opencv - 无法访问网络摄像头 OpenCV 3.3 Python 3

Question

Python 2.7 上的 OpenCV 可以毫无问题地访问我的网络摄像头。出于某种原因，它不能在 Python 3 中使用。VideoCapture::read 始终不返回...

我什至尝试从源代码编译。

这是我的 cmake(我不认为我做错了什么):

cmake -D CMAKE_BUILD_TYPE=RELEASE \
    -D CMAKE_INSTALL_PREFIX=/usr/local \
    -D INSTALL_PYTHON_EXAMPLES=ON \
    -D INSTALL_C_EXAMPLES=OFF \
    -D WITH_V4L=ON \
    -D WITH_QT=ON \
    -D WITH_OPENGL=ON \
    -D OPENCV_EXTRA_MODULES_PATH=../../opencv_contrib/modules \
    -D PYTHON_EXECUTABLE3=/usr/bin/python3.6
    -D PYTHON_EXECUTABLE2=/usr/bin/python2.7
    -D PYTHON3_NUMPY_INCLUDE_DIRS=/usr/lib64/python3.6/site-packages/numpy/core/include \
    -D BUILD_EXAMPLES=ON ..

实现之间是否有任何变化可以表明是什么导致了我的问题？

编辑:

根据要求:

% python3.6 -c 'import cv2; print(cv2.getBuildInformation())'

General configuration for OpenCV 3.3.0 

=====================================
  Version control:               3.3.0

  Extra modules:
    Location (extra):            /io/opencv_contrib/modules
    Version control (extra):     3.3.0

  Platform:
    Timestamp:                   2017-09-03T11:00:53Z
    Host:                        Linux 4.4.0-83-generic x86_64
    CMake:                       3.9.0
    CMake generator:             Unix Makefiles
    CMake build tool:            /usr/bin/gmake
    Configuration:               Release

  CPU/HW features:
    Baseline:                    SSE SSE2 SSE3
      requested:                 SSE3
    Dispatched code generation:  SSE4_1 SSE4_2 FP16 AVX AVX2
      requested:                 SSE4_1 SSE4_2 AVX FP16 AVX2
      SSE4_1 (2 files):          + SSSE3 SSE4_1
      SSE4_2 (1 files):          + SSSE3 SSE4_1 POPCNT SSE4_2
      FP16 (1 files):            + SSSE3 SSE4_1 POPCNT SSE4_2 FP16 AVX
      AVX (5 files):             + SSSE3 SSE4_1 POPCNT SSE4_2 AVX
      AVX2 (7 files):            + SSSE3 SSE4_1 POPCNT SSE4_2 FP16 FMA3 AVX AVX2

  C/C++:
    Built as dynamic libs?:      NO
    C++ Compiler:                /opt/rh/devtoolset-2/root/usr/bin/c++  (ver 4.8.2)
    C++ flags (Release):         -fPIC   -fsigned-char -W -Wall -Werror=return-type -Werror=non-virtual-dtor -Werror=address -Werror=sequence-point -Wformat -Werror=format-security -Wmissing-declarations -Wundef -Winit-self -Wpointer-arith -Wshadow -Wsign-promo -Wuninitialized -Winit-self -Wno-narrowing -Wno-delete-non-virtual-dtor -Wno-comment -fdiagnostics-show-option -Wno-long-long -pthread -fomit-frame-pointer -ffunction-sections  -msse -msse2 -msse3 -fvisibility=hidden -fvisibility-inlines-hidden -O3 -DNDEBUG  -DNDEBUG
    C++ flags (Debug):           -fPIC   -fsigned-char -W -Wall -Werror=return-type -Werror=non-virtual-dtor -Werror=address -Werror=sequence-point -Wformat -Werror=format-security -Wmissing-declarations -Wundef -Winit-self -Wpointer-arith -Wshadow -Wsign-promo -Wuninitialized -Winit-self -Wno-narrowing -Wno-delete-non-virtual-dtor -Wno-comment -fdiagnostics-show-option -Wno-long-long -pthread -fomit-frame-pointer -ffunction-sections  -msse -msse2 -msse3 -fvisibility=hidden -fvisibility-inlines-hidden -g  -O0 -DDEBUG -D_DEBUG
    C Compiler:                  /opt/rh/devtoolset-2/root/usr/bin/cc
    C flags (Release):           -fPIC   -fsigned-char -W -Wall -Werror=return-type -Werror=non-virtual-dtor -Werror=address -Werror=sequence-point -Wformat -Werror=format-security -Wmissing-declarations -Wmissing-prototypes -Wstrict-prototypes -Wundef -Winit-self -Wpointer-arith -Wshadow -Wuninitialized -Winit-self -Wno-narrowing -Wno-comment -fdiagnostics-show-option -Wno-long-long -pthread -fomit-frame-pointer -ffunction-sections  -msse -msse2 -msse3 -fvisibility=hidden -O3 -DNDEBUG  -DNDEBUG
    C flags (Debug):             -fPIC   -fsigned-char -W -Wall -Werror=return-type -Werror=non-virtual-dtor -Werror=address -Werror=sequence-point -Wformat -Werror=format-security -Wmissing-declarations -Wmissing-prototypes -Wstrict-prototypes -Wundef -Winit-self -Wpointer-arith -Wshadow -Wuninitialized -Winit-self -Wno-narrowing -Wno-comment -fdiagnostics-show-option -Wno-long-long -pthread -fomit-frame-pointer -ffunction-sections  -msse -msse2 -msse3 -fvisibility=hidden -g  -O0 -DDEBUG -D_DEBUG
    Linker flags (Release):
    Linker flags (Debug):
    ccache:                      NO
    Precompiled headers:         YES
    Extra dependencies:          /opt/Qt4.8.7/lib/libQtGui.so /opt/Qt4.8.7/lib/libQtTest.so /opt/Qt4.8.7/lib/libQtCore.so /lib64/libz.so stdc++ dl m pthread rt
    3rdparty dependencies:       ittnotify libprotobuf libjpeg libwebp libpng libtiff libjasper IlmImf

  OpenCV modules:
    To be built:                 core flann imgproc ml objdetect phase_unwrapping photo plot reg surface_matching video xphoto bgsegm dnn face fuzzy img_hash imgcodecs shape videoio xobjdetect highgui superres bioinspired dpm features2d line_descriptor saliency text calib3d ccalib datasets rgbd stereo structured_light tracking videostab xfeatures2d ximgproc aruco optflow stitching python3
    Disabled:                    world contrib_world
    Disabled by dependency:      -
    Unavailable:                 cudaarithm cudabgsegm cudacodec cudafeatures2d cudafilters cudaimgproc cudalegacy cudaobjdetect cudaoptflow cudastereo cudawarping cudev java python2 ts viz cnn_3dobj cvv dnn_modern freetype hdf matlab sfm

  GUI: 
    QT 4.x:                      YES (ver 4.8.7 EDITION = OpenSource)
    QT OpenGL support:           NO
    OpenGL support:              NO
    VTK support:                 NO

  Media I/O: 
    ZLib:                        /lib64/libz.so (ver 1.2.3)
    JPEG:                        libjpeg (ver 90)
    WEBP:                        build (ver encoder: 0x020e)
    PNG:                         build (ver 1.6.24)
    TIFF:                        build (ver 42 - 4.0.2)
    JPEG 2000:                   build (ver 1.900.1)
    OpenEXR:                     build (ver 1.7.1)
    GDAL:                        NO
    GDCM:                        NO

  Video I/O:
    DC1394 1.x:                  NO
    DC1394 2.x:                  NO
    FFMPEG:                      NO
      avcodec:                   NO
      avformat:                  NO
      avutil:                    NO
      swscale:                   NO
      avresample:                NO
    GStreamer:                   NO
    OpenNI:                      NO
    OpenNI PrimeSensor Modules:  NO
    OpenNI2:                     NO
    PvAPI:                       NO
    GigEVisionSDK:               NO
    Aravis SDK:                  NO
    UniCap:                      NO
    UniCap ucil:                 NO
    V4L/V4L2:                    NO/NO
    XIMEA:                       NO
    Xine:                        NO
    Intel Media SDK:             NO
    gPhoto2:                     NO

  Parallel framework:            pthreads

  Trace:                         YES (with Intel ITT)

  Other third-party libraries:
    Use Intel IPP:               NO
    Use Intel IPP IW:            NO
    Use Intel IPP Async:         NO
    Use VA:                      NO
    Use Intel VA-API/OpenCL:     NO
    Use Lapack:                  NO
    Use Eigen:                   NO
    Use Cuda:                    NO
    Use OpenCL:                  YES
    Use OpenVX:                  NO
    Use custom HAL:              NO

  OpenCL:                        <Dynamic loading of OpenCL library>
    Include path:                /io/opencv/3rdparty/include/opencl/1.2
    Use AMDFFT:                  NO
    Use AMDBLAS:                 NO

  Python 2:
    Interpreter:                 NO

  Python 3:
    Interpreter:                 python (ver 3.6.0)
    Libraries:                   
    numpy:                       /opt/python/cp36-cp36m/lib/python3.6/site-packages/numpy/core/include (ver 1.11.3)
    packages path:               /opt/python/cp36-cp36m/lib/python3.6/site-packages

  Python (for build):            python

  Java:
    ant:                         NO
    JNI:                         NO
    Java wrappers:               NO
    Java tests:                  NO

  Matlab:                        Matlab not found or implicitly disabled

  Tests and samples:
    Tests:                       NO
    Performance tests:           NO
    C/C++ Examples:              NO

  Install path:                  /usr/local

  cvconfig.h is in:              /io/opencv/build
-----------------------------------------------------------------

Answer 1

遵循本指南:https://www.scivision.co/anaconda-python-opencv3/

在安装之前删除了所有失败的 pip 尝试。

确保您在上述指南中执行的命令使用您所针对的 python 版本。将 python 别名为 python36 或在命令中替换它。