randframes.py

#!/usr/bin/env python3
import sys

from videoseeker import VideoSeeker


def main():
    seeker = VideoSeeker(sys.argv[1])
    for i in range(100):
        seeker.seek()
        seeker.get_image().save('output/test-%03d.jpg' % i)

    #seeker.seek()
    #for i, image in enumerate(seeker.get_images(10)):
    #    print(i)
    #    image.save('output/test-%03d.jpg' % i)


if __name__ == '__main__':
    main()

videoseeker.py

#!/usr/bin/env python3
from random import SystemRandom
import av


class VideoSeeker:
    def __init__(self, path):
        self.path = path
        self._container = av.open(path)
        self._video = next(s for s in self._container.streams
                           if s.type == 'video')
        self._random = SystemRandom()


    def seek(self, pos=None):
        if pos is None:
            pos = self._random.random()
        elif pos < 0 or pos > 1:
            raise ValueError('pos must be a float between 0 and 1.')
        self._video.seek(round(self._video.duration * pos), any_frame=True)


    def get_images(self, interval=0):
        packets = self._container.demux(self._video)
        frame_count = 0
        for packet in packets:
            for frame in packet.decode():
                frame_count += 1
                if frame_count % (interval + 1) == 0:
                    yield frame.to_image()


    def get_image(self):
        return next(self.get_images())