Upmix & upconvert from mono/stereo to DD 5.1

[tom para]

I just checked out the Creative Inspire 5.1 5700 box which has the CMSS thing Creative Multi Surround System ???).

What it does : you put in an analog stereo signal (using a mini jack), select 5.1 "movie", "music" or "4 point" (quad?) and you get an instant upmix out to the 6 speakers.

In short, on-the-fly upmix to 5.1 using some kind of DSP chip.

(I know that upmixing is possible using an audio editor but I figure it would be really tedious. Hollywood does it all the time for old movies, i.e. "Gone With The Wind").

I wonder if anybody can implement this in an app:
Drop a mono/stereo file into it, adjust to your taste and the app spits out 6 mono files (L/R/C/LS/RS/LFE).

tom para
PS: boink me on the head if this sounds stupid !

[Doom9]

lots of dsp chips allow some kind of virtual surround giving you 4 or 6 channel from a 1 or 2 channel source.. but this is not really true surround.. so why would you want it?

[Taric25]

It's better than nothing. :)

I choose this option on my reciever when watching a mono movie. I hate all the sound coming from my center speaker.

[tom para]

I know this is not true surround. Well, if I have only a mono/stereo source and a surround speakers set, such an app would be really useful to play around with. Come to think of it, it could be like this:

Center = L + R - 3dB (or run it thru Semi 3D filter
LS/RS = L/R -10dB + (adjustable) delay + (adjustable) reverb
LFE = C + low-pass + stripped-out silence -10dB

just a thought,
tom

[FlimsyFeet]

Just found this thread; I've recently got one of these systems too.

Sound comes from all 5 speakers so it is true surround. Virtual surround is a system used on some TVs to give the effect of there being more speakers, even though there are only two. By all accounts virtual surround is to be avoided.

CMSS movie mode basically attempts to be a rival to Dolby Pro Logic II, i.e. a stereo source is upmixed to 5.1 channels. I've had varying results; sometimes it sounds great, on other movie tracks there is an annoying amount of leakage of the centre channel to the other speakers. Luckily is also has Dolby Pro Logic decoder that sounds better in these cases.

It has to be said I would have preferred DPLII instead of CMSS, but the price of the 5700 has come down alot now and they are very good value.

What I would really like, you know that thread A better Dolby Pro Logic II downmix (http://forum.doom9.org/showthread.php?s=&threadid=57988) (which I only understand about a quarter of the posts) could something be added to BeSweet/AC3Filter to get a 2-channel downmix from AC3, that is correctly upmixed again when using CMSS movie mode?