Frame delayed in OpenCV and IP cam Hikvision

Question

I have a task to process a streaming video from Hikvision IP cam using OpenCV

I try this

RTSP

"""

cap = cv2.VideoCapture()
cap.open("rtsp://yourusername:yourpassword@172.16.30.248:555/Streaming/channels/1/")

and this

using API Hikvision

"""

cam = Client('http://192.168.1.10', 'admin', 'password', timeout=30)
cam.count_events = 2 
response = cam.Streaming.channels[101].picture(method='get', type='opaque_data')
    for chunk in response.iter_content(chunk_size=1024):
        if chunk:
            f.write(chunk)

img = cv2.imread('screen.jpg')
cv2.imshow("show", img)
cv2.waitKey(1)

In the first case, I have a delay between realtime and cap.read() about 9-20 seconds. I solved it with such a "hack", but no results.

"""

class CameraBufferCleanerThread(threading.Thread):
    def __init__(self, camera, name='camera-buffer-cleaner-thread'):
        self.camera = camera
        self.last_frame = None
        super(CameraBufferCleanerThread, self).__init__(name=name)
        self.start()

    def run(self):
        while True:
            ret, self.last_frame = self.camera.read()

"""

The second case shows frames with a delay of 1-2 seconds, which is acceptable, but fps = 1, which is not very good.

Are there any options that can help you get a stream with low latency and normal fps?

why are you throttling the camera? you must read frames as quickly as possible. you can't throttle that. — Christoph Rackwitz, Aug 10 '21 at 14:10

score 0 · Answer 1 · answered Aug 11 '21 at 20:32

In nathancys's post I finded working solutuion. it is done. I used simple modification his code for my case for getting frame in main function.

from threading import Thread
import cv2, time


from threading import Thread
import cv2, time

class ThreadedCamera(object):
    def __init__(self, src=0):
        self.capture = cv2.VideoCapture(src)
        self.capture.set(cv2.CAP_PROP_BUFFERSIZE, 1)

        self.FPS = 1/100
        self.FPS_MS = int(self.FPS * 1000)
        # First initialisation self.status and self.frame
        (self.status, self.frame) = self.capture.read()

        # Start frame retrieval thread
        self.thread = Thread(target=self.update, args=())
        self.thread.daemon = True
        self.thread.start()

    def update(self):
        while True:
            if self.capture.isOpened():
                (self.status, self.frame) = self.capture.read()
            time.sleep(self.FPS)


if __name__ == '__main__':
    src = 'rtsp://admin:password@192.168.7.100:554/ISAPI/Streaming/Channels/101'
    threaded_camera = ThreadedCamera(src)
    while True:
        try:
            cv2.imshow('frame', threaded_camera.frame)
            cv2.waitKey(threaded_camera.FPS_MS)
        except AttributeError:
            pass

Frame delayed in OpenCV and IP cam Hikvision

1 Answers1