title: Select specific frame fast OpenCV Python
body: <p>I am trying to rapidly select and process different frames from a video using OpenCV Python. To select a frame, I have used the 'CAP_PROP_POS_FRAMES' (or cap.set(2, frame_no)).  However when using this I noticed a delay of about 200 ms to decode the selected frame. My script will be jumping in between frames a lot (not necessarily chronological) which means this will cause a big delay between each iteration. 
  I suspected OpenCV is buffering the upcoming frames after I set the frame number. Therefore I tried pre-decoding of the video by basically putting the entire video as a list so it can be accessed from RAM. This worked fantastic except bigger videos completely eat up my memory.
  I was hoping someone knows a way to either set the frame number without this 200ms delay or to decode the video without using all of my memory space. Any suggestions are also welcome!</p>