[MEncoder-users] frame size confusion

Dave M G martin at autotelic.com
Sun Dec 2 10:07:53 CET 2007

Mencoder list,

Thank you to everyone who has responded and I'm sorry because I feel I 
have been unfocused in resolving this issue.

I've read more on the link provided and experimented with some different 
settings, and I hope I understand my situation better.

I think when I asked about saving in 720x406, I was not approaching the 
problem correctly. I think I was not taking into account the difference 
between square pixels and anamorphic pixels.

For saving my 720x480 images as AVI files, I shouldn't be converting the 
pixel size, I should instead preserve the aspect ration. Is that correct?

If so, then what exactly is the command to do so? I looked on the 
Mencoder documentation and found this:

But I'm unsure as to how to apply that in the command I have running.

The example they give is:
mencoder sample-svcd.mpg -vf crop=714:548:0:14 -oac copy -ovc lavc \ 
-lavcopts vcodec=mpeg4:mbd=2:trell:autoaspect -o output.avi

And my command is:
mencoder input.mpg -ovc lavc -lavcopts 
-vf scale=720:406,pp=lb -oac mp3lame -lameopts preset=standard -o output.avi

So I tried combining them, and putting the pixel scale to 720x480, like so:
-vf scale=720:480,pp=lb -oac mp3lame -lameopts preset=standard -o output.avi

But then I got a weird result. The image came back as 854x480 pixels, 
and it seems to have a fair amount of jpeg compression artifacts. I'm 
not sure if the compression artifacts are just more noticeable at a 
larger size, or if I've somehow hosed my quality settings.

Or maybe I'm just doing everything completely wrong here.

Can someone straighten me out here?

Thank you for any advice.

Dave M G

More information about the MEncoder-users mailing list