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TV Master - Loudness vs Max peak

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Joseph Barnett
TV Master - Loudness vs Max peak
on Sep 23, 2009 at 1:55:41 pm

Hello,

I'm hoping you can help me. I'm starting to do more and more file based TV masters and there is a common thread that keeps popping up in specs supplied to me by different broadcasters. Often the max peak is a long way away from the stated loudness requirements e.g.

(SBSTV requirements)
Audio: Files
Max Peak: -12 dBFS truepeak (Digital-scale).
The commercial’s loudness level shall not exceed –4dBu to 0dBu according to Leq (A) (IEC 60804), measured with Dolby LM100 in short-term mode.

Does this mean that I normalize my audio to -12DBFS or I normalize the audio to 0DB (-18dbfs)?

Does the term loudness mean the audio should be in -18dbfs to -22 dbfs with the option of the odd thing hitting -12 at the maximum?

Any advice gratefully received, Thanks in advance.

Joe

http://www.guiltybynature.com


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Ty Ford
Re: TV Master - Loudness vs Max peak
on Sep 23, 2009 at 8:33:54 pm

Hello Joseph and welcome to the Cow Audio Forum.

I think what it means is you need a Dolby LM 100, or read up on one.
http://www.dolby.com/professional/pro_audio_engineering/lm100_01.html

Discovery runs all submissions through it and if they don't make the specs, they kick the project back.

Regards,

Ty Ford

Want better production audio?: Ty Ford's Audio Bootcamp Field Guide






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Peter Groom
Re: TV Master - Loudness vs Max peak
on Sep 23, 2009 at 9:39:10 pm

Hi
You dont necesarily need a Dolby unit, but you do need a loudness meter. This measures not the peak value, but the listener perceived loudness after such processes like eq and compression. There are various ones on the market such as the dk audio, and tc electric pro tools plug in, and the dolby unit.
This is an age old arguement and problem but one that only in the last few months (in the uK) has resulted in any sort of a clear standard and set of rules.
As I dont know where you are, i cant comment on your platform but would advise looking around at loudness metering.
Peter

Dubbing Mixer



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Joseph Barnett
Re: TV Master - Loudness vs Max peak
on Sep 24, 2009 at 9:33:18 am

Hi Guys,

Thanks for the responses it's really helpful. We are based in Denmark and create mainly 3D and special effects, however we also offer Grading and editing so more and more we are the last link in the chain. What I'm wondering is our audio masters come in from many different sound companies, is this loudness spec something that they would have implemented already? if so is it relative to the max peak, so if i normalize to say -12dbfs then the loudness should be correct.

We currently use Autodesk Smoke and FCP to deliver our masters. Would you advise any additional software/hardware to ensure correct delivery. Thanks again guys any advice or info you have would be great.

Joseph

http://www.guiltybynature.com


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Ty Ford
Re: TV Master - Loudness vs Max peak
on Sep 24, 2009 at 12:39:22 pm

Joe,

Loudness (apart from sheer volume) is a function of RMS to peak ratios. Here in the US, radio broadcasters in particular like to mash the audio with compressors and limiters to make it as loud as they can. Production companies making commercials for radio and TV and music companies do the same.

You can tell a track has been compressed by looking at it on the timeline. The denser the section, usually, the more it has been processed. This means that two pieces of audio with the same peak values can have very different loudnesses. Because there is no standard, if you're just mixing audio from different sources just by levels, the apparent loudness may be all over the place.

Dolby has a piece of software that you may find helpful.
http://www.dolby.com/professional/pro_audio_engineering/dolby-media-meter-o...

Regards,

Ty Ford



Want better production audio?: Ty Ford's Audio Bootcamp Field Guide






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Peter Groom
Re: TV Master - Loudness vs Max peak
on Sep 24, 2009 at 1:09:01 pm

You cant presume that a peak value of anything will be the correct loudness value. Its a function affected by compression primarily.
Peter



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Joseph Barnett
Re: TV Master - Loudness vs Max peak
on Sep 24, 2009 at 3:28:51 pm

Hi guys,

Thanks again, they are really helpful comments.

Joe

http://www.guiltybynature.com


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