[MPlayer-users] Why create video in 1st pass?

[Tshepang Lekhonkhobe]

Hello,
Why is it default behaviour that MPlayer creates a video during 1st
pass when we are interested in the 2nd pass output?
I see some people directing it to /dev/null but isn't this unnecessary overhead?
>From the docs, I get that the 1st pass is used to study the input
video to make a superior 2nd pass video, so why need the 1st pass
video output?
Thanks...