Stereo to 5.1 upmix
#1
to start: yes, i searched the faq. i've searched the wiki, and i've searched the forums here. i have been unable to find any specific info on what, exactly, xbmc does when upmixing stereo to all speakers.

which one of the following does xbmc do to upmix stereo media to 5.1 when using the spdif output?
stereo x2 (plays the same in both front and rear speakers)
stereo x2 with effects (simulates room acoustics)
or does it use a matrix mixer of some sort?

i ask, because out of all the various upmix setups i've heard over the years, i've become quite partial to the matrixmixer directshow filter made by the same author that made the ac3 decoder for winamp (which is also available as a directshow filter).

if xbmc does not already include such, i think i might submit a feature request on the sourceforge project.
#2
it doubles left and right to the rear channels, and mixes the fronts into the center which is then attenuated (in order to keep stereo separation).

please note that directshow filters aren't much use as xbox doesn't use the same system. xbox does, however, have a fairly high-spec audio processor, which we aren't taking advantage of as noone has taking the time to look into it (multichannel upsampling being done reasonably well in most receivers).

cheers,
jonathan
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#3
i understand that it doesn't use directshow filters, but the matrixmixer source is available at http://sourceforge.net/projects/matrix-mixer

you have answered my question, though, thanks. i recently picked up the advanced a/v pack and ran my optical cable between the a/v pack, and my audigy 2 zs (don't have a tv, play on my pc using a tv tuner Wink ). the effect you guys already have there is plenty good, while not fancy. props on a great piece of software overall. makes me wish for a pc version. Wink

anyway, if i had the knowledge, or the means, i'd offer to try porting the code of the matrixmixer... but as it is, i don't even know if it would be possible, let alone how to do it. i know some html, some php, and some nwscript... all useless for this. heh

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