[MPlayer-users] Cropping in original-size vs reduced-size
Jorge Fábregas
jfabregas at onelinkpr.net
Sat Mar 24 14:32:18 CET 2007
On Friday 23 March 2007 12:52 pm, Nico Sabbi wrote:
> -vf crop=704:480:8:0,scale=640:-10
> scales to y' (closest x16) keeping A/R, even after having cropped
Thanks Nico but I think you're not getting my point. I can put this way:
My AR goal is: 512 x 384 (x16's dimensions and 4:3)
My source: NTSC DVD (720 x 480) with 4:3 AR
Problem: I need to remove 8 pixels on each side (black bands) and I know how
to do it. I just have a dilemma right now which I can describe with the 2
ways I could encode this footage:
Way #1:
--------------------
Before encoding:
mplayer dvd://1 -chapter 4 -vf cropdetect
...to get where to crop exactly
Actual encoding:
... -vf crop=704:480:8:0,scale=512:384
Way #2:
------------------
Before encoding:
mplayer dvd://1 -chapter 4 -vf scale=512:384,cropdetect
...Notice here that in order to get the proper crop values I'm actually
dowscaling first..thus I'll get the values for the downsized image.
Actual encoding:
... -vf scale=512:384,crop=496:384:8:0
Could you guys please tell me which on is the best one? In Way#1 I'm scaling
to 4:3 the ACTUAL content. In Way #2 I'm scaling the WHOLE frame. Obviously
these are 2 different things. Ok, for the regular eye, there won't be much
difference but I think Way#2 is the way to go. In Way#2 even though I end up
with 496x384 (which isn't 4:3) the thing is that this frame was cropped from
a 4:3 one (which already considered square pixels).
Thanks,
Jorge
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