[MPlayer-users] Cropping in original-size vs reduced-size
Jorge Fábregas
jfabregas at onelinkpr.net
Fri Mar 23 13:02:10 CET 2007
Hello guys,
I would like to downscale some NTSC clip from a DVD to 640x480. I like this
resolution since it's 4:3 and multiples of 16. However, I need to crop 16
pixels on each side. I plan to:
1- downscale to 640x480. At this point the video is 4:3 and already
vertically compensated (ready for square pixels).
2- now I'll crop 32 pixels horizontally (16 in each side) and I end up with
608x480. It's not really 4:3 but it doesn't matter as the video was already
vertically compensated in previous step.
Now, my problem is... How do I go from step #1 to step #2 in just one
encoding? It's not the same thing to crop in full size than to crop on the
downscaled version. How can I know beforehand that what I want actually is
608x480?
I'm assuming that we should downscale to 4:3 considering the WHOLE frame (in
this case 720x480) including the black bars. If I crop in original size, and
I just leave THE ACTUAL CONTENT, the aspect ratio of that content may not be
4:3 right? The quesition is: Should you do the 4:3 conversion considering
the whole frame or JUST the actual content (geting it by cropping)?
Please help me understand this.
Thanks for your comments.
Best regards,
Jorge
More information about the MPlayer-users
mailing list