video snapshots with gstreamer

gistfile1.py

# coding: utf-8
import os
import sys

from gi.repository import Gst

SEC = 1

Gst.init(None)
caps = Gst.Caps.from_string('image/jpeg')
pipeline = Gst.parse_launch('playbin')
path = os.path.abspath(sys.argv[1])
pipeline.set_property('uri', 'file://{}'.format(path))
audio_sink = Gst.ElementFactory.make('fakesink', 'audiosink')
video_sink = Gst.ElementFactory.make('fakesink', 'videosink')
pipeline.set_property('audio-sink', audio_sink)
pipeline.set_property('video-sink', video_sink)
pipeline.set_state(Gst.State.PAUSED)
pipeline.get_state(Gst.SECOND)
duration = pipeline.query_duration(Gst.Format.TIME)[1]/Gst.SECOND
for i in range(0, duration/SEC):
    assert pipeline.seek_simple(
        Gst.Format.TIME, Gst.SeekFlags.FLUSH, i*SEC*Gst.SECOND)
    pipeline.get_state(Gst.SECOND)
    sample = pipeline.emit('convert-sample', caps)
    buffer = sample.get_buffer()
    image = buffer.extract_dup(0, buffer.get_size())
    with open('JPEG/frame{}.jpeg'.format(i), 'wb') as f:
        f.write(image)
pipeline.set_state(Gst.State.NULL)