[FFmpeg-trac] #11366(undetermined:new): Regression when prepending/concatenating still image to video

[FFmpeg]

#11366: Regression when prepending/concatenating still image to video
-------------------------------------+-------------------------------------
             Reporter:  mahozad      |                     Type:  defect
               Status:  new          |                 Priority:  normal
            Component:               |                  Version:  7.1
  undetermined                       |
             Keywords:  concat       |               Blocked By:
  concatenate filter_complex         |
             Blocking:               |  Reproduced by developer:  1
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
 **Summary of the bug:**
 I'm using FFmpeg to create clips with ability to concat an image to be
 shown at the start of the clip for the specified duration:
 https://github.com/mahozad/cutcon

 It uses FFmpeg CLI.

 FFmpeg version 6.1.1 (and I think also version 5.1.2) worked as expected.
 When upgrading to FFmpeg 7.1, the result video just contains the intro
 image and then just ends.

 I'm not sure if this is a regression. Maybe my FFmpeg command is "wrong"
 and it should have failed in previous versions as well?

 **How to reproduce:**
 FFmpeg 7.1 and also FFmpeg-full 2024-12-19-git-494c961379 downloaded from
 https://www.gyan.dev/ffmpeg/builds/
 both tested on Windows 11.

 Here is an example FFmpeg invocation (formatted, each option in a new
 line) to reproduce the problem.
 It tries to create a clip from an input MP4 file and show an image at the
 start for 8 seconds. The image size is coerced to be at maximum the size
 of video and is padded with black color if its aspect ratio is different
 than the video. There is some other filters too.

 {{{
 path/to/ffmpeg.exe
   -y
   -nostdin
   -loglevel
   info
   -stats_period
   0.1s
   -accurate_seek
   -ss
   356500ms
   -to
   378500ms
   -i
   path/to/a/video.mp4
   -loop
   1
   -framerate
   25
   -t
   8s
   -i
   path/to/a/picture.jpg
   -t
   8s
   -f
   lavfi
   -i
   aevalsrc=0
   -filter_complex
       [0] yadif=1 [media-de-interlaced];
       [media-de-interlaced] scale=iw*sar:ih [media-anamorphic-fixed];
       [media-anamorphic-fixed] pad=ceil(iw/2)*2:ceil(ih/2)*2 [media-odd-
 pixel-number-fixed];
       [media-odd-pixel-number-fixed] setsar=1/1 [media-source-aspect-
 ratio-normalized];
       [media-source-aspect-ratio-normalized] null [media];
       [1][media]
 scale2ref='if(gt(main_a,a),min(main_w,iw),min(main_h,ih)*main_a)':'if(gt(main_a,a),min(main_w,iw)/main_a,min(main_h,ih))'
 [intro-image-max-size-coerced][media];
       [1][media] scale2ref=iw:ih [size-template][media];
       [size-template] drawbox=w=iw:h=ih:t=fill:color=#000000 [intro-
 background];
       [intro-background][intro-image-max-size-coerced]
 overlay=x='(W-w)/2':y='(H-h)/2' [intro-with-background];
       [intro-with-background] setsar=1/1 [intro-source-aspect-ratio-
 normalized];
       [intro-source-aspect-ratio-normalized] null [intro];
       [intro][2][media] concat=n=2:v=1:a=1
   -c:v
   libx264
   -c:a
   aac
   -crf
   23
   -r
   25
   -metadata
   encoding_tool=Cutcon v1.2.3
   path/to/output.mp4
 }}}
-- 
Ticket URL: <https://trac.ffmpeg.org/ticket/11366>
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