问Flask with opencv-python:在访问@app.route之前保持摄像头处于运行状态，并在发送GET请求时拍摄图像
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Stack Overflow用户

提问于 2020-12-14 19:08:26

回答 1查看 174关注 0票数 1

我正在尝试初始化摄像头并启动视频馈送，然后打开@app.route功能，只有当我收到GET请求的网址时，才会保存帧。

我的代码是：

from flask import Flask, jsonify
from flask import request
from flask_restful import Resource, Api, reqparse
from datetime import datetime
import time
import numpy as np
import glob
import os
import sys
import cv2

# initialize the flask application
app = Flask(__name__)


# initialize the camera and grab a reference to the raw camera capture
cap = cv2.VideoCapture(0)
ret, frame = cap.read()
while(True):
    # Capture frame-by-frame
    ret, frame = cap.read()

    # Our operations on the frame come here
    #gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)

    # 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()

#RESTAPI for image
@app.route('/take_image')
def image():
    start_time = time.time()       
    jobnummer = request.args.get('JOB') #if key doesn't exist, returns None
            
    #save the frame when GET Request is sentt
    if jobnummer: 
        cv2.imwrite('test.jpg', frame) 
        
    end_time = time.time()
    time_tot = end_time-start_time
    res = {"jobnummer" : jobnummer,
           "time":time_tot
           }
    return jsonify(res) , 200
    
if __name__ == "__main__":
#     run flask application in debug mode
    app.run(debug=True,port=5000,host='0.0.0.0')

但是当我运行这段代码时，由于while循环的原因，我无法进入@app.route函数。有没有办法让视频保持运行的感觉，然后访问@app.route？

python-3.x

flask

回答 1

Stack Overflow用户

回答已采纳

发布于 2020-12-15 05:50:58

下面是一个解决这个问题的demo：

from flask import Flask, render_template, Response
import cv2

app = Flask(__name__)

'''
for ip camera use - rtsp://username:password@ip_address:554/user=username_password='password'_channel=channel_number_stream=0.sdp' 
for local webcam use cv2.VideoCapture(0)
'''

camera = cv2.VideoCapture(0)


def gen_frames():  
    while True:
        success, frame = camera.read()  # read the camera frame
        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')  

@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; boundary=frame')

if __name__ == "__main__":
    app.run(debug=True)

index.html (使用引导，但不是必需的)

<!doctype html>
<html lang="en">
<head>
    <!-- Required meta tags -->
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">

    <!-- Bootstrap CSS -->
    <link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.1.3/css/bootstrap.min.css"
          integrity="sha384-MCw98/SFnGE8fJT3GXwEOngsV7Zt27NXFoaoApmYm81iuXoPkFOJwJ8ERdknLPMO" crossorigin="anonymous">

    <title>Live Streaming Demonstration</title>
</head>
<body>
<div class="container">
    <div class="row">
        <div class="col-lg-8  offset-lg-2">
            <h3 class="mt-5">Live Streaming</h3>
            <img src="{{ url_for('video_feed') }}" width="100%">
        </div>
    </div>
</div>
</body>
</html>