poet john at BlueSkyTours.com
Tue Mar 29 17:41:06 UTC 2005

On Tue, 29 Mar 2005, Kevin Kuphal wrote:

> John Patrick Poet wrote:
> >
> > I have AC3 passthrough turned on, and currently have ALSA:iec958 in
> > the driver box.  I have also tried ALSA:default, and I have even tried
> > ALSA:cards.pcm.iec958.  Myth does not complain about any of those
> > setting, it just doesn't work.
> Try turning off AC3 passthrough.  Unless your broadcast content that you
> are recording in MythTV has AC3 sound, the AC3 passthrough option should
> not be checked.  By checking it, you're telling Myth that all your
> content has AC3 sound and that is should be passed through to the
> hardware.  However, if your sound is normal stereo or something other
> than AC3, then I believe that setting will result in no sound if activated.
> Kevin

Thank you for trying to help.

Unfortunately, that is not the problem.  As long as I use mplayer or aplay
to do it, I can play both AC3 material as well as WAV/MP3/MP2 material just

My asound.conf file looks something like:

pcm.!default {
  type plug
  slave.pcm iec958

pcm.ice1712 {
  type hw
  card 0

ctl.ice1712 {
  type hw
  card 0

With it configured that way, I don't even have to tell mplayer or aplay what
device to use.  AC3 and non-AC3 material all gets routed to the iec958
interface, and plays beautifully.  The hardware is also not locked to 48k,
so I can send 44.1k material as well, and it also plays beautifully.

I have used mplayer to play some of my HD material with AC3 audio, and all
I have to do is "mplayer -ao alsa movie.nuv", and the sound is perfect.  My
pre-amp decodes the AC3 stream and it sounds great.

Playing non-AC3 material is exactly the same.  I don't have to tell aplay or
mplayer anything about the device, just to use ALSA, and it works.

Myth is the only thing giving me trouble.

David George, can you give me some guidance in debugging what is going on in
Myth's ALSA code?



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