[mythtv-users] 7.1 channel audio

Bob spam at homeurl.co.uk
Tue Mar 13 23:54:50 UTC 2007


Bill Williamson wrote:
> 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.
>   

Bad, see my thread here,
http://www.gossamer-threads.com/lists/mythtv/users/196611#196611
and for some old but still relevant info on digital sound in linux go
http://lau.linuxaudio.org/audio_quality_HOWTO.htm



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