Thread: Mp3 or Not???
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Old 2005-03-01, 08:15 PM
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paddington paddington is offline
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Join Date: Jan 2005
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Re: Mp3 or Not???

The steep 16kHz rolloff is a dead giveaway, in MOST cases. It's possible that the microphone sucked or that type of thing.

If you get 16k roll-off, you can be pretty sure it's MP3, BUT one more thing you can check beyond that is this:

When an UGLY roll-off filter is applied, like what the MP3 compression algo does, you get audible "aliasing" at the high edge of the low-pass band. LISTEN to it, and see if your high frequencies sound "watery" instead if crisp.

If you hear that mess and show a 16k roll off, you probably have MP3. If the taper used a crappy mic with bad freq response, you could still have the 16kHz roll off (as a coincidence), but you wouldn't hear the aliasing (watery high end) because no shitty filter was applied - the mic just didn't get it at all.

If I had to guess without listening, I'd say MP3.





As an aside - 16kHz is PLENTY high enough to enjoy a recording, it's the dirty steep roll-off filter on MP3s that ruin the audio. Yes, you are missing 16-20kHz, but the only things really there are harmonics and some REALLY high stuff you usually don't miss. When the you encode in MP3, the aliasing creates jagged stepped edges around 16kHz and those resonate harmonics down much lower, effectively ruining the audio well BELOW 16kHz, where it's very audible (and irritating).
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Last edited by paddington; 2005-03-01 at 08:21 PM.
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