Difficulty with clipping and meters

[4DanQuestt]

Hello everyone,

I am trying to master some recordings of my songs done on Audacity 2.4.2 Windows 10. My goal is to get them mastered for eventual uploading onto Youtube. As I understand it, they require audio to be -14 LUFS. During the mastering process, I have taken my final mix (of my first song), imported it into a new Audacity Project file, and have applied limiting to it in order to reduce the gap between the “highs” and the “lows”. I DON’T want to end up with a flattened or deadened sound though, so I have not done too much in this regard. Then, after limiting, I used Amplify to raise the volume or loudness of the entire song/track. Then. I used Loudness Normalization to bring the entire song/track up to the level of perceived loudness that I mentioned above: -14 LUFS. This sounds and looks fine to me on the Waveform (i.e. there are no red lines indicating clipping), BUT when I play it, the Audacity playback meter CLEARLY shows lots of red, indicating clipping. I am totally confused about this apparent contradiction! If it is clipping, then shouldn’t this be indicated in BOTH the playback meter AND the waveform? And, if it does mean that my mastered recording is NOT ready for professional purposes, then how can I get there from where I am currently?

I would greatly appreciate any help and insight anyone can offer me, because I cannot proceed with my work until I can remedy this problem.

Thank you,
Dan

[DVDdoug]

@4DanQuestt

As I understand it, they require audio to be -14 LUFS.

No, not exactly. All of popular streaming services apply their own loudness normalization. If your audio is above the target they turn it down. If it’s below the target they turn it up, but if they won’t boost it into clipping so it can still end-up quieter than the target.

Normally you should do loudness normalization first. Then limit (and/or compress) to prevent clipping. (Audacity can go over 0dB internally/temporarily without actually clipping.) Since limiting only affects the highest peaks, it usually has little or no effect on the LUFS (or RMS) level.

Note that the limiter in 3.6 is “weird”. There is no freekin’ “limit” setting and I don’t know how it works! It might change the LUFS level. The old limiter would only do that if you selected the Make-up Gain option.

This sounds and looks fine to me on the Waveform (i.e. there are no red lines indicating clipping)

Just FYI - Audacity “shows red” for potential clipping. It’s not looking at the wave shape. Audacity uses floating point so it essentially has no upper (or lower) limits. You can boost the volume, or boost the bass, etc., and your peaks go over 0dB it will “show red” even though the waveform is not (yet) clipped.

Or, you can have a truly-clipped waveform and if you lower the volume that doesn’t remove the clipping but as long as it doesn’t hit, or go over, 0dB Audacity won’t show red.

BUT when I play it, the Audacity playback meter CLEARLY shows lots of red, indicating clipping. I am totally confused about this apparent contradiction!

I believe the meters show red as a warning when you get close to 0dB. You could generate some sine waves at different levels to confirm that. That’s more important on the recording meter because you don’t know how loud the incoming signal will get.

I trust what the waveform is showing. If I want to check the exact peaks, I run the Amplify effect. Audacity has already scanned the file and it will default to whatever gain or attenuation is needed for 0dB peaks. If Amplify defaults to +1dB, your peaks are currently -1dB. If Amplify defaults to -1dB, your peaks are currently +1dB. Then you can cancel the effect if you just want to check.

One more thing… MP3 and other lossy compression changes the waveshape making some peaks higher and some lower. MP3 can go over 0dB without clipping, but your DAC cannot so you can clip your DAC if you play it at “full digital volume”.

CDs cannot go over 0dB but probably half of my MP3s ripped from CD show red and have peaks around +1dB. I don’t believe that slight clipping is audible so I don’t worry about it but some people peak-normalize to around -1dB to prevent it.

[Trebor]

@4DanQuestt

BUT when I play it, the Audacity playback meter CLEARLY shows lots of red, indicating clipping.

Only if the very end of the meter goes red is there clipping …

https://manual.audacityteam.org/man/meter_toolbar.html#playback

[4DanQuestt]

Thank you DVD Doug and Trebor for the information. It definitely clears up a lot for me. I just went back and watched the playback meter closely while I played my -14 LUFS master and there were no red lines at the end of the meter at any time. I didn’t realize before that red showing up on the meter didn’t automatically mean that actual clipping was taking place. That is great and essential information. Thank you for that and all the other info.

I am going to go back now and re-do the master in the way that you, Doug, explained: Applying loudness normalization FIRST, and then applying the limiter (and/or compressor). I’m very happy with the overall sound quality that I achieved, and I strongly dislike very compressed recordings, so I think I will stick to just the limiter (as some of you on this forum suggested to me a while back). But, I have one more question for you two:

After I import my final mix into a [new] Audacity Project file for mastering , and cut-off the excess length at both the beginning and ending of the song/track, should I apply Amplify (to bring the volume/loudness up at least somewhat) and THEN apply loudness normalization to get it to -14 LUFS (and then. of course, apply the limiter after that to prevent clipping), OR should I skip the Amplify effect altogether and just go directly to the loudness normalization effect in order to get it loud enough?

Thanks again for all your help!

Dan

[4DanQuestt]

Sorry about the mess-up in my last post. I don’t know what I did or what happened to make the typing in my second? paragraph turn out so awful. But I would really appreciate it if you could read it anyway and respond to the question that I asked in it.

Thanks,
Dan

[DVDdoug]

You can skip the 1st Amplify unless you want a “starting point”.

Amplify, Loudness Normalization, and regular (peak) Normalization are all linear volume adjustments. They all do the same thing (but usually making different volume changes) so only the last one “sticks”. That’s assuming no limiting or compression in-between. Limiting and compression are non-linear.

Sorry about the mess-up in my last post. I don’t know what I did or what happened to make the typing in my second? paragraph turn out so awful.

I don’t know but I fixed it for you. I have moderator super-powers! There were apparently some hidden control characters. I just backspaced to delete whatever was between the paragraphs and then entered another carriage return to make them separate paragraphs again.

[4DanQuestt]

Thanks DVDdoug for both the added info./explanations and for the corrections you made to my earlier post that had some problems with the type (those Moderator super-powers are indeed impressive!).

I just went back in and re-did the mastering process for the song in question, and I would like to briefly outline my steps for you to make sure I now understand it correctly:

1. I imported my final mix/WAV into a new Audacity Project and cut off some excess length at both the beginning and end of the imported track;

2. I then applied Loudness Normalization to the track and got it to -14 LUFS;

3. Then, because the red lines appeared on the track in several locations, indicating clipping (and because you typically need to narrow the gap between the highs and lows of the recording, at least to some extent), I applied the limiter to the track and eliminated the clipping;

4. However, I don’t (yet) have a VST plug-in LUFS meter (are there any good free ones available online?). So, as I wasn’t sure if the track was still at -14 LUFS at this stage of the process (and because I thought that the top of the waveform appeared to be slightly further away from the top of the actual track), I re-applied the Loudness Normalization effect at -14 LUFS. I hope that this makes sense and is OK to do. I wasn’t sure if it was still at -14 LUFS after the limiting was completed. I made a copy of the track before I re-applied Loudness Normalization, just in case re-applying it is a no-no. Please let me know if this, and all my previous steps outlined here were correct and appropriate. Most importantly, is it OK to do the Loudness Normalization one or more subsequent times AFTER the application of limiting IF the waveform looks as if it shrank OR if you are simply unsure if the finished Mastering track is STILL at -14 LUFS (again, I don’t have an LUFS meter yet)?

Thank you again for everything!

Dan

[Trebor]

@4DanQuestt

there any good free ones available online?

Youlean Loudness Meter - Free VST, AU and AAX plugin

But applying Audacity’s native “Loudness Normalization” at -14LUFS will ensure it’s optimized for YouTube.

[4DanQuestt]

Hi Trebor,

Thank you for the recommendation of the Youlean VST meter. I may download it, but, as you said, the Loudness Normalization effect inside Audacity will ensure that the perceived loudness is exactly where I want/need it to be.
I would be fine going with this, but I don’t know if the -14 LUFS level that I set my master to will remain a -14 if I apply Limiting (and/or compression) to it AFTER setting the LUFS level with the Loudness Normalization feature? This is the big question I have at the moment, since I am very new to the Mastering process. If you can answer this for me I should be fine without an actual LUFS meter. Or do I need to apply Loudness Normalization (at -14 LUFS) a second time AFTER applying Limiting and/or compression to ensure that I end up at -14 LUFS? Limiting and/or compression will lower the loudness (and LUFS level), won’t it?

Thank you,

Dan

[DVDdoug]

Backing-up a bit… If you are using 3.6 you might want to go-back to the old limiter. With the old limiter you can set the limit to 0dB (or -1dB, or whatever) and it behaves as exactly expected (Make-up Gain should be turned OFF… Make-up Gain re-amplifies after limiting and that WILL foul-up your loudness level).

I’ve had on-and-off trouble with the YouLean plug-in depending on the version of Audacity and I don’t know if it works in 3.6. But he has an Online Loudness Meter that you can drag/drop your file into.

@4DanQuestt

if I apply Limiting (and/or compression) to it AFTER setting the LUFS level with the Loudness Normalization feature? This is the big question I have at the moment, since I am very new to the Mastering process. If you can answer this for me I should be fine without an actual LUFS meter. Or do I need to apply Loudness Normalization (at -14 LUFS) a second time AFTER applying Limiting and/or compression to ensure that I end up at -14 LUFS? Limiting and/or compression will lower the loudness (and LUFS level), won’t it?

Don’t get obsessed with getting it “perfect”! Perceived loudness is complicated and two different songs/programs normalized to -14dB LUFS may not sound exactly-equally loud. (1) Or one person may say “A” is louder and another person might say “B” is louder. And a song might start-out quiet and end loud, etc.

Limiting should have very-little effect on LFUS and it depends on the program content. I would guess the difference will be less than 1dB and it may not even make a big enough difference to show up in the measurement.

Of course if you run loudness normalization again after limiting, there is a chance of pushing the peaks over 0dB again. That’s worse than the loudness being off by a little. It’s not worth going around in circles.

And remember, YouTube is going to make their own adjustment.

With YouTube, you can’t make your sound louder than everybody else because they will just turn it down. But you can end-up quieter than everybody else if your track is quiet but has high peaks (no headroom) and they can’t turn it up enough. That’s the main idea of all this… To make sure your track isn’t a lot quieter on YouTube than everybody else.

BTW - Most commercial music is louder than -14dB LUFS and YouTube (and all of the other streaming services) turns it down.

(1) Mastering engineers who are mastering a CD MIGHT have an LUFS target but in the end they use their ears to loudness-match the tracks, or to make a quiet song intentionally quieter, etc. With a small number of tracks that’s the best way to do it.

[Trebor]

@4DanQuestt

I don’t know if the -14 LUFS level that I set my master to will remain a -14 if I apply Limiting (and/or compression) to it AFTER setting the LUFS level

The LUFS level can be changed by compression and limiting, but if you apply loudness normalization again, as the final step, then it will optimized for YouTube.

[4DanQuestt]

I’m using Audacity version 2.4.2 Windows 10, so I guess my limiter is the old one. Thanks to both DVDdoug and Trebor for bearing with me in my attempt to learn the basics of Limiting, etc. in a few days! I appreciate all the help. After having re-mastered the song in question, everything looks good to me on the various meters and in the waveform, and it sounds great to my ear, so I’m quite pleased with the results. I will keep all of your info. and advice in mind as I move forward to other recordings.

Best wishes,

Dan

[tjfria]

1. Adjust the gain on the Scarlett interface until your voice falls between -12 and -6 on the meter. This should avoid clipping and give you plenty of head room.
2. Make sure you have used the Preferences to designate the Scarlett interface as your playback and recording device. you can use AirPods plugged into the interface for monitoring; any other wired eartips will work also. Earphones are not essential.
3. To record, there is no need to arm the track; just press record button and begin.
4. You don’t normalize voiceovers. Audacity will give you the RMS value of your recording in the Analysis menu.
5. Get the Thomas Mundt Loudmax plugin. It is free and it will take care of your levels to meet ACX specs. I can help you use it; it is free on the web.