A new bug in the Amplify effect?

Hi, I’ve been using Audacity, including the Amplify effect, for many years, and recently upgraded to 3.1.3. I think I found a bug. Here are the steps to reproduce the problem I’ve run into lately (not always, just sometimes):

  1. Select all (the entire project is just a single stereo track, around 3 hours, Split into multiple sequential clips)
  2. Effect > Amplify…
  • Notice the suggested Amplification (dB) is something much less than expected, e.g. -0.045 (since New Peak = 0.0, this implies clipping somewhere, right?)
    • Cancel out of the Amplify effect
  1. Effect > Limiter
  • Type: Hard Limit
    • Input Gains (L&R): 0.0
    • Limit to: -8.00
    • Hold: 10.00
    • Apply Make-up: No
    • Click OK
  1. Now, try the Effect > Amplify… again
  • I would expect the default Amplification to be something closer to 8 dB but it has not changed, still -0.045. So, I go looking for the peak (If there is there a way to ask Audacity where the peak is, I haven’t found it; there are no red vertical lines anywhere in the track to indicate clipping)
    • Cancel out of the Amplify effect
  1. Select the first 22:00 minutes of the waveform
  2. Effect > Amplify…
  • The suggested Amplification is different but still very low, e.g. 0.973
    • Cancel out of the Amplify effect
  1. Select the first 11:00 minutes of the waveform
  2. Effect > Amplify…
  • The suggested Amplification is 7.966 (as expected, given the -8 dB Limiter above)
    • Cancel out of the Amplify effect
  1. Select the next 11:00 minutes (11:00 to 22:00) of the waveform
  2. Effect > Amplify…
  • The suggested Amplification is 1.205 (shouldn’t it be 0.973?? This is why I say it’s a bug.)
  • Cancel out of the Amplify effect
  1. Ignore the data and press on! Effect > Amplify…
  • Enable Allow Clipping
    • Amplification: 6.0 (why not, given the -8.0 Limiter above)
    • Click OK
  1. Look for red clipping lines (none found)
  2. Effect > Amplify…
  • The suggested Amplification is -3.61 (the saga continues)
    • Cancel out of the Amplify effect

Please let me know if I need to clarify anything.

there are no red vertical lines anywhere in the track to indicate clipping)

Do you have the red lines turned on?

Screen Shot 2022-01-14 at 4.31.24 PM.png
Koz

It wasn’t turned on but, it is now. Thank you.

Sadly, that doesn’t solve my problem. The apparent bug still bites:

This time, I selected a ~2-hour section of a very similar project and clicked Effect > Amplify…; the suggested Amplification (dB) was 8.798. I entered 10 dB (New Peak = 1.2018), enabled Allow Clipping, and clicked OK. When that finished, I expected to see at least one red vertical line, as there should be clipping somewhere.

But, no, when it finished, the project still looks rather quiet with no red lines anywhere. Sure enough, when I immediately tried Effect > Amplify… again (same selection), the new suggested Amplification was 2.951 dB (not -1.2018 as expected).

This is frustrating enough that I will probably just go back to using Audacity 2.3.3. (It’s still on the machine; is that known to cause problems? I wasn’t going to uninstall it until I was sure 3.x was preferable… I’ll try that now…)

Does this look like the bug you are seeing? https://github.com/audacity/audacity/issues/2435

After saving my project, executing the Audacity 2.3.3 uninstaller and reinstalling 3.1.3, my problem appears to be resolved. However, …

That certainly could be the same bug; I was able to reproduce it.

Therefore, I won’t be surprised if my problem reappears.