ffmpeg -f lavfi -i video.mp4 -loop 1 -i logo.png -filter_complex "[1:0] format=rgba,fade=in:st=0:d=2:alpha=1,fade=out:st=6:d=3:alpha=1 [ovr];[0:0][ovr] overlay=0:0" -t 10 -y out.mp4

ffmpeg -i video.mp4 -loop 1 -t 15 -i logo.png -filter_complex "[1:0] format=rgba,fade=in:st=0:d=2:alpha=1,fade=out:st=6:d=3:alpha=1,loop=-1:375:0[ovr];[0:0][ovr]overlay=0:0" -y out.mp4