[MEncoder-users] CPU usage in two pass encoding

[Stjepan Brbot]

I use the following mencoder commands for two pass xvid encoding:

mencoder dvd://1 -alang hr -passlogfile FILE.xvid.log \
-oac mp3lame -lameopts abr:br=128:aq=3:mode=1:vol=2 \
-ovc xvid -xvidencopts bitrate=1200: ... :threads=2:pass=1:turbo \
-vf crop=704:544:8:16,scale=600:480 \
-o /dev/null

mencoder dvd://1 -alang hr -passlogfile FILE.xvid.log \
-oac mp3lame -lameopts abr:br=128:aq=3:mode=1:vol=2 \
-ovc xvid -xvidencopts bitrate=1200: ... :threads=2:pass=2 \
-vf crop=704:544:8:16,scale=600:480 \
-o FILE.xvid.avi

(tehere are more xvindenc parameters but for sake of simplicity I put
here only three dots).

In both passes I set "threads=2" but I see that my CPU usage in first
pass is only 55% while in second pass it is 88% (Of course both passes
run in the same conditions - no other apps are running.)

What's the reason for different CPU usages of these two passes?