Python - camera broadcast stops if there are multiple users, how to fix?

M

mcrack2020-02-15 13:18:52

Python

mcrack, 2020-02-15 13:18:52

Hello everyone, I found several scripts on the Internet for displaying an image from the camera on the page and redid it a little, but they all do not work correctly.

For example, I launched the server, opened the browser and see myself, but as soon as I go to the same page from the phone, the video on the computer freezes, as soon as I reload the page on the computer, the video on the phone freezes. I don't understand what the problem is.

# camera.py

import cv2

class VideoCamera(object):
    def __init__(self):
        # Using OpenCV to capture from device 0. If you have trouble capturing
        # from a webcam, comment the line below out and use a video file
        # instead.
        self.video = cv2.VideoCapture(0)
        # If you decide to use video.mp4, you must have this file in the folder
        # as the main.py.
        # self.video = cv2.VideoCapture('video.mp4')

    def __del__(self):
        self.video.release()

    def get_frame(self):
        success, image = self.video.read()
        # We are using Motion JPEG, but OpenCV defaults to capture raw images,
        # so we must encode it into JPEG in order to correctly display the
        # video stream.
        ret, jpeg = cv2.imencode('.jpg', image)
        return jpeg.tobytes()

# app.py

#!/usr/bin/env python
from flask import Flask, render_template, Response

# emulated camera
from camera import VideoCamera

app = Flask(__name__)

@app.route('/')
def index():
    """Video streaming home page."""
    return render_template('index.html')

def gen(camera):
    """Video streaming generator function."""
    while True:
        frame = camera.get_frame()
        yield (b'--frame\r\n'
               b'Content-Type: image/jpeg\r\n\r\n' + frame + b'\r\n')

@app.route('/video_feed')
def video_feed():
    """Video streaming route. Put this in the src attribute of an img tag."""
    return Response(gen(VideoCamera()),
                    mimetype='multipart/x-mixed-replace; boundary=frame')

if __name__ == '__main__':
    app.run(host='0.0.0.0', debug=True, threaded=True)

index.html

<html>
  <head>
    <title>Video Streaming Demonstration</title>
  </head>
  <body>
    <h1>Video Streaming Demonstration</h1>
    <img src="{{ url_for('video_feed') }}">
  </body>
</html>

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1 answer(s)

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Sergey Gornostaev, 2020-02-15
@mcrack

Flask is synchronous and single-threaded, so it can handle as many connections at the same time as there are workers running by the wsgi server. Simply put, it is not suitable for video broadcasts.