[MEncoder-users] x264 2-pass, FAAC, smearing

[GM]

Hello,

I have the following problem occuring:
When doing 2-pass encoding and using (simplified to highlight the cause):

1st pass: mencoder -ovc x264 -oac copy
2nd pass: mencoder -ovc x264 -oac faac

Then there is a sort of time shift.
Iframes always come too late...
What I mean is, that on every single scene change, there is a huge lot
of smearing for a couple of frames, because the rate distribution is
off (the iframe comes in 2-3 frames later than needed).
Meaning that the first pass is offset, compared to the second pass.
This happens with any input video.

I tried toning down all options, making sure 1st pass and 2nd pass are
identical etc. Doesn't help.
What instantly solves the problem is using:

1st pass: mencoder -ovc x264 -oac faac
2nd pass: mencoder -ovc x264 -oac faac

But this way you encode the audio _twice_
My FAAC settings are: -faacopts mpeg=4:object=2:br=xxx

Could this be a bug? Or am I doing something wrong?
I can upload some screenshots if needed. But it's simple. Take any
movie/clip/whatever, and step frame-by-frame on a scene change.

Took a lot of time to hunt this down, very unexpected behaviour.