python - Flask应用程序中的Opencv视频

Question

我正在尝试在Raspberry Pi 3 B +型的apache 2服务器中运行的Flask应用程序中运行面部检测脚本。

每当我从浏览器访问该应用程序时，都会出现此错误:

******************************************************************
* FATAL ERROR:                                                   *
* This OpenCV build doesn't support current CPU/HW configuration *
*                                                                *
* Use OPENCV_DUMP_CONFIG=1 environment variable for details      *
******************************************************************
Required baseline features:
NEON - NOT AVAILABLE
terminate called after throwing an instance of 'cv::Exception'
what():  OpenCV(3.4.4) /home/pi/packaging/opencv-python/opencv/modules/core/src/system.cpp:538: error: (-215:Assertion failed) Missing support for required CPU baseline features. 
Check OpenCV     build configuration and required CPU/HW setup. in function 'initialize'
[Tue Mar 03 14:20:36.611427 2020] [core:notice] [pid 776:tid 1995485424] AH00052: child pid 6966 exit signal Aborted (6)

但是当作为单独的脚本运行时，它可以正常工作。
这里出现上述错误的原因是什么？

使用Flask蓝图在 /videostream中注册 index.py路由

更新:
似乎import cv2导致了错误。
videostream.py

import cv2
from flask import Blueprint, render_template, Response
videoStreamBp = Blueprint('videoStream', __name__)
# import the necessary packages
from picamera.array import PiRGBArray
from picamera import PiCamera
from imutils.video import FPS
import time

# initialize the camera and grab a reference to the raw camera capture
camera = PiCamera()
camera.resolution = (480, 320)
camera.framerate = 32
rawCapture = PiRGBArray(camera, size=(480, 320))

time.sleep(0.5)
fps = FPS().start()
face_cascade = cv2.CascadeClassifier('haarcascade_frontalface_alt.xml')

def gen(camera):
    # Video streaming generator function.
    while True:
        from camera_pi import Camera

        # capture frames from the camera
        for frame in camera.capture_continuous(rawCapture, format="bgr", use_video_port=True):
            # grab the raw NumPy array representing the image, then initialize the timestamp
            # and occupied/unoccupied text
            image = frame.array
            gray = cv2.cvtColor(image,cv2.COLOR_BGR2GRAY)
            faces = face_cascade.detectMultiScale(gray, 1.1, 5)

            for (x,y,w,h) in faces:
                cv2.rectangle(image,(x,y),(x+w,y+h),(255,0,0),2)
            # show the frame
            #cv2.imshow("Frame", image)
            yield (b'--frame\r\n'
               b'Content-Type: image/jpeg\r\n\r\n' + image + b'\r\n')
            key = cv2.waitKey(1) & 0xFF

            # clear the stream in preparation for the next frame
            rawCapture.truncate(0)

            # if the `q` key was pressed, break from the loop
            if key == ord("q"):
                break
            # update the FPS counter
            fps.update()
        # stop the timer and display FPS information
        fps.stop()
        print("[INFO] approx. FPS: {:.2f}".format(fps.fps()))

@videoStreamBp.route('/videoStream')
def getVideo():
    return Response(gen(Camera()),
                    mimetype='multipart/x-mixed-replace; boundary=frame')

Answer 1

并非所有的Raspberry Pi型号都支持NEON。我有一个Pi Zero W，在安装OpenCV 4之后也遇到了同样的问题。