variable bitrates

[ilitherian]

i have a question, when the first pass is being run of a 2 pass encode, is it making its own assumptions for bitrate, or is it just looking at the bitrate the movie is encoded at. For example, when i play a DVD, i can look at the bitrate, and it changes. why don't we use that bitrate as what to go by, just scale it down to how big you want the movie to be? seems to me like that would save time.

[N_F]

On the first pass the bitrate you indicated in the divx configuration is used.

Other codecs don't use any bitrate at all (or perhaps maximum), XviD for instance.

[Teegedeck]

XviD uses a fixed quantizer for first pass (quant=2), thus the 'bitrate' changes from frame to frame depending on its complexity.