RMS / LUFS / PEAK

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DavidSweeneyBear
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Post by DavidSweeneyBear »

Hi all,

Apologies if this has been covered elsewhere...

Are there any agreed-upon specs for submitted mp3 files in terms of loudness and peak?

As many people are probably aware ACX specs are >-23RMS, <-18RMS with max -3db peak.

Personally, I've always felt this is a bit restrictive in terms of dynamic range (particularly if bass is rolled of and/or you're a female narrator I guess) but I can understand why they do it.

LUFS is a slightly more useful measure than RMS and has been the standard measure in music mastering for some time now.

Personally, I use -19 LUFS (mind you, I normally produce stereo files) with a -3db peak... OR : -17LUFS with a -1db peak

Just wondering if this has been discussed before, or if there are any particular standards for Librivox?
philchenevert
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Post by philchenevert »

Well ... LibriVox has used the term decibel to measure loudness and asks readers to submit recordings of around 89 dB. plus or minus 3 dB. This is a hard thing to nail down especially for people like me who are not trained in audio stuff. We do have a tool called the Checker which, among other things, gives a dB reading of an entire track.

With that said, I used Audacity Effect Loudness Normalization wich lets me set -19 LUFS and it adjusts the track to that. Gives me close to 89dB on the Checker every time. So the agreed upon specs for LV is 89 dB and no clipping. We don't do peaks like ACX.

Others with more technical knowledge will tell you a lot more but those are our specs. Actually the test is if the loudness sounds OK to a proof listener. :D We are simple folk here.
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DavidSweeneyBear
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Post by DavidSweeneyBear »

Thanks for that, simple is good!

Could you perhaps link to the checker tool? I'd like to take a look :)
philchenevert
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Post by philchenevert »

DavidSweeneyBear wrote: December 9th, 2021, 7:23 am Thanks for that, simple is good!

Could you perhaps link to the checker tool? I'd like to take a look :)
Here is a video I made about Checker. It has the information in it somewhere! (I am lazy)
https://www.youtube.com/watch?v=QKVOYsaDoRo&feature=youtu.be
Peruvian owls always hunt in pairs because they are inca hoots.
89 Decibels? Easy Peasy ! https://youtu.be/aSKR55RDVpk
DavidSweeneyBear
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Post by DavidSweeneyBear »

Thank you kind sir!

In case anyone stumbles across this thread in future....

HERE IS THE DIRECT LINK FOR THE LIBRIVOX CHECKER:

https://cgjennings.ca/projects/checker/#install-checker
knotyouraveragejo
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Post by knotyouraveragejo »

Jo
philchenevert
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Post by philchenevert »

David, since you are obviously knowledgeable about RMS/LUFS/Peak stuff, what is your opinion about the Audacity Effect 'Loudness Normalization'? I like it because i don't need to check my recordings any more with Checker for volume; just run it at -19 LUFS and it is done. But someone told me that different setups will produce different volumes with the same LUFS. Is this true? Anyway, if you have an opinion I'd like to hear it; if not, I want to hear that too.
Peruvian owls always hunt in pairs because they are inca hoots.
89 Decibels? Easy Peasy ! https://youtu.be/aSKR55RDVpk
loon
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Post by loon »

In the days of yore when I worked in television we used LKFS - almost the same as LUFS, but not quite. The FCC made US stations follow that standard after too many people complained about programs that sounded like this AND ADS THAT SOUNDED LIKE THIS. The cool thing is we found carefully-made recordings made 40 years before using analog tape and mechanical VU meters easily met the new standard.

LibriVox wants to make audio books where the listener doesn't need to go diving for the volume control every time a new chapter starts. The LibriVox 'gold standard' is Checker, but once you have a few successful recordings you should get fine results by going for the same metering result as whatever worked for you before, no mater what metering system you prefer.
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TriciaG
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Post by TriciaG »

after too many people complained about programs that sounded like this AND ADS THAT SOUNDED LIKE THIS.
I remember those days. :shock:
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lurcherlover
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Post by lurcherlover »

And those days are still here, at least in the UK!!
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