Compare() and AssumeFPS() problem

For properly using Compare with a logfile, you need to understand how avisynth request frames. That's because writing to the logfile is a side effect (the purpose of a filter is to produce an output clip, not to write a logfile), and - as all side effect functions - is a bit nasty. The last filter in the script produce the output, and this filter is responsible for calling the other filters. In your first script, AssumeFPS has no effect since it isn't called by Compare: Compare refers to the "orig" and "encoded" clips from the source. This is probably what you're trying to achieve: Code:

Thank you for your answer. Using avifilesource("f:\war3.avi").assumefps(100, 1, false) did the trick :D I can compute an average psnr of 3-minute clip in just above one minute (I think I'll overclock my pc a bit more ;> ) If you're just looking to blast through the .avs file as fast as you can to generate the log file, you could have loaded it up in VDub, and chose XviD as the compressor using "Null mode (test speed)". That'll just request frames from the frameserver as fast as it can serve them up, but just write null frames to the AVI. Pete added it as a decompression speed test. -h

OK now I understand why you want AssumeFPS. What I usually do to speed test avisynth scripts is, in vdub, set audio to No audio, video to Direct Stream Copy, press F9 (to disable "display input video"), F10 (disable "display output video")and F5 (launch preview). No need to speed up the clip.

And don't forget to use Fast Compress Mode (YUY2) with Preview (F5) !!! you'll not see the preview, but the speed will override all limitations, and it would be much faster (no RGB conv). i can use Compare at 35 fps like this :devil: