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Surround Downmix
Old 14th December 2017
  #1
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Surround Downmix

Hi,

I have recently started to do post production for some short movies and I have following question. When mixing a 5.1 version of the project are you doing a completely new mix for stereo or are you relying on the downmix sheme that advices you to lower the rear and center at -3db?

Having the surround mix done, i would save the project as a new file and start to assign the tracks to a stereo masttrack and adjust the levels of the single tracks etc.

What is your workflow when downmixing a 5.1 to a stereo mix. And how do you deal with changes coming from the client after you have completed both mixes.
Old 14th December 2017
  #2
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Andrew Mottl's Avatar
 

Hey there,

a common way would be to export (re-record) 5.1 (or whatever the groups are in size) stems of at least Dia, FX, Music (you could break up into ambiences, foley, sound designy stuff etc.) and import these into a new project to downmix manually like you mentioned.

If you destructively re-record changes into your master project then those stem file changes appear in your downmix-project too.
It's great if you get/have the time to do these kinds of detailed downmixes! Then again, it is sometimes pretty difficult on quiet films as you might end up altering the balances of things by changing levels/processing (I once had a director who was very sensitive to this kind of thing, ambiences, piano music reverbs etc.)

Hope this helps!
Old 14th December 2017
  #3
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Leverson's Avatar
I rely on the standard ITU downmix formula (-3 C, -3 Ls & Rs). If you create a separate project file and remix everything for stereo, you hit problems with it a.) taking more time, which is not often a luxury that films have, b.) it makes changes far more complex as now you have to track any changes across multiple project files and that can be a huge pain, and c.) depending on where you are delivering some broadcasters or distributors will discard your stereo version and make their own fold downs from your 5.1 anyways so you want to make sure everything sounds the best it can be from that.

It is far FAR simpler to use the same session and route your main stem audio to separate downmix buses and print tracks. And also to keep the stereo downmix in mind when editing and mixing in 5.1. Be aware of when you are placing sounds all around how they might downmix and how things might play in stereo, be aware if you are putting mission critical stuff in the surrounds only (generally not advised), and if you are upmixing music make sure to use one of the upmixers that offers a perfect downmix that preserves the original stereo.

If you need to make separate stereo adjustments you can use the downmix buses for that, but I find mostly if I need to make adjustments to the stereo downmix they are adjustments I should probably make in the 5.1 as well. And usually over the course of a project I'll have to export out some online review mixes for various producers which means I'm making and monitoring in stereo at least some of the time as I go.

I think if you are creating different projects with different individual sound effect changes and levels changes you will be opening yourself up to a world of hurt if change notes come down the pike. Or at the very least extra effort and confusion when you are trying to track changes.

Plus if you route everything properly in your single session you can print all of your exports simultaneously if you need or are crunched on time, although I still prefer to do separate print passes just so I have one more chance to re-watch everything and catch any mistakes.
Old 14th December 2017
  #4
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Why don't use any Dolby certificated plugin for LtRt encoding?
Old 14th December 2017
  #5
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Leverson's Avatar
Quote:
Originally Posted by Jack Wong View Post
Why don't use any Dolby certificated plugin for LtRt encoding?
First off a stereo downmix isn't the same thing as an LtRt encode. When I need to make an LtRt I do, once again sending the main 5.1 stems to a separate LtRt encoder bus (or busses) with an appropriate plugin on it. But again, LtRt (Dolby Pro Logic) is NOT regular stereo. It's a phase encoded stereo/surround hybrid file.

Personally I prefer the sound of a discrete 5.1 and discrete stereo LoRo over an LtRt. But I'll deliver whatever the client or the spec sheets want. Luckily, LtRt's seem to be gradually becoming more rare over time (although slowly).

And for the record I use down mixer plugins for the stereo LoRo's as well, both Spanner and Avid's downmixer are great. Just make sure to select the ITU stereo setting so that it follows the -3 C, -3 Ls Rs standard as neither default to this.

Again, you can have one master session with all of your multiple different downmixes and deliverables within it if you use good bussing and routing.
Old 14th December 2017
  #6
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On the same topic, I was going to ask what most people do when they're not sure what the final format will be, which I've found to often be the case with short docs or art films that may or may not end up in festivals. Do you default to 5.1 and downmix for LoRo, or is it easier to work in stereo and create a new project for 5.1 afterward if needed?
Old 14th December 2017
  #7
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dr.sound's Avatar
 

Quote:
Originally Posted by seanmccoy View Post
On the same topic, I was going to ask what most people do when they're not sure what the final format will be, which I've found to often be the case with short docs or art films that may or may not end up in festivals. Do you default to 5.1 and downmix for LoRo, or is it easier to work in stereo and create a new project for 5.1 afterward if needed?
I always mix for 5.1 and give them a Lo/Ro also.
Anywhere they go to sell it will always want a 5.1

Hopefully Mr. Leverson will chime in. Doc's are one of
his specialties.
Old 14th December 2017
  #8
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Quote:
Originally Posted by dr.sound View Post
I always mix for 5.1 and give them a Lo/Ro also.
Anywhere they go to sell it will always want a 5.1

Hopefully Mr. Leverson will chime in. Doc's are one of
his specialties.
Thanks, Marti, that does seem to make the most sense. Many of these little projects that I do are pretty low-budget, but it's really not more complex to mix in 5.1. And more pleasant, too.

How do you normally go from the 5.1 to the LoRo? Downmix, or separate mix?
Old 15th December 2017
  #9
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Leverson's Avatar
I do the same as Marti, I primarily work in 5.1, even if the main distribution method will be stereo on the internet or something. If a client is sure they only want or need a stereo version I'll just do the work in that, but most of the time there is also a need for 5.1 or a theatrical version. I've done short docs for places like the NY Times Op-Docs, Field of Vision, etc etc whose primary distribution are stereo online videos, but they will often also play at various film festivals as well. My rule of thumb is that if there is a chance it'll play somewhere in a theater it is best for it to be in surround, if you have the tools and setup for it.

So to summarize, if there is any doubt, I'll work in 5.1 and downmix from there. It is much much easier to downmix from 5.1 than to take a stereo project and turn it into surround. Also easy to take something mixed for theatrical levels and boost it for TV or internet consumption. And while you can certainly upmix a stereo project into surround fairly quickly using upmixing plugins, it won't sound as good as something sound edited in 5.1 from the get go.

And like you said Sean, it's generally not too much extra effort to work in 5.1 over stereo if you have the setup for it already.
Old 15th December 2017
  #10
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We do a lot of documentaries, and everything that Leverson said is spot-on.
Old 15th December 2017
  #11
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Quote:
Originally Posted by kosmokrator View Post
We do a lot of documentaries, and everything that Leverson said is spot-on.
Cool. Unfortunately I can't use Spanner because I'm on PC, but I do find Halo Downmix to be more flexible than the Avid version.
Old 15th December 2017
  #12
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I too work on a lot of docs, and while they may broadcast (if they get a broadcast) or youtube or get sold or distro'ed on DVD etc as stereo, they will show with the filmmaker in personal appearances and festivals off a DCP. So they need both a 5.1 and a stereo mix. We don't make LtRts anymore unless someone has a contract spec for one (hasn't happened in several years now), ever since festivals and regular movie venues all went to DCP. I for one am happy about this--it eliminates most of the panic phone calls from directors showing at uncooperative or incompetent venues who couldn't make their LtRts work off of BluRay or file playbacks.
Old 15th December 2017
  #13
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Quote:
Originally Posted by seanmccoy View Post
Cool. Unfortunately I can't use Spanner because I'm on PC, but I do find Halo Downmix to be more flexible than the Avid version.
Hmm. I never missed anything from the Avid downmixer.
And as Leverson said, it's not advisable to use anything else than the ITU formula anyway if your mix goes to broadcast, because chances are very high that your stereo downmix won't ever be used. Instead the 5.1 mix will be downmixed with a standard formula, and this is the 'stereo mix' that 99% of people will listen to at home.

When mixing 5.1 for broadcast you really should listen most of the time (and make mix decisions ) to the stereo downmix, since this is the version that almost everyone will listen to later on.
Old 15th December 2017
  #14
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Quote:
Originally Posted by philper View Post
I too work on a lot of docs, and while they may broadcast (if they get a broadcast) or youtube or get sold or distro'ed on DVD etc as stereo, they will show with the filmmaker in personal appearances and festivals off a DCP. So they need both a 5.1 and a stereo mix. We don't make LtRts anymore unless someone has a contract spec for one (hasn't happened in several years now), ever since festivals and regular movie venues all went to DCP. I for one am happy about this--it eliminates most of the panic phone calls from directors showing at uncooperative or incompetent venues who couldn't make their LtRts work off of BluRay or file playbacks.
Yes indeed.
Just last week I got a panic call from one executive producer.
They somehow managed to play a stereo-only mix off some BluRay in some cinema, and apparently sound came out of all speakers.
Of course they insisted on needing only a stereo mix and no, it will never play in any theater, only TV broadcast.
Old 15th December 2017
  #15
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Lots of what I do is stereo only, but for "dual" 5.1+stereo jobs I've found that I need to be able to jump back and forth during the work to make sure both mixes are in the zone, both "legal" and in how the mix is sounding. I found that if I don't do these quick checks there are often unpleasant surprises when rendering out deliverables at the end.
Old 16th December 2017
  #16
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Quote:
Originally Posted by philper View Post
Lots of what I do is stereo only, but for "dual" 5.1+stereo jobs I've found that I need to be able to jump back and forth during the work to make sure both mixes are in the zone, both "legal" and in how the mix is sounding. I found that if I don't do these quick checks there are often unpleasant surprises when rendering out deliverables at the end.
I find I also do that, due to a combination of instinct, curiosity, and fear. It's also a good way to check how solid the phantom center is.

Which downmix plugin do you prefer?
Old 16th December 2017
  #17
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No plugin, just the "formula" mix down on separate buses, tweaked until it sounds and measures correct. In other words a separate LoRo mix going at the same time as the 5.1 to separate outputs. I have Surcode for checking 5.1>stereo.

Last edited by philper; 16th December 2017 at 01:48 AM..
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