can't open URL video source with opencv-python cv2.VideoCapture()

asked 2019-06-06 19:34:23 -0500

TomH gravatar image

I'm using a 3rd party python app which uses the opencv-python module to retrieve mp4 video and do object detection. However when I try to run this on my local fedora 28 desktop, I am unable to retrieve any video using a URL. The extracted code is basically like so;

import cv2
import numpy as np
import re

url = ""
vid = cv2.VideoCapture(url)

if not vid.isOpened():
  print("not opened")

always returned "not opened".

However if I download the file, I can open it:

import re
import requests

resp = requests.get(url)

print("url is {}".format(url))

if resp.status_code == 200:
      with open('Big_Buck_Bunny_720_10s_10MB.mp4', 'wb') as f:

vid = cv2.VideoCapture('Big_Buck_Bunny_720_10s_10MB.mp4')

if not vid.isOpened():
  print("not opened")


url is
frames in video are 300.0

The buildinformation returns this:

General configuration for OpenCV 4.1.0 =====================================
  Version control:               4.1.0

    Timestamp:                   2019-04-11T16:10:20Z
    Host:                        Linux 4.4.0-101-generic x86_64
    CMake:                       3.9.0
    CMake generator:             Unix Makefiles
    CMake build tool:            /usr/bin/gmake
    Configuration:               Release

  CPU/HW features:
    Baseline:                    SSE SSE2 SSE3
      requested:                 SSE3
    Dispatched code generation:  SSE4_1 SSE4_2 FP16 AVX AVX2
      requested:                 SSE4_1 SSE4_2 AVX FP16 AVX2 AVX512_SKX
      SSE4_1 (13 files):         + SSSE3 SSE4_1
      SSE4_2 (1 files):          + SSSE3 SSE4_1 POPCNT SSE4_2
      FP16 (0 files):            + SSSE3 SSE4_1 POPCNT SSE4_2 FP16 AVX
      AVX (4 files):             + SSSE3 SSE4_1 POPCNT SSE4_2 AVX
      AVX2 (27 files):           + SSSE3 SSE4_1 POPCNT SSE4_2 FP16 FMA3 AVX AVX2

    Built as dynamic libs?:      NO
    C++ Compiler:                /usr/lib/ccache/compilers/c++  (ver 4.8.2)
    C++ flags (Release):         -Wl,-strip-all   -fsigned-char -W -Wall -Werror=return-type -Werror=non-virtual-dtor -Werror=address -Werror=sequence-point -Wformat -Werror=format-security -Wmissing-declarations -Wundef -Winit-self -Wpointer-arith -Wsign-promo -Wuninitialized -Winit-self -Wno-delete-non-virtual-dtor -Wno-comment -Wno-missing-field-initializers -fdiagnostics-show-option -Wno-long-long -pthread -fomit-frame-pointer -ffunction-sections -fdata-sections  -msse -msse2 -msse3 -fvisibility=hidden -fvisibility-inlines-hidden -O3 -DNDEBUG  -DNDEBUG
    C++ flags (Debug):           -Wl,-strip-all   -fsigned-char -W -Wall -Werror=return-type -Werror=non-virtual-dtor -Werror=address -Werror=sequence-point -Wformat -Werror=format-security -Wmissing-declarations -Wundef -Winit-self -Wpointer-arith -Wsign-promo -Wuninitialized -Winit-self -Wno-delete-non-virtual-dtor -Wno-comment -Wno-missing-field-initializers -fdiagnostics-show-option -Wno-long-long -pthread -fomit-frame-pointer -ffunction-sections -fdata-sections  -msse -msse2 -msse3 -fvisibility=hidden -fvisibility-inlines-hidden -g  -O0 -DDEBUG -D_DEBUG
    C Compiler:                  /usr/lib/ccache/compilers/cc
    C flags (Release):           -Wl,-strip-all   -fsigned-char -W -Wall -Werror=return-type -Werror=non-virtual-dtor -Werror=address -Werror=sequence-point -Wformat -Werror=format-security -Wmissing-declarations -Wmissing-prototypes -Wstrict-prototypes -Wundef -Winit-self -Wpointer-arith -Wuninitialized -Winit-self -Wno-comment -Wno-missing-field-initializers -fdiagnostics-show-option -Wno-long-long -pthread -fomit-frame-pointer -ffunction-sections -fdata-sections  -msse -msse2 -msse3 -fvisibility=hidden -O3 -DNDEBUG  -DNDEBUG
    C flags (Debug):             -Wl,-strip-all   -fsigned-char -W -Wall -Werror=return-type -Werror=non-virtual-dtor -Werror=address -Werror=sequence-point -Wformat -Werror=format-security -Wmissing-declarations -Wmissing-prototypes -Wstrict-prototypes -Wundef -Winit-self -Wpointer-arith -Wuninitialized -Winit-self -Wno-comment -Wno-missing-field-initializers -fdiagnostics-show-option -Wno-long-long -pthread -fomit-frame-pointer -ffunction-sections -fdata-sections  -msse -msse2 -msse3 -fvisibility=hidden -g  -O0 -DDEBUG -D_DEBUG
    Linker flags (Release):      -L/root/ffmpeg_build/lib  -Wl,--gc-sections  
    Linker flags (Debug):        -L/root/ffmpeg_build/lib  -Wl,--gc-sections  
    ccache:                      YES
    Precompiled headers:         NO
    Extra dependencies:          ade ...
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