[MPlayer-users] [BUG] naq & bframes can cause horrible results and bandwidth consumption

[Jindrich Makovicka]

Hello,

I just found a reproducible case when usage of naq, *_mask and b-frames 
causes lavcodec produce terrible output. After the encoder encounters a 
high motion scene, or a scene with a lot of noise (as in the example), 
it starts producing a sequence of P & B frames, where P-frames are with 
low detail and blocky, while B-frames are with high detail. The 
resulting video looks extremely crappy for the rest of the file and the 
encoder starts consuming high amount of bandwidth, which doesn't 
decrease with time. Removing naq causes the problem disappear.

code used to reproduce the case:

#!/bin/sh

VCODEC="-ovc lavc -lavcopts vcodec=mpeg4:vbitrate=746:vlelim=-4:vcelim=7:\
lumi_mask=0.05:dark_mask=0.01:scplx_mask=0.02:tcplx_mask=0.08:\
mbd=2:vmax_b_frames=1:naq:vqmin=2"

mencoder -v -nosound $VCODEC -o out.avi test1.avi

input video is available at http://kmlinux.fjfi.cvut.cz/~makovick/test1.avi

-- 
Jindrich Makovicka