[mythtv-users] AC3 and/or S/PDIF (again)

Michael T. Dean mtdean at thirdcontact.com
Tue Jan 24 06:52:02 UTC 2006


On 01/23/2006 11:01 PM, Mario Limonciello wrote:
>>> A quick question if I may. Am I right in thinking that if I buy a new 
>>> sound-card with 6 analogue channels on the output it will drive my 5.1 
>>> amp (it has 6 channel input) for surround sound.
>>>       
>> Yes (assuming you mean by 6-channel input that you have at least 6 RCA 
>> connectors or 3 headphone connectors for input).
>>
>> Note, though, that many cards use line in for surround output in 
>> surround modes, so if you've got a software encoder that requires a 
>> sound card for audio, you may have to keep your on-board card enabled as 
>> well for sound capture.
>>     
>>> i.e. I guess I am asking does myth decode the 5.1 happily from DVDs 
>>> and from DVB-T broadcasts?
>>>       
>> Yep.  It's been doing this for a long time--just disable AC-3 pass 
>> through.  Mark Spieth recently created a patch to support timestretch 
>> with multi-channel streams.  He did the analog patch in no time, but 
>> it's the re-encoding to AC-3 that's taking some time.  I don't think the 
>> patch has been put in SVN, yet, though, so it may not make it into 0.19.
>>     
> On this exact note - I was having trouble just today with a recent SVN
> release attempting to do 5.1 native from myth the analogue route.
>
> I have a HD5000 that records a few streams with 5.1.  I also have xine
> setup to use the analogue 5.1 outputs to drive my receiver for dvds.
> Now in myth, when I change from ALSA:default to ALSA:surround51 (which I
> use for xine), I get no audio in myth.  If I try to force it to the
> exact pcm available for my card, ALSA:hw:0,3 I also get no audio.  Is
> there something else I'm missing here?
>
> Here is relavent info from my mythfrontend console output:
> 2006-01-23 21:59:58.595 Opening audio device 'hw:0,3'.
> 2006-01-23 21:59:58.637 Access type not available: Invalid argument
> 2006-01-23 21:59:58.637 Unable to set ALSA parameters
> 2006-01-23 21:59:58.637 NVP: Disabling Audio, reason is: Unable to set
> ALSA parameters
>   
What are you using for an ALSA conf (~/.asoundrc or /etc/asound.conf)?

Mike


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