[MEncoder-users] Can't get enough quality with xvid

[Vladimir Mosgalin]

Hi Pepe!

 On 2006.09.26 at 03:03:48 +0200, Pepe wrote next:

> > > Is there any other option I should use to improve quality?
> >
> > try
> > me_quality=6:quant_type=mpeg:keyframe_boost=15:trellis:chroma_me:chroma_opt
> >:hq_ac:vhq=1
> 
> Just to be sure. The values for me_quality, quant_type, trellis, chroma_me, 
> hq_ac and vhq are already the default values that mencoder would use, so I 
> don't need to explicitly use them, do I?

No you don't. Defaults change, I don't want to track them all, and there
are different defaults depending on whether you are using mencoder,
transcode or anything else.  I just gave you options I use, disregarding
the fact you are using recent version of mencoder and some defaults are
the same.

> > and use higher bitrate. If you reencode together with increasing
> > resolution and disabling b-frames, it's quite possible that you won't be
> > able to avoid blockness unless you increase your bitrate. Try 1500,
> > 2000, 2500...
> 
> Yesterday I encoded the video again, but this time using a lower resolution 
> (576x432), and quality improved.
> 
> Anyway I've just re-encoded the video using your options, and I also enabled 
> b-frames, using the same bitrate and the same resolution (704x576) as before. 

OK. IF you are using b-frames, try this:
min_iquant=1:max_iquant=4:min_pquant=1:max_pquant=6:min_bquant=2:
max_bquant=9:me_quality=6:quant_type=mpeg:trellis:chroma_me:
chroma_opt:hq_ac:vhq=1:bvhq=1:

(the difference is min/max options and bvhq option)
Also you may try using keyframe_boost=10:curve_compression_high=10, but
I'm not sure if it will help in your case, it helps me sometimes..

Also, don't lower resolution THAT much. It won't really help, you'll
lose more details.

> Now definitely image quality is best than before, although some blocks can 
> still be seen. Unfortunately when watching it in my dvd player the image 

Increase bitrate a bit and use min/max parameters I provided. (they are
tweaked to higher bitrates, starting from 1500, but ~may~ work in your
case).

> blinks sometimes a little bit in the lower part of the screen. That happens 
> when I use b-frames in videos with high resolution. I don't know why it is.

Does this happen only with max_bframes=2 or even with max_bframes=1?

-- 

Vladimir