Am 20.02.2020 um 12:49 schrieb Paul B Mahol:
On 2/20/20, Michael Koch <[email protected]> wrote:
Am 20.02.2020 um 11:07 schrieb Paul B Mahol:
On 2/20/20, Michael Koch <[email protected]> wrote:
I'd like to understand how the new "fill" option in the remap filter
works.
What is an "unmapped pixel"? How is it possible that pixels are
unmapped, if the xmap and ymap files have the same size as the output
image? Is a pixel "unmapped" if it has invalid coordinates (negative or
too big) in the xmap or ymap files?
Previously all unmapped pixels were set to black for rgba or dark
green for y420p.
It is very obvious to understand even for every little kid in the block.
Finally I got it working. A pixel can be declared as "unmapped" by
setting the values to 65535 in the xmap and ymap files. However using a
negative value (for example -1) doesn't work. In this case the pixel is
mapped to the top left pixel of the input image.
This behaviour might be obvious for little kids, but not for me. Should
be added to documentation.
Nope. Documentation does not need trivial information.
Obviously by having even limited programming experience one would
found out that remaps are unsigned short, thus can not be negative.
I that case I did make the PGM file with C# code and some coordinates
were set to -1. Obviously I shouldn't have done that because the PGM
specification doesn't allow negative values. But FFmpeg did not report
any errors when reading this file. May be a warning should be added if
negative values are found.
Michael
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