[MPlayer-users] LAVC-MPEG4 vs DIVX4 vs XVID??

[D Richard Felker III]

On Tue, Oct 21, 2003 at 09:50:57AM +0200, JJ2Dogs wrote:
> [Automatic answer: RTFM (read DOCS, FAQ), also read DOCS/bugreports.html]
> Hi all. Finally I got some time to try out these 3 codecs. For testing I used the first 3 chapters of We were soldiers because the in the first scene there is the desert dust which is allways difficult for the codecs. Any way here is what I used for settings and some info... 
> DIVX4: 
> -sws 2 -ovc divx4 -divx4opts br=2200:q=5:crispness=100:key=50 -oac copy -vop scale=512:288 
> speed was 24fps {very fast} 
> output size was 305,1MB 
> XVID: 
> -sws 2 -ovc xvid -xvidencopts bitrate=2200:4mv:min_key_interval=50 -oac copy -vop scale=512:288 
> speed was about 8fps 
> output size was 307,3MB 
> LAVC 
> -sws 2 -ovc lavc -lavcopts vcodec=mpeg4:vqscale=2:vme=1:vhq:keyint=20 -oac copy -vop scale=512:288 
> speed was 5fps 
> output size was 461,7MB 
>  
> The best quality was the lavc codec then it was a bit better the
> xvid. But lavc is the winer in quality category... Divx was the
> fastest..
>  
> I wonder... Many people say that the lavc is faster than Divx?? So
> why it is so slow on my PC?? I got PIII-1Ghz 512Ram 128Mb-AGP.. Can
> any body tell me how to increase the speed? But the quality must be
> very good..

Because they RTFM and leave vme at the default rather than setting the
(insanely slow and probably lower-quality) vme=1. From the fine
manual:

       vme=<0-5>
              motion  estimation method.  Note: 0-3 currently ig-
                                          ^^^^^^^^^^^^^^^^^^^^^^^
              nores the amount of Bits spent, so quality  may  be
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
              low.  Available methods are:
              ^^^^
                 0    none (very low quality)
                 1    full (slow)
                 2    log (low quality)
                 3    phods (low quality)

In fact at constant-qscale, vme=1 will probably give maximal quality,
but normally people encode by setting a bitrate instead, in which case
vme=1 will reduce quality. In any case, using the default (vme=4,
epzs) will give very good quality, still much better than divx4 and
better than xvid.

BTW, you're not using very fair options for comparison. You've got
xvid using 4mv mode while lavc isn't, and you should probably use the
newer mbd=2 option for lavc rather than vhq (same as mbd=1) for better
quality. You're also using single-pass bitrate-based encoding for divx
and xvid whereas you're using constant q=2 for lavc.

Rich