How to live steam webcam using python-flask and opencv?

Question

I want to set up a web server using python-flask. I tried to follow the tutorial form chioka.in , but when I run the app it initializes but when i try to access the address from localhost I get this error.

 * Running on http://127.0.0.1:5000/ (Press CTRL+C to quit)
127.0.0.1 - - [18/Aug/2016 02:15:46] "GET / HTTP/1.1" 200 -
Traceback (most recent call last):
  File "main.py", line 22, in <module>
    app.run()
  File "/usr/local/lib/python2.7/dist-packages/flask/app.py", line 843, in run
    run_simple(host, port, self, **options)
  File "/usr/local/lib/python2.7/dist-packages/werkzeug/serving.py", line 694, in run_simple
    inner()
  File "/usr/local/lib/python2.7/dist-packages/werkzeug/serving.py", line 659, in inner
    srv.serve_forever()
  File "/usr/local/lib/python2.7/dist-packages/werkzeug/serving.py", line 499, in serve_forever
    HTTPServer.serve_forever(self)
  File "/usr/lib/python2.7/SocketServer.py", line 238, in serve_forever
    self._handle_request_noblock()
  File "/usr/lib/python2.7/SocketServer.py", line 297, in _handle_request_noblock
    self.handle_error(request, client_address)
  File "/usr/lib/python2.7/SocketServer.py", line 295, in _handle_request_noblock
    self.process_request(request, client_address)
  File "/usr/lib/python2.7/SocketServer.py", line 321, in process_request
    self.finish_request(request, client_address)
  File "/usr/lib/python2.7/SocketServer.py", line 334, in finish_request
    self.RequestHandlerClass(request, client_address, self)
  File "/usr/lib/python2.7/SocketServer.py", line 655, in __init__
    self.handle()
  File "/usr/local/lib/python2.7/dist-packages/werkzeug/serving.py", line 216, in handle
    rv = BaseHTTPRequestHandler.handle(self)
  File "/usr/lib/python2.7/BaseHTTPServer.py", line 340, in handle
    self.handle_one_request()
  File "/usr/local/lib/python2.7/dist-packages/werkzeug/serving.py", line 251, in handle_one_request
    return self.run_wsgi()
  File "/usr/local/lib/python2.7/dist-packages/werkzeug/serving.py", line 193, in run_wsgi
    execute(self.server.app)
  File "/usr/local/lib/python2.7/dist-packages/werkzeug/serving.py", line 183, in execute
    for data in application_iter:
  File "/usr/local/lib/python2.7/dist-packages/werkzeug/wsgi.py", line 703, in __next__
    return self._next()
  File "/usr/local/lib/python2.7/dist-packages/werkzeug/wrappers.py", line 81, in _iter_encoded
    for item in iterable:
  File "main.py", line 12, in gen
    frame = camera.get_frame()
  File "/media/moithil/STORAGE/PROJECTS/PROJECTS/webcam Server/camera.py", line 24, in get_frame
    return jpeg.tobytes()
AttributeError: 'numpy.ndarray' object has no attribute 'tobytes'

How to I convert this jpeg into bytes to return it properly?

The code blocks with error are

from camera.py file

import cv2

class VideoCamera(object):
    def __init__(self):
        self.video = cv2.VideoCapture(0)


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

    def get_frame(self):
        success, image = self.video.read()
        ret, jpeg = cv2.imencode('.jpg', image)
        return jpeg.tobytes()

from main.py file

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

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

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

Answer 1

Your numpy version is probably < 1.9.

According to the release notes ( http://docs.scipy.org/doc/numpy/release.html ):

ndarray.tobytes and MaskedArray.tobytes have been added as aliases for tostring > which exports arrays as bytes. This is more consistent in Python 3 where str and > bytes are not the same.

Try using tostring instead, or upgrade numpy to latest version.

Answer 2

you need to encode you image in jpeg format before passing it to yield. You can use " return jpeg.tostring() " in camera.py.

Answer 3

you can use the bellow templet to convert and yield

ret, jpeg = cv2.imencode('.jpg', frame)
            frame = jpeg.tobytes()
            yield (b'--frame\r\n' b'Content-Type: image/jpeg\r\n\r\n' + frame + b'\r\n\r\n')