I have a couple of videos with poorly encoded MP3 audio that has nasty artifacts. You know the ones. That warbly,flanged, hollow underwater sound.

Does anyone know a way to reduce those? I'm not asking about restoring it to a pristine 24 bit 96KHz Wav; I know that you can't put back what was never there in the first place. I'm only asking about reducing the artifacts. I know the end result would still be low quality.

I'm kind of expecting the answer to be "no," so it won't hurt my feelings to hear the truth, if that's what it is.

Unfortunately, no. Sorry.

^^^ Correct. Those aliased frequencies are baked into the audio now, so there's no way to remove them except by re-encoding.
 
This is probably not relevant, but just in case...make sure it's not the playback system that's doing the aliasing. Many years ago I bought my first MP3 player, with the idea that I'd listen to my mixes while out on walks. It was a cheap device from Office Depot, and it sounded just awful. I'd had no prior experience with MP3 encoding, so at first I thought I must be doing something wrong. But the artifacts weren't there when I played the files on my computer, leading to the epiphany that not all decoders are created equal.

Turn down the volume. ☺

I figured that was the case but that it wouldn't hurt to ask.