1 trackBar for 2 windows or 1 window with 2 videos

Python
1

I have 2 video files that 1 want to review frame by frame with 1 trackbar.

Is it possible to show 2 videos in 1 named window and have the trackbar
scroll through the frames of both videos? The videos are sports-motion captures that I want to keep in sync.

Or do I need to create 2 separate named windows and have the trackbar update both positions with

while (cap1.isOpened()):
pos = cv2.getTrackbarPos(trackbar_name, title_window_1)
cap1.set(cv2.CAP_PROP_POS_FRAMES, pos)
cap2.set(cv2.CAP_PROP_POS_FRAMES, pos)

2

Nevermind, I found I can just combine the 2 frames vertically and use 1 window and trackbar.

def main():
    global preview
    cap1 = cv2.VideoCapture("raw-swing.mp4")
    cap2 = cv2.VideoCapture("annotated-swing.mp4")

    trackbar_name = "Frame"
    window_name = 'dual-view'
    cv2.namedWindow(window_name, cv2.WINDOW_GUI_EXPANDED)
    cv2.resizeWindow(window_name, 800, 1300)
    cv2.setWindowProperty(window_name, cv2.WND_PROP_AUTOSIZE, cv2.WINDOW_GUI_EXPANDED)

    framecount = int(cap1.get(cv2.CAP_PROP_FRAME_COUNT))
    cv2.createTrackbar(trackbar_name, window_name, 0, (framecount - 1), onchange)
    cv2.setTrackbarMin(trackbar_name,window_name,0)
    cv2.setTrackbarMax(trackbar_name,window_name,(framecount - 1))
    cv2.setTrackbarPos(trackbar_name,window_name,0)
    cv2.setMouseCallback(window_name, onclick)

    while(cap1.isOpened() and cap2.isOpened()):
        ret1, frame1 = cap1.read()
        ret2, frame2 = cap2.read()
        pos = cv2.getTrackbarPos(trackbar_name, window_name)
        cap1.set(cv2.CAP_PROP_POS_FRAMES, pos)
        cap2.set(cv2.CAP_PROP_POS_FRAMES, pos)
        vertical_join = cv2.vconcat([frame1, frame2])
        cv2.imshow(window_name,vertical_join)

        key = cv2.waitKey(1)
        if key == 27:  # esc key
            break
        elif key == 2:  # Left arrow key
            cv2.setTrackbarPos(trackbar_name,window_name,pos-1)
            cap1.set(cv2.CAP_PROP_POS_FRAMES, pos-1)
            cap2.set(cv2.CAP_PROP_POS_FRAMES, pos-1)
        elif key == 3:  # right arrow key
            cv2.setTrackbarPos(trackbar_name,window_name,pos+1)
            cap1.set(cv2.CAP_PROP_POS_FRAMES, pos+1)
            cap2.set(cv2.CAP_PROP_POS_FRAMES, pos+1)

    cap1.release()
    cap2.release()
    cv2.destroyAllWindows()

trackbar
trackbar811×1057 89.8 KB