[FFmpeg-trac] #10987(avutil:new): Blend video filter *_expr options don't handle store and load functions correctly.

[FFmpeg]

#10987: Blend video filter *_expr options don't handle store and load functions
correctly.
-------------------------------------+-------------------------------------
             Reporter:  Fallan       |                    Owner:  (none)
                 Type:  enhancement  |                   Status:  new
             Priority:  normal       |                Component:  avutil
              Version:  git-master   |               Resolution:
             Keywords:  "blend       |               Blocked By:
  filter" "store and load" st()      |
  ld()                               |
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
Comment (by Michael Koch):

 Simplified examples for reproducing:

 This does not work:
 ffmpeg -f lavfi -i color=red -f lavfi -i color=yellow -lavfi
 blend=all_expr='st(0,Y/H);A*ld(0)+B*(1-ld(0))' -frames 1 -y out1.png

 This does work:
 ffmpeg -f lavfi -i color=red -f lavfi -i color=yellow -lavfi
 blend=all_expr='A*Y/H+B*(1-Y/H)' -frames 1 -y out2.png

 It seems the memory for variable 0 is overwritten by something else in
 most cases (but not always).
-- 
Ticket URL: <https://trac.ffmpeg.org/ticket/10987#comment:2>
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