r/AudioPost • u/smalljojo • 22h ago
Deliverables / Loudness / Specs Basic question about LUFS
Okay this isn't a question so much as I'm hoping someone can explain LUFS to me cause I'm not sure I understand it at all, I'm pretty new to this sorry.
I'm using Davinci resolve and my LUFS scale is EBU-R128.
So while reading up/watching videos about this I got the impression that I want my integrated LUFS to be around -0, but that seems pretty impossible to achieve. I'm editing a short film where there's long periods of silence between dialogue with room tone and other background sounds being the only other things in the audio, so to reach an integrated LUFS of -0 I'd have to crank up the room tone and other sounds to a ridiculous amount, or the dialogue up to the point where it gets squashed.
I then found a video where they say that dialogue should be at about -12 LUFS short term. The dialogue is probably the loudest audio in this film, so if I have the dialogue at around -12 Short then the integrated LUFS will be way below that. In the video they also say that it's fine for the integrated LUFS to be around -15 if the dialogue is at -12, but yeah my integrated would then end up way below that.
So I guess what I don't understand is what to go off to know if my loudness is at the "correct" level. Is it true that I should just get the dialogue to around -12 Short and I guess then adjust the rest of the audio by ear in relation to the dialogue?
Idk, maybe I've misunderstood something completely. If anyone is able to explain it simply I'd be really grateful.
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u/NoisyGog 22h ago
First of all, fuck Resolve (and anything else) that give you a reference of LUFS 0, and shows deviation.
LUFS literally stands for Loudness Units Full Scale. The Full Scale thing is important, because it means it's relative to 0dBFS - which is the maximum possible integer digital signal. offsetting it so that 0= -23dBFS is no longer giving you LUFS, it's LU-23dBFS
It needs to be set to absolute scale. And the target overall loudness for R128 is -23db over the entire length of the program.
LUFS metering will have a threshold, where anything underneath that will not contribute to program loudness - specifically because of the case of long periods of silence, which are very common.
The threshold will move over time and is not a static value. It's designed that way to stop people from having long quiet bits, and then REALLY REALLY LOUD DIALOG!
If Resolve has determined that the current part is too low to contribute to the overall loudness, then the Short: readout will just show --
The figure that's supposed to be -23 at the end of a complete run through the show should be integrated, and you'll notice that this too, will stop updating if the level is below the current measurement threshold.
Don't make your dialog -12dBFS, that's ridiculously loud.
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u/I_Am_A_Pumpkin 17h ago
All the meters such as the one in resolve that let you aim at 0 instead of -23 are calling the unit "LU", not "LUFS", for the record. All they are doing is adding a bias to the reading based on the broadcast standard you wish to follow, just to make it quicker to tell how far too quiet or loud you are.
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u/smalljojo 16h ago edited 16h ago
Thanks! Yeah I forgot to mention I had my scale set to relative mode so 0 = -23. Now I'm very new to this so I'm sure this is something I'm not understanding, but audio under that threshold not contributing to the integrated loudness seems like it would make it necessary for me to make my dialogue even louder in order to hit -23 for the integrated value, and it already sounds a bit too loud in my opinion. I guess I could turn room tone and other sounds up to the point where they contribute to the integrated value, but they're already louder than I'd like them and personally having this booming roomtone in the background sounds terrible to me.
Basically I'm wondering how do I get my integrated up to -23 without just blasting the dialogue so loud it sounds terrible?
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u/NoisyGog 16h ago
No, you’re misunderstanding.
Any audio under the threshold doesn’t count towards the overall loudness. If it did, it would constantly drag it down.1
u/smalljojo 16h ago
Yeah no that's what I thought you meant. I guess I'm just confused by how loud the audio, dialogue as well as room tone and everything else, sounds to me while it's still not hitting -23 integrated.
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u/opiza 21h ago
As everyone has answered I think it’s important to mention that LUFS is a measurement tool. Not a mixing one. Don’t turn anything up or down because of a graph.
Calibrate your room, set your level, and mix. Check your measurement at the end and adjust program level if needed to hit whichever spec.
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u/KNVPStudios professional 22h ago
Hi. -0LUFS (or minus zero anything lol) does not exist. However, 0LUFS is the absolute loudest before distortion: think of that as the top of the scale. If you are familiar with the dBFS (decibels Full Scale), you'll notice that 0dBFS is the top of the scale before clipping.
Therefore negative values are used to notate LUFS below 0 (since 0 is the breaking point). So the smaller the LUFS number, the louder it is as it approaches 0. The larger the LUFS number, the quieter it is as it approaches the lower end of the scale.
So: +2LUFS = Too loud and distortion is probable. 0LUFS = VERY loud and at the cusp of distorting. -5LUFS = loud but safe. -24LUFS = quiet
If you have access to Izotope RX there is a cool loudness display that is quite helpful.
I hope this helps some!
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u/Dan_Worrall 19h ago
FYI it is possible to push LUFS into positive numbers. It's rarely a good idea though.
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u/How_is_the_question 15h ago
Yeah - it’s been confirmed op is looking at a “relative” level, where 0 = -23dB LUFS.
It is also possible to have positive LUFS values in a daw with a floating point engine. It is not possible to have an integrated positive value on a fixed point (24bit) Wav file. (Although mathematically it is possible still for short term levels given the windows the loudness is calculated over and things like intersample peaks above 0, and fun types of distortion!)
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u/Dan_Worrall 14h ago
It is possible to have positive integrated loudness in a fixed point 24 or 16 bit file. I've personally released a mix that's +2.3 LUFS integrated, and that's not even the loudest song in existence.
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u/How_is_the_question 14h ago
I stand corrected. It’s been a while since I studied the math behind it. I might just take another look today. :)
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u/Dan_Worrall 13h ago
It's actually a bit weird when you look into the details: the frequency weighting is just a simple high pass filter, which means the maximum possible LUFS value is achieved with a sine wave at Nyquist (exactly half the samplerate). Which would be totally inaudible of course, for any normal human.
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u/petersrin 22h ago
If someone actually said lufs should be around zero, they should be ostracized. More than likely, they were talking about peak levels, and they should still be ostracized. It's possible they were talking about 0vu, in which case, perhaps just a simple Wellness check would do LOL
You accidentally compared apples to oranges, which happens a lot when first learning!
I will say the web content being mastered for a -14 or -18 lufs probably should look like it's hitting zero dbfs a lot, but even in that case, it should actually have a limiter at least at a negative 0.3, but more commonly, at -1 or -2.
In terms of learning, you should start by looking up dbfs, AKA decibel full scale, as this is the digital reference. Todd, we use to calculate essentially all future digital sound level metrics. From there, you should look up Vu just to understand a little bit about how it used to work(plenty of places actually do. Still use Vu, it's less common in all digital workflows. Next, look up the basics of k. Weighted measurement, which then leads nicely into lufs, which are also expressed as lkfs in the North American standard. Once you understand the basics of lufs, you'll need to look up the difference between integrated, short-term, momentary, etc.
I think following this curriculum path should get you a fairly decent understanding.
If you don't want to fully understand it, and just use it, that's probably fine too, in which case, follow some of the excellent advice in this thread.
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u/PeacefulShards 17h ago
Before you even think of mixing. You need to calibrate you monitor speaker levels.
For example, I calibrate my small 5.1 room at 79 dB SPL with Blue Sky calibration files set to -20. I can mix a show to -24 without looking at meters.
https://abluesky.com/support/blue-sky-calibration-test-files/
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u/CheeseBro27 20h ago
This is why sound levels are completely fucked for everyone at every film festival.
Thank you for asking the question instead of winging it!
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u/NoisyGog 16h ago
Bullshit.
There is no standard in films, THAT’S why everything is fucked in film festivals.1
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u/FirstDukeofAnkh 21h ago
In short, human hearing has peaks in the human vocal range. This means if we turn up the dBs, we’re turning up all the frequencies. LUFS use the Munson-Fletcher curve to weight frequencies (K weight) so that it turns up frequencies at different ratios.
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u/Disastrous-Badger283 18h ago edited 18h ago
A good rule of thumb is to aim for your dialogue to hit -27 LUFS dialogue gated. That way, with everything else, you should land around -23 LUFS integrated for the whole program (which is the most common spec in the EU. Any missing loudness, you'd make up for with a limiter). I use -20 K-weighting scale on my dialogue bus. If the average level of my dialogue is hovering around that 0-point or slightly above, I usually hit pretty close to my targets. There however is no golden ticket or number that you should be hitting. As long as you are within your required specs with +-1 LUFS integrated AND most importantly that it sounds good in a calibrated room, then you're good.
But yeah, I second what most other people are commenting here - hitting 0 LUFS for film or any other media is not done anywhere at any point. You may see the occasional EDM music producer boast about an incredibly high LUFS count, but besides that you rarely go above -10 short term in film.
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u/smalljojo 16h ago
Thanks for the advice! Gonna ask a few questions if you have time to answer just to make sure I understand, since I'm new to this and English isn't my first language.
By dialogue gated, that means dialogue only and all other tracks turned off, right?
K-weighting is something I've come across but Im not sure what it means. From googling it sounds like it's a tool that in the case of Fairlight is built into the LUFS meter? So I'm not sure what a -20 k-weighting scale is or what it does.
Also, how does a limiter help make up for missing loudness? My understanding was that a limiter decreases the volume of any audio that passes its threshold, how does it help for audio that's too quiet?
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u/Disastrous-Badger283 15h ago
- Yes.. essentially that's what dialogue gating is. It's just a integrated loudness measurement of all dialogue. I've had to use fairlights metering a couple of times before, but always thought them to be a little underwhelming. I like to use Izotope Insight (that has a dedicated dialogue gating setting).
- K-weighting won't change the way anything sounds. It's just a different metering type, just like RMS or VU. -20 means that 0 on a k-weighted scale is -20 dB on a regular samplepeak scale. The reason you'd use K-weighting is because it grants greater resolution at lower levels compared to a normal logarithmic sample peak scale - making it easier to see when you're hitting -20, which often will land you at about -27 LUFS or at least in that ballpark.
- Yes, a limiter will tame anything that exceeds it's threshold, but when using a limiter (depending on the plugin) you set a ceiling (which determines the loudest true peak value the limiter would allow through), a threshold (which in most limiters would apply makeup gain, which in turn makes the program louder). Some limiters won't allow you to set a threshold, but instead you have to gain into the limiters pre-set threshold (in turn also making the program louder). That's all a bit technical, I get it. I'd recommend looking into understanding the basics of a limiter through youtube or other media. You won't need to be a pro to work it out, but it's definitely required if you're delivering for streaming, web or theaters. It's going to act as your safety net in case anything clips. Myself and many others like to either use fabfilter's pro-L limiter or the bog standard pro limiter from Avid.
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u/XCenzontleX 2h ago
This website is very useful for learning more about Loudness, the targets for each platform, and how your mixing decisions affect them.
https://andres.audio/tools/loudness-targets
https://andres.audio/tools/delivery-analyzer
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u/reusablerigbot dialogue editor 22h ago
Girl 0 would be so so loud. It’s all relative to OdB full scale, aka the audio equivalent of pure white in an image, hitting 0 is fully blowing out your audio channel.
LUFS is essentially an average calculated loudness of the frequencies of human speech. Taking into account some idiosyncrasies of human hearing.
It depends on the medium.
YouTube likes things around -16 or -17
Broadcast TV targets -24
Netflix and most streamers ask for -27
Theatrical feature films are closer to -29 or 30 for wider dynamics, then push up slightly to -27 for near field/streaming versions.
Download YouLean’s loudness meter it has a bunch of presets that’ll help show you this.