cv2 python frames can be shown, but not saved to file-CodePudding

i'm trying to record a video clip. I have an object "observer" that created frames.

When i "imshow" images - i can see everything OK. I have an "avi" file being generated. But when i try to view it - it is empty. clip is 0 seconds of black screen.

What am i missing?

frames_count = 0

fourcc = cv2.VideoWriter_fourcc(*'XVID')
writer = cv2.VideoWriter('output.avi', fourcc, 15.0, frame_size)
while True:
    img_pil = observer.get()
    draw = ImageDraw.Draw(img_pil)

    frame = cv2.cvtColor(np.array(img_pil), cv2.COLOR_BGR2GRAY)
    writer.write(frame)
    cv2.imshow(f"frame (q: {observer.q.qsize()})", frame)
    frames_count  = 1

    if cv2.waitKey(1) & 0Xff == ord('q'):
        break
    if frames_count > 30:
        break

writer.release()

CodePudding user response：

The issue is that the image is grayscale. This line:

writer = cv2.VideoWriter('output.avi', fourcc, 15.0, frame_size)

Should be replaced with:

writer = cv2.VideoWriter('output.avi', fourcc, 15.0, frame_size,0)