How to open IP Camera Url by OpenCV and python?

Question

I have install opencv on MacX(Lion) with ffmpeg support

import cv2
import cv
import base64
import time
import urllib2
import numpy as np

from cv2 import __version__

print(__version__)
video="http://xxx.223.91.91/mjpg/1/video.mjpg?dummy=param.avi"
vv = cv.CaptureFromFile(video)
cv2.namedWindow("preview")
vc = cv2.VideoCapture("http://xxx.223.91.91/mjpg/1/video.mjpg?dummy=param.mjpg")

but Show WARNING

2.4.2

WARNING: Couldn't read movie file http://xxx.223.91.91/mjpg/1/video.mjpg?dummy=param.avi

WARNING: Couldn't read movie file http://xxx.223.91.91/mjpg/1/video.mjpg?dummy=param.mjpg

I Google a lot of code, but could not find a solution to the problem. Please help me, thank you.

Zaw Lin · Accepted Answer · 2013-08-23 20:18:58Z

4

import cv2
import urllib 
import numpy as np

stream=urllib.urlopen('http://localhost:8080/frame.mjpg')
bytes=''
while True:
    bytes+=stream.read(16384)
    a = bytes.find('\xff\xd8')
    b = bytes.find('\xff\xd9')
    if a!=-1 and b!=-1:
        jpg = bytes[a:b+2]
        bytes= bytes[b+2:]
        i = cv2.imdecode(np.fromstring(jpg, dtype=np.uint8),cv2.CV_LOAD_IMAGE_COLOR)
        cv2.imshow('i',i)
        if cv2.waitKey(1) ==27:
            exit(0)

answered Aug 23, 2013 at 20:18

Zaw Lin

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3 Comments

Sky Over a year ago

Are you saying that OpenCV can not directly open MJPG stream? But I searched on Google code indicates that the code is using OpenCV open directly MJPG stream, but I experiment does not work.

Martin Haeberli Over a year ago

It is my experience that a correctly configured OpenCV can directly open an MJPG stream. However, there seems to be some configuration magic, which I don't fully understand.

Zaw Lin Over a year ago

yes, opencv can open an mjpg stream with the following conditions. 1) it is compiled with ffmpeg. 2) url string must end in mjpg 3) stream will not start immediately due to max_analyze_duration not set when opencv call into ffmpeg. of course, fixing is trivial by editing the opencv code by enforcing -f mjpeg and setting a lower max_analyze_duration. but this method avoids the fat dependency and allows finer control over the stream. i have an explanation and a usage example @ stackoverflow.com/questions/21702477/…

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