[mythtv-users] stereo+AC3/DTS sound to both analog+digital outputs

Petr Stehlik pstehlik at sophics.cz
Thu Jul 30 08:24:43 UTC 2009


Steve V píše v St 29. 07. 2009 v 19:31 -0700:
> I don't know if that is the solution. It seems that the OP wanted to
> work in 2 different modes. I have to say something I would like to see
> working as well.
> 
> Mode 1 is the everyday mode, sound through the TV no use of the
> amplifier. If his family is anything like mine the TV is on for 7 or 8
> eight hours a day so running the amp for this time is kind of wasteful
> - I don;t need to hear the .
> 
> Mode 2 is the sometimes mode, sound through the amplifier not the TV.
> This would be for the times that using the amp would really be
> appreciated, eg when watching a movie that has an AC3 track.

exactly. well explained.

> For example, my TV is connected via HDMI and I send the sound over
> HDMI, but the TV cannot handle AC3 so when sending digital sound over
> HDMI I must disable AC3 passthrough or pass it to the spdif rather
> than to default.
> 
> the motherboard has a spdif output which handles AC3 and anything else.
> 
> So just sending the same signal to different outputs will not always satisfy the requirements

why not? I was suggesting that "Enable AC3 passthrough" basically does
not turn off the software decoding on the default output. So instead of
"switch to AC3 passthrough only" it would be more like "enable _also_
the AC3 passthrough (on the passthrough output device)".

This way you'd get stereo (or more, upmixed) sound on HDMI (alsa:hdmi,
defined in the Default sound output of Myth) and at the same time the
digital on alsa:spdif (defined in Myth passthrough output device).

I'd say that if the passthrough device is not equal the standard sound
output device then it could output both analog sound to standard and
unmodified digital to the passthrough device automatically. Only if the
devices are the same then the AC3 passthrough would have to disable the
software decoding. Why else there would be two different output devices
if this wasn't supposed to work like this? :)

Petr




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