I have an odd problem. I’m trying to raise the volume of a certain WAV file: The Athletic theme from Mario 3.
Right now it looks like it does in the photo: everything above the 0. I can’t adjust the amplitude much without major clipping, so I’ve tried the Normalize effect. It does work, as long as I check “Remove DC offset” in the popup box. However, this makes the track produce an odd POP sound whenever I play, stop, or pause the track.
If you’d like to try it out, here’s the file: https://files.catbox.moe/zuzrx6.wav
You’ll have to Normalize it (dB doesn’t matter, it’s a problem with “Remove DC offset”) to produce the same effect.
I’ve tried it on two different computers (Win 7 and 10) and it’s had the same effect. The effect is still there, even if I export the file. Really weird.
That is an amazingly damaged sound file. Where did it come from? I think you are going to spend most of your time “rescuing” it instead of changing it to do what you want. Can you get a cleaner copy?
Now knowing that the track itself is damaged, I managed to find the culprit.
In the program I’m using, NSFPlay (a player for NES playlists), I can set the “LPF” and “HPF” strengths. However, if I set the HPF strength to its max, it creates the effect as shown in the photo. If I turn it even the tiniest bit down, the track evens out in the center.
You do have a DC offset, but you don’t have a constant offset. It’s different at the beginning and end. Plus the waveform is asymmetrical (similar to a DC offset).
Instead of offset removal, try a 20Hz high-pass filter. DC is zero-Hz so a high pass filter will remove it, and it will also tend to balance-out the asymmetry.
If you still hear clicks at the beginning & end, add a fade-in and fade-out. (They can be very short fades of several milliseconds so they are not heard as fades. The end is faded-out anyway.
