Issue getting OpenCV stream to work with flask on Raspberry Pi Zero 2 W

Question

I am attempting to get an OpenCV video stream running on my Raspberry Pi Zero 2 W using Flask.

The code is as follows:

from flask import Flask, render_template, Response
import cv2
import time

# Initialize the Flask App
app = Flask(__name__)


def gen_frames():
    camera = cv2.VideoCapture(0)
    while True:
        success, frame = camera.read()
        if not success:
            break
        else:
            ret, buffer = cv2.imencode('.jpg', frame)
            frame = buffer.tobytes()
            yield(b'--frame\r\n'
                  b'Content-Type: image/jpeg\r\n\r\n' + frame + b'\r\n') #concat frame one by one and display results
            time.sleep(0.01)

@app.route('/')
def index():
    return render_template('index.html')

@app.route('/video_feed')
def video_feed():
    return Response(gen_frames(), mimetype='multipart/x-mixed-replace; boundry=frame')



if __name__ == "__main__":
    app.run(host="192.168.7.80", port="5000")

I'm running Raspian Version 10 (Buster), OpenCV version 3.2.0, Python version 3.7.3, and Flask version 1.0.2.

The issue that is occuring is that when I run the above code (with the proper index.html) the page displays, but the image does not. If I run the same code on a Windows machine (versions are different [Python 3.9.6, OpenCV 4.5.5, and Flask 2.1.1] it displays properly.

Is there an issue with the versions I am running on the rPi or is it something different?

Thanks in advance.

-- Mike

Answer 1

One probable cause is the internal debugger conflicting with the reloader. Suggest enabling debug without the reloader:

app.run(host="192.168.7.80", port="5000", debug=True, use_reloader=False)