3 pass mode

[miha]

can anyone tell me why the mpeg2 encoders have this option, and what is the benefit from it and why the mp4 codec do not use it ?

[ReferenceDivx]

On each pass it refines the bitrate allocation. If I remember correctly CCE can do upto 7 passes. I imagine that xvid doesn't do multiple passes because the programmers are so awsome that they have figured out a way to do in 2 passes what others do in 7.