python cv2.Videocapture() does not work, cap.isOpened() returns false

Question

cv2.Videocapture() works fine while using webcam but while trying to read from hard drive it shows error cap.isOpened() returns false

import cv2
import numpy as np
background=cv2.imread('background.png')
cap = cv2.VideoCapture('car video.mp4')
cap.open('car video.mp4')
print cap.isOpened()
while 1:
    ret,img=cap.read()
    cv2.imshow('a',img)
    print img.shape


    if cv2.waitKey(1) & 0xFF == ord('q'):
        break

cap.release()
cv2.destroyAllWindows()

It shows this error

    cv2.imshow('a',img)
    error: ..\..\..\..\opencv\modules\highgui\src\window.cpp:266: error:       (-215)        size.width>0 && size.height>0 in function cv::imshow

my opencv version 3.0.0, python 2.7, windows10 32 bit

Firstly, remove cap.open() call; it's redundant. Second, check if your video is in the same directory as your code. Third, remove the space in its filename. Try car_video.mp4 — Saransh Kejriwal, Feb 14 '17 at 03:22
I change file name and remove cap.open() . but error message remains same — Joy Mazumder, Feb 14 '17 at 04:06
This link helps me a lot and solve my issue. http://stackoverflow.com/questions/23119413/how-to-install-python-opencv-through-conda — Mohammed Awney, Feb 21 '17 at 23:20

score 10 · Accepted Answer · edited Oct 20 '20 at 02:54

10

You need the ffmpeg codec to be able to read the video.

edited Oct 20 '20 at 02:54

Casey Jones

155
9

answered Feb 20 '17 at 22:12

Mohammed Awney

1,292
16
21

yes it's works thanks. At first i didn't copy the ffmpeg codec file – Joy Mazumder Feb 21 '17 at 02:46
5

could you please tell me how to add ffmpeg codec file? – Mohammed Awney Feb 21 '17 at 03:21
2

Copy all the file from **OpenCV\3rdparty\ffmpeg\** to **C:\Python27\** or to a directory that is in the PATH. Renaming the opencv_ffmpeg.dll file may also be necessary. For OpenCV version X.Y.Z opencv_ffmpeg.dll ==> opencv_ffmpegXYZ.dll For 64-bit OpenCV version X.Y.Z opencv_ffmpeg.dll ==> opencv_ffmpegXYZ_64.dll – Joy Mazumder Feb 21 '17 at 04:51
i am using opencv 3.0.0 and win 32 so rename the file just like this opencv_ffmpeg300.dll – Joy Mazumder Feb 21 '17 at 04:56

user7199416 · Answer 2 · 2018-10-24T09:04:14.507

I was getting the same error while using opencv in anaconda3 virtual environment. I checked the buildinformation for current opencv version and ffmpeg was marked "no".

To resolve this

I uninstalled opencv from my conda environment (conda uninstall opencv)
Installed latest ffmpeg using conda-forge channel (conda install -c conda-forge ffmpeg)

Name Version Build Channel

ffmpeg 4.0.2 ha6a6e2b_0 conda-forge
Then installed opencv again using conda-forge channel (conda install -c conda-forge opencv)

Name Version Build Channel

opencv 3.4.1 py36_blas_openblash829a850_201 [blas_openblas] conda-forge

Restart the python console after doing this and import cv2.

To check the build information: `python -c "import cv2; print(cv2.getBuildInformation())"` — Alex Fortin, Nov 08 '20 at 16:46

score 5 · Answer 3 · edited Jul 26 '18 at 05:22

5

try

pip install opencv-contrib-python

It worked for me

edited Jul 26 '18 at 05:22

CertainPerformance

356,069
52
309
320

answered Jul 26 '18 at 05:04

L.xp

89
1
2

for issues with pygame's webcam module, this made things *worse* – Khlorghaal Mar 04 '23 at 12:17

score 2 · Answer 4 · answered Feb 14 '17 at 07:33

I am not sure that you are writing your file name correctly. I've never seen a file directory like 'car video.mp4'. When you are using the zero based index your webcam and cv2.VideoCapture works fine; however VideoCapture cannot read a file like 'car(space)video.mp4' A working code is something like this;

import numpy as np
import cv2

cap = cv2.VideoCapture('video.mp4')

while(cap.isOpened()):

    ret, frame = cap.read()

    if ret==True:

        cv2.imshow('frame',frame)

        if cv2.waitKey(1) & 0xFF == ord('q'):
            break
    else:
        break

# Release everything if job is finished
cap.release()
cv2.destroyAllWindows()

python cv2.Videocapture() does not work, cap.isOpened() returns false

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