I just figured out how to make a slideshow with crossfade. It's a two-step process. The first step reads the pictures with framerate 0.5 (which means 2 seconds for each picture), and produces an intermediate video with framerate 2. That means each picture is repeated 4 times. The second step applies the framerate filter. The result is that each picture is shown for 1.5 seconds, followed by a 0.5 second crossfade.
ffmpeg -framerate 0.5 -i IMG_%3d.jpg -r 2 -codec:v mpeg4 temp.mp4 ffmpeg -i temp.mp4 -vf "framerate=fps=25" -codec:v mpeg4 out.mp4
This two step process works fine, but I have two questions:
- Is it also possible to get the same result in one step, without an intermediate video file?
- If the answer to the first question is no, can someone please show me how the above commands must be modified for a lossless intermediate file, for example RAWVIDEO?