It seems there is a bug in mencoder (0.90rc4) when encoding multiple PNG files using -ovc lavc. Create some PNG files (320x240) and try encoding them using mencoder -mf on:w=320:h=240:fps=25:type=png -ovc lavc -lavcopts vcodec=mpeg4 -o film-lavc.avi "f00*.png" The result will be a strangely disorted image: the rightmost 25% of the image stay black, the rest appears grey with vertical lines. No compression artifact, this is actually a bug in mencoder, probably in RGB -> YUV conversion (because encoding JPG files instead of PNG works fine). Note: encoding the same PNG files with -ovc divx4 has no problems. Please check that. Please CC me as I'm not subscribed. ----------<snip>-------- Opening video filter: [expand=-1:-1:-1:-1:1] Expand: -1 x -1, -1 ; -1 (-1=autodetect) osd: 1 ========================================================================== Opening video decoder: [mpng] PNG Images decoder Selected video codec: [mpng] vfm:mpng (PNG images decoder) ========================================================================== Writing AVI header... VDec: vo config request - 640 x 480 (preferred csp: BGR 24-bit) Could not find matching colorspace - retrying with -vop scale... Opening video filter: [scale] VDec: using BGR 32-bit as output csp (no 0) Movie-Aspect is undefined - no prescaling applied. SwScaler: reducing / aligning filtersize 1 -> 4 SwScaler: reducing / aligning filtersize 1 -> 4 SwScaler: reducing / aligning filtersize 1 -> 1 SwScaler: reducing / aligning filtersize 9 -> 8 SwScaler: BICUBIC scaler, from BGR 32-bit to Planar YV12 using MMX2 videocodec: libavcodec (640x480 fourcc=58564944 [DIVX]) ----------------