[mythtv] [mythtv-commits] Ticket #1608: Proper Handling of Alsa AC3-PassThru

[Simon Levitt]

On Saturday 01 April 2006 15:17, Markus Schulz wrote:
> [...]
> Best way will 
> be an additional input field (next to passthru checkbox) where you can
> enter the alsa-pcm-device string for ac3 streams differently to
> uncompressed pcm data.
>
This could very well form the basis of what I'd like from my MythTv system, 
and in that sense properly implment pass-through on my system; the ability to 
choice audio output device on the fly (or have two outputs active at a single 
time).

I'm very close to replacing our main DVD player with a MythTv system, but the 
audio is a problem:

- Most of the time (normally when my wife and kids watch DVDs; or when the 
kids are in bed) having non-passtrough and the stereo output from the TV is 
just fine.

- However, at other times, I like to use our 5.1 system to get the best 
experience.

So what I'd like is an easy way to switch between the two (or have normal 
stereo output even when using pass-through), rather than needing to enter the 
setup screens and changes device names and options. An option in the playback 
menu would be ideal.

I've mucked around with all kinds of ALSA config, and can't get what I'd like.  
I'm almost convinced my onboard soundcard (ALC850 based I believe; machine is 
off and at home) can't successful provide stereo output whilst doing 
pass-through (or the ALSA drivers don't support it or has missing/buggy 
controls).

I've also tried experimenting with things in NuppelVideoPlayer.cpp, 
tv_play.cpp and audiooutputalsa.cpp and can't quite force enough of a context 
change to reinitialise the audio properly on device change to successfully 
switch between two working device configurations. (I was hooking into 
NuppelVideoPlayer::Pause() to attempt the toggle).

If you'd be willing to implement this, then great, otherwise any hints you 
could give to allow me to implement/hack it locally would be glady welcomed.

Cheers,

Simon.,