Block switching

Psycoacoustic model decides when to switch to short blocks and back to long blocks (block switching).

In MP3, switching to short blocks will isolate the attack to 192 sample window, so the oscillations are only spread over 192 samples instead of 576. Block switching is also used by Ogg Vorbis and AAC. but MPC, being a subband coder doesn't need it.

Switching to short blocks and increasing of the bitrate to encode lots of MDCT coefficients of a transient are the 2 main ways to combat Pre echo.

Java applets to examine fourier series behaviour (note that MDCT behaviour is not totally identical):

http://www.jhu.edu/~signals/fourier2/ 

You can draw a sharp attack here, and use calculate with a large number of coefficients... if you start to reduce the number of coefficients you will see the pre echo appear.

http://www.gac.edu/~huber/fourier 

Doesnt seem to work in netscape. iirc this one lets you listen to the sound.

http://www.univie.ac.at/future.media/moe/galerie/fourier/fourier.html 

Maths online fourier series applet.