On 2/20/20, Michael Koch <[email protected]> wrote: > 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.
Negative values can not be represented in PGM, they are cast to some other positive value depending on implementation. > > Michael > _______________________________________________ > ffmpeg-user mailing list > [email protected] > https://ffmpeg.org/mailman/listinfo/ffmpeg-user > > To unsubscribe, visit link above, or email > [email protected] with subject "unsubscribe". _______________________________________________ ffmpeg-user mailing list [email protected] https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email [email protected] with subject "unsubscribe".
