Audio loudness/normalisation
 

Hi guys,

Quick question (I hope).

I've just finished producing my first TV commercial. I'm trying to get my head around the broadcaster requirements for audio loudness. The standards I need to adhere to are: loudness must be normalised to -24LKFS, and measurements should be to ITU BS.1770-3 standard.

So, does this mean (using Avid) if I normalise to -24dB I should be safe? Or is it not quite that simple?

Thanks for any info.

Re: Audio loudness/normalisation
 

The International Standard is -23LUFS - the -24dBLKFS is an old standard.

You *have* to have a loudness meter to the new standard to do all this as the standard is averaged over the programme and not instantaneously.

You will need the loudness meter plug-in for the Avid if you have an old version without the Loudness Meter.

A current Loudness Meter will also normally display to LKFS as well as the standard LUFS if you desire the old standard.

Re: Audio loudness/normalisation
 

The standard is still -24LKFS here in NZ..

Maybe we're behind the times a bit? This is straight from the technical requirements document from the Commercials Approvals Bureau:

"The audio loudness of a commercial must be normalised to -24LKFS. Measurement should be to ITU BS.1770-3 standard and related documents.".

So, is there any way to tell which standard my version of Avid is using? The basic audio monitoring tool doesn't seem to have a function to record the average loudness, only peak. Honestly, I don't have a lot of experience with audio normalisation, especially for broadcast. So any tips are appreciated.

Re: Audio loudness/normalisation
 

Jody, I am in NZ. Where will I see your commercial?

Re: Audio loudness/normalisation
 

TV One. It's pretty low budget - nothing fancy, but as it's my first one I'm just trying to make sure the audio is within spec.

Re: Audio loudness/normalisation
 

That's interesting. New Zealand has until now been pretty lax on these things. There hasn't really been an average loudness standard like that before. With TVNZ the main thing was to keep the peaks below -9 dBFS, and work to a tone of -18. I suppose it was inevitable that they would find some average loudness standard in keeping with the way it's gone internationally.

Re: Audio loudness/normalisation
 

Don't normalize as in having your peaks at -24...that will be way too quiet. Peaks at -9dBFS. The -24LKFS is an average, not peak level.

Re: Audio loudness/normalisation
 

Brilliant, thanks for that. -9 for the peaks is what I needed to know - I was just guessing up to this point which was taking a lot of time. Thanks.

One further question - I got a metering plugin for Avid which measures LUFS. Is this going to be suitable or do I need a specific LKFS plugin?

Re: Audio loudness/normalisation
 

Pretty sure -24 LUFS should be ok, as these days it's pretty much the same standard as LFKS.
Not sure how you are doing your audio compression/limiting...but essentially you need to compress till your audio averages out at -24, and use a limiter to keep peaks below -9.

Re: Audio loudness/normalisation
 

Hmm well to this point I've just been doing it by ear and trying to keep the peaks below -9. But I'll have a look into using a limiter, thanks.

Re: Audio loudness/normalisation
 

You won't be able to get the necessary average loudness while also taming peaks if you don't use a limiter. You could do this hit and miss and have it rejected by QC at TVNZ. Get your audio right...it's just as important as the picture. Doing it yourself is one way to go, or sending the audio to someone in Hamilton who knows how to do audio for TV. Otherwise an audio professional (like me) in other parts of the country with the gear to do it will take the guesswork out of the equation.

Re: Audio loudness/normalisation
 

Thanks for the tips.

I worked in broadcast a while back doing QC, so hopefully I can remember enough of that to get it right. Would rather do it myself and learn from any mistakes I make, so I'm sorted for next time.

Thanks again :)

Re: Audio loudness/normalisation
 

Since nobody has explictly said:

dBFS and LUFS are completely different units, metered measured in completely different ways: apples and oranges. Not to be confused.

Re: Audio loudness/normalisation
 

From my understanding, dBFS is a measure of the max volume or loudness, and LUFS is a measure of the average.. I could be completely wrong though

Re: Audio loudness/normalisation
 

What would be the acceptable peak level for web video and DVD/BluRay discs. at the moment I am working to -6db

Re: Audio loudness/normalisation
 

That is what I work to as well and it is -6dbfs (decibels full scale) which is a scaled level measurement as opposed to dblu which is an average loudness measurement normally dblufs-23.

People should note that levels and loudness are not the same thing as two mixes can have the same levels but may not have the same loudness.

dbfs is a level measurement that equates to digital full scale metering and the new dblufs reading is a relative loudness measurement for audio delivery.

So whilst your broadcast material may be lined up with 1khz tone at -18dbfs with a max peak level of -10dbfs (-20dbfs and -12dbfs for the USA) the loudness measurement for the whole programme content must be -23dblufs.

DVD and web content is different and you can put the levels where you wish but -6dbfs seems to be a good compromise for peak levels, loudness measurements tend not to apply as you are not trying to even out programme content to loud commercial breaks.

Of course good metering is essential if you are delivering for broadcast or critical applications and I personally have some old BBC type PPM meters but also use this plug in for my pro tools set-up: http://www.zplane.de/products/plugins/ppmulator

More reading matter on loudness here: http://tech.ebu.ch/loudness

Re: Audio loudness/normalisation
 

You will need a loudness meter and not a standard meter to monitor to this standard.

I would discuss this with Avid to make sure you have the correct metering.

And a modern Loudness meter will be switchable to measure to the -23LUFS standard or the -24LKFS standard.

So - check with Avid.

Re: Audio loudness/normalisation
 

They are numerous loudness meter plugins available.. the 'WLM' for instance.
Broadcast Loudness Meter Plugin - WLM | Waves

Re: Audio loudness/normalisation
 

That looks perfect. However, at risk of sounding cheap, I'm trying to find a free one.

I very rarely do broadcast work (maybe once a year, if that), so I can't justify the cost of purchasing one at the moment.

Re: Audio loudness/normalisation
 

ToneBoosters has a free demo that works well. The Audiocation loudness meter is another free option if they have your PTs plugin format.

Re: Audio loudness/normalisation
 

Excellent, thanks very much :)

Re: Audio loudness/normalisation
 

No chance - these have cost a great deal of money to develop.

However - you may find a limited free-trial version of one with, say, 30-day usage.