SCXvid produces first pass xvid logs from avisynth at the equuivalent of the default vfw preset. These logs are primaliy intended to get scenechange information from but could probably be used in some kind of twisted encoding setup too with lossless encoding of the output.
1.1 - Updated to use xvid 1.2.2 and multithreading
Mpeg2source("some_progressive.d2v")
SCXvid("C:\xvid_first_pass.log")
SCXvid(clip, string log)
All arguments are required
The clip can be in any colorspace and will be converted internally to yv12 with xvid's routines
Log is the output filename
SCXvid was created by Fredrik Mellbin. You can find my avisynth related things at ivtc.org.