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reduction of quantization noise by taking average of multiple encoded
post Feb 29 2012, 13:53
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Youtube hosts lots of music transcoded using faac and quality isn't great. As popular tracks are usually uploaded by multiple users, one might reduce encoding noise by averaging waveforms of duplicates (can be done either in client app or intermediate server). Noise std should decrease as 1/sqrt(N:). Do you guys think this would work?
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post Feb 29 2012, 18:44
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I strongly suspect knutinh is right... Phase/timing differences in the different lossy encoders will probably cause weird comb filtering effects. (This will definitely happen if you mix two different analog recordings of the same-exact performance.)

It's EASY to try!!! Just MIX the files and then normalize to bring-down volume. Do you have an audio editor? If not, Audacity is FREE!

Mixing is done by addition and volume adjustments are done by multiplication (up) or division (down), so this is an averaging process.

Mixing two full-volume files will usually push the level above 0dB (the "digital maximum"). Most audio editors can handle levels above 0dB, but you should bring the levels down before saving to prevent clipping/distortion in the saved format. And of course, if you re-save in a lossy format, that's an additional lossy-compression step.

I hope this question is of a purely academic nature, because of course the right answer is if you want the music then buy your own copy.
Good point... If you find more than one copy of a recording, it's probably a copyrighted commercial release.
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