[MEncoder-users] lavc or xvid

[Vladimir Mosgalin]

Hi Alex Samad!

 On 2007.09.03 at 07:39:10 +1000, Alex Samad wrote next:

> > Try these xvid settings:
> > pass=1:bitrate=2000:min_iquant=1:max_iquant=3:min_pquant=1:max_pquant=5:min_bquant=2:max_bquant=8:me_quality=6:quant_type=mpeg:trellis:chroma_me:chroma_opt:max_bframes=2:hq_ac:vhq=1:bvhq=1:keyframe_boost=15
> > 
> > Note that you'll probably have to increase max_ parameters if you set
> > bitrate much lower. However, these settings aren't really suited for
> > bitrates lower than 1200-1500 (for dvd-sized video). You don't necessary
> > need 2k bitrate to get high quality encode, though.. On the other hand,
> > some material (esp. noisy one) needs even more if you want it to look
> > really good.
> 
> I have gone through a couple of iterations of xvid and lavc.  I have tried the 
> above xvid options (which seem to produce a much larger file compared to lavc, 
> compared by bitrate).

Well if you try to set 800kbit bitrate, they obviously would be bigger!
look at that max_quant settings, they limit lowest bitrate. And if you
hit this limit, that means that you shouldn't use these settings - the
quality would be lower, because xvid can't use higher quants with these
settings at all, some frames eat too much bitrate and the rest of frames
suffer from bitrate starvation.

These options are for high-quality, "just like dvd" encodes. These
options forbid xvid to take away quality from some frames, even if
xvid's ratecontrol tells it so for some reason - thus making quality
more uniform.

At 800 kbit, remove all max_?quant options and maybe keyframe_boost
option too.

Also I'm not sure whether you should use xvid at such low bitrates (if
you source video is dvd-sized, that is). If you need quality on this
bitrate, your only choice is x264.

> The one thing that is a sort of unknown is I changed the camera settings to XP 
> from normal - meant to save 10Mb instead of 5Mb to disk (higher definition ??)
> and I am not sure when I changed it, so I am not sure which video's have it on 
> and which have it off!

Hehe. Bad idea, to mix sources like that. However, by all means set it
to save 10Mb, if you are reencoding anyway, at very least you want the
source to be as good as possible.

PS you don't forget to deinterlace your video with some
reencoding-friendly deinterlacer, do you?

-- 

Vladimir