Original HD 1920x1080 progressive file
Convert that to an interlaced HD video file
ffmpeg -loop 1 -r 25 -i lines.png -vframes 100 -vcodec libx264 -crf 21 -top 1 -an lines-1920.mov
Scale that to an SD video file in interlaced mode
ffmpeg -i lines-1920.mov -vf scale=704:576:interl=1,pad=720:576:8:0:black -aspect 16:9 -vcodec libx264 -crf 21 -top 1 -an lines-720.mov
Export a frame from that, so I can put it on this web page
ffmpeg -i lines-720.mov -vframes 1 lines-720.png
