Finding frames in video that match an image

Question

I'm trying to find frames in a video that match a certain input image. I'm currently using this command:

ffmpeg.exe -i video.mp4 -loop 1 -i image.jpg -an -filter_complex "blend=difference,blackframe=99:32" -f null -

This spits out the frames whose difference between the input image is less than 32 for 99% of the pixels. The problem is the process doesn't appear to stop.

Sample output (exited manually - video is only 8mins long):

[Parsed_blackframe_1 @ 0000000003421660] frame:6498 pblack:100 pts:3326976 t:216.600000 type:P last_keyframe:6496
[Parsed_blackframe_1 @ 0000000003421660] frame:6499 pblack:99 pts:3327488 t:216.633333 type:P last_keyframe:6496
[Parsed_blackframe_1 @ 0000000003421660] frame:9839 pblack:99 pts:5037568 t:327.966667 type:P last_keyframe:9832
[Parsed_blackframe_1 @ 0000000003421660] frame:9840 pblack:99 pts:5038080 t:328.000000 type:P last_keyframe:9832
frame=18321 fps=495 q=-0.0 Lsize=N/A time=00:10:25.26 bitrate=N/A speed=16.9x
video:8731kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown
Exiting normally, received signal 2.

Is there a way to tell ffmpeg to stop once it reaches the end of the file, or is there maybe a different way to achieve what I'm trying to do?

I'm using version ffmpeg version n3.2.9-1-g519a54c

Answer 1

The blend filter can be told to terminate with the shortest input, which in your command, will be the video.

-filter_complex "blend=difference:shortest=1,blackf...