Old 07-02-2019, 07:14 AM   #1
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Default Why the peak meters are clipping ?

Hey,

I have a simple question, with certainly a simple answer already on the forum for a long time, but I can't find it. Maybe I don't use the good words... Anyway. I ask !

I never really understand why, when I put a normalized sound on a track, the peak meter clips. And of course the master track also does it.

Theoretically, I take a normalized sound like a commercial music, 0dBFS max. And because it's digital, it can't be more. If I put it on a normal track (stereo), and the fader is at 0dB, the left channel goes to the left, the right to the right, and there is no mixing. So why I have a red peak at +0.2dB on my meter ? It just should be 0dB.

There is no saturation, and I know if I put the master at -0.2dB it's transparent because the floating bits and anything. So there is no big deal, but why ?

And I never notice any kind of headroom parameters in the preferences. But maybe I missed something.

Thanks a lot.

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Old 07-02-2019, 08:01 AM   #2
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I never really understand why, when I put a normalized sound on a track, the peak meter clips. And of course the master track also does it.
I don't know how the REAPER clipping algorithm works but it can be difficult to know if the audio was normalized to 0dB or clipped to 0dB.

You can get false positives or a miss... If you take a badly-clipped file and normalize it to -1dB and it won't "show clipping".

Quote:
Theoretically, I take a normalized sound like a commercial music, 0dBFS max. And because it's digital, it can't be more. If I put it on a normal track (stereo), and the fader is at 0dB, the left channel goes to the left, the right to the right, and there is no mixing. So why I have a red peak at +0.2dB on my meter ? It just should be 0dB.
Regular (integer) WAV files and CDs cannot go over 0dB.


But, MP3s can go over 0dB and MP3 changes the save shape making some peaks louder and some lower (without affecting the sound of the dynamics). So, if you normalize to 0dB and then make an MP3 the new highest-peaks often go over 0dB.


Resampling can also make new-higher peaks. i.e. There can be inter-sample peaks that only show-up in the reconstructed analog or when resampling. (There is no inter-sample information in the digitized file/data.)

Last edited by DVDdoug; 07-02-2019 at 08:09 AM.
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Old 07-02-2019, 08:28 AM   #3
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Originally Posted by DVDdoug View Post
I don't know how the REAPER clipping algorithm works but it can be difficult to know if the audio was normalized to 0dB or clipped to 0dB.

You can get false positives or a miss... If you take a badly-clipped file and normalize it to -1dB and it won't "show clipping".
You right but the weird thing is it's not only clipping, it's shows +0.2dB


Quote:
Originally Posted by DVDdoug View Post
But, MP3s can go over 0dB and MP3 changes the save shape making some peaks louder and some lower (without affecting the sound of the dynamics). So, if you normalize to 0dB and then make an MP3 the new highest-peaks often go over 0dB.
Good to know ! But actually I tried with .wav and .flac

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Originally Posted by DVDdoug View Post
Resampling can also make new-higher peaks. i.e. There can be inter-sample peaks that only show-up in the reconstructed analog or when resampling. (There is no inter-sample information in the digitized file/data.)
Good to know too ! So I quickly tried by resampling clipping files from 44.1kHz to 48kHz. Both are read at 48kHz (I mean the 44.1 is resample) but there is no difference in flac and in wave. They still clip.

The mystery stays. But thanks anyway for your answer and to try to understand what's happened.

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Old 07-06-2019, 09:02 AM   #4
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Up !

I hope I have to do this on this forum. But it's soooooo, important.
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Old 07-06-2019, 09:05 AM   #5
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The meters peak at about 1/1000th of a dB below zero.
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Old 07-06-2019, 09:10 AM   #6
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Originally Posted by karbomusic View Post
The meters peak at about 1/1000th of a dB below zero.
Before it has gone over.

Bugged the shit out of me but I got used to it. My previous DAW I could put a brickwall limiter set to limit at 0db on a track, and I'd never get a peak light. Gotta go -1db with the exact same brickwall limiter in REAPER to get the same results.
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Old 07-06-2019, 09:12 AM   #7
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Before it has gone over.
That's what below zero means. It's a practicality vs perception thing, literally and in every way and there is no actual 'over' since the digital audio universe ends at 0 - so it means before it hits zero. It's a great test for identifying OCD though.
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Old 07-06-2019, 09:17 AM   #8
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Originally Posted by karbomusic View Post
That's what below zero means. It's a practicality vs perception thing, literally and in every way and there is no actual 'over' since the digital audio universe ends at 0 - so it means before it hits zero. It's a great test for identifying OCD though.
Hehe, I just brickwall all my drum tracks at -1db and call it a day.

REAPER never makes me see RED now.
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Old 07-06-2019, 09:21 AM   #9
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I remember you apply limiting to make sure an indicator that isn't actually clipping audio doesn't appear... even though it still wouldn't be clipping if it waited until zero to appear. I've never found a good reason to be that close to zero, pretty much ever.
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Old 07-06-2019, 09:33 AM   #10
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well, because you increased the numbers summing to master
so if unnormalized, it had a +0.1 summ peak level within tracks at some particular point
now it may be +3 in overall peak level
maybe
I didn't think too much
but the idea with true peaks seems not for this case
but if master level uses a true peak thing
it is
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Old 07-06-2019, 09:37 AM   #11
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The reaper meters actually do peak red at something like -0.001 dbFS, this has been shown in past threads and unrelated to ISPs IIRC.
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Old 07-06-2019, 10:01 AM   #12
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Originally Posted by karbomusic View Post
I remember you apply limiting to make sure an indicator that isn't actually clipping audio doesn't appear... even though it still wouldn't be clipping if it waited until zero to appear. I've never found a good reason to be that close to zero, pretty much ever.
I primarily use brickwall limiting on my drum tracks, and was doing it before I moved from Sonar to REAPER. Not only is it to hold back the peak light but more so for the altered sound a drum track gets as you push it into the brickwall. If I disable all brickwall limiting, I'll get five or six peaks on any given track.

Initially I found REAPER's lower threshold in calling a peak quite annoying because it behaved differently than I was used to seeing in both Sonar and in Sony Vegas which call stuff that is over zero a peak. I thought my favorite Brickwall limiter was NOT working properly in REAPER, but like NBC sez, "Now I know!".
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Old 07-07-2019, 06:54 AM   #13
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Hey,

My question isn't about limiters, or how to stay under 0dB. It's much more basic.

How a wave file normalized a 0dBFS can clip at +0,2dB on a simple stereo track, with the fader at 0 and no plug, no pan, nothing. I understand it clips at -0.001dBFS. It's normal with a true normalized file, but it technically can't go over.
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Old 07-08-2019, 03:21 PM   #14
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Check your pan setting on the track & project. Set it to 0 dB on both.
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Old 07-08-2019, 06:47 PM   #15
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Quote:
Originally Posted by GGB.C. View Post
Hey,

My question isn't about limiters, or how to stay under 0dB. It's much more basic.

How a wave file normalized a 0dBFS can clip at +0,2dB on a simple stereo track, with the fader at 0 and no plug, no pan, nothing. I understand it clips at -0.001dBFS. It's normal with a true normalized file, but it technically can't go over.
who or what did the normalizing? could be something not exact right there, eh?
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Old 07-09-2019, 01:23 PM   #16
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AFAIK any sound processing, even changing a volume to a 0.000001db
brings changes to phase and sound properties,
I don't wanna test it right now
but any processing should change the bit-depth of a file to a DAW settings
which is might be another change to its amplitude and phase
or has to be
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Old 07-09-2019, 03:50 PM   #17
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AFAIK any sound processing, even changing a volume to a 0.000001db brings changes to phase and sound properties
I don't see how that relates to the issue, but...


A volume change doesn't affect phase and I don't know what you mean by "sound properties". It's inaudible and meaningless in the practical audio world. You can't even make a change that small with a file quantized to 16 bits (according to my quick Excel calculations).
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Old 07-11-2019, 05:03 AM   #18
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Quote:
Check your pan setting on the track & project. Set it to 0 dB on both.
They both are at 0dB. I also try all the possible pan configs, nothing change.

Quote:
who or what did the normalizing? could be something not exact right there, eh?
The guy who produce the recording, I don't know ! Anyway, a wave file can't go over 0dB.


It's about reliability of Reaper for a professional using like I do. I never seen this problem in PT, Live or Ocenaudio.

But am I the only one to notice that ? If it's the case, it could be a preference I changed (even if I don't know wish one), and it's definitely not a problem.

If it's not, I'm surprise nobody, and also the programmers, don't think it's weird.
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Old 07-11-2019, 12:23 PM   #19
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if you want, upload your file, lets test it
also wave file can go over 0db
especially if it is 32bit or higher
all the 16\24bits clippped to 0db
as far as I experienced always show clipping

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Old 07-12-2019, 02:03 PM   #20
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Originally Posted by GGB.C. View Post
Hey,

My question isn't about limiters, or how to stay under 0dB. It's much more basic.

How a wave file normalized a 0dBFS can clip at +0,2dB on a simple stereo track, with the fader at 0 and no plug, no pan, nothing. I understand it clips at -0.001dBFS. It's normal with a true normalized file, but it technically can't go over.

In Reaper it can. Audio inside Reaper is processed as 32 or 64 bit floating point, not as integers. So waveform values up to about +300 dB can be represnted without clipping *internally*. You can, for example, use a plugin to boost the signal by 200 dB, then another plug to reduce it by 200 dB, and the result would not clip.

You cannot, of course, output that level to your interface. But you could, in theory, render it to a .wav file if you use floating point .wav file as the format.
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Old 07-12-2019, 02:20 PM   #21
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When it's the master, the internal bit rate is mostly irrelevant unless you are rendering at those bit depths, which you aren't when you are playing back and monitoring because it's going through the converters. I agree with his +0.2 question but I haven't had time to sit down and figure it out. The only thing I can think of is that if it is smashed enough and pushed as close as can be to the ceiling it becomes more likely to see weird anomalies - it's one of those here be dragons things.

Last edited by karbomusic; 07-12-2019 at 02:27 PM.
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Old 07-12-2019, 11:43 PM   #22
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Originally Posted by GGB.C. View Post
I put a normalized sound on a track, the peak meter clips. And of course the master track also does it.
The red color is just for your information and technically completely irrelevant. If you measure the length of a house with a foot rule, it will "clip" and the length of the stick, but no effect on the reality .

(This argument can be extended to the usefulness of "gain staging" - OK, mostly )

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Old 07-12-2019, 11:48 PM   #23
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Red happens here at 0 and it also bugs me quite a lot. There should be an option to disable this behaviour imo.

Not sure about the +0.2 boost though.
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Old 07-13-2019, 12:20 AM   #24
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Red happens here at 0 and it also bugs me quite a lot. There should be an option to disable this behaviour imo.

Not sure about the +0.2 boost though.
Not a good idea IMHO.

There are certain instances when you dedicatedly want to be warned when the level just occasionally hits 0 dB (e.g when you want to convert to a non-real format). In other cases it's easy jut to ignore the red light .
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Old 07-13-2019, 09:42 AM   #25
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A red light by design shouldn't be ignored.

I am ok having this behaviour, but it wouldn't harm to have the option to change it. You know, for the remaining 90% of the users
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Old 07-13-2019, 09:48 AM   #26
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Originally Posted by 1111Eugene View Post
AFAIK any sound processing, even changing a volume to a 0.000001db
brings changes to phase and sound properties,
Changing volume digitally is a completely linear process (basic multiplication) that doesn't introduce any phase or spectral changes.
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Old 07-13-2019, 11:41 AM   #27
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Originally Posted by reapero View Post
A red light by design shouldn't be ignored.
If you think so just decrease the volume by 0.2 dB to kill the red light. This does exactly nothing to the quality of the audio.

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Old 07-13-2019, 12:14 PM   #28
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If you think so just decrease the volume by 0.2 dB to kill the red light. This does exactly nothing to the quality of the audio.
I just put a piece of black electrician's tape over the peak indicators on my monitor. Problem solved!
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Old 07-13-2019, 12:30 PM   #29
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Old 07-13-2019, 07:25 PM   #30
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here's what changes
also don't know
gif - https://drive.google.com/file/d/1CqE...ew?usp=sharing
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Old 01-15-2020, 07:14 AM   #31
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Hey,

I finally forgot this thread for some times then...

Then I try again this week and it's quite clear now. DVDdoug was right at the first reply. It was simply a resampling story.

Anyway, just you to know. When I play a loud 44,1kHz file in a Reaper resampling live at 48kHz I have some clip. The peak meter goes to +2,5dB(FS). If I convert this file at 48kHz and play it again, it logically goes to 0db(FS) max.

I've already notice some differences between 2 files played resmapled or not, but it's interesting to see/ear the rest, if you put one out of phase. The sound is still clearly recognizable. And there is sound at -20dB in the master. A clear (and already known) proof of the big degradation happening in live conversion...

I don't understand what's happened 6 months ago when I did my tests, and why I just didn't understand the problem.

Thanks Doug.
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Old 12-31-2023, 10:16 PM   #32
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necrobumping rather than reposting the same thing,

can confirm this behavior. i've got an mp3 that's causing realimit at 0 threshold to pump up to 2db. I suppose it's because the mp3 codec regenerates wrongly. First assumption is that it would reproduce what the author of the mp3 put into it, and I don't see how they could put anything louder than 0db into it.Mind ye, I don't think this is a Reaper problem, but an mp3 infrastructure one.

happy new year folks.
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Old 01-01-2024, 02:23 AM   #33
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AFAIU, the mp3 decoder when correctly working, absolutely is able to produce peaks of more than 0 dB height when the incoming data requests so - which is perfectly legal, even if the original data stream to be encoded was completely below Zero dB: mind that mp3 is not lossless. As the output data stream is floating point format, that does not harm, (other than triggering the red light which means "Zero db" but does not mean "clip").
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Old 01-01-2024, 05:05 AM   #34
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Originally Posted by reapercurious View Post
necrobumping rather than reposting the same thing,

can confirm this behavior. i've got an mp3 that's causing realimit at 0 threshold to pump up to 2db. I suppose it's because the mp3 codec regenerates wrongly. First assumption is that it would reproduce what the author of the mp3 put into it, and I don't see how they could put anything louder than 0db into it.Mind ye, I don't think this is a Reaper problem, but an mp3 infrastructure one.

happy new year folks.
This is not on the artist, this is on the mastering engineer who mastered the track.

Most of the mastering engineers don't really care about this, for multiple reasons but I don't want to go deep on that.

All Mp3 encoders compress data on the frequency spectrum, they are not lossless, they lose frequencies.

If the original wave file ceiling is close to 0 dbfs it will be messed up either by the mp3 encoding and the decoding and eventually peak above 0 dbfs (sometimes only for 1000 samples out of 44100 samples/sec on an entire song, sometimes way more than that)

If the original wave file ceiling is between -0.5 and -1 dbfs it most likely will never peak during encoding and decoding.

If you want to see it with your eyes,
Take a mastered wave file with ceiling at 0 and put a subtractive EQ (even the smallest amount) or even better a steep low pass filter at 15khz (like mp3 encoding),
I'm sure you will see some peaks.

There are tools used during Mastering to prevent encoding and decoding peaks like those.
TruePeak Limiting and
real time AAC/mp3 converters (like https://www.apple.com/apple-music/ap...gital-masters/)

Bypass your Realimit and export a DRY RUN of the mp3 item to see how many true peaks it develops.

Last edited by 80icio; 01-01-2024 at 09:01 AM.
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Old 01-01-2024, 06:22 AM   #35
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Quote:
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I just put a piece of black electrician's tape over the peak indicators on my monitor. Problem solved!
That works for the oil pressure light on my car too.

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Old 01-01-2024, 09:43 AM   #36
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That works for the oil pressure light on my car too.

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LMAO! My wife had a Honda Civic with a temp gauge that would increment its starting position every time you started it such that it couldn't be used. I told her to just keep an eye out for steam.

When I first switched to REAPER from Cakewalk Sonar 16 years ago, the peak lights in REAPER really bothered me a LOT!

I've since started using the LV2 Peak Limiter from the x42 guys.

https://x42-plugins.com/x42/x42-limiter

Unlike so many other limiters, if you set it to hold the line at 0db, it actually does it, and you won't see red peak lights in REAPER anymore.
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