Old 08-15-2019, 07:09 AM   #1
Slick
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Default Incorrect mp3 import

Hello everyone. Could you please advise? I've faced an issue: importing mp3 audio to reaper makes master db meter reach about 2db over 0. Problem doesn't appear in any other DAW.
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Old 08-15-2019, 08:12 AM   #2
DVDdoug
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MP3s can go over 0dB so it's probably the MP3.


The lossy MP3 compression process makes some peaks higher and some peaks lower so if you make an MP3 from a 0dB normalized file it's not unusual for the MP3 to go over 0dB by one dB or so. Since many MP3s are ripped from 0dB normalized CDs you see that all the time. It's more likely to happen when the original file is "artificially" compressed/limited.


Maybe there's something wrong with the MP3 decoder in the other DAW... I believe there are some MP3 decoders that will clip to 0dB.


Try opening the file in Audacity. Audacity is a lot simpler than REAPER so it's harder to accidently change the volume. Run the Audacity Amplify effect. The Amplify effect is similar to normalization and it will default to whatever change is needed for 0dB peaks. If it defaults to -2dB, that confirms your current peaks are +2dB. (Of course you can cancel the effect and exit without saving.)


If that's not the problem you may have an unknown setting or effect that's boosting the levels. (And you should see the same thing with WAV files).
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Old 08-15-2019, 10:01 AM   #3
Dreiko
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Default Incorrect mp3 import

Have the same problem! +2.5 db on master & span peak control... wtf?

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Old 08-25-2019, 08:49 AM   #4
Dreiko
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Default Incorrect mp3 import

Hey guys, here you can see the differences between Reaper & Ableton, I also checked with other DAW's and everything works perfectly in Logic & Studio 1!

Link: https://youtu.be/9n2PgMXDUt4
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Old 08-25-2019, 01:43 PM   #5
Philbo King
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Unlike a .wav, there's nothing inherent in an MP3 to keep it below 0 dB. You can go above. Sounds like ass, but it can be done.

Keep in mind MP3 playback is creating calculated audio on the fly from brief spectral snapshots. That's how it saves disk space.
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Old 08-25-2019, 03:12 PM   #6
DVDdoug
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Quote:
Hey guys, here you can see the differences between Reaper & Ableton,
OK, but that's an incomplete experiment.


What happens if you have an MP3 that peaks over 0dB and you open it in Ableton?


Does it clip at 0dB or does it show the true peak?


...I suggested Audacity because I know from experience that it will not clip and if your MP3 goes over 0dB Audacity will correctly show that. And, it's hard to accidently change the volume in Audacity.
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Old 08-25-2019, 04:32 PM   #7
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mp3 can go over +0dB internally. The ISO spec says that the output should be clipped, but we chose not to clip because we're a DAW and want to give you the option of doing something with those overs. So if you really care you can put a limiter on your mp3 files, or glue to non-FP .wav which will automatically clip.
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