Front and Rear Channels in a matrix encode

[kinglerch]

I have a recording that is encoded in SQ-quad, but my question deals with all forms of encoded quad. I understand the encoding of rear channels in the stereo mix, where you get a recording quite distinct from the front channels. But what about the front channels themselves? Are they always going to be front+rear? By that I mean, I can run a filter to generate rear channels from front channels, but shouldn't I also have to then "remove" the rear channels from the front mix, so they are also distinct? Or are encoded quad mixes always this way, where the front is actually front+rear, and the rear is read-only? Or is the encoding done in such a way where you don't actually hear the rear mix in the front channels?

 

[DKA]

I certainly do not feel that ALL surround recordings have a full signal in the front channels, although it's not the most noticeable thing in the world when they do. If we're talking about having a unique, "discrete" signal in all channels then, no, fronts would not be a full signal.

Don't know about exclusively quad recordings, as that's not my forte in the least, but what is out there in surround runs the full gamut from Jero to Wilson.

 

[oxforddickie]

All forms of matrix decoding do leave the rear information intact on the fronts after decoding. Removal of that information from the fronts is one of the positive things that can be dealt with when doing software decoding


OD

 

[kinglerch]

If I have Front.wav and a Rear.wav files, extracted from an SQ quad recording, what tool or method would I use to remove the Rear from the Front mix? I have Soundforge 10.

 

[jsrstereo]

I'm not positively certain of this, but my belief is that the "Synthesizer" circuit of Sansui's QS VarioMatrix decoder, when properly tweaked, strips what it deems to be the rear info from the total signal, then places it in the rear channels without duplication in the front channels, and does the same vice/versa for what it deems to be the front info - thus yielding the separation for which it is well known.

Please correct me if this is not right.

 

[oxforddickie]

I can't imagine that is right