Permanent fix for Opencv videocapture
This answer is written with Linux and Python in mind, but the general idea can be applied to any OS and language supported by OpenCV.
The VideoCapture
class not opening the video file can have many causes, but the following three applies to most cases.
OpenCV FFMPEG support:
By default OpenCV uses ffmpeg to read video files. OpenCV may not have been built with FFMPEG support. To find out if OpenCV was built with FFMPEG support, in terminal enter:
python -c "import cv2; print(cv2.getBuildInformation())" | grep -i ffmpeg
The output should be something like:
FFMPEG: YES
If the output is No
then follow an online guide to build OpenCV from source with ffmpeg support.
FFMPEG Codec:
It's possible that FFMPEG does not have codec for your specific file. We are going to use this video as an example, to show if FFMPEG has decoding capability for this file.
First, we need to find the encoding format used in this video file. We will be using the mediainfo
program. In terminal, enter:
mediainfo video_file.mp4
In the output, under the video heading, look for format. In this case the video encoding used is AVC, which is another name for H264.
Now, we try to find if FFMPEG supports codec for decoding AVC encoded files. In terminal:
ffmpeg -codecs | grep -i avc
On my machine, the output is:
DEV.LS h264 H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10 (decoders: h264 h264_crystalhd h264_vdpau ) (encoders: libx264 libx264rgb )
We are interested in DEV, which stands for Decoding, Encoding and Video. This means that AVC is a video encoding format and FFMPEG supports both encoding and decoding capabilities for this format.
File PATH
Lastly, check if the file path is correct or even if the file exists.
Related videos on Youtube
Ishan Sharma
Updated on June 04, 2022Comments
-
Ishan Sharma almost 2 years
This question has been posed numerous times on many websites, but not definitive solution. I am trying to run Opencv with a video using function:
import cv2 cap = cv2.VideoCapture('video.mp4') if(cap.isOpened()==False): print "Error opening camera"
But it fails every time. I have tried almost all steps from various sites, but couldn't get it to work (including rebuilding ffmpeg separately).
Any help would be much appreciated.
My platform is Ubuntu17 and Python3.
-
Ishan Sharma over 6 yearsWas a fix on github. Tried with Opencv, same issue.
-
Ishan Sharma over 6 years@zindarod updated the code
-
Ishan Sharma over 6 years@zindarod The 1st one - not built properly. I have looked at various pages to do so, any suggested links i can check out to build opencv with ffmpeg?
-
Saurabh Dange about 3 yearsI faced the same issue.Putting complete path of the video starting from /home solved the issue for me.
-
-
Jeanne over 6 yearsI am working on fedora 26 and I have the same problem. In the first command , I get FFMPEG: No. How to resolve this