How to create video thumbnails with Python and Gstreamer

Question

I\'d like to create thumbnails for MPEG-4 AVC videos using Gstreamer and Python. Essentially:

1. Open the video file
2. Seek to a certain point in time (e.g

Answer 1

It's an old question but I still haven't found it documented anywhere.
I found that the following worked on a playing video with Gstreamer 1.0

import gi
import time
gi.require_version('Gst', '1.0')
from gi.repository import Gst

def get_frame():
    caps = Gst.Caps('image/png')
    pipeline = Gst.ElementFactory.make("playbin", "playbin")
    pipeline.set_property('uri','file:///home/rolf/GWPE.mp4')
    pipeline.set_state(Gst.State.PLAYING)
    #Allow time for it to start
    time.sleep(0.5)
    # jump 30 seconds
    seek_time = 30 * Gst.SECOND
    pipeline.seek(1.0, Gst.Format.TIME,(Gst.SeekFlags.FLUSH | Gst.SeekFlags.ACCURATE),Gst.SeekType.SET, seek_time , Gst.SeekType.NONE, -1)

    #Allow video to run to prove it's working, then take snapshot
    time.sleep(1)
    buffer = pipeline.emit('convert-sample', caps)
    buff = buffer.get_buffer()
    result, map = buff.map(Gst.MapFlags.READ)
    if result:
        data = map.data
        pipeline.set_state(Gst.State.NULL)
        return data
    else:
        return

if __name__ == '__main__':
    Gst.init(None)
    image = get_frame()
    with open('frame.png', 'wb') as snapshot:
        snapshot.write(image)

The code should run with both Python2 and Python3, I hope it helps someone.