Changing PiCamera Settings about flask-video-streaming

[miguelgrinberg]

It's been a while since I played with picamera, but I would imagine you need to stop the stream, make the necessary changes and then restart the stream with the new settings. So you need to use some signaling mechanism (maybe an event object) to let the background thread know that it needs to exit the streaming loop before you make changes.

[root-hal9000]

Hey Miguel,

here are some preliminary results, managed to stop/start thread - see code below. Seems like a dirty method, since I am sure it is probably horrible for performance, but here it is. I have managed to stop and start the thread by setting a 1 or 0 flag in a file using a route for /start & /stop and then checking for it on the base_camera._thread() method. Then I can change settings on camera_pi.frames() - If you have any other suggestions, please let me know. I didn't even know where to look for how to use events as you mentioned (really new on python and flask, first project), so any tips on where to start for a better method than using writing/reading files would be great - tried to use session, but couldn't read it in base_camera._thread(). or is there a way to control the thread from app.py?

app.py

@app.route('/start')
def start():
    file = open('status', 'w+')
    file.write('1')
    file.close()
    return render_template('index.html')


@app.route('/stop')
def stop():
    file = open('status', 'w+')
    file.write('0')
    file.close()
    return render_template('index.html')

base_camera.py

  @classmethod
    def _thread(cls):
        """Camera background thread."""
        print('Starting camera thread.')
        frames_iterator = cls.frames()
        for frame in frames_iterator:
            BaseCamera.frame = frame
            BaseCamera.event.set()  # send signal to clients
            time.sleep(0)

            # check to see if a stop flag has been set
            try:
                file = open('status', 'r+')
                status = file.read()
                file.close()
                if status == '0':
                    print('stopping camera')
                    break
            except:
                print('no file')

            # if there hasn't been any clients asking for frames in
            # the last 10 seconds then stop the thread
            if time.time() - BaseCamera.last_access > 10:
                frames_iterator.close()
                print('Stopping camera thread due to inactivity.')
                break

        BaseCamera.thread = None

then handle files for changing settings here on camera_pi.py

class Camera(BaseCamera):
    @staticmethod
    def frames():
        # with Camera.set_res(1920, 1080) as camera:
        with picamera.PiCamera() as camera:
            # let camera warm up
            time.sleep(2)
            
            # TODO - check files and adjust settings here, tested with hflip and resolution and they work if set in this method
            # file = open('flip', 'w+')
            # if file.read() == '1':
            #     camera.hflip = True
            # if file.read() == '0':
            #     camera.hflip = False
            # print(file.read())
            # file.close()
            # camera.resolution = (1024, 768)

            stream = io.BytesIO()
            for _ in camera.capture_continuous(stream, 'jpeg',
                                                 use_video_port=True):
                # return current frame
                stream.seek(0)
                yield stream.read()

                # reset stream for next frame
                stream.seek(0)
                stream.truncate()

[hyansuper]

This may help. picamera settings can be changed via url parameter, see https://github.com/hyansuper/picam-video-streaming