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-   -   automatic loudness correction that can handle split stems too? (http://duc.avid.com/showthread.php?t=404825)

alexeymohr 05-20-2019 05:06 PM

automatic loudness correction that can handle split stems too?
 
I'm looking for a plugin-based workflow for doing broadcast loudness correction to both my full mix stem and split stems.

I understand that the correct answer for broadcast loudness compliance is to get the mix right in the first place. But the fact is that sometimes schedules don't allow for leisurely mix tweaking to get 100% perfect LKFS compliance.

So I'd like to use a plugin like iZotope RX Loudness Control or Nugen LM-Correct to do that final adjustment for me. But here's my main concern:

I have to deliver a full mix stem and a huge array of split stems for any given program (dialog-only, VO-only, MX-only, SFX-only, etc). My splits stems, when played together, must equal my full mix stem. If I only do LKFS-targeting level adjustments to the full mix stem with one of these plugins, the splits will no longer match it.

So, does anyone know of a loudness correction plugin that allows for the same exact loudness adjustments to be made to the splits as the full mix stem? Can either RX Loudness Control or LM-Correct do this somehow? Or is there another alternative that can?

reichman 05-20-2019 08:35 PM

Re: automatic loudness correction that can handle split stems too?
 
Whatever gain value that was applied to the full mix can be applied to the stems. Don't overthink this. Even if you use the standard issue Avid Loudness Analyzer, and it tells you your mix is, for example, 2.1 db under, just apply that change to all the stems.

For the record, I never do this. During the dialog predub I get in the zone for LKFS compliance and mix to the spec instead of adjusting afterwards. If I'm off at the end of a pass, I can trim the VCAs.

Cheesehead 05-22-2019 02:22 PM

Re: automatic loudness correction that can handle split stems too?
 
I asked Nugen about this at a trade show as its something I've always wished I could do for short form and fast turnaround TV delivery.


Unfortunately they said they understood the issue, but if they put the feature in, it could potentially lead to files that were not in spec if it was misapplied.



Personally, I would say put it in and don't make it easily accessible to anyone who doesn't know what they are doing. :confused:


I've often wondered if you analyse your mix and then rename your stem to the same as your mix, would the plugin know it was different when you hit process? Not tried it yet.

Led 05-23-2019 02:31 AM

Re: automatic loudness correction that can handle split stems too?
 
Why not just mix with realtime loudness metering? I'm with Nathaniel, it's so easy to tweek things a little here and there to comply when you are following the loudness in realtime, then your stems will sum to the right target. I find working without realtime metering a bit like driving with the windscreen covered up after getting used to it.

Although the nerd in me thinks it's an interesting mathematical question, I mean summing is just numbers in theory right..? Provided you are doing all your processing on the stem masters when you run out the full mix,
and not doing any sort of 'master bus' processing, wouldn't it just be a matter of applying the same gain (in LU) to each stem that Nugen applies to your stereo mix to get it to target? You can just analyze each stem in Nugen, then set the target to equal the stem lkfs + the amount of gain Nugen applied to your stereo mix then process.
I'll have to try it tomorrow.

its2loud 05-23-2019 06:17 AM

Re: automatic loudness correction that can handle split stems too?
 
LM correcting or any other batch processing of stems will not work. Nugen, Izotope, etc, do not know the difference between your FX, DIA, MX stems. Those algorithms only look at overall levels and adjust accordingly to make the spec. Therefore, if you run your music stem through the process to meet -24LKFS the end result will be completely inaccurate to what is in your mix.

Like others said, Meter while mixing and adjust accordingly and use the history feature in these olugins to see where things are over in your timeline.

If you still want to do a batch adjustment the do a global gain adjustment across all your files. Example, if you measure your full mix and you are +3dB over spec then lower everything 3dB. However, this will also compromise your mix as it was approved by the client and making any low level material even lower.

alexeymohr 05-23-2019 09:57 AM

Re: automatic loudness correction that can handle split stems too?
 
We're all getting too far away from the question here. Obviously the best answer is "mix it right."

But the question wasn't about that. It was specifically about whether or not any of these plugins could process splits. Clearly they cannot. I've contact both iZotope and Nugen and they confirmed that their plugins cannot do this.

The current remedial solution, when slight adjustments to the mix itself are not an option for whatever reason (if you're the transfer or layback tech and not the mixer), is to measure the composite mix stem and apply precise corrective clip gain to all the stems based on the measurement (if it's -23.5, then reduce all stems by 0.5dB. If it's -24.7, then add 0.7dB of gain).

Of course when applying negative gain this pulls your peaks down which isn't great, and when applying positive gain this probably pushes your peaks out of spec which then requires another limiting pass. Also not great.

The better answer is for the mixer to take the same measurements, then make adjustments to VCAs that sit upwind of the limiting. But if these VCAs control individual mix tracks which live before the respective chains that contain any kind of dynamics (or even significant EQ for that matter), then there will be some amount of guess-work and trial and error involved as 0.1dB of pre-chain VCA trim ≠ 0.1dB of change in the level of the final stem in the majority of cases.

Better still is to simply instantiate AAX trim plugins just before the final true-peak limiter in any given master path and use those to make the fine-tuning adjustments to guarantee spec.

So these workflows already exist. The question was simply whether or not any of the purpose-built auto-leveling plugins were actually useful in a production environment where split stems are required. The current answer is still "no."

its2loud 05-23-2019 06:57 PM

Re: automatic loudness correction that can handle split stems too?
 
I have been know adjust my Subs in plus/minus .5 increments to adjust for mix levels on occasion. This keeps all source material processing intact and only lowers going to print tracks or through Master Fader processing to Print Tracks with minimal compromise to the original mix aside from overall Print level.

Mike Thornton 05-26-2019 12:43 AM

Re: automatic loudness correction that can handle split stems too?
 
Quote:

Originally Posted by alexeymohr (Post 2526550)
I'm looking for a plugin-based workflow for doing broadcast loudness correction to both my full mix stem and split stems.

I understand that the correct answer for broadcast loudness compliance is to get the mix right in the first place. But the fact is that sometimes schedules don't allow for leisurely mix tweaking to get 100% perfect LKFS compliance.

So I'd like to use a plugin like iZotope RX Loudness Control or Nugen LM-Correct to do that final adjustment for me. But here's my main concern:

I have to deliver a full mix stem and a huge array of split stems for any given program (dialog-only, VO-only, MX-only, SFX-only, etc). My splits stems, when played together, must equal my full mix stem. If I only do LKFS-targeting level adjustments to the full mix stem with one of these plugins, the splits will no longer match it.

So, does anyone know of a loudness correction plugin that allows for the same exact loudness adjustments to be made to the splits as the full mix stem? Can either RX Loudness Control or LM-Correct do this somehow? Or is there another alternative that can?

In my view stems cannot and shouldn't be delivered to loudness specs. The underlying principle of stems is that if you put them together in a session with the faders all at 0dB then you will get the full mix.

If you make the stems and components loudness compliant then gain changes will have been made and so when you put them back together the resulting full mix will not be as you intended and will not be loudness compliant.

My advice would be to produce a loudness compliant full mix and then output the stems that mix produced and do not worry that the stems are not loudness compliant. Only the full mix is to be loudness compliant, components like stems cannot and should not be delivered as loudness compliant as they are parts of the mix, not the whole mix.

TVPostSound 05-26-2019 11:10 AM

Re: automatic loudness correction that can handle split stems too?
 
Quote:

Originally Posted by Mike Thornton (Post 2527243)
In my view stems cannot and shouldn't be delivered to loudness specs. The underlying principle of stems is that if you put them together in a session with the faders all at 0dB then you will get the full mix.

If you make the stems and components loudness compliant then gain changes will have been made and so when you put them back together the resulting full mix will not be as you intended and will not be loudness compliant.

My advice would be to produce a loudness compliant full mix and then output the stems that mix produced and do not worry that the stems are not loudness compliant. Only the full mix is to be loudness compliant, components like stems cannot and should not be delivered as loudness compliant as they are parts of the mix, not the whole mix.

Netflix demands the DX stem match the MIX in the dial norm reading!!!

Seriously!!

Farhoof 05-27-2019 03:40 AM

Re: automatic loudness correction that can handle split stems too?
 
Quote:

Originally Posted by Mike Thornton (Post 2527243)
In my view stems cannot and shouldn't be delivered to loudness specs. The underlying principle of stems is that if you put them together in a session with the faders all at 0dB then you will get the full mix.

If you make the stems and components loudness compliant then gain changes will have been made and so when you put them back together the resulting full mix will not be as you intended and will not be loudness compliant.

My advice would be to produce a loudness compliant full mix and then output the stems that mix produced and do not worry that the stems are not loudness compliant. Only the full mix is to be loudness compliant, components like stems cannot and should not be delivered as loudness compliant as they are parts of the mix, not the whole mix.

That is exactly what the TS is trying to achieve. Apply the same gain to the stems as was applied to the composite mix. Only he is trying to find a plugin that can do it with a single press of a button instead of two.

Personally I measure how much I need to gain to be in spec and apply it to all deliverables so the stems together equal the composite mix. So that's 2 buttons, 1 for measuring and 1 for applying the +/- gain (which can be part of the print chain as well).


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