[FFmpeg-trac] #8766(documentation:new): find_rect documentation

[FFmpeg]

#8766: find_rect documentation
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             Reporter:  mkoch        |                     Type:
                                     |  enhancement
               Status:  new          |                 Priority:  normal
            Component:               |                  Version:  git-
  documentation                      |  master
             Keywords:               |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
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 I suggest to add the following to the documentation of the find_rect video
 filter:

 -- If the input video contains multiple instances of the object, find_rect
 will find only one of them.
 -- threshold = 0.01 means only exact matches, threshold = 0.99 means
 almost everything matches
 -- find_rect writes the result to these internal variables:
    lavfi.rect.w    width of object
    lavfi.rect.h    height of object
    lavfi.rect.x    x position of object
    lavfi.rect.y    y position of object
 -- If the threshold value isn't met, then these variables aren't written
 to.
 -- It is possible to write these variables to a file with ffprobe and
 -show_entries

 Examples section:

 Find the position of an object in each frame and write it to a log file:
 ffprobe -f lavfi movie=test.mp4,find_rect=object=object.pgm:threshold=0.3
 -show_entries
 frame=pkt_pts_time:frame_tags=lavfi.rect.x,lavfi.rect.y -of csv 1> log.csv


 Suggestion for improvement:

 Please make also the internal variable "best_score" available, so that it
 can be written to the log file as well.

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Ticket URL: <https://trac.ffmpeg.org/ticket/8766>
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