[MEncoder-users] filter question (converting low quality dvds to xvid = larger files)

[James Hastings-Trew]

Kerry Kirk wrote:
> First some background:
> I am on an Ubuntu 8.10 box and am using MEncoder 2:1.0~rc2-0ubuntu17 with
> libxvidcore4 2:1.1.2-01ubuntu3 (according to Synaptic)
>
> When I convert my dvds to xvid my process is as follows.
>
> Using dvdshrink via wine I rip out the parts I want, decrypt them and save
> the results as an iso.
>
> I have a script file that will process as many iso files as I request by
> mounting each iso as an iso9660 loop and issuing the following commands
>
> first pass
> mencoder -dvd-device /pathtoisofile dvd://1 -nosound -ovc xvid -xvidencopts
> pass=1:turbo -passlogfile xvidlog -o /dev/null 2>>errorlog
>
> second pass
> mencoder -dvd-device /pathtoisofile dvd://1 -oac mp3lame -lameopts
> cbr:br=96:vol=8 -alang en -ovc xvid -xvidencopts pass=2:bitrate=900
> -passlogfile xvidlog -o outputfile.avi 2>>errorlog
>
> I generally get a 2 hr movie down to about 650-700 megs.  With a few dvds of
> very old movies where the quality of the original is lacking the files end
> up being much larger.  I am guessing that the static and jitteriness(sp?) of
> some of these old films is the cause of the difference in compression and
> thus file size.
>
> Are there any commands or filters I should add to my encoding commands that
> might get some better quality xvids out of the older films.  I have used
> grayscale in the xvidencopts and it does seem to help with the b&w films.
> Any other ideas?
>   
Couple of things come to mind - pullup, deinterlace, scaling, cropping, 
hqdn3d. You are encoding the movies without doing any of these things 
which means you are burning bitrate on more frames than you need to 
(unless these are PAL DVDs, you didn't say), more detail than you should 
be (interlace is for TV, not for computers), pixels you don't need (DVDs 
are encoded at TV aspect ratios, generally storing more pixels than the 
computer needs to display them properly), black borders, and noise.

-vf pullup,softskip,pp=lb,hqdn3d,harddup will give you a push in the 
right direction IF the DVD source is NTSC, a movie shot on film, and I 
can't guess at valid values for cropping and scaling, but in gneral a 
full screen DVD with no cropping needs should be scaled to 640x480 to 
maintain proper aspect ratio.




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