[mythtv-users] Funny problem with alsa and AC3 passthrough / rate conversion

David Maher dm at netsol.com.au
Tue Sep 27 06:04:41 UTC 2005


Hi 
I am using ALSA rate conversion for my analogue tuner with spdif output
on my intel8x0 based onboard sound card. I'm using the .asoundrc from
here http://www.mythtv.info/moin.cgi/DigitalSoundHowTo

Everthing was working fine using ALSA:mixed-digital, but lately, if I
enable AC3 passthrough in the mythfrontend, my amp outputs a horrible
buzzing sound when it gets a dolby digital signal from myth.

Ok, you say, something's wrong with the amp? No I don't believe so. 
If I change my audio out string to ALSA:plug:iec958, the AC3 passthrough
works fine, the digital tv tuner's audio is fine, but the analogue tv
tuner's 32khz audio stream is choppy and speeds up dramatically. I guess
this would be the expected behaviour. 

If I go back to ALSA:mixed-digital and turn off AC3 pass through,
everthing works fine, as long as I don't want to listen to dolby
surround. 
Anyway, if anyone has any suggestions, or perhaps a different .asoundrc,
that I should try I would be very grateful

Thanks

David Maher




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