VideoCapture fails every time about pedestrian-cam HOT 6 CLOSED

The failing command is ofc plt.imshow(frame)

from pedestrian-cam.

Hi @turbo , I am unable to recreate this bug-- I wrote this using Python 3.6 and OpenCV 3.3.0, can you check to make sure you have the right versions?

from pedestrian-cam.

This seems to be a very widely known issue: ContinuumIO/anaconda-issues#121

None of the workarounds work for me though.

from pedestrian-cam.

Hmm. I installed OpenCV 3.3 using Conda Forge. I think this may have helped me avoid those issues.

from pedestrian-cam.

Even with Conda Forge OpenCV, the stream loading fails:

OpenCV: Couldn't read video stream from file "http://192.65.213.243/mjpg/video.mjpg"

So I used this minimal mjpeg frame proxy (PHP):

<?php

header("Access-Control-Allow-Origin: *");

function mjpeg_grab_frame($url) {
    $f = fopen($url, 'r');
    if($f) {
        $r = null;
        while(substr_count($r, "\xFF\xD8") != 2) $r .= fread($f, 512);
        $start = strpos($r, "\xFF\xD8");
        $end = strpos($r, "\xFF\xD9", $start)+2;
        $frame = substr($r, $start, $end-$start);
        fclose($f);
        return $frame;
    }
}
header("Content-type: image/jpeg");
die(mjpeg_grab_frame($_REQUEST['src']));

Started with php -S localhost:8000. Then this will work:

URL = 'http://localhost:8000/?src=http://192.65.213.243/mjpg/video.mjpg'

# Test capturing a frame from mJPG
cap = cv2.VideoCapture(URL)

ret, frame = cap.read()

from pedestrian-cam.

Wow, clever solution! I'll keep an eye out for this problem in the future, should I encounter it.

from pedestrian-cam.