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Measuring LUFS Levels

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Measuring LUFS Levels

Postby Mike Stranks » Mon Jun 15, 2020 8:42 am

I have the Klangfreund LUFS Meter, but haven't really used it much.

Following recent discussions here about levels in general and LUFS, I decided to explore it a bit more.

[Explanatory deviation here: I'm currently producing weekly 30-40 minute videos which are delivered via YouTube. The audio is the primary part and levels are tightly controlled. I use standard RMS level-setting on each individual clip and the overall mix is processed through a broadcast processor. So I know my levels are consistent and don't require constant level-twiddling on the part of the listener-viewer. Everything transfers perfectly acceptably into YouTube.]

In reading-up on how to use my LUFS meter to set levels I read that it's a two-stage process:

1) Let the LUFS software measure your LUFS-level by playing the required clip so that it can get the current averaged LUFS level.
2) Use the meter settings to trim your level to the desired LUFS setting.

I'm assuming this means that I have to play a 30-minute audio-track in real time to let the software analyse the levels. Is that right? If not how do I analyse the track levels in less-than-real-time?

I thenk yew...
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Re: Measuring LUFS Levels

Postby The Elf » Mon Jun 15, 2020 8:50 am

Mike Stranks wrote:I'm assuming this means that I have to play a 30-minute audio-track in real time to let the software analyse the levels. Is that right? If not how do I analyse the track levels in less-than-real-time?
I don't think you can? This is something I hadn't questioned until now, so thank you for bringing it up.

With some of the music I produce the LUFS reading can change dramatically in the last 30 seconds of a song - maybe with something less dynamic you could use a shorter section as an example for the reading to take?

I can't speak for other DAWs, but Cubase will give this information by analysing a mixed file - which is pretty much instantaneous. But I don't know of any way to do this before rendering a mix.

TBH when I first found out that this was the way we would have to measure LUFS I had to do a double-take of disbelief, but it's something I just take for granted now.
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Re: Measuring LUFS Levels

Postby CS70 » Mon Jun 15, 2020 9:36 am

The Elf wrote:
Mike Stranks wrote:I'm assuming this means that I have to play a 30-minute audio-track in real time to let the software analyse the levels. Is that right? If not how do I analyse the track levels in less-than-real-time?
I don't think you can? This is something I hadn't questioned until now, so thank you for bringing it up.

I am pretty sure there are tools that go over the sample set (the WAV file), run the calculations and return a table with the results. I vaguely remember exploring them when I looked into that a couple years back. But then, since I mix music and I have full track listens as part of my regular workflow, I always use the youlean loudness meter while I listen to the entire track without looking at the DAW, so I've never really explored them.

But you need either to bounce (and run the tool on the WAV file or whatever format you have and is accepted by the tool) or to play it in real time.

Check for example http://r128gain.sourceforge.net/ and https://www.orban.com/meter but there are others
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Re: Measuring LUFS Levels

Postby The Elf » Mon Jun 15, 2020 10:10 am

CS70 wrote:
The Elf wrote:
Mike Stranks wrote:I'm assuming this means that I have to play a 30-minute audio-track in real time to let the software analyse the levels. Is that right? If not how do I analyse the track levels in less-than-real-time?
I don't think you can? This is something I hadn't questioned until now, so thank you for bringing it up.
I am pretty sure there are tools that go over the sample set (the WAV file), run the calculations and return a table with the results.
Yes, Cubase has this, so I'm sure other DAWs will, but not out of real-time from the multi-track project - only from a rendered file.
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Re: Measuring LUFS Levels

Postby Hugh Robjohns » Mon Jun 15, 2020 10:26 am

Mike Stranks wrote:I'm assuming this means that I have to play a 30-minute audio-track in real time to let the software analyse the levels. Is that right? If not how do I analyse the track levels in less-than-real-time?

Yes, the Integrated Loudness value needs to analyse the entire programme. There are systems that can do it in less than real time (see below) as an off-line process, but for your application I don't the expense would be necessary or justifiable.

Background info: Loudness meter have three different Loudness display values. A core point of the loudness normalisation standard is that it is programme-based, and thus it is the Integrated Loudness (I) figure which matters as this is derived by analysing the entire programme duration. It is also this figure which is specified by the distribution outlet's target loudness value (-14LUFS in the case of YouTube).

And it is an integrated figure (not an average figure) which is why, as the Elf pointed out, the value can change quite quickly if you have a loud section at the end, for example. It's also worth noting that the Integrated value tends to increase easily but is quite difficult to bring down again!

In addition to the I value, there is also a Momentary (M) loudness value which has a similar characteristic to a VU meter and is intended primarily as an aid for setting initial levels -- not for mixing.

The Sliding or Short-term (S) Loudness figure is a good guide to use while mixing as it is obviously more responsive since it looks at a 3-second time window. And you can use this along with the developing Integrated value to help you hit the right target level by the end of the mix.

Practical advice: If you're used to mixing to broadcast standards -- as I know you are, Mike -- I find hitting the target value comes surprisingly naturally, but the key is setting the monitoring to the right level so that what your ears tell you is the right loudness corresponds to what the meter thinks is too. For YouTube the monitoring needs to be pretty much the same as it would be for Radio 4 mixing... ;-)

For straight-forward radio-style programmes I suggest you mix as per usual, keeping a weather eye on the Integrated and Sliding Loudness values. Hopefully, the Integrated figure at the end will be within a gnat's of -14LUFS with peaks below -1dBTP -- and if so that's great. Save the mix file, job done.

If it's a decibel or two high or low (and I doubt it will be much more than that) simply select the whole mix file and give it a level shift of the appropriate amount (and if shifting up tweak any peaks that exceed -1dBTP if necessary -- but it rarely is in speech-based programming). Save the tweaked file, job done. So if the Integrated figure is -12LUFS, simply load the file into an audio editor and attenuate the file by 2dB. Job done.

There are off-line Loudness analysers-and-adjusters that can scan a file on a hard-drive or server, analyse and correct it to match preset values... but they are generally aimed at professional broadcasters and streamers and so tend to be pricey!

For example, Nugen Audio have an excellent product called LM Correct: https://nugenaudio.com/lm-correct ... but it's $400...

However, several other DAWs and audio editors have built-in file Loudness analysers -- Adobe Audition does for example, but my favourite is in iZotope RX in the Utility section. You simply load the file and open the Loudness module. It then analyses the file in a second or two to give all the values. If you need to change anything there are sliders to set the target True Peak and Integrated loudness values, so set those and hit Process. Hey Presto! A corrected file in much faster than real time....

I believe other DAWs have similar options and the will become more prevalent in future updates.

HTH
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Re: Measuring LUFS Levels

Postby Mike Stranks » Mon Jun 15, 2020 11:22 am

Thanks Hugh

As always, very informative... As you've indicated, because I'm used to mixing/balancing for broadcast, everything is sitting very nicely in the final mix and I've no issues that need addressing. My question was really along the lines of 'So if I want to... does that mean...?'. Clearly it does! :)

My terminology is sloppy... I should have used 'Integrated' in my question. That's the metering I've been looking at when I've been experimenting. I wanted to see how close I was to -14LUFS... and I'm pretty close so am not getting in a sweat. The mixes sound fine on YouTube... it ain't broke so I shan't be fixing it.

My hope rose when I saw the reference to Izotope 7 as I've recently purchased the full version. Sadly they were quickly dashed... apparently I need the full version with added cream! :lol: Ah well...

Thanks for the various responses... I'll have a broader understanding should I ever have to come out of retirement again and produce more radio mixes.

:thumbup:
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Re: Measuring LUFS Levels

Postby The Elf » Mon Jun 15, 2020 11:32 am

For what you might pay for an upgrade to Ozone it may also be worth looking at the TC Clarity. That device just sits there doing its thing. Often I've played back a mix and then remembered I need to check the LUFS - and there it is already displayed.

I set the option for it to reset on my DAW's playback and I run it as a VST plug-in, No, it isn't a cheap option, but it is very definitely a time-saver.
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Re: Measuring LUFS Levels

Postby Matt Houghton » Mon Jun 15, 2020 11:34 am

Youlean Loudness Meter has a drag/drop function to for offline analysis of individual files. Not sure if it is in the free version or not. They also have a web-based drag/drop analyser. Takes seconds for a 3m30s-ish pop song... shouldn't be too onerous for a 30 min show.
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Re: Measuring LUFS Levels

Postby Ramirez » Mon Jun 15, 2020 1:09 pm

If you’re using Reaper, the SWS Extensions (whcih you really shouldn’t be without!) have a loudness analyzer. It also enables you to ‘normalise’ any item or track to a LUFS value of your choice.
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Re: Measuring LUFS Levels

Postby CS70 » Mon Jun 15, 2020 3:06 pm

Matt Houghton wrote:Youlean Loudness Meter has a drag/drop function to for offline analysis of individual files. Not sure if it is in the free version or not. They also have a web-based drag/drop analyser. Takes seconds for a 3m30s-ish pop song... shouldn't be too onerous for a 30 min show.

Fun, that's the one I use and didn't know at all. It shows how much I use offline analysis.. :)
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Re: Measuring LUFS Levels

Postby Martin Walker » Mon Jun 15, 2020 3:24 pm

Hi Mike,

I use Wavelab's Global Analysis function to do this, on every track I create, as it's a great way to get basic level balance between tracks in an album format.

It provides separate tabs for Peaks (both digital and the more important true peak values), Loudness (Integrated - the one you want, I currently aim for an Integrated Loudness of -13dB for my work, but you'll obviously have specs for your broadcast stuff Mike), plus Loudness range, and both Short term and Momentary min and max values).

It also offers extras such as any measured DC offset (can't remember the last time I used this now that audio interfaces and plug-ins are mostly so well designed), apparent bit resolution, and a readout of possible glitches in your audio file, based on sudden large changes in sample value.

All useful stuff in my opinion!


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Re: Measuring LUFS Levels

Postby Peevy » Mon Jun 15, 2020 10:22 pm

Matt Houghton wrote:Youlean Loudness Meter has a drag/drop function to for offline analysis of individual files. Not sure if it is in the free version or not. They also have a web-based drag/drop analyser. Takes seconds for a 3m30s-ish pop song... shouldn't be too onerous for a 30 min show.

+1 for the Youlean Loudness Meter. It can be used in real time in your daw, but can also sit as a standalone plugin on your computer’s desktop. Open it on your desktop, drag and drop any file onto it and it will give a full readout on anything lufs related in seconds.
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Re: Measuring LUFS Levels

Postby Zukan » Tue Jun 16, 2020 7:59 am

Matt Houghton wrote:Youlean Loudness Meter has a drag/drop function to for offline analysis of individual files. Not sure if it is in the free version or not. They also have a web-based drag/drop analyser. Takes seconds for a 3m30s-ish pop song... shouldn't be too onerous for a 30 min show.

Nice one Matt. I haven't visited this gem for a while and the added features look very useful.
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Re: Measuring LUFS Levels

Postby Mike Stranks » Tue Jun 16, 2020 8:14 am

Thanks for the heads-up on Youlean.... I shall investigate. :thumbup:
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Re: Measuring LUFS Levels

Postby ConcertinaChap » Tue Jun 16, 2020 12:23 pm

Hugh Robjohns wrote: but my favourite is in iZotope RX in the Utility section. You simply load the file and open the Loudness module. It then analyses the file in a second or two to give all the values

I was a bit puzzled by this because I couldn't find a Loudness module in the Utility section. I found Waveform Stats in the Measurements section would calculate all the loudness stuff along with other measurements like true peak. However there were no sliders like you describe. I'm on the standard edition. Would this be in the advanced one?

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