On Thu, 14 Dec 2000 20:35:55 +0100, Gabriel Bouvigne wrote:
The pre-releases just keep getting cooler, thanks Rob! The auto attenuation is fantastic. On one track I have, ZZ Top's 'La Grange', taken from the Armageddon soundtrack (which has incredible amounts of clipping on the CD itself),
There is something I don't understand. Clipping is sound above the maximum allowed sound. As the sound of a CD is stored on a CD, and the maximum amplitude sound that can be stored on a CD is obviously the maximum allowed intensity on a CD, how can there be clipping on a CD, ie the sound of the CD exceding the sound that can be stored on this CD. That seems strange to me.
I'll repeat what I sent to Peter.
You're thinking lossless compression here, 'cause you won't get a signal different from the original with lossless compression such as Monkeyaudio. However, MP3 reconstructs an audio signal from less than the original signal plus noise. Add for example one frequency x and another frequency 2*x, then you'll have some areas that are boosted, and some that are attenuated. When 2*x is filtered out again(or gets discarded in some places, because the encoding algorythem thought you won't hear it) then some places will get attenuated that were peaks and some will be boosted that weren't peaks before. And sometimes in complex signals that are mastered to use the maximum of the 16 bit resolution on a CD and are mastered to extreme loudness(single releases are mangled this way a LOT), the signal's reconstruction overshoots, because the stuff that got filtered out in the encoding process meant that the tightly controlled frequencies of the signal will have some things missing. You get some peaks and attenuations you previously didn't have. You can check this easily, by taking a ripped track and using an EQ in a sample editor to EQ 100Hz by -6 dB for example. You almost always get clipped samples, because of the great energy that lower frequencies take and thus command more amplitude and heavier changes to the signal.
Tony