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0 pointsCountSessine11y ago0 comments

Yes - that's sort of what I was wondering.

What effect would the MP3 compression have on the signal's entropy? He says, "MP3 format was chosen not only for its length..." which implies that he managed to compress it at least a bit - if so, there goes his entropy! I can't see how an MP3 compressor could make any headway against a really noisy signal using psycho-acoustic masking, so I'm guessing that any compression he realized came purely from coefficient quantization, which in the case of a really high-entropy signal should actually lower the entropy.

If anyone knows more about this, please feel free to correct me.

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cozzyd11y ago

I think the psychoacoustic masking would certainly degrade the spectrum... time for a little experiment!

Step 1) Generate 1 second of white noise in audacity, look at spectrum Step 2) export to mp3 Step 3) Import back, look at spectrum

Result: http://i.imgur.com/vZtZ6xE.png (left is original, right is mp3 roundtripped)

The mp3 (at least with this encoder) kills some of the high frequencies, so the noise is no longer white.

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