MythTV Backend fails to record audio, due to PulseAudio

Binary package hint: mythtv

I have my MythTV backend set up to record audio directly from an ALSA device provided by my capture card. Most attempts to record produce the following errors in mythbackend.log:

2010-09-08 11:42:36.208 AudioInALSA(tuner) Error: pcm open failed: Device or resource busy
2010-09-08 11:42:36.401 NVR(/dev/tuner/video) Error: Failed to open audio device ALSA:tuner
2010-09-08 11:42:36.459 NVR(/dev/tuner/video) Error: Failed to init audio input device

I have determined that this is due pulse's support for re-routing ALSA access to the pulseaudio daemon. This behavior doesn't make much sense for the MythTV backend, since pulseaudio is a user-level daemon by default and mythbackend is system-wide and should work even when no users are logged in. Therefore it's best to bypass pulseaudio in mythbackend. The environment variable PULSE_INTERNAL can do that.

If mythbackend is started with PULSE_INTERNAL=1 in its environment, the problem goes away and it records sound successfully every time.

What I'm doing right now is I edited /etc/init/mythtv-backend.conf and replaced
  exec /usr/bin/mythbackend --logfile /var/log/mythtv/mythbackend.log --user mythtv
with
  script
      PULSE_INTERNAL=1 exec /usr/bin/mythbackend --logfile /var/log/mythtv/mythbackend.log --user mythtv
  end script