Joining many AVI files together & changing framerate

convert into one file:

for i in $(ls); do cat $i >> bigavi.avi; done

mencoder -forceidx -oac copy -ovc copy bigavi.avi -o FINAL.avi

framerate (25):

ffmpeg -i FINAL.avi -f yuv4mpegpipe - | yuvfps -s 25:1 -r 25:1 | ffmpeg -f yuv4mpegpipe -i  - -b 1000k  faster.avi