the S in LCRS...

[Brent_in_Sydney]

Hi guys,

Just wondering if the gurus in the room could shed some light on the old school LCRS 4 channel deliverable. In particular the surround channel.

If you just sum the Ls and Rs from a 5.1 mix, depending on content, aren't you likely to get washy/phasey verb artifacts and so on?

So, if you hear that, could you use something to Bx Control or some other MS tool to pull the mono component forwards easily, leaving a pleasant to listen to single surround channel?

Then I guess there's the issue of perceptual loudness, to match the intensity of the summed version?

Thoughts? Georgia, Gary, Charles, Minister, Henchman, DrS, et al?

I realise the LtRt of the 5.1 mostly makes an LCRS version redundant but for some reason its still on some deliverable schedules over here.

[kk@jamsync.com]

Why not just mix the proper LCRS and matrix with the proper sw? Adding Ls and Rs and then tossing out information and THEN matrixing to Lt Rt doesn't make a lot of sense. If the target is using a ProLogic II decoder, you run the real risk of throwing out information that is useful.

One reason to mix proper stems for LCRS is that the LFE is thrown out on downmix from 5.1 to LCRS in traditional downmix algorithms.

This is the reason that for over a decade when we have delivered DVD masters, we've included (if bandwidth allows) a PCM LtRt as well as an AC3 track. It takes a little longer (but not much if you know what you're doing), but it's worth it. Assuming that the target audience will know how to set the decoder is another thing...

[ggegan]

Originally Posted by Brent_in_Sydney

Hi guys,

Just wondering if the gurus in the room could shed some light on the old school LCRS 4 channel deliverable. In particular the surround channel.

If you just sum the Ls and Rs from a 5.1 mix, depending on content, aren't you likely to get washy/phasey verb artifacts and so on?

So, if you hear that, could you use something to Bx Control or some other MS tool to pull the mono component forwards easily, leaving a pleasant to listen to single surround channel?

Then I guess there's the issue of perceptual loudness, to match the intensity of the summed version?

Thoughts? Georgia, Gary, Charles, Minister, Henchman, DrS, et al?

I realise the LtRt of the 5.1 mostly makes an LCRS version redundant but for some reason its still on some deliverable schedules over here.

I haven't had to deliver a discrete LCRS print master in several years. I would just sum ls and rs. It should be fine.

[georgia]

I agree with Gary... just listen to it! both in the mix and soloed a few times here and there.... just make sure it sounds ok and is appropriate for the mix.


cheers
geo

[kk@jamsync.com]

Originally Posted by ggegan

I haven't had to deliver a discrete LCRS print master in several years. I would just sum ls and rs. It should be fine.

And what would you do with the LFE? Just toss it? I wouldn't.

I think you at least have to mix the LFE back into L and R...otherwise it doesn't matter whether the mono surround sucks or not. My pref would be to remix, but then I've only done a couple hundred of these...and the original poster asked about 5.1, not 5.0 discrete.

[minister]

Hi Brent,

Gary and Georgia gave you the short answer.

The other short answer is, the LtRt is always a compromise (unless you are mixing a Woody Allen film).

But, it looks like you are asking more of a theoretical question. Are you? Or a practical mix deliverables question? Almost all of my deliverables include an LtRt, if not as a matrixed 2-track, but the stereo version. Also, remember, for foreign deliverables, they will use the LtRt for a lot of things, even if you distribute domestically in 5.1.

For what it's worth, I have heard also some people say (including a Dolby Engineer) that they like the "blended" sound of the LtRt, it sounds more "like a film".

In regards to summing Ls and Rs, if you do it through a Dolby encoder, it takes care of it for you. Are you using and Encode/Decode setup?

You will find that the S can sound kind of "closed in", and something like this "strange shaft of sound" (my image) going down the center of the back half of the room. You may also find that with stereo music that is matrixed to either derive a surround, or simply sent to there through steering and the mix matrix, that it sounds "phasey", "pumpy" and ugly. But this is usually when you just focus on the S and not the LCRS. I find if I solo the S, I am aghast! But when I put it all together, it is usually better than plain vanilla stereo.

Tricks for improving the S include adjusting the delay and EQ'ing busses sending to the sides material that is being summed into the matrix. But this is not a default position. I start with a standard matrix and listen. Most of the time it works.

Problem with your idea of introducing a MS processor to derive a MONO and steer it forward is you have now too much signal in the C as that is where it will go. The MS process is not different enough from the encode to be of all that much value. And, you will have to make sure it survives the decode process.

Oh, and I do fold in some LFE content to taste.

[kk@jamsync.com]

Originally Posted by minister

In regards to summing Ls and Rs, if you do it through a Dolby encoder, it takes care of it for you. Are you using and Encode/Decode setup?

......

Oh, and I do fold in some LFE content to taste.

The DP563 allows for soft limit on the LFE before it is added to L/R. Somehow I don't think the original poster is using one...not the short way to do it, maybe, but per Dolby spec.

[ggegan]

Originally Posted by kk@jamsync.com

And what would you do with the LFE? Just toss it? I wouldn't.

I think you at least have to mix the LFE back into L and R...otherwise it doesn't matter whether the mono surround sucks or not. My pref would be to remix, but then I've only done a couple hundred of these...and the original poster asked about 5.1, not 5.0 discrete.

No, I wouldn't toss it. I would band pass it at around 40Hz to 80Hz, delay one side slightly (enough to fool the matrix into thinking it is stereo instead of 2 track mono, but not enough to cause excessive phase cancellation) and bus it L/R. I was just addressing his question about the surrounds.

No Hollywood producer I have ever encountered would pay to remix a film in LCRS on a stage - they might pay for it to be done in transfer, but more than likely they'd just say, "Screw it, give me the LtRt and call it a day."

[Brent_in_Sydney]

Sorry for the confusion here. Its a deliverable. We've done 5.1 mixes in 24 and 25 and 2398. We also have MEs in 24 and 25 and all the above included LtRts generated from the 5.1s so the LtRts are covered.
So to be clear we have 5.1s and LtRts thereof.

The deliverable sheet also requests an LCRS discrete 4 track mix of the ME. In addition to the 5.1 and LtRt (generated from the 5.1).
Seems odd and I'm guessing its a producer covering all their bases for wider markets.

Regards the LFE, I think the best advice Ive had to was bring a bit of that into C to taste, so it best represents the 5.1 which is what Ive done.

My question is a bit theoretical about the Surround channel and if anyone had been here before, summing the Ls and Rs should be fine to all accounts but Im hearing some washyness that making it more mono would remove and "clean up" so it sounds nicer. Stereo/Quad verbs are phasing in the rear surrounds and purely summing them is making for a bit of unpleasantness in mono.

I was just wondering if anyone with more experience could shed some light on best practices in this sort of situation. Id prefer a nice sounding discrete S channel. Hopefully that's clearer?

[kk@jamsync.com]

Originally Posted by Brent_in_Sydney

I was just wondering if anyone with more experience could shed some light on best practices in this sort of situation. Id prefer a nice sounding discrete S channel. Hopefully that's clearer?

You need to mix it and be happy with LCRS (or find a DP563 and use that). If you sum and are unhappy with that channel and then you "tweak" it to make it sound better, you will get that mix on decode, but it will *not* necessarily resemble the 5.1 mix or the LtRt you already have. You cannot break the laws of physics. If the summed surround channel sounds "wishy-washy" to you, that's not good. You need to deliver an acceptable mix that will decode properly. Anyone who tells you different, guru or not, is not telling you helpful information.

Best option would be to get hands on a DP563, encode it, decode it and listen to that. If the best advice you've had about the LFE is to put it into the center, I'd suggest you read the docs on the DP563 (and other tech docs) which say to put it in L/R. This has been common technique for years, so I'm not sure what kind of "guru" would give this advice.

Wishy-washy means flanging to me. Somehow you need to get FX in that mono channel that sound right to you, but still sound very close to the 5.1 mix and the LtRt decode.

[kk@jamsync.com]

Originally Posted by ggegan

but more than likely they'd just say, "Screw it, give me the LtRt and call it a day."

He's not in Hollywood and he ALREADY HAS AN LtRt! Not an answer that works for him. I'd go with the DP563...they have those in Hollywood don't they?

[minister]

Hi Brent,

Excuse me if this seems simple-minded, but, since you made LtRt's, then you heard the LCRS, right? I mean, you monitored it decoded as a discrete LCRS 4-channel mix. So, if you like the LtRt, then just print off of the LCRS decode monitor in the session.

And Gary gave you one of the best tricks for folding in the LFE to the LtRt.

[Brent_in_Sydney]

chuckles. There are no simple answers... Thanks so much for your patience all.
I generated the LtRts using Neyrincks SoundCode Stereo LtRt from the 5.1s, at no point have I got a 4 channel mix until now. Hence the problem.
The LtRts sound great as stereo, but there's no decoder in that package to break them out to 4 channel.

The original question to the room was about generating the 4 channel mix from the 5.1 printmaster without doing an encode decode pass to try to keep it as close to the PM as possible. Specifically, issues relating to phasey content in the surround(s).

I tried using the old Dolby surround tools plug to decode the LtRt generated but found it to be washy in the surround channel also. (similar to simply summing the LsRs from the 5.1...which is to be expected in theory)

Is the Dolby surround tools plugin to be trusted? I don't have any dolby hardware to do this sort of thing. If the plug is to be trusted then I guess I'll have to play around with the 51 stems and re-balance the surround diffusion to make a mix that encode/decodes to LtRt more effectively than the one IVe been given from the dub stage (!). I'm guessing the mixer has put too much movement in the surrounds, I just would have thought he would have been ABing this sort of thing before committing to the final stems and printmaster on the dub stage with his fancy DFC and dolby hardware.

Incidently all, the LFE is fine and under control. I understand how to bring the LFE into an LtRt. I've always had that under control, somewhere someone misread the content of the thread and brought up LFE folddown practices but my interest here is all to do with the surround(s) and phasing/mono compatibility issues between a 6 channel and 4 channel mix.

[kk@jamsync.com]

Originally Posted by Brent_in_Sydney

Incidently all, the LFE is fine and under control. I understand how to bring the LFE into an LtRt. I've always had that under control, somewhere someone misread the content of the thread and brought up LFE folddown practices but my interest here is all to do with the surround(s) and phasing/mono compatibility issues between a 6 channel and 4 channel mix.

No one misread your post...I was commenting on the idea that just summing Ls and Rs was the only consideration put forth. It's hard to tell what someone knows beyond the question and since you mentioned 5.1, that came into play. I wouldn't put the LFE in the center channel for a lot of reasons on an LCRS deliverable.

Dolby Surround Tools 3.0 should emulate the DP564 and thus give you Pro Logic II (as well as Pro Logic). One thing Dolby is strict about is that if it's a Dolby decoder, hw or sw, it follows all things Dolby.

>>>>"I'm guessing the mixer has put too much movement in the surrounds, I just would have thought he would have been ABing this sort of thing before committing to the final stems and printmaster on the dub stage with his fancy DFC and dolby hardware."

No comment on various mixers' methods for QC...sounds like you are disappointed in the mix and mixer.

Very difficult to decorrelate 'verb that is already mixed in the stems. When you say "Id prefer a nice sounding discrete S channel. Hopefully that's clearer?" it's very clear, but again, making it do what you want will also make the QC between 5.1 and LCRS markedly different...if that's what your client intends to do.

[Brent_in_Sydney]

Sorry KK, no disrespect intended, I appreciate any and all guidance freely given and absolutely its difficult to guess what people know and don't know from bulletin board questions etc.
I think I'm going to have to make some calls on Monday about how they were monitoring their 5.1 mix for encode/decode compliance...

[kk@jamsync.com]

Originally Posted by Brent_in_Sydney

Sorry KK, no disrespect intended, I appreciate any and all guidance freely given and absolutely its difficult to guess what people know and don't know from bulletin board questions etc.
I think I'm going to have to make some calls on Monday about how they were monitoring their 5.1 mix for encode/decode compliance...

If you get a chance to post about the origin of the problem, it would be a great read. Thanks!

[minister]

You didn't monitor the downmix, LCRS, then? (I believe you need the Neyrinck Dolby E package to get the LtRt decode). If you had listened to the S, you might be shocked. Just judging the stereo playback of the LtRt and then listening to your jury-rigged S from the 5.1 mix will not tell you enough about the LtRt you have.

Since you have no way of decoding, then I would obtain one.

AFAIK, The Dolby code is the Dolby code. Paul Neyrinck is a smart guy and knows more about this, so perhaps he will chime in about that and if his diverges from the Dolby Surround Tools in the audio matrixing portion.

[kk@jamsync.com]

Originally Posted by minister

You didn't monitor the downmix, LCRS, then? (I believe you need the Neyrinck Dolby E package to get the LtRt decode). If you had listened to the S, you might be shocked. Just judging the stereo playback of the LtRt and then listening to your jury-rigged S from the 5.1 mix will not tell you enough about the LtRt you have.

Since you have no way of decoding, then I would obtain one.

AFAIK, The Dolby code is the Dolby code. Paul Neyrinck is a smart guy and knows more about this, so perhaps he will chime in about that and if his diverges from the Dolby Surround Tools in the audio matrixing portion.

He could certainly monitor LCRS (dematrixed) from the LtRt he says he has with Dolby Surround Tools that he also says he has; it did 4:2:4 from ver 1 (I beta'd it and later wrote the review for Audio Media in 1998).
If it sounds wishy-washy via Dolby Surround Tools dematrix, it will sound the same via dematrix with Neyrinck, Minnetonka, Lexicon, or DP562. You have to *license* this stuff from Dolby. It isn't art...it's a patented process.

Chapter 2 in the following doc shows you how to set up LCRS from 5.1 http://akmedia.digidesign.com/suppor..._v80_56083.pdf. You can just monitor the LCRS path rather than bussing it to the encoder.

[Brent_in_Sydney]

Originally Posted by minister

You will find that the S can sound kind of "closed in", and something like this "strange shaft of sound" (my image) going down the center of the back half of the room. You may also find that with stereo music that is matrixed to either derive a surround, or simply sent to there through steering and the mix matrix, that it sounds "phasey", "pumpy" and ugly. But this is usually when you just focus on the S and not the LCRS. I find if I solo the S, I am aghast! But when I put it all together, it is usually better than plain vanilla stereo.

OK I've had a shower and a coffee and Im re-reading everything shared and this is very telling. I was worried about the washyness I was hearing with a band playing in an arena when I isolated the S on the LCRS decode using dolby surround tools from the LtRt. "Aghast!" indeed!

I need to re-check and listen to other scenes without arenas and bands and not solo the surround and see if it is actually acceptable given the description and experience Minister shares. I just was not prepared for what I heard!
I might also get the local dolby rep in to have a listen, he works next door.

So this is pretty typical of music and big spaces on decode and I shouldn't be overly concerned? That if you solo the S it will be rather...interesting?

Also, of course, if I make it more mono it will be markedly different to the LCRS decode of the already supplied LtRt which is something to avoid of course.

Great stuff. Consider light shed!! Thank you so much to you all! I read this forum almost every day and am super grateful to all the mentoring that you guys and gals share. Truly appreciated by those of us in smaller markets OS with less apprenticeship opportunities.

[kk@jamsync.com]

Originally Posted by Brent_in_Sydney

So this is pretty typical of music and big spaces on decode and I shouldn't be overly concerned? That if you solo the S it will be rather...interesting?

It should be no more disconcerting than the solo'd center channel sans reverb to the ears of an arrogant vocalist, which I can assure you, is very disconcerting to some rock 'n' roll types who have *always* heard themselves drenched in 'verb.

You definitely "livened up" the place...