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Crippled MP3 playback revisited

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Avrin

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As it turns out, the crippled MP3 playback "feature" of second-generation Hi-MD units was not created out of thin air. The transformation applied to the signal is not just an arbitrary decrease of higher frequencies. It exactly coincides with the de-emphasis curve provided by the Red Book Standard for audio CDs. And the pre-emphasis/de-emphasis feature, when used properly, can actually increase sound quality by lowering quantization noise in the higher frequency range (which is most affected by it) by 10 dB.

Green - white noise with the de-emphasis transformation applied (using SonicStage).

Red - an MP3 of pure (flat) white noise played back on the RH10.

b0a8f8798fa1t.jpg

A practical use for the improperly implemented function follows immediately: if you have a pre-emphasized CD (the first pressing of Pink Floyd's "The Wall" is the most famous example), rip it by a non-deemphasizing program (i.e., not SonicStage or iTunes), compress to MP3 and enjoy perfect sound on a second-generation Hi-MD unit!

Edited by Avrin
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