[FFmpeg-trac] #9453(undetermined:new): Overlay with negative x/y produces artefacts

[FFmpeg]

#9453: Overlay with negative x/y produces artefacts
--------------------------------------+----------------------------------
             Reporter:  Jozef Chutka  |                     Type:  defect
               Status:  new           |                 Priority:  normal
            Component:  undetermined  |                  Version:  4.3.2
             Keywords:  overlay       |               Blocked By:
             Blocking:                |  Reproduced by developer:  0
Analyzed by developer:  0             |
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 Summary of the bug:

 Overlaying image/movie over main with alpha channel (see [shape]) produces
 ugly artefacts esp. when used with negative x/y.

 However, when color=c=0x000000 (no alpha) or x/y is positive there are no
 visible artefacts.

 How to reproduce:

 {{{
 ffmpeg -filter_complex_script filter.txt -frames:v 1 out.png -y
 }}}

 filter.txt:

 {{{
 color=c=0xff0000:size=1280x720[main];
 color=c=0x00000000:size=500x500[shape];
 movie=640x640.jpg,[shape]overlay=y=-10,[main]overlay
 }}}
-- 
Ticket URL: <https://trac.ffmpeg.org/ticket/9453>
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