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

[James Hastings-Trew]

Kerry Kirk wrote:
> James,
>
> Thanks for the reply.  Yes it is an NTSC video and I also forgot to mention
> that I am running a 64bit os if that matters.
>
> Should filters be applied to both passes or to the second pass only?
>
> K.
>
> On Sun, Mar 22, 2009 at 2:44 AM, James Hastings-Trew <jimht at shaw.ca> wrote:
>
>   
>> 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.
>>     
both passes. :)



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