Don’t Shout! – it’s Nugen Audio’s VisLM2 – The Daddy Of All Loudness Meters


Who Are Nugen Audio?
Nugen Audio Is an audio software company, based in Leeds. It was founded in 2004 by Dr Paul Tapper and Jon Schorah, who share between them a PhD in mathematics and a Masters Degree in Engineering (no shortage of academic horse power there then!). They have backgrounds in both producing/engineering and mastering a plethora of electronic dance music hits and in software programming.

Nugen Audio supports the Fairtrade foundation by donating some of its profits towards public education work – so they are not only ‘audio software egg heads’, but also ‘good eggs’ too! Ethically clever – nice!

Nugen Audio are EBU (European Broadcasting Union) P/Loud committee members, so therefore sit on the panel that sort out and discuss our loudness needs, and are therefore highly placed to make sure their meters are highly compliant (and fully EBU tested) and have the latest metering standards implemented. So they really “know their loudness onions”.

What Is VisLM2?
VisLM2 (Visual Loudness Meter) is loudness measuring meter software that comes in two versions: the compact (C version) and the history (H version) with all the history and data logging options you could possibly want. The H version also comes with a stand-alone application so that you can use it outside of your favorite DAW or video editing software, which is ideal for live or outside broadcast applications. It has arguably become the ‘de facto standard’ in loudness measurement. To see why – read on.

Why Do I Need A Loudness Meter?
Unless you live underneath a rock, you will have noticed that these days, on most TV channels, adverts no longer deafen you and pin you to the back wall compared to programme material. Trailers and “interstitial tit bits” are about the same loudness as the ins and outs of programmes they interrupt. This is all due to the jolly clever boffins of P/Loud at the EBU (European Broadcasting Union) who have brought in some new ways to measure audio levels – using loudness. You have to be loudness compliant these days for broadcast, or you will fail your tech review! You even need to be loudness aware these days for You Tube and itunes.

A little Background History on Audio Levels in TV
Traditionally in the UK, due to our historically analogue transmission infrastructure, the broadcasting industry didn’t measure loudness, but measured peak levels (the loudest bits) using the PPM (peak programme meter).

Levels measured on PPM
To stray over ppm 6 (the old max) was to incur the wrath of the transmission gods and allegedly bring the national grid down due to the extra power drain (remember that power = current squared x resistance). In “the good old days”, every stage of broadcast had an experienced hand on a fader to control levels, and likely some toast warming up on their trusty old peak limiters (from the likes of Neve).

The problem with this paradigm was that it was designed to prevent transmitter overload and not to look at loudness, which was always taken care of by the technical operators. Adverts on some networks were becoming savagely compressed to sound very loud and were very different in loudness to the programmes. The advent of modern technology in dynamic range compression was having a profoundly unpleasant effect on the viewers as the commercials battled it out to become the loudest advert on TV and sadly the most annoying to listen to.

These days, however things are very different!

• We now have digital file delivery (no tapes) and digital transmission paths; meaning the end viewer can now theoretically get very close to what was heard in the mix
• We are no longer constrained with peak levels of transmission power as it is a digital signal, and therefore can have more dynamic range (difference between loud and quiet bits)
• We can transmit discreet 5.1 multi-channel audio as well as stereo
• We have more discerning viewers with much more choice available who will vote with their feet if the loudness of adverts vs programmes is too inconsistent.
• Broadcasters no longer have so many human hands on faders at every stage of broadcast, so the interstitial elements and the programmes must have much more carefully chosen loudness values.

PPMs Are Old Hat Now – So What’s New? (The Classroom Bit)
To sort out loudness and dynamic range issues on TV, the EBU (European Broadcasting Union) wisely decided to use an open standard (sorry Dolby with your proprietary Dialogue Intelligence technology) to make an objective measurement of a subjective impression (try saying that after two pints!). They opted for a K weighted curve (a modified second-order high-pass filter – yeah really!), so that higher frequencies mean more to loudness measurement than bass does.

The K weighted curve, graphic from “Using B.S. 1770-1 for Fun and Profit” by Dave Moulton
The K weighted curve, graphic from “Using B.S. 1770-1 for Fun and Profit” by Dave Moulton

This curve is applied to all channels (except the LFE when in multichannel – which is ignored), then some geeky maths is then applied, and the result is LKFS (loudness, K weighted, referenced to digital full scale). Simples!
For relative measurements, Loudness Units (LU) are also used, where 1LU = 1dB.

Some New Things to Measure
To measure the loudness of a programme, the EBU has these new measurements that should be included in any loudness meter worth its salt:

• Integrated Programme Loudness (I)
• Loudness Range (LRA)
• True Peak Level (TP)
• Short Term Loudness (S)
• Momentary Loudness (M)

I (Integrated Loudness) is the “loudness overview” of the loudness landscape of the entire programme material being measured, from start to finish. It is measured in LUFS or LKFS.

In the EBU we use an audio gate in the integration meter to pause any loudness measurement when any really quiet sections occur, so that they do not skew the readings of the bits we really care about (the normal average level stuff and the really loud bits). This gate comes into play on any material that is 10dB below the integrated reading with a block length of 400ms. This differentiates us from out friends “over the pond”, that do not use a gate in their metering.

TP (True Peak Level). What sets the true-peak meter apart from sample-peak meters is that they not only look at the actual samples, but also inter sample peaks, i.e. peaks in-between actual samples that would otherwise cause distortion. This is achieved by oversampling (measuring at 3 or 4 times the sample rate of the audio). Therefore, a true peak meter actually measures above digital zero (0dBFs).
A reading using a traditional sample-peak meter of -0.1 dBFs could go as far as +3 dBTP on a true-peak meter.

LRA (loudness Range) describes the statistical distribution or consistency of short-term loudness within a programme. Another way of describing this is the average range of overall program material loudness, from the softest part to the loudest part. The top 5% and the lowest 10% of readings are excluded to avoid extremes from affecting the overall result. The range is quantified in LU.

S (Short Term Loudness) is the rolling average loudness of the past three seconds

M (Momentary Loudness) is the rolling average loudness of the last 400 milliseconds

VisLM2 – Versions
The plugin comes as both Mac and PC versions, and supports AAX, VST, VST3, AU and AudioSuite in both 64-bit and 32-bit versions (RTAS for Pro Tools 10 is obviously 32 bit only).
Requirements are for OSX 10.7 and Microsoft Vista (64bit) upwards, with a minimum of 512MB RAM.

In Pro Tools land (my weapon of choice these days), you can either buy the Native version (which uses your computer processing power) or rather interestingly a DSP hybrid version. This is really clever thinking by Nugen, as the DSP version allows the audio to pass through with no latency (0.19ms), rather than the native x2 version round trip to the computer processor and back. The loudness calculations are still done by the computer, so there is a seamless workflow. This is cunning stuff indeed.

Another ace up VisLM2’s DSP sleeve is its low DSP thirst. One instantiation was 2% of one of the 18 chips on an HDX card, and with 10 instantiations (way more metering than you would likely to commonly want) using 5% of one chip and 6% of my quad i7 3.5Ghz CPU power. Converting this merry lot of 10 DSP meters to native meters puts the cpu load to 15%.

Both Nugen VisLM2 versions, VisLM2-C (compact) and VisLM2-H (history) can also be run as faster than real-time audiosuite plug-ins.

Licensing options are super flexible too. With either the traditional challenge & response, ilok usb key, or Site (Nugen Audio’s server-based seat licensing solution for enterprise clients with 10 seats or more across a network).

What Standards Can VisLM2 Measure?
VisLM2 is based upon the international standard ITU-R B.S. 1770, revisions 1, 2, 3 and 4 can measure pretty well any loudness standard

• EBU R128
• EBU R128 S1
• OP-59
• AGCOM 219/9/CSP
• Portaria 354

• VisLM 2 also supports Leq(a) and Leq(m) measurement (TASA & SAWA) for cinema commercials

A Quick Tour Around VisLM2
Here is the compacted view of VisLM2-H (which is the most similar to the Compact version)

Nugen VisLM2-H
Here you can clearly see:

• the Integrated loudness of a 30 second promo = -23.7 LUFS
• the short term loudness of the last 3 seconds = -22.5 LUFS
• the loudness range – this dialogue music and FX mix is modestly dynamic (8.6)
• the max momentary loudness (-17.6 LUFS)
• the current momentary reading on the bar graph
• the short term (3 sec) loudness is described with an arrow on the right hand side of the momentary loudness meter
• there is a gate in operation (G10 in blue writing beneath the transport keys)
• the play cursor is lit, so the transport will follow Pro Tools timecode

now let’s see the expanded H history display

Expanded view of Nugen VisLMH-2
The expanded H display additionally shows:

• On the far left hand side the optional D (distribution) view vertically represents the distribution of loudness measurement within the Integrated loudness measurement.
• In the middle of the view is the optional H (history) view that presents the historical loudness and true-peak clip values over time.
• At the top (with the purple selection) is the optional M (loudness history Macro view) that shows the overall loudness history stored by the plug-in. This view can be used to rapidly locate areas of specific interest in the main loudness history view.
On the far right hand side are LR true peak meters (which is why they can go to +3LU over digital zero). You can select whether you wish to see these by clicking the little plus sign by the orange loudness tab on the bottom right.
The eagle eyed amongst you will have spotted that there is a small icon in the bottom right of the plug-in window for re-sizing the plugin. This is an H series software feature only.

True Peak View
If you want to see the True Peak meters in greater detail then you can select the orange True Peak tab and see this (in the compact view in this case)..

True Peak view of Nugen VisLMH-2

ReMEM – Nugen Audio’s Secret Weapon in VisLM2-H
Have a look at the History version of the plug-in and you will see timecode (in this case of Pro Tools) underneath the graph; a settings box telling the plugin to follow timecode; and to the bottom right of the History graph, a yellow play button that makes the timeline update and scroll following the timecode (of Pro Tools).

This feature is completely and utterly pure genius and worth the price of admission alone for the H version and will save the savvy post mixer years of his life and may even, once in a while, get him home for dinner in time!

The plug-in version of VisLM2-H is able to lock to your NLE timecode if your DAW/NLE supports time-code referenced audio data in it’s plug-in architecture. I use Pro Tools, which most certainly can, and this brings huge smiles to my face!

In time-code mode, loudness measurements are logged by the plug-in with time-code referencing. This means that the plug-in knows precisely where the data belongs in the time-line and enables the ability to change small sections of audio that have changed in the loudness history to immediately re-calculate the overall Integrated Program Loudness without having to re-measure all of the audio again.

So in case you are as excited as I was when I heard about this I will explain again. You have finished mixing your show, your integrated loudness is compliant and you have no True Peak excess, but your director would like to go back and remix a scene (surely not to make it louder and more exciting?). You remix the scene to his satisfaction, but what has happened to the loudness? With anyone else’s meters you have to go back to the start and re-measure the whole programme again in real time. Not so with VisLM2-H. As long as you have 3 sec of pre-roll (so that the meter can lock back on and measure the S again) you can remix a section of the mix, post roll 3 seconds after you have finished, and it will re-calculate the new integrated loudness over the whole programme duration. That is so well beyond cool!

Another nifty application that this technology allows is that if you have a quick offline bounce of something, you can measure its loudness and TP in faster than real-time using an audiosuite version of the software, and dump the data into the real time version (as it is timecode locked data), as the audiosuite version can send the data to a plug-in version, rather than play the whole programme though from start to finish.

VisLM2 is a tweaker’s paradise as the display and the operations are customizable to the hilt. There are plenty of really useful presets and there is no need at all to have to touch the options section to do useful easy to read metering work.

Metering Option of Nugen VisLMH-2

As I predominately work on EBU broadcast productions I have chosen the EBU R128 preset (that meters in LUFS with a gate), that is aiming for -23 LUFS integrated, with a maximum true peak of -1.
I have chosen to zoom the history display in vertically ( LM scale lower and upper) and to make -23 LUFS (+ or – 1 LU) to be green, anything quieter to be blue, anything louder to be red – as you can clearly see in the history display. You can choose you own loudness standard, colours and opacity etc and what alerts you would like.

Text Logging

Text Log control of Nugen VisLMH-2
The Text log control determines whether text logging is activated. The frequency of data logging is specified as number of seconds between each entry using the Log Freq parameter.
The file name and path are user determined using the text log box.

The Auto Log controls toggles on/off the automation logging feature. When active, a series of automation parameters will be generated at the set interval Log Freq.
The data is exported as a csv file, and as such can be readily imported in to common spreadsheet programs for graphing and analysis.

csv export Auto Log from Nugen VisLMH-2

Audio Routing
You may need to set the audio routing standard for your DAW or your audio (if using the stand alone meter variant of the software).
Pro Tools users note that Pro Tools internally always uses film format (LCRLsRsLFe) with 5.1multichannel, and Dolby order for 7.1 multichannel (LCRLsRsLbRbLFE).s

VisLM2 can handle the following formats:

5.1 routings:

c) Film: LCRLsRsLFE

7.1 routings:

a) DTS1: L C R Ls Rs Lr Rr LFE
b) DTS2: L R C LFE Ls Rs Lr Rr
c) Dolby1: L C R Ls Rs Lb Rb LFE
d) Dolby2: L R C LFE Ls Rs Lb Rb
e) SDDS1: L Lc C Rc R Ls Rs LFE
f) SDDS2: L R C LFE Ls Rs Lc Rc

VisLM2-H really is “the daddy of all loudness meters” on the market, and nothing else compares to it. As well as the C version, there is the H version of the plug-In that not only has audiosuite (like the C version), but a stand-alone software version too. The H version has some completely unique tricks up its sleeve like Pro Tools HDX DSP capability. The Re-Mem time-code functions will save you hours of your time.
VisLM2 is solid as a rock, with a low processor overhead. It is completely and utterly accurate, and kept very current. It is highly configurable, but easy to use, a very delicate balance that has been deftly handled indeed.

VisLM2 is something I am very happy to shout very loud about and I won’t do post production mixes without it. I put my trust in Nugen. Period!

Click here for more info or to buy Nugen VisLM2 from the ESV Store


  1. User beware: There’s a bug preventing the import of the offline AudioSuite readout. You can use AudioSuite to check your mix offline but the import to online plug-in will bring incorrect information.

    1. Hi Maciek,

      Thanks for the comment – This is a bug in the current version. The problem is that the Mmax and Smax values aren’t pulled across, everything else is okay we believe. Ie. Integrated program, LRA and True Peak values are correct. Nugen are working on a fix for the next update.

  2. I really don’t think this is a train smash. In 99% of post workflows you mix down the timeline in a linear fashion and all your loudness values are continually updated. When you go back and start adding music or Fx to your dialogues all your values are updated. The actual values that matter are what’s on the print track when you finish. I have never in all the years I used VisLM (since it’s initial inception) used an audiosuite measurement in VisLM. I might check the printed tracks at the end with LM Correct (which is an audiosuite plugin) as a belt and braces before sending off for QC, and they have never disagreed with the VisLM2 readings.

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Mike Aiton
Mike Aiton was weaned at the BBC in the 80s, but after breaking free 30 years ago and becoming a senior mixer at Molinare, he ran several London post-production sound departments. He is now mostly found mixing and sound designing in his boutique Twickenham post production studio, mikerophonics. In his spare time, when not thrashing gear to within an inch of its life, he takes therapy for his poor jazz guitar playing and his addiction to skiing & Nikon lenses.