[MPlayer-users] libavcodec mpeg4 - blocky clip

[Michael Waters]

Hi,

I came across a clip from a dvd which is difficult to encode well with lavc
mpeg4.  I tried several different options and with bitrates between 750 and
2000 kbs.  The encoded file ends up very blocky especially in the moving
grass and in the sky during scene transitions.

If you look in divx2pass.log, lavc seems like it's possibly not sensing
motion or something and assigns q values which are too large. (...just my
uninformed guess :) ).  In case the clip is useful in improving libavcodec,
I uploaded to incoming/ :

wtness_lavc_enc_prob.avi
wtness_lavc_enc_prob-encoded.avi
wtness_lavc_enc_prob.txt
wtness_divx2pass.log

I'm using mencoder 0.90.  It's about 70sec and for the encoded file, I used:

mencoder wtness_lavc_enc_prob.avi \
 -vop denoise3d,scale=656:352,crop=706:480:8:0 \
 -ovc lavc -lavcopts vcodec=mpeg4:vbitrate=1200\
:vhq:v4mv:keyint=300:vlelim=-4:vcelim=9:lumi_mask=0.05:dark_mask=0.01:vpass=1 \
 -oac copy  -o wtness_lavc_enc_prob-encoded.avi 

...and vpass=2 for the 2nd pass.

Michael