Okay, here's a really geeky one for 'ya. I had noticed for quite a while
that some of my mp3 files just didn't sound right, but couldn't quite place
the problem. I, of course, being a complete and total freak, have the ears
of a bat or something; I can hear at least up to 22050 hz (that's the
highest I've been able to generate a test tone, at least...). Here's the
problem I discovered... SOME craptacular mp3 encoder out there is doing this to poor innocent audio streams. What
you're looking at in that screenshot is a Fourier transform of the audio
stream, showing the brutal massacre that has occured. Look around 16035 hz
or so... WHACK. I guess whoever wrote this encoder decided that nobody would
ever want the signal above that point. It's not just a nonlinearity in the
encoder's frequency response --- the response just does not exist at all
beyond that point. Occasionally it will attempt to make up for this by
hurling in little pulses of what looks like almost white noise above that
point.
Why am I babbling about this? I want this encoder banished to the Evil
Toilet forever.
If you're using some archaic old piece of software to create mp3s, ditch
that cruddy encoder and get LAME. For more info on mp3
quality, I suggest looking at
r3mix.net.
If anybody can help me identify just what piece of evilware creates mp3s
with this awful 16khz dropoff, please e-mail me at vxo at
xidus.net so I can put that information up here.
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