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  • ubantu打开摄像头失败

     摘要-针对ubantu20

    sudo apt install v4l-utils
    v4l2-ctl --list-devices


    - cv2 install on ubantu20
    ```
    针对ubantu20

    sudo apt install v4l-utils
    v4l2-ctl --list-devices

    pip uninstall opencv-python
    conda install pyqt
    pip install opencv-python==4.1.2.30
    ```


    (py38) itdb@ai:/opt/aisty/doc/aitools$ /opt/aisty/app/anaconda3/envs/py38/bin/python /opt/aisty/doc/aitools/case/face/04-tt.py
    VIDEOIO ERROR: V4L2: Could not obtain specifics of capture window.
    [ WARN:0] global /io/opencv/modules/videoio/src/cap_v4l.cpp (802) open VIDEOIO ERROR: V4L: can't open camera by index 1
    /dev/video1 does not support memory mapping
    Traceback (most recent call last):
      File "/opt/aisty/doc/aitools/case/face/04-tt.py", line 18, in <module>
        img_gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY) # 转换为灰度图 
    cv2.error: OpenCV(4.1.2) /io/opencv/modules/imgproc/src/color.cpp:182: error: (-215:Assertion failed) !_src.empty() in function 'cvtColor'

    查看摄像头编号

    v4l2-ctl --list-devices
    (base) itdb@ai:~/Desktop$ find /lib/modules/ -name "*v4l2*.ko"
    /lib/modules/5.8.0-59-generic/kernel/drivers/media/v4l2-core/v4l2-dv-timings.ko
    /lib/modules/5.8.0-59-generic/kernel/drivers/media/v4l2-core/v4l2-flash-led-class.ko
    /lib/modules/5.8.0-59-generic/kernel/drivers/media/v4l2-core/v4l2-fwnode.ko
    /lib/modules/5.8.0-59-generic/kernel/drivers/media/v4l2-core/v4l2-mem2mem.ko
    /lib/modules/5.8.0-59-generic/kernel/drivers/media/i2c/adv7511-v4l2.ko
    /lib/modules/5.8.0-59-generic/kernel/drivers/media/common/v4l2-tpg/v4l2-tpg.ko
    /lib/modules/5.8.0-59-generic/kernel/drivers/media/common/videobuf2/videobuf2-v4l2.ko
    /lib/modules/5.8.0-43-generic/kernel/drivers/media/v4l2-core/v4l2-dv-timings.ko
    /lib/modules/5.8.0-43-generic/kernel/drivers/media/v4l2-core/v4l2-flash-led-class.ko
    /lib/modules/5.8.0-43-generic/kernel/drivers/media/v4l2-core/v4l2-fwnode.ko
    /lib/modules/5.8.0-43-generic/kernel/drivers/media/v4l2-core/v4l2-mem2mem.ko
    /lib/modules/5.8.0-43-generic/kernel/drivers/media/i2c/adv7511-v4l2.ko
    /lib/modules/5.8.0-43-generic/kernel/drivers/media/common/v4l2-tpg/v4l2-tpg.ko
    /lib/modules/5.8.0-43-generic/kernel/drivers/media/common/videobuf2/videobuf2-v4l2.ko
    /lib/modules/5.8.0-63-generic/kernel/drivers/media/v4l2-core/v4l2-dv-timings.ko
    /lib/modules/5.8.0-63-generic/kernel/drivers/media/v4l2-core/v4l2-flash-led-class.ko
    /lib/modules/5.8.0-63-generic/kernel/drivers/media/v4l2-core/v4l2-fwnode.ko
    /lib/modules/5.8.0-63-generic/kernel/drivers/media/v4l2-core/v4l2-mem2mem.ko
    /lib/modules/5.8.0-63-generic/kernel/drivers/media/i2c/adv7511-v4l2.ko
    /lib/modules/5.8.0-63-generic/kernel/drivers/media/common/v4l2-tpg/v4l2-tpg.ko
    /lib/modules/5.8.0-63-generic/kernel/drivers/media/common/videobuf2/videobuf2-v4l2.ko
    (base) itdb@ai:~/Desktop$ sudo apt-get install v4l2-ctl
    Reading package lists... Done
    Building dependency tree       
    Reading state information... Done
    E: Unable to locate package v4l2-ctl
    (base) itdb@ai:~/Desktop$ v4l2-ctl --list-devices
    
    Command 'v4l2-ctl' not found, but can be installed with:
    
    sudo apt install v4l-utils
    
    (base) itdb@ai:~/Desktop$ sudo apt install v4l-utils
    Reading package lists... Done
    Building dependency tree       
    Reading state information... Done
    The following packages were automatically installed and are no longer required:
      linux-headers-5.8.0-43-generic linux-hwe-5.8-headers-5.8.0-43 linux-image-5.8.0-43-generic linux-modules-5.8.0-43-generic
      linux-modules-extra-5.8.0-43-generic
    Use 'sudo apt autoremove' to remove them.
    The following additional packages will be installed:
      libv4l2rds0
    The following NEW packages will be installed:
      libv4l2rds0 v4l-utils
    0 upgraded, 2 newly installed, 0 to remove and 15 not upgraded.
    Need to get 602 kB of archives.
    After this operation, 2,274 kB of additional disk space will be used.
    Do you want to continue? [Y/n] Y
    Get:1 http://cn.archive.ubuntu.com/ubuntu focal/main amd64 libv4l2rds0 amd64 1.18.0-2build1 [15.8 kB]
    Get:2 http://cn.archive.ubuntu.com/ubuntu focal/universe amd64 v4l-utils amd64 1.18.0-2build1 [586 kB]
    Fetched 602 kB in 3s (180 kB/s)     
    Selecting previously unselected package libv4l2rds0:amd64.
    (Reading database ... 252070 files and directories currently installed.)
    Preparing to unpack .../libv4l2rds0_1.18.0-2build1_amd64.deb ...
    Unpacking libv4l2rds0:amd64 (1.18.0-2build1) ...
    Selecting previously unselected package v4l-utils.
    Preparing to unpack .../v4l-utils_1.18.0-2build1_amd64.deb ...
    Unpacking v4l-utils (1.18.0-2build1) ...
    Setting up libv4l2rds0:amd64 (1.18.0-2build1) ...
    Setting up v4l-utils (1.18.0-2build1) ...
    Processing triggers for libc-bin (2.31-0ubuntu9.2) ...
    Processing triggers for man-db (2.9.1-1) ...
    (base) itdb@ai:~/Desktop$ v4l2-ctl --list-devices
    Synaptics RMI4 Touch Sensor (rmi4:rmi4-00.fn54):
        /dev/v4l-touch0
    
    USB Camera: USB Camera (usb-0000:00:14.0-1):
        /dev/video2
        /dev/video3
    
    Integrated Camera: Integrated C (usb-0000:00:14.0-6):
        /dev/video0
        /dev/video1
    Integrated Camera 电脑集成摄像机的编号是0,1
    外部插的USB摄像机编号是2,3
    编号改为2,即可调用外部摄像头
    # 摄像头
    cap = cv2.VideoCapture(2)
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  • 原文地址:https://www.cnblogs.com/perfei/p/15056355.html
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