[mythtv] [patch] multichannel ac3 audio v11

Mark Spieth mark at dclabs.com.au
Sun Jan 15 13:05:15 UTC 2006

thanks to bill cizek and martin ebourne I got a bit of testing done so Id 
thought Id release another public test version.
It appears to work in 6 channel mode with timestretch however it appears to 
shift the channels for bill.
I need this confirmed on other setups if possible.
this could mean a52 decoder and ac3enc in avcodec do things slightly 
differently but have not determined what yet after looking at it for a 
Ill need to run some back to back enc/dec tests but havent had time yet.
It also appears to work for analog out 6 channels in alsa though cant 
confirm that 100%.
3 channels appears not to work due to a52 decoder doing something wrong ( 
not that this is important for ac3 passthru people :)
analog will probably not rematrix 2 to 6 channels correctly due to the 
different output arrangement unless something can be done to tell the driver 
what the channel->speaker pos mapping is but I doubt that has been 
considered ATM.
note it still requires a decent cpu to do timestretch due to lack of mmx but 
does work (so Im told) and ac3 5.1 enc requires 5ms per 32ms audio frame on 
my XP2000+. nice to hear the ticking of the dig stream in my analog speakers 
If you have a nice 3G+ machine you shouldnt have any problems.
feedback always welcome.
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