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标题: opencv无法打开USB摄像头 [打印本页]
作者: sunzhongmeng    时间: 2019-3-26 14:28
标题: opencv无法打开USB摄像头
按照人工智能开发系列(3) YOLOV3开发与实现这个帖子搭建的环境，执行
  1. sudo dnf install gstreamer-rockchip
复制代码后，无法打开UVC摄像头：camera.py:

  2. import numpy as np
  3. import cv2
  4. import matplotlib.pyplot as plot
  5. cap = cv2.VideoCapture(0)
  6. while(True):
  7. ret,frame = cap.read()
  8. cv2.imshow("capture",frame)
  9. if cv2.waitKey(1) & 0xFF == ord('q'):
  10.        break
  11. cap.release()
复制代码
执行：python camera.py
  1. OpenCV(3.4.1) Error: Unspecified error (GStreamer: unable to start pipeline
  2. ) in cvCaptureFromCAM_GStreamer, file /builddir/build/BUILD/opencv-3.4.1/modules/videoio/src/cap_gstreamer.cpp, line 890
  3. VIDEOIO(cvCreateCapture_GStreamer(CV_CAP_GSTREAMER_V4L2, reinterpret_cast<char *>(index))): raised OpenCV exception:

  5. OpenCV(3.4.1) /builddir/build/BUILD/opencv-3.4.1/modules/videoio/src/cap_gstreamer.cpp:890: error: (-2) GStreamer: unable to start pipeline
  6. in function cvCaptureFromCAM_GStreamer

  8. OpenCV(3.4.1) Error: Unspecified error (unicap: failed to get info for device
  9. ) in CvCapture_Unicap::initDevice, file /builddir/build/BUILD/opencv-3.4.1/modules/videoio/src/cap_unicap.cpp, line 139
  10. VIDEOIO(cvCreateCameraCapture_Unicap(index)): raised OpenCV exception:

  12. OpenCV(3.4.1) /builddir/build/BUILD/opencv-3.4.1/modules/videoio/src/cap_unicap.cpp:139: error: (-2) unicap: failed to get info for device
  13. in function CvCapture_Unicap::initDevice

  15. OpenCV(3.4.1) Error: Assertion failed (size.width>0 && size.height>0) in imshow, file /builddir/build/BUILD/opencv-3.4.1/modules/highgui/src/window.cpp, line 364
  16. Traceback (most recent call last):
  17.   File "camera.py", line 7, in <module>
  18.     cv2.imshow("capture",frame)
  19. cv2.error: OpenCV(3.4.1) /builddir/build/BUILD/opencv-3.4.1/modules/highgui/src/window.cpp:364: error: (-215) size.width>0 && size.height>0 in function imshow
复制代码本地视频也无法打开！


作者: sunzhongmeng    时间: 2019-3-30 11:16
hisping 发表于 2019-3-27 20:51
试下

你好，这个已经安装了，现在可以打开本地视频，但是USB摄像头还是无法开启（USB摄像头是UVC免驱，且在UBUNTU上验证可用）
作者: sunzhongmeng    时间: 2019-3-30 12:01
hisping 发表于 2019-3-27 20:51
试下

本地视频可以打开，但是USB免驱摄像头还是无法打开
  1. OpenCV(3.4.1) Error: Unspecified error (GStreamer: unable to start pipeline
  2. ) in cvCaptureFromCAM_GStreamer, file /builddir/build/BUILD/opencv-3.4.1/modules/videoio/src/cap_gstreamer.cpp, line 890
  3. VIDEOIO(cvCreateCapture_GStreamer(CV_CAP_GSTREAMER_V4L2, reinterpret_cast<char *>(index))): raised OpenCV exception:

  5. OpenCV(3.4.1) /builddir/build/BUILD/opencv-3.4.1/modules/videoio/src/cap_gstreamer.cpp:890: error: (-2) GStreamer: unable to start pipeline
  6. in function cvCaptureFromCAM_GStreamer

  8. OpenCV(3.4.1) Error: Unspecified error (unicap: failed to get info for device
  9. ) in CvCapture_Unicap::initDevice, file /builddir/build/BUILD/opencv-3.4.1/modules/videoio/src/cap_unicap.cpp, line 139
  10. VIDEOIO(cvCreateCameraCapture_Unicap(index)): raised OpenCV exception:

  12. OpenCV(3.4.1) /builddir/build/BUILD/opencv-3.4.1/modules/videoio/src/cap_unicap.cpp:139: error: (-2) unicap: failed to get info for device
  13. in function CvCapture_Unicap::initDevice

  15. OpenCV(3.4.1) Error: Assertion failed (size.width>0 && size.height>0) in imshow, file /builddir/build/BUILD/opencv-3.4.1/modules/highgui/src/window.cpp, line 364
  16. Traceback (most recent call last):
  17.   File "open_camera.py", line 13, in <module>
  18.     video_demo()
  19.   File "open_camera.py", line 7, in video_demo
  20.     cv.imshow("UVC",frame)
  21. cv2.error: OpenCV(3.4.1) /builddir/build/BUILD/opencv-3.4.1/modules/highgui/src/window.cpp:364: error: (-215) size.width>0 && size.height>0 in function imshow
复制代码

作者: eeyeh    时间: 2019-4-2 10:12
之前遇到相似的问题, ls /dev/video*看看是不是有多个摄像头设备
如果有多个摄像头设备, USB不一定是video0, 插拔下看下是video#
然后改代码中打开摄像头部分
cap = cv2.VideoCapture(“/dev/video#”)
作者: jon    时间: 2020-8-27 10:10
4.此时应该可以正常显示图片及打开摄像头，但无法打开视频文件，需安装gstreamer

    sudo dnf install https://download1.rpmfusion.org/ ... usion-free-release-$(rpm -E %fedora).noarch.rpm
    sudo dnf install gstreamer1-libav



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