This is also why in the Netflix Audio Mix Specifications & Best Practices v1.0 Netflix state...

For best results, measure with a dialog-gated meter and aim for average dialog levels between -25 LKFS to -29 LKFS with -27 LKFS as a target. We suggest Dolby Media Meter or NUGEN Vis-LM, which should be set to 1770-1 dialog-gated.

So why would Netflix be adopting an outdated measurement protocol?

Maybe It Isn’t Such A Crazy Idea?

In my article Loudness and Dialog Intelligibility in TV Mixes - Are TV Mixes Becoming To Cinematic? we learn that a number of broadcasters have added LRA recommendations to their delivery specifications.

The Digital Production Partnership (DPP) recently updated their unified UK delivery specs for all UK broadcasters and added this Guidance On Loudness Range…

Loudness Range - This describes the perceptual dynamic range measured over the duration of the programme - Programmes should aim for an LRA of no more than 18LU

Loudness Range of Dialogue - Dialogue must be acquired and mixed so that it is clear and easy to understand - Speech content in factual programmes should aim for an LRA of no more than 6LU. A minimum separation of 4LU between dialogue and background is recommended.

In Canada, the CBC and Radio Canada both now require that the LRA be less than 10 and some request 8. Also, the Integrated loudness for the complete program AND the integrated loudness of the dialogue stem must BOTH be -24 LUFS. Lastly, the momentary loudness must not exceed +10LU above the target loudness. So with a -24 LUFS target there, your momentary must always remain below -14 LUFS.

In my conclusion I suggested...

I completely agree with the Canadians in specifying the loudness for the dialog stem, it is almost as if they are resurrecting the old Dolby Dialnorm. Dialog is key and I always prefer to set the dialog to be around target loudness in my loudness planning and then build everything around it.

We need a way to measure the dialog level. We could just take the centre channel, but that is only possible on 5.1 systems. Also, dialog can be in other channels of a 5.1 mix although I am not a fan of this as divergence can result in comb filtering especially when it comes the downmix and have a negative impact on intelligibility.

What we need is an algorithm that can analyse a mixed track and extract the dialog. Then use that to measure the dialog component of the mix.

This would need a new piece of code to be developed and then approved by the standards authorities which could take years or we could use ‘one we made earlier’ in the Dolby Intelligence algorithm, which is now freely available for any brand to use in their loudness metering products.

It turns out from conversations with developers that although it is relatively old code is still remarkably fit for purpose. There is no doubt that a new algorithm could be developed using all the research and work that has been done by the likes of iZotope with tools like Dialog Isolate but as I have said, all of this would take time and then would need to approved and made available to everyone, which would be a licensing challenge, to say the least.

What we have with the Dolby algorithm is a ‘fit-for-purpose’ solution, with a proven track record, that Dolby has now opened up for anyone to use without charge. This means we have a solution that enables us to measure both the loudness of the dialog in a mix as well as the possibility to measure the LRA so that the dynamic range of the dialog can also be specified.

Changes To LRA

Staying with LRA - reading the Netflix Audio Mix Specifications & Best Practices v1.0 they provide LRA recommendations…

The following loudness range (LRA) values will play best on the service:

5.1 program LRA between 4 and 20 LU

2.0 program LRA between 4 and 18 LU

Dialog LRA of 7 LU or less

Difference between FX content and Dialog of 4 LU

This includes a Dialog LRA. It is not clear exactly how this can be measured yet as BS 1770 doesn’t have a Dialog LRA as until now it hasn’t been possible to do. You could put a BS 1770 based loudness meter across the dialog stem in the mix, or for complete mixes, you could put a loudness meter on the output of the Dolby Dialog Intelligence algorithm.

Whilst we are on these Netflix recommendations and LRA, it is my view that an LRA of 18 to 20 is way too large as an acceptable maximum LRA.

Look at the Canadian recommendations, they require that the LRA be less than 10 and some request 8. The DDP delivery spec here in the UK says that programmes should aim for an LRA of no more than 18LU (which I think is still too high for domestic consumption), that the dialog LRA should be no more than 6LU in speech programmes and a minimum separation of 4LU between dialogue and background.

Do these not look remarkably similar to the new Netflix delivery spec? My only concern is the overall LRA of up to 20.

Consumers Are Still Reaching For The Remote Control

It is my view and experience, even with a decent quality speaker system in a relatively quiet living room, that a mix with an LRA of 18 to 20 is far too much, we find ourselves reaching for the TV remote to adjust the volume during a program, and that for me is a fail.

Remember that one of the key reasons for introducing loudness normalisation workflows was to stop consumers from having to reach for the remote control during a program, across program junctions or when switching from one channel to the next. So if a mix has an LRA that is too large like The Grand Tour or Blue Planet as I outlined in my article Are TV Mixes Becoming Too Cinematic? so that consumers have to adjust the volume, then we need to do something about it, which is what broadcasters like Canadians and the British are doing with their revisions.

The other issue I discovered when I studied The Grand Tour and Planet Earth 2 was that the dialog loudness had been pushed down because the integrated loudness had been skewed by the use of extended sequences of loud dramatic music and effects. We are lucky that we have a living room with a relatively low ambient noise level. A lot of domestic environments will be much noisier than ours.

All of which makes me question the underlying validity of offering content with a high dynamic range as permitted by Netflix and others. Our experience as a family is that it is these very networks, where more dynamic mixes are permitted, these are the very networks that we have to turn on the subtitles for, to save us from constantly turning the volume up so we can hear and understand the dialog and then turning the volume down when we get to the loud dramatic music and effects.

But if the mixes did not have extended loud sections then surely the dialog would not be pushed down as far and the LRA would not be as large?

So Why Does Netflix Have Such A Large LRA?

I can see why Netflix might want a delivery spec with a wider dynamic range because a lot of their content was made for the big screen rather than the small screen and it seems they have been transferring the same production values to the content they commision for the small screen. The ethos that they can transfer the content from the big screen to the small screen in my view is flawed. Commenting on my recent article Loudness and Dialog Intelligibility in TV Mixes - What Can We Do About TV Mixes That Are Too Cinematic? Reid Caulfield referring to the new Netflix specs says...

Mixes meant for the "At-Home" environment MUST be mixed - or remixed, if it was originally done in a large theatre - in a near-field environment at 79dB. NOT a large theatre at 85 because someone needed to fit 40 people in the room. And, it cannot be mixed in that large environment simply with the large speaker arrays turned off and the near fields turned on. It needs to be mixed in a much smaller TV-oriented room.

He then suggests how this could be policed...

By specifying all elements be delivered in a Dolby Atmos-At-Home "wrapper." Even if the show has not been mixed as an Atmos presentation, by specifying delivery as an ADM file, they guarantee that the source room's size data and speaker layout is included in the associated metadata that travels with the data file and program content.

I couldn't agree more about the need to remix cinema content or mixing content commisioned for consumption "At-Home" in smaller spaces at a more appropriate monitor level, like 79. I like his idea of using the Dolby Atmos-At-Home Wrapper as it will include the metadata of the room it was mixed in.

But until the powers-that-be take up Reid's suggestion what can we do about mixes that have an excessive LRA for domestic consumption?

Let’s Do Some Tests

In the latest Netflix delivery specs, the Dialog Target loudness with the Dolby Dialog Intelligence Gating at -27 LKFS seems to be on the low side to me. When I am mixing to R128 I aim to get my dialog to be close to but just under the target loudness of -23 LUFS (remember LUFS and LKFS are the same) which makes the Netflix dialog gated target of -27 LKFS, 4 LU lower, but in reality does that make the dialog lower or is it similar to the dialog in a conventional BS 1770 mix?

To find out I tested some examples I have referred to in previous articles when I looked at The Grand Tour and Blue Planet to see how they fare using the Dialog Gated settings as well as 2 examples of broadcast documentaries I have mixed.

Cow Dust Time was a documentary I mixed for BBC Radio 3. This is the public service classical music channel here in the UK and the house style permits a wider dynamic range and also it was for the strand Between The Ears, which is a strand where the brief positively encourages soundscapes and more sound design, than most radio documentaries.

Doctor’s Dementia was a more conventional documentary for BBC Radio 4, the public service speech channel here in the UK.

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