GStreamer和Opencv3 VideoCapture-打开bin错误：不允许使用空管道

Question

I've searched and searched and I cannot find anyone else with this error so here I am!

I am using OpenCV 3.1.0 and GStreamer 1.0 in python for video/image processing tasks. Everything functions perfectly (and has for multiple versions of OpenCV in the past and both GStreamer and ffmpeg) but continually gives an error before functioning as intended.

The Error is as follows:

GStreamer: Error opening bin: empty pipeline not allowed  
GStreamer: Error opening bin: empty pipeline not allowed  

This error occurs due to 2 OpenCV calls:

# video_src is a valid .h264 video

# First GStreamer Error
self.cam = cv2.VideoCapture(video_src)

self.operator = BackgroundSubtractor(2000, self.threshold, True)

# Second GStreamer Error
self.operator.model_bg2(video_src)

For the life of me I cannot isolate the cause of this GStreamer error. After I get this error; however, OpenCV functions completely as expected and encounters no errors. I only get an error upon calls to cv2.VideoCapture() initialization and BackgroundSubtractor's model_bg2.

Any ideas, suggestions, or questions are welcome!

Answer 1

It seems like OpenCv is trying to open the video file with Gstreamer instead of FFMPEG. Probably, you're missing FFMPEG from your OpenCv build. You might want to re-build OpenCv making sure that all sub components of FFMPEG are marked YES in cmake.

--     FFMPEG:         YES
--       codec:        YES     
--       format:       YES     
--       util:         YES         
--       swscale:      YES