How do i create an LtRt mix from 5.1?

[Andy Hay]

Hi,

So I'm tweaking and then laying back a 5.1 mix this week - short film. What do I need in order to also derive an LtRt mix from the 5.1 mix?

cheers
-andy

[JKD99]

Hi
If you're talking about a true, matrixed Lt/Rt (not Lo/Ro stereo), then you need to either use the hardware Dolby encoders which are readily available from a few rental houses here in LA, or you need to use Dolby Surround Tools or SRS Circle Surround to do the matrix encoding.

Hope this helps, good luck!

[Mixchump]

Here's what I do, you can try this and see if it works for you.

Create a 5.1 Mix Bus and assign all your mixer channels to it. In your IO setup, go in and create a bunch of Mono Subpaths under your 5.1 Mix Bus for L, C, R, Ls, and Rs. (Normally, you don't fold the LFE channel into the LtRt mix so don't bother making a SubPath for LFE)

Also, create a stereo Bus called 'Downmix'.

Now, in your mixer, create 5 Mono Aux Inputs that are picking up the mono subpaths from L, C, R, Ls, and Rs, and are each assigned to your new stereo mix bus called 'Downmix'. Make sure you Solo-Isolate all of these Aux inputs.

Now, you can create two Audio Tracks in your session for laying mix stems. (one 5.1 audio track, and one Stereo audio track). You'll probably want to assign the output for the Downmix track to output 7&8 on your interface...

You can monitor your mix by putting the two audio tracks in 'Input' Mode (providing you're running 6.4x). If you're running an earlier version of ProTools, then create a couple of Aux Inputs (a 5.1 and a Stereo) for monitoring these two busses.

You can now pan the L, C, R, Ls, and Rs downmix channels to where they should be in the downmix, and play with the levels.

When you're ready to lay the mix, just arm the two audio tracks and press F12

It's just that simple.

Nice eh?

Cheers...

[Andy Hay]

Re: Micxchump's approach - is that all that the software encoder is doing also? Would a mix created through MixChump's approach decode correctly through a Dolby decoder? Hmm....

[JKD99]

Hi
Mixchump's approach is a stereo (Lo/Ro) folddown, and works fine. However, it is NOT an Lt/Rt.

Lt/Rt means "Left Total/ Right Total" and denotes a matrix-encoded LCRS mix, 4 channels encoded onto 2, and de-coded back to 4 when played through a Dolby (or similar) Decoder. When "The Simpsons" says "Broadcast in Dolby Surround", this is what you hear. At a theater, when you see Dolby SR, or Dolby Stereo, you're hearing the film version of the Lt/Rt which requires Dolby to be at your printmaster.Straight, plain-vanilla stereo (like a typical CD) is defined as "Left Only/ Right Only".

This mis-conception (unfortunately) happens all the time, where people say Lt/Rt when they mean Lo/Ro, and vice versa. So, be sure of your delivery requirements:)

If you're making an Lt/Rt, you need to be monitoring throgh the encode/decode processing, as strange things can occur. Thimgs like music collapsing to mono, and dialog being "hooked" into the surrounds or at least off-center by string pads in the same frequency range, etc.

Check out dolby.com, and read all the Dolby stuff in the "Room Calibration" thread for more info.

Hope this helps, good luck!

[dr sound]

Once again Joe is on the money. I was going to post a reply but i think "JKD99" said it better than I could!

[JKD99]

awwwww, shucks!
And how 'bout that there "The Grudge"? Numero uno again! Way to go!

[dr sound]

Poster: JKD99
Subject: Re: How do i create an LtRt mix from 5.1?


awwwww, shucks!
And how 'bout that there "The Grudge"? Numero uno again! Way to go!

Joe,
Thanks!
Give me a call.

[jimlongo]

If you're talking about a true, matrixed Lt/Rt (not Lo/Ro stereo), then you need to either use the hardware Dolby encoders which are readily available from a few rental houses here in LA, or you need to use Dolby Surround Tools or SRS Circle Surround to do the matrix encoding.

Hi,
Does the Waves Surround bundle do this properly?

Mixchump's approach is a stereo (Lo/Ro) folddown, and works fine. However, it is NOT an Lt/Rt.

Lt/Rt means "Left Total/ Right Total" and denotes a matrix-encoded LCRS mix, 4 channels encoded onto 2, and de-coded back to 4 when played through a Dolby (or similar) Decoder. When "The Simpsons" says "Broadcast in Dolby Surround", this is what you hear. At a theater, when you see Dolby SR, or Dolby Stereo, you're hearing the film version of the Lt/Rt which requires Dolby to be at your printmaster.Straight, plain-vanilla stereo (like a typical CD) is defined as "Left Only/ Right Only".

This mis-conception (unfortunately) happens all the time, where people say Lt/Rt when they mean Lo/Ro, and vice versa. So, be sure of your delivery requirements:)

If you're making an Lt/Rt, you need to be monitoring throgh the encode/decode processing, as strange things can occur. Thimgs like music collapsing to mono, and dialog being "hooked" into the surrounds or at least off-center by string pads in the same frequency range, etc.

Check out dolby.com, and read all the Dolby stuff in the "Room Calibration" thread for more info.

Hope this helps, good luck!

If I'm watching the Simpsons on my 17" tv in the kitchen am I listening to the Lt/Rt mix undecoded?

Quite a few broadcasters are asking for 5.1 and stereo. They are doing any matrix encoding for broadcast or DVD. So do you think that in that scenario the Lo/Ro mix (or a simultaneous stereo mix in ProTools) is acceptable?

TIA,
jim

[dr sound]

Jim,
The "Waves 360" folds a 5.1 into a Lo/Ro not a Lt./Rt.
You have to go through a Dolby Matrix (or even a SRS Circle Surround) to get it properly.
Also when you are listening to a Lt./Rt. by itself played back on your Stereo TV (through the small front speakers)and not through a receiver playing through the built in Dolby decoder, you can hear out of phase information playing very wide usually on one side of the speakers. It’s like your mix is out of phase but only a part of it such as whatever the Re-recording Mixers sent to the Matrix in the rear speakers such as BG's or Music reverbs delays etc. For the cost of a plug in such as the Dolby Plug in or Circle surround Plug in (somewhere around $650) you can encode/ decode and hear what it will sound like to those at home both with and without a decoder. It is a small price to pay and it makes your studio much more competitive in the marketplace by offering something a competitor might not. I've done only a handful of projects since 91 that haven't been mixed in surround. It makes the client’s product more valuable for future use since it is "Mixed in Surround"!