/ Audio/ LAME MP3-Encoder Presets Decoded

I hate not knowing how things work. This includes not knowing exactly what options are being invoked when I use shortcuts in my favourite MP3 encoder, LAME! (It's an absolutely fantastic open source (that means free!) MP3 encoder! You should go get it now at http://www.mp3dev.org/mp3/ ).

You see, there is no documentation to tell the average person exactly what the presets "--alt-preset extreme" and "--alt-preset insane" actually are doing inside LAME. And I keep forgetting. So I'll put them here, and we'll both be happy!

"--alt-preset extreme" results the following:

LAME version 3.91 MMX (http://www.mp3dev.org/)
(Win32 binaries from http://mitiok.cjb.net/)
CPU features: i387, MMX (ASM used)
Using polyphase lowpass filter, transition band: 19383 Hz - 19916 Hz
Encoding a.wav to a.mp3
Encoding as 44.1 kHz VBR(q=2) j-stereo MPEG-1 Layer III (ca. 7.4x) qval=2

"--alt-preset insane" results the following:

LAME version 3.91 MMX (http://www.mp3dev.org/)
(Win32 binaries from http://mitiok.cjb.net/)
CPU features: i387, MMX (ASM used)
Using polyphase lowpass filter, transition band: 20094 Hz - 20627 Hz
Encoding a.wav to a.mp3
Encoding as 44.1 kHz 320 kbps j-stereo MPEG-1 Layer III (4.5x) qval=2

In both cases I've tried to bold the important bits to notice.