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Ty Ford
DialNorm and audio levels
on Jul 24, 2011 at 4:01:42 pm

Here's a great article about DIALNORM and how it uses metadata to achieve better level control.

http://www.tvtechnology.com/article/120058

Regards,

Ty Ford

Cow Audio Forum Leader
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André Engelhardt
Re: DialNorm and audio levels
on Jul 26, 2011 at 3:04:00 pm

Interesting read, thanks for posting Sir!

--
Audio Engineer, Sound Designer
Video- and Photographer
http://www.andreengelhardt.net


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Jean-Christophe Boulay
Re: DialNorm and audio levels
on Jul 28, 2011 at 1:21:26 pm

On this same subject, the ATSC has just published a new version of its CALM recommended practices. Most of the document is the same but there are additional annexes relating to techniques to be used on non-AC3-coded signals, so bypassing the standard LM100-DialNorm workflow. Basically, we fall back to a broadcaster's LKFS norms in that situation.

Of course, it's rather dry and techy but important reading for anyone who'll be producing broadcast audio in the next few years. Pass the word.

http://www.atsc.org/cms/standards/a_85-2011a.pdf

JC Boulay
Technical Director
Audio Z
Montreal, Canada
http://www.audioz.com


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Ty Ford
Re: DialNorm and audio levels
on Jul 28, 2011 at 1:23:56 pm

JC,

Thanks, as always, for tossing in.

Can you expound on LKFS?

Regards,

Ty

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


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Jean-Christophe Boulay
Re: DialNorm and audio levels
on Jul 28, 2011 at 3:23:46 pm

Hi Ty,

LKFS is a newer level measurement measure. It's "Loudness, K-Weighed, relative to Full Scale". The process takes all the channels of your multichannel audio signal, dumps the LFE, applies a filter to all channels (the K-Filter, which mostly cuts some low end and boosts about 2dB above 4kHz), measures the average power (Leq) and sums the channels back up, with some weighing. The surrounds are boosted 1.5dB before summing, for example. All this process is done within the metering tool as long as it conforms to the ITU-R BS.1770 standard. The measure is in decibels, but is reported as LKFS alone, not dB LKFS. I know TC Electronics have updated their metering tools with this algorythm. I like AudioLeak for its simplicity (http://www.channld.com/audioleak/).


I haven't seen a spec sheet with LKFS on it yet, but some contacts at local broadcasters say that shouldn't be too long, especially in the US where this will become the law by december. We'll probably have to specify Dialog Level when delivering broadcast audio, so the DialNorm can be set accordingly by the operator. Either that or we'll receive precise Dialog Level specs to respect. Because of the dumping of the LFE and the filtering and weighing, LKFS is really hard to guess based on more traditional measurements. You really have to measure it, which probably means new tools. And we all know how exciting it is to invest in metering! Clients go crazy for that stuff.

IHTH,

JC Boulay
Technical Director
Audio Z
Montreal, Canada
http://www.audioz.com


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Ann Clark
Re: DialNorm and audio levels
on Aug 23, 2011 at 4:02:01 am

JC,

I just got a spec for commercial audio levels from DirecTV: "Average audio levels shall be -24LKFS +/- 2dB".

Since I'm working with FCP7, I don't have a meter that addresses LKFS. How would I determine if my audio levels will work? The peak on the commercial is around -6dB according to the FCP meters. This has worked well in the past. Shall I roll off a bunch of tapes and chance it, or has DirecTV gone off the deep end with a new standard?

Your quick thoughts would be very helpful.

MacPro 2 x 2.8 GHz Quad-Core Intel Xeon 14GB memory - OSX10.6.4 FCP7


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Ty Ford
Re: DialNorm and audio levels
on Aug 23, 2011 at 4:16:05 am

Hello Ann and welcome to the Cow Audio Forum.

Lets see what others say, but....... After I read an article that tried to explain the system, I was left with more questions than when I started. It was like the statisticians had escaped from the computer farm and accidentally ended up on the audio farm...and I've been doing this a while.

At the end, someone popped in and said, peaks no higher than -6 dB and don't let it get too quiet either, so watch the peaks and use a little compression and/or limiting. Without the Dolby plugin or hardware, "knowing" is still debatable due to the convoluted method of their calculations.

I'd say do your best with the -6 dB peak, push up the low stuff a bit still making it sound good and send it in to see what they say. Oh, and then let us know what happened.

Regards,

Ty Ford

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


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Ann Clark
Re: DialNorm and audio levels
on Aug 23, 2011 at 4:36:51 am

Ty,

Thanks for the advice. I'll be sure the peaks stay within the -6 range and slap a Compressor/Limiter on it. I only saw one peak that went over the -6dB mark, so maybe I'm okay once I add the C/L filter.

As for sending it in to see what they say, I have two choices -- the audio is right, or it's right. If it is not right, let the yelling begin. ;-o

In Space Race parlance, this is an "all-up-test" -- because of media and shipping costs, I get just the one chance to make a Beta SP tape, ship it in, and hope DirecTV doesn't have a problem with it. I also have to send another copy of the tape directly to the client at the same time, so if it's wrong, it's wrong twice. Yipes.

Often, if these things are wrong, the net tells the client before telling us here, and it's just a big, messy blowout over some smallish technical details that would otherwise be easy to fix.

I'm just trying to keep the yelling down, as well as tape costs, by being proactive, here.

I'll keep you in the loop as to how this goes.

:-)

MacPro 2 x 2.8 GHz Quad-Core Intel Xeon 14GB memory - OSX10.6.4 FCP7


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Ty Ford
Re: DialNorm and audio levels
on Aug 23, 2011 at 11:58:24 am

Back at you, Ann.

Thanks for your sense of humor.

There are more and more facilities who have purchased the Dolby LM100 for over $3000.
http://www.dolby.com/professional/solutions/broadcast/loudness.html

There's also the Media Producer Suite for about $4k.
http://www.dolby.com/professional/products/pro-audio/mastering-dvd-hd/dolby...

If you could find such a facility near you or buy what you need, you can run the show and feel more secure in your deliverables. Otherwise, you're sort of stuck with that uncertain feeling and the advice of someone who only has half a clue.

IMO, audio shouldn't be this big of a problem, but then audio level disparities are at criminally wild levels because broadcasters haven't, for years, wanted to hire audio techs to sit at master control and ride gain. In the end, this loudness issue is a personnel issue. Broadcasters have simply abandoned what used to be their responsibility.

Regards,

Ty Ford

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


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Ty Ford
Re: DialNorm and audio levels
on Aug 23, 2011 at 4:42:34 pm

from a friend...

"A reliable workaround is included in every copy of Pro Tools. I have been using it successfully for 4 years. It is the LEQ A analyzer in PhaseScope. Mix for an average reading that is 3 dB softer than the LEQ A analyzer (because of a difference in meter ballistics between LM100 and PhaseScope. Put the PhaseScope analyzer on 2 second sampling while you are mixing and try to keep the reading predominantly at the desired dialnorm spec. On final playack of the completed mix, set sample time to infinite. You should get a reading that is 3 dB quieter than the LM100 spec. Your mix will pass QC. "

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


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Ty Ford
Re: DialNorm and audio levels
on Aug 23, 2011 at 4:50:38 pm

"Sorry, I meant to say mix for an LEQ A reading that is 3 dB softer than the LM 100 dialnorm spec. Darned chopsticks!"

Cow Audio Forum Leader
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tyler smith
Re: DialNorm and audio levels
on Dec 12, 2011 at 11:48:48 pm

does anybody have an idea of how I can achieve a -24dBFS in adobe premiere? I have a music video to dump to beta tomorrow and aint sure how to do it.


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Ann Clark
Re: DialNorm and audio levels
on Oct 15, 2012 at 9:15:04 pm

Hey Ty, and the rest of the group,

So, over a year later the CALM Act stuff is still a mystery. I have workarounds to attain a complaint signal, but there just isn't an easy plug-in or low-budget meter that does the trick. It's all hand work and guess work.

We had a production recently (30-sec spot) that went to the dub house in good shape, then to the network -- which made a point of rejecting the ad for "low volume." They wouldn't tell me what they meant (how low?), but they made quite a stink about it before telling me they raised it a little bit and went ahead with airing it. Indeed, broadcasters have mostly abdicated responsibility to output a good signal.

Long and short - got the tape back and the dub house reported that the dub itself was just recorded a little bit low, not wildly low, just a bit.

Since our productions are often budget priced TV spots, we won't be buying any $4,000 sound equipment any time soon (we're not an audio post house, either). Going to an audio post house would actually be great, except that it would be an expensive thing to do, and unappreciated by our tight-budget customers. We're hoping for some simpler, cheaper solutions that can be added to the current workflow without a lot of hoops.

Anything new out there? :-)

MacPro 2 x 2.8 GHz Quad-Core Intel Xeon 14GB memory - OSX10.6.8 FCP7


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Ty Ford
Re: DialNorm and audio levels
on Oct 15, 2012 at 9:38:52 pm

Hello Ann,

How about something like this?

http://www.videotoolshed.com/product/68/loudnesschange

Regards,

Ty


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


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Ann Clark
Re: DialNorm and audio levels
on Oct 16, 2012 at 1:12:10 am

Ty,

An interesting find. Downloaded the demo version.

The Loudness Change test drive...

This could be a good tool for finding peaks and overall level problems. It does what it says it will.

What the tool does quite well is point out a potential problem, and you can do the math in your head to reset the level for the flagged item, since LKFS measures in decibels.

I may go ahead and buy the real thing, but I do have a few reasons to hesitate:

* It's set up for the European standard, so you have to manually type in US info. (I sent them the US broadcast standards that I'd received from a national network - maybe they'll create a new US template)
* The screens and reports are a bit clumsy, as they're designed by a non-English person and with European designations for all the things it measures.
* It requires a WAV file as input, an extra round-trip for us.
* There's a technical translation that must happen between the many new flavors of information that make up the CALM Act standard and what systems like FCP tell you about your levels.

I've been tweaking the audio within FCP and other software such as Soundtrack Pro and ye olde Soundbooth. All of these systems have no clue as to LKFS. So I've followed the rule of keeping the peaks below -6dB on the FCP Audio meter, and keeping the lows around -12dB, and the overall levels pretty even throughout. Aside from the tape dub problem, I've been doing okay with this method.

Loudness Change provides data, but it's up to the editor to interpret, make corrections, re-test, etc.

What I'd really like (and which will never happen) is a CALM filter within FCP (or another Mac friendly NLE) that's as simple as Final Cut's Broadcast filter for luma/chroma level corrections. Drop it in, render, done.

BUT - I'll see what I can do using Loudness Change - might be the only game in town!

- Ann

MacPro 2 x 2.8 GHz Quad-Core Intel Xeon 14GB memory - OSX10.6.8 FCP7


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Bouke Vahl
Re: DialNorm and audio levels
on Oct 19, 2012 at 3:53:03 pm

For the records / future reference.
(I'm the developer of Loudness Change, and i already have off-list contact with Ann, but it might be good for the others to keep up with developments)

Indeed it's set up for the EU, since i'm from there and did not have any US specs. Thanks to Ann i do have them now, so i'll build in a template.

But, even with a template, there is no guarantee YOUR broadcaster has the same specs (oh, the joy of a standard...)
So, it still is the end users responisbility to see if the settings are right. (Not that hard though.)
And, the settings will remain the next time you start up the application, so you only have to do this once.
I'll build in an option to save the settings you like under a custom name, if you have different broadcasters to deliver to.

For the English/American, quilty as charged. (I'm not a native speaker...)

For a plugin for FCP, / wave roundtrip, it ain't going to change. Few reasons:
FCP 7 is dying. New NLE's are on their way.
Even if i got that covered, there is a shift to MXF for delivery.
For most NLE's that means track one goes to track one, not to left / right.
So with lots of channels (as we all have), it won't work anyway.
You need a mixdown to put under your final video, then export.

It's not that many roundtrips. As the manual (well, that's mostly on the site now, still have to work on the manual) states, if you make a decent mix and let this thing render out a new file, it should be up to specs in one or two tries max.
(if not, i would love to see some examples!)

Bouke

Bouke

http://www.videotoolshed.com/
smart tools for video pros


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