我正在尝试在我的raspberry pi（Ubuntu系统）上运行一个脚本。现在，我正在刷新自己对opencv的基础知识，因为我已经有一段时间没有使用它了。所以我直接从OpenCV网站上复制粘贴了这段代码并运行了它。

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()

只是，运行它给了我一个坚实的灰色窗口作为一个弹出窗口，并抛出这些错误：

[ 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

代码仍然可以运行，因为我可以通过按“q”关闭窗口。但是视频流部分出现了可怕的错误。我甚至不知道GStreamer是什么，更不用说GStreamer管道是什么了。我不知道如何修复这个问题，也没有在网上找到任何有效的东西。