girotour
29th September 2007, 13:49
I'm doing some tests in order to find the right way to resize a MPEG2 file recorded from satellite.
As AutoGK says, the file has the following format:
[29/09/2007 13.56.15] Source resolution: 704x576
[29/09/2007 13.56.15] Found PAL source.
[29/09/2007 13.56.15] Source aspect ratio: 4:3
Since I don't know if it is correct to apply ITU resize method for this source, I've tried to compress it with and without "Force ITU resize method" checked.
In both my tests, I used the following settings:
Auto crop: off (by setting Threshold to 0)
Manual crop: Left=4, Right=4, Top=2, Bottom=2
Detect and force 4:3 AR: off
Output resolution: 640 pixels (fixed width)
In my understanding, in the first case (ITU on) the input PAR should be 1.094, so the output height should be:
(640 * (576 - 2 - 2)) / (1.094 * (704 - 4 - 4)) = 480.78 rounded to 480
In the second case (ITU off) the input PAR should be 1.067, so the output height should be:
(640 * (576 - 2 - 2)) / (1.067 * (704 - 4 - 4)) = 492.95 rounded to 496
Despite of this, I always obtain an output height of 480 pixel with or without ITU resize method checked.
What I'm doing wrong or not understanding?
As AutoGK says, the file has the following format:
[29/09/2007 13.56.15] Source resolution: 704x576
[29/09/2007 13.56.15] Found PAL source.
[29/09/2007 13.56.15] Source aspect ratio: 4:3
Since I don't know if it is correct to apply ITU resize method for this source, I've tried to compress it with and without "Force ITU resize method" checked.
In both my tests, I used the following settings:
Auto crop: off (by setting Threshold to 0)
Manual crop: Left=4, Right=4, Top=2, Bottom=2
Detect and force 4:3 AR: off
Output resolution: 640 pixels (fixed width)
In my understanding, in the first case (ITU on) the input PAR should be 1.094, so the output height should be:
(640 * (576 - 2 - 2)) / (1.094 * (704 - 4 - 4)) = 480.78 rounded to 480
In the second case (ITU off) the input PAR should be 1.067, so the output height should be:
(640 * (576 - 2 - 2)) / (1.067 * (704 - 4 - 4)) = 492.95 rounded to 496
Despite of this, I always obtain an output height of 480 pixel with or without ITU resize method checked.
What I'm doing wrong or not understanding?