GStreamer warning when running OpenCV on Ubuntu

Question

I’m trying to get a script running on my raspberry pi (Ubuntu system). Right now, I was just refreshing myself on the basics of opencv, since it’s been a little while since I worked with it. So I copy pasted this code straight from the OpenCV website and ran it.

import numpy as np
import cv2 as cv

cap = cv.VideoCapture(0)

if not cap.isOpened():
    print("Cannot open camera")
    exit()

while True:
    # Capture frame-by-frame
    ret, frame = cap.read()
    
    # if frame is read correctly ret is True
    if not ret:
        print("Can't receive frame (stream end?). Exiting ...")
        break
        
    # Our operations on the frame come here
    gray = cv.cvtColor(frame, cv.COLOR_BGR2GRAY)
    
    # Display the resulting frame
    cv.imshow('frame', gray)
    
    if cv.waitKey(1) == ord('q'):
        break
        
# When everything done, release the capture
cap.release()
cv.destroyAllWindows()

Only, running it gave me a solid gray window as a pop-up and threw these errors:

[ WARN:0] global /usr/local/src/opencv-4.4.0/modules/videoio/src/cap_gstreamer.cpp (1761) handleMessage OpenCV | GStreamer warning: Embedded video playback halted; module v4l2src0 reported: Internal data stream error.
[ WARN:0] global /usr/local/src/opencv-4.4.0/modules/videoio/src/cap_gstreamer.cpp (888) open OpenCV | GStreamer warning: unable to start pipeline
[ WARN:0] global /usr/local/src/opencv-4.4.0/modules/videoio/src/cap_gstreamer.cpp (480) isPipelinePlaying OpenCV | GStreamer warning: GStreamer: pipeline have not been created

The code does still run, since I can close the window by pressing ‘q’. But the video streaming part has gone horribly wrong. I don’t even know what GStreamer is, let alone what a GStreamer pipeline is. I have no idea how to fix this and haven’t found anything online that works.

Asked By: Grant Allan

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Answer 1

my code worked running on jetson nano

def __gstreamer_pipeline(
        camera_id,
        capture_width=1920,
        capture_height=1080,
        display_width=1920,
        display_height=1080,
        framerate=30,
        flip_method=0,
    ):
    return (
            "nvarguscamerasrc sensor-id=%d ! "
            "video/x-raw(memory:NVMM), "
            "width=(int)%d, height=(int)%d, "
            "format=(string)NV12, framerate=(fraction)%d/1 ! "
            "nvvidconv flip-method=%d ! "
            "video/x-raw, width=(int)%d, height=(int)%d, format=(string)BGRx ! "
            "videoconvert ! "
            "video/x-raw, format=(string)BGR ! appsink max-buffers=1 drop=True"
            % (
                    camera_id,
                    capture_width,
                    capture_height,
                    framerate,
                    flip_method,
                    display_width,
                    display_height,
            )
    )
   
stream = cv2.VideoCapture(__gstreamer_pipeline(camera_id=0, flip_method=2), cv2.CAP_GSTREAMER)

Answered By: Ali Mustofa

GStreamer warning when running OpenCV on Ubuntu

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