With a Canon EOS 1D X Mark II (released this summer just in time for the Olympics in Rio) you can shoot 4k video up to 60 frames per second and then grab individual 8 Mp images in JPEG format. Today I tested this with my new camera sent to me from Canon:
Choose maximum resolution behind the HD icon to see the video in the highest quality (1080p 4K above and below) on your current monitor!