I have two images and I want to create a simple fading transition between them.
I also want the final output to be a sequence of images rather than a video? So if the fading transition was 10 frames long I'd want the output to be a sequence of 10 images.
How can I achieve this with ffmpeg?
See the blend video filter:
ffmpeg -loop 1 -i input0.png -loop 1 -i input1.png -filter_complex "[1:v][0:v]blend=all_expr='A*(if(gte(T,3),1,T/3))+B*(1-(if(gte(T,3),1,T/3)))'" -t 4 frames_%04d.png
This example will make a 3 second cross-fade of input1.png over input0.png.
To crossfade/dip-to-black multiple images see Create video with 5 images with fade-in/out effect in ffmpeg.
To the best of my knowledge you cannot achieve this just with ffmpeg. Please take a look at MLT framework if you want to do it in scriprs; take a look at openshot if you want an interactive app.
Try this:
ffmpeg \
-loop 1 -t 3 -i input1.png \
-loop 1 -t 3 -i input2.png \
-loop 1 -t 3 -i input3.png \
-loop 1 -t 3 -i input4.png \
-loop 1 -t 3 -i input5.png \
-filter_complex \
"[1:v][0:v]blend=all_expr='A*(if(gte(T,3),1,T/3))+B*(1-(if(gte(T,3),1,T/3)))'[v0]; \
[2:v][1:v]blend=all_expr='A*(if(gte(T,3),1,T/3))+B*(1-(if(gte(T,3),1,T/3)))'[v1]; \
[3:v][2:v]blend=all_expr='A*(if(gte(T,3),1,T/3))+B*(1-(if(gte(T,3),1,T/3)))'[v2]; \
[4:v][3:v]blend=all_expr='A*(if(gte(T,3),1,T/3))+B*(1-(if(gte(T,3),1,T/3)))'[v3]; \
[v0][v1][v2][v3]concat=n=4:v=1:a=0[v]"
-map "[v]" out.mp4
Haven't tried with images, but you could try -t 12 frames_%04d.png at the end or whatever.
