How do I use a Stereo sound editor to create a matrixed surround track? (1 Viewer)

[AaronMK]

I was wondering how I would use a program such as Cool Edit or maybe Sound Forge to create a Dolby Surround sound track.
Thanks for any assistence.
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My DVD's
If a movie is not available in OAR, than it might as well not be available at all.

 

[Wayne Bundrick]

Don't know exactly how you would do it with those programs, but anything you mix in-phase to both the left and right for a stereo phantom center image will be decoded to the center speaker, and anything you mix out-of-phase will be decoded to the rear speakers. It will take some trial and error because the decoder steering logic can cause some unexpected behavior.

 

[Zacha R]

I believe the centre image is at 45 degrees to either the left or right (like Wayne says), and you want to encode the rear channels at 180 degrees to each other - i.e. each at ninety degrees. This is so that the rear channel cancels out if played in 2 channel.
See: http://www.dolby.com/tech/whtppr.html
and maybe (I haven't read it): http://www.dolby.com/tech/l.ml.9811.surmix.s.pdf

 

[Zacha R]

Have just read a little of that second one. At 8.1 it says:
Centre channel at -3dB
The out-of-phase surround signal should also be -3dB, and not go below 100Hz or above 7 kHz.
This is all at 8.1, and should fit with the principles outlined in the first document.
If you need more help, hopefully someone else has a better technical understanding.
Good luck.
[Edited last by Zacha R on September 23, 2001 at 07:28 AM]

 

[AaronMK]

Thanks for the info. Came up with something that works half decently, although there is a lot of channel leakage during playback.
Also, what if there is a sound that is common between the left and right channels that is supposed to come out of the L and R cahnnels as opposed to the center? This would be good for mixing in music.
Thanks again for the assistence.
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My DVD's
If a movie is not available in OAR, than it might as well not be available at all.

 

[Alex Shk]

Also, what if there is a sound that is common between the left and right channels that is supposed to come out of the L and R channels as opposed to the center? This would be good for mixing in music.

I don't think you can do it. The capability you speak of is unique to the discreet formats. I cannot recall ever hearing a DPL soundtrack that had that type of soundfield. That is probably why very few musical programs were mixed using DPL, while the DD/dts formats have many audio releases. However - if you eliminate the center channel, and mix for Dolby Surround - you end up with a matrix system similar to the old QS/SQ Quadraphonic. Don't fret - there are still many who feel that the center channel is essentially useless for musical programs. I believe the Peter Frampton live DVD is actually 4.1 - eliminating the center channel.
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[Scott Simonian]

Now we just have to figure out how to take advantage of ProLogic 2.
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Yes, these are bruises from fighting. Yes, I am comfortable with that. I am enlightened.

 

[AaronMK]

When I said "mixing in music", I didn't mean mixing a track in respect to mixing a stand alone music track.
I have heard many matrixed soundtracks where accompaning music and songs have common elements that are directed to the left and right channels. Is this clever trickery, or is it possible in a matrixed soundtrack?
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My DVD's
If a movie is not available in OAR, than it might as well not be available at all.

 

[Zacha R]

I'm not sure how you'd make the sound appear in both channels. I think there is definitely some kind of phase shift in the centre (45 deg. from each speaker), so maybe if you made sure the phase shift isn't there.
As for channel separation, Dolby Pro-Logic uses a real-time chip to detect the dominant sound - i.e. the loudest at any one time, and make it louder than its neighbours. doing this might help enhance channel separation. I understand that when you get this effect across the front, the separation is often only 3dB.