Michael Niedermayer (high overlord of lavc mpeg-4) just added a "Rate distorted optimal coded block pattern" option. I don't understand the particulars of what that means, but I decided to give a few tests of trell+cbp vs. mbd=2 vs. all the other options I usually use. The 200-second clip I used has low graininess but lots of fast motion and moderate amounts of chaotic changes. It's probably reprentative of non-grainy movies with lots of fast motion and moderate amounts of chaotic changes. Your results WILL vary. :) All the encoding lines look like this, plus more lavcopts: for i in 1 2 ; do mencoder test.vob -ss 205 -endpos 200 -aid 128 -vf \ crop=714:352:2:62,scale=688:288 -sws 1 -ovc lavc -lavcopts \ vbitrate=800:vcodec=mpeg4:vpass="$i":psnr -oac copy -ofps 23.976 -o \ small"$i".avi ; done For clarity, I'll only report the additions to lavcopts below; thus, the first test has no changes from the command above. Also for clarity, I will collectively reference the following options as <stuff>: v4mv:precmp=3:cmp=3:subcmp=3:vmax_b_frames=1:qpel:vlelim=-2:vcelim=7:\ lumi_mask=0.05:naq:vqcomp=0.7:mbcmp=2 The PSNR line listed is for the second pass. <no changes to lavcopts> PSNR: Y:39.13, Cb:43.22, Cr:43.91, All:40.17 mbd=2 PSNR: Y:39.44, Cb:43.56, Cr:44.31, All:40.49 trell PSNR: Y:39.36, Cb:43.26, Cr:43.97, All:40.37 mbd=2:trell PSNR: Y:39.62, Cb:43.56, Cr:44.34, All:40.64 trell:cbp PSNR: Y:39.37, Cb:43.09, Cr:43.82, All:40.35 mbd=2:trell:cbp PSNR: Y:39.52, Cb:43.27, Cr:44.05, All:40.51 <stuff> PSNR: Y:39.78, Cb:43.24, Cr:43.96, All:40.72 <stuff>:mbd=2 PSNR: Y:40.08, Cb:43.64, Cr:44.41, All:41.04 <stuff>:trell PSNR: Y:40.07, Cb:43.31, Cr:44.05, All:40.97 <stuff>:mbd=2:trell PSNR: Y:40.08, Cb:43.64, Cr:44.41, All:41.04 NOTE: After I ran the following two tests, I noticed that the encoding was seriously screwed up, and reduced the problem down to vlelim/vcelim. I reported the bug, Michael fixed it, and I re-ran the two tests. The results below are from after the bugfix. <stuff>:trell:cbp PSNR: Y:40.10, Cb:43.30, Cr:44.03, All:40.99 <stuff>:mbd=2:trell:cbp PSNR: Y:40.33, Cb:43.65, Cr:44.42, All:41.25 My perception is neither discerning nor unbiased enough to properly detect visual differences between the tests; I showed them to my friend, and the best I could get out of him was that the early tests looked good and the later tests looked really good. Regardless, I can certainly notice no qualitative loss when cbq is enabled. Decide what you want based on the PSNR figures. I think it's interesting that cbp contributed a 0.21 PSNR increase to the last test, though. :) Depending on how much time I have, I might do some more tests with different clips, and throw mv0 into the mix. Is anyone else testing these options? -Corey