[mythtv] [mythtv-commits] Ticket #1104: multichannelaudio support
Paul Catchpole
paul at paulcatchpole.co.uk
Thu Jan 10 18:45:10 UTC 2008
Ed Wildgoose wrote:
>> It works fine with the audio device for the frontend changed to a
>> 2-channel one. It's only when using the real 6-channel device and hence
>> the upmixer where the clipping occurs.
>>
>>
> #Often you have multiple volume controls for multichannel versus two
> channel - perhaps the multichannel mixer is too loud and causing the
> clipping?
>
> Ed
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The 2-channel device used for testing is a simple ALSA upmixer with an
additional soft-volume added on top. I set the relative mixer levels a
long while ago and they've not changed since. I don't have a master on
this card, hence the softvol. I don't change the levels to test the 5.1
direct output, just move to another device which is the surround51 with
a softvol on top.
For the previous testing I did of patch-38 [I think], where I had
clipping problems, I tried reducing mixer levels to no avail - the
'clipped' output just happily scaled with the rest of the sound.
I think Mark is probably correct in thinking it's a mathematical issue
with the new upmixer code, which seems to use lots of floating-point
maths...
PC
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