create new window video stream in tkinter

Question

In my program, i want to show the camera stream and gui in apart. I think i have to use thread for this in python but i dont know how to do that?

cap = cv2.VideoCapture(0)

while(True):
    # Capture frame-by-frame
    ret, frame = cap.read()

    # Display the resulting frame
    cv2.imshow('frame',frame)
    if cv2.waitKey(1) & 0xFF == ord('q'):
        break

# When everything done, release the capture
cap.release()
cv2.destroyAllWindows()

How can i change above code to open a new window and display the video stream with thread.

Answer 1

I hope I understand you correctly, that you want to run:

1. the capturing of the images from the camera in one thread,
2. while in parallel show the captured images (when available) in another thread.

• A classic "producer-consumer problem"!

Consider then the following code:

import cv2
import threading
from threading import Event

class multi_thread_stream:
    def __init__(self, ready=None):
        self.ready = ready
        self.cap = cv2.VideoCapture(0)
        self.frame = {}
        #Create the Threads
        self.t1 = threading.Thread(target=self.capture_stream)
        self.t2 = threading.Thread(target=self.display_image)
        self.t1.name = 'capture_thread'
        self.t2.name = 'display_thread'
        self.t1.start()
        self.t2.start()

    def capture_stream(self):
        while True:
            # Capture frame-by-frame
            self.ret, self.frame = self.cap.read()
            self.ready.set()
            if cv2.waitKey(1) & 0xFF == ord('q'):
                break

    def display_image(self):
        while True:
            # Display the resulting frame
            self.ready.wait()
            cv2.imshow('frame_2nd_trhead', self.frame)
            self.ready.clear()
            if cv2.waitKey(1) & 0xFF == ord('q'):
                break;

    def __del__(self):
        # When everything done, release the capture
        self.cap.release()
        cv2.destroyAllWindows()

if __name__ == '__main__':
    ready = Event()
    mts = multi_thread_stream(ready)
    mts.t1.join()
    mts.t2.join()

There are two functions, that run in two threads. The display-thread waits for a trigger and until the capture-thread has already read a frame and sent a trigger to the display-thread, the display-thread cannot continue further and hence cannot show an image (or throw an error of invalid variable size).

Hope it helps. (or at least it can be a basis for your further solution).