[MPlayer-users] DVD rip Crop & scale little problems

[Alain Barthélemy]

Hi,

I first started to rip "The ninth Gate"

With tcprobe, I read:

import frame size -g 720x576 (*) [720x576]
.....
.....
mpeg2 pal 16:9 only letterboxed UO 720x576 video

On the DVD box I can read 16/9 compatible 4/3

Now if I add the option -vf cropdetect with mencoder I read the following
values for cropping:

718:432:2:72

If I read the movie with mplayer dvd://1 I have a image that takes the full
width o the PC screen (something like 1024x576).

I used the following options for encoding:

mencoder dvd://1 -aspect 16:9 -ovc lavc 
-lavcopts vcodec=mpeg4:vbitrate=1700:mbd=2:trell:cbp 
-vf hqdn3d=3:2:5,crop=718:432:2:72,scale=576:352 -sws 1 -oac mp3lame temp.avi

=======

Now I understand that the DVD has a 720x576 PAL dimension but can be resized to
wide-screen 16x9 dimension (anamorphic resizing?). MPlayer, when reading, does
it without problem but mencoder -vf cropdetect gives me a cropping dimension of
718x432 (1.66:1 not 1.77:1). If I rescale, respecting the dimensions, to a
width of 576, I get a scaling of 576x352. If I read now the movie on a
standalone reader, I have a vertically distorted image and I have to force the
reader to read the movie with a 16:9 aspect.

I don't have that distorsion problem if I use:  mencoder -aspect=16:9 ... -vf
hqdn3d=3:2:5,crop=718:432:2:72,scale=576:-2 ...  So I have an image with a
correct aspect of 16:9 or about but the scaled height is, I suppose, not a
multiple of 16 but it is like the image was not cropped because 718:432 is not
equal to 16:9.

Thus how can I calculate manually the cropping and rescaling of the image? Or
is scale=576:-2 the right way to do it?

-- 
Alain Barthélemy
cassandre at bartydeux.be
http://bartydeux.be
Linux User #315631