I would like to make transitions via concat with ffmpeg for a slideshow. In my case the number of images is often changing. Is there a way to use concat to set the transition or can i define a crossfade with one single line for all images that have been linked via index.txt. My idea was to set it via bat script after every image link but didn't found a concat var for this.
Currently i'm using concat and
ffmpeg -f concat -safe 0 -i index.txt -y -vf fade=in:0:30 -vsync vfr -vf "scale=1920:1080:force_original_aspect_ratio=decrease,pad=1920:1080:(ow-iw)/2:(oh-ih)/2" -c:v libx264 -r 30 -b:v 12M -pix_fmt yuv420p -pix_fmt yuv420p tmp.mp4
