[pulseaudio-discuss] PulseAudio, pcHDTV hd-5500 card, tvtime, and mythtv

Colin Guthrie gmane at colin.guthr.ie
Mon Dec 6 01:38:48 PST 2010

Hi Trevan,

'Twas brillig, and Trevan Richins at 06/12/10 01:01 did gyre and gimble:
> Hello,
> I'm attempting to use pulseaudio to play back sound from my hd-5500 tv
> card (I use the analogue part of it) and I'm hitting a brick wall.
> My /etc/asound.conf file is:
> pcm.pulse {
>     type pulse
> }
> ctl.pulse {
>     type pulse
> }
> pcm.!default {
>     type pulse
> }
> ctl.!default {
>     type pulse
> }
> If I run the command "sox -c 1 -t alsa default -t alsa default", I hear
> the TV sound correctly.  Opening up pavucontrol shows the sound bar
> moving back and forth indicating that pulse is getting the sound.  But
> if I run tvtime or MythTV, I don't get any sound.

MythTV in particular does very silly things with pulseaudio. I've tried
several times to argue with them about it, but sadly they've not headed
me yet.

How is your sound configured in MythTV? Do you get sound from e.g. a
pre-recorded video file or music etc.?

To explain MythTV will automatically try to outsmart your system and
deliberately take action to suspend PulseAudio unless you configure
MythTV correctly. If you use "ALSA:pulse" or "PulseAudio:default" then
MythTV should let PA do the audio but if you set "ALSA:default" then
MythTV will do something really dumb, which is to suspend PA even though
it will ultimately try and push audio to it. I've always patched this
behaviour in the Mandriva MythTV packages so I would suggest using the
patches there on your build of MythTV (or point your distro maintainer
at it).

> I don't know if the problem is with pulseaudio, the card, or
> tvtime/mythtv.  Any ideas on what I should do?

Well the problems are actually quite different. tvtime and MythTV
operate quite differently.

MythTV should properly read the audio and play it back through the sound
card of your choice, but tvtime expects a "loopback" to be used. e.g. a
physical cable coming out of the TV card and into the line in of your
sound card.

For the tvtime case you can likely use module-loopback in PA (just type:
pactl load-module module-loopback, then use pavucontrol on the Recording
and Playback tabs to move the loopback streams to the correct recording
device (i.e. the tv card) and the correct playback device (i.e. your
sound card))

For MythTV, they need to fix their braindead configuration, but you can
maybe get it working by setting the audio device to either "ALSA:pulse"
or "PulseAudio:default"


Feel free to ask on IRC. I think I saw you drop by and ask this question
the other day, but didn't get a change to reply before you logged out -
you need to stick around for a while :)

Take care



Colin Guthrie

Day Job:
  Tribalogic Limited [http://www.tribalogic.net/]
Open Source:
  Mageia Contributor [http://www.mageia.org/]
  PulseAudio Hacker [http://www.pulseaudio.org/]
  Trac Hacker [http://trac.edgewall.org/]

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