import av
import av.datasets


content = av.datasets.curated('pexels/time-lapse-video-of-night-sky-857195.mp4')
with av.open(content) as container:
    # Signal that we only want to look at keyframes.
    stream = container.streams.video[0]
    stream.codec_context.skip_frame = 'NONKEY'

    for frame in container.decode(stream):

        print(frame)

        # We use `frame.pts` as `frame.index` won't make must sense with the `skip_frame`.
        frame.to_image().save(
            'night-sky.{:04d}.jpg'.format(frame.pts),
            quality=80,
        )