[MEncoder-users] High quality encoding of anime

[Vladimir Mosgalin]

Hi Jean Hoderd!

 On 2005.04.19 at 09:23:14 -0700, Jean Hoderd wrote next:

> I scaled down because I noticed block artifacts in the
> unscaled version.  As a matter of fact, I still notice
> some blocks even at 640x480.  Perhaps I am doing something
> very wrong with my lavc and xvid options, in which case
> your help would be appreciated.
> 
> Or does scaling down introduce other kind of artifacts?

lavc likes to produce blocking artifacts a lot, it does it even with
vqscale 2 on some scenes. There are some options related to masking
blocks - haven't tried them, though.

It all depends whether you want to watch video with postprocessing (will
remove blocks, but some detail will be thrown as well) or not. If this
is a first case, use lavc. However, at this bitrate you can encode video
that will look better without pp, if you will do the things right. xvid
is more suited for this.

I generally use these parameters for encoding with xvid:
pass=1:bitrate=XXX:min_iquant=1:max_iquant=4:min_pquant=1:max_pquant=6:
min_bquant=2:max_bquant=9:me_quality=6:quant_type=mpeg:keyframe_boost=15:
trellis:chroma_me:chroma_opt:max_bframes=2:hq_ac:vhq=1:bvhq=1

Don't forget you should always do 2-pass encoding when using xvid, first
pass doesn't even takes bitrate into account.

for bvhq=1, you need xvid 1.1-beta1 or later. If you use older one,
upgrade (it will improve quality) or drop this option.

For lavc I use something like this:
vcodec=mpeg4:vbitrate=XXX:vqmin=1:lmin=1:v4mv:mbd=2:trell:subcmp=2:
cmp=2:precmp=2:mv0:autoaspect:vpass=1:mpeg_quant:psnr:vqcomp=0.7:
vqblur=0.3

When you get blocks even on scenes with qscale=2, vqmin=1:lmin=1 can
help a lot. Sometimes, they can do wonders. However, if the picture is
always good enough with qscale=2, it's better not to use these options.


Don't scale to 640x480, crop black borders and colored lines (check it
manually! mplayer -vo x11 and xmag are your friends - cropdetect isn't
good enough, use it for a start), then downscale to nearest numbers
divisible by 16 with bicubic scaler, if needed - the difference won't be
noticeable at all, but this can help encoding.

Use hqdn3d filter, don't forget to lower the settings, they are way too
high for dvds. Something like 3:3:5 for anime and 3:2:4 for real life
contents usually is the best. Use postprocessing (pp=ac or spp) if you
see blocks on original material, but check if details aren't destroyed
after this.


But if you haven't solved problem with interlacing/ telecine/ incorrect
NTSC to PAL transform/ whatever, do it first, if you will do it
incorrectly, it will hurt quality really a lot. I have several PAL discs
that apparently were produced of telecined NTSC-version.. they are
simply awful. I can't think of any way to get something descent looking
of them. Probably something like pp=lb,unsharp=l3x3:1.2:c3x3:1.2 is the
best...  Don't use if for encoding, though.

-- 

Vladimir