[MEncoder-users] lavc or xvid

[Alex Samad]

On Thu, Aug 30, 2007 at 01:37:51PM +0400, Vladimir Mosgalin wrote:
> Hi Alex Samad!
> 
>  On 2007.08.30 at 08:58:50 +1000, Alex Samad wrote next:
> 
> > This was my original thought, but a few emails, have suggested that xvid blurs 
> > stuff...
> 
> It depends on what are you trying to get. If you are aiming at
> low-bitrate encode and will use postprocessing on playback, use lavc. If
> you want to preserve a lot of detail, you'd have to use high bitrate, no
> postprocessing and definitely xvid..
> 
> xvid has a few very nice features like working (and useful) B-frames,
> which aren't recommended for lavc for some reasons, so don't forget to
> utilize them.
> 
> Also don't forget that 1-pass xvid encodes are absolutely useless. xvid
> ignores bitrate on first pass, so never ever compare 1-pass xvid encode
> to anything..
> 
> 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).

I have made png from 5 frames and then jump in 5 sec's and another 5 frames and 
copied off 6 sec worth of video, packaged this all together - done with the 
original and all the re encoded files.  I have saved the stdout and stderr 
(used bash -x to capture all the commands run).  I can place them online if 
somebody would like to look at them, see if I am missing something. cause the 
xvid is looking better now, but at 800kbit rate it is only 1/2 the size of the 
original, were as lavc is much better.

each package is about 5M, I have done 800, 1200, 1600 and 2000 bitrate for each 
of lavc (3 pass) and xvid (2 pass).  There a about 10-20 original files

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!


> 
> -- 
> 
> Vladimir
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> 
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