[mythtv-users] 7.1 channel audio

Bill Williamson bill at bbqninja.com
Sat Mar 10 06:04:45 UTC 2007

On 3/10/07, Al McIntosh <junkmail at allanmcintosh.com> wrote:
> Hey,
>    I have a Sound Blaster Live! card connected to 7.1 amp via optical
> coax cable. When I watch DVDs or anything with xine I get nice, rich
> full surround sound. However, when I watch recorded shows within mythtv
> there is no output from LS or RS. The front , center and rear channels
> all output.   Is this a shortcoming of my current version
> *mythtv-0.20-153.fc6.at*? With the below .asoundrc I set playback to
> ALSA:default.  Any ideas?

Your card does not support realtime dolby digital encoding.  You get
surround from DVDs because it is passing through the stream directly.
When watching TV, it sends a PCM stereo signal as that is the best the
card can produce from scratch.  Your receiver is smart enough to go
into "pro logic" mode, and it invents front and rear channels from the
stereo signal.

THere are a few cards on the market that do real time surround
encoding, but I do not know how linux support is for them.

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