[mythtv] [mythtv-commits] Ticket #1104: multi channel audio support

Mark Spieth mark at digivation.com.au
Sun Feb 3 10:51:45 UTC 2008

> Ok, so in my testing so far ALSA:analog works great at 2ch and 5.1ch.
> Kudos.

thats because I can use it :)
there is another patch for #chan changes within a stream to stop the hiccup 
when audio is reinited.
Im halfway done lavc fft mods with config but for some reason it doesnt 

> But with "ALSA:spdif":
>   AC3 passthrough only when "Max Audio Channels" is set to "Stereo".
>     When time stretch is engaged (disabling passthrough) CPU usage
>     goes through the roof (110% of on an AMD 64 X2 4200+), there
>     is sound, but it is very corrupted.
>   Without AC3 passthrough checked, there is no sound at all.

perhaps some of those using it can advise settings. I cant remember names. 

> I have not tested with other audio output methods yet or to see if DTS

Only alsa so far.

> passthrough sound still works.

I suspect DTS should be ok. not sure of the 8 ch behaviour though if that is 

>Before I do, had you tested SPDIF output?

no. only through others and they havent complained recently so I only assume 
its still ok.
I dont have a spidf setup yet until I get my new frontend done.
I should get the hardware this coming week on order.

> If so and you got sound, what kind of CPU usage were you seeing?

on my combined XP2000+ analog upmixing fftw3 uses about 39% vs 21% for 2ch 
for same video.
no figures for passthru.


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