我在Ubuntu 16.04上使用Python 2.7和virtualenv＆amp; virtualenvwrapper。
通过关注this guide，我设法让以下脚本与我的全局安装cv2的系统Python2.7一起使用。
我用这个脚本来安装它：
######################################
# INSTALL OPENCV ON UBUNTU OR DEBIAN #
######################################
# | THIS SCRIPT IS TESTED CORRECTLY ON |
# |----------------------------------------------------|
# | OS | OpenCV | Test | Last test |
# |----------------|--------------|------|-------------|
# | Ubuntu 16.04.2 | OpenCV 3.2.0 | OK | 20 May 2017 |
# | Debian 8.8 | OpenCV 3.2.0 | OK | 20 May 2017 |
# | Debian 9.0 | OpenCV 3.2.0 | OK | 25 Jun 2017 |
# 1. KEEP UBUNTU OR DEBIAN UP TO DATE
sudo apt-get -y update
sudo apt-get -y upgrade
sudo apt-get -y dist-upgrade
sudo apt-get -y autoremove
# 2. INSTALL THE DEPENDENCIES
# Build tools:
sudo apt-get install -y build-essential cmake
# GUI (if you want to use GTK instead of Qt, replace 'qt5-default' with 'libgtkglext1-dev' and remove '-DWITH_QT=ON' option in CMake):
sudo apt-get install -y qt5-default libvtk6-dev
# Media I/O:
sudo apt-get install -y zlib1g-dev libjpeg-dev libwebp-dev libpng-dev libtiff5-dev libjasper-dev libopenexr-dev libgdal-dev
# Video I/O:
sudo apt-get install -y libdc1394-22-dev libavcodec-dev libavformat-dev libswscale-dev libtheora-dev libvorbis-dev libxvidcore-dev libx264-dev yasm libopencore-amrnb-dev libopencore-amrwb-dev libv4l-dev libxine2-dev
# Parallelism and linear algebra libraries:
sudo apt-get install -y libtbb-dev libeigen3-dev
# Python:
sudo apt-get install -y python-dev python-tk python-numpy python3-dev python3-tk python3-numpy
# Documentation:
sudo apt-get install -y doxygen
# UI stuff
sudo apt-get install libgtk-3-dev libatlas-base-dev gfortran
# 3. INSTALL THE LIBRARY (YOU CAN CHANGE '3.2.0' FOR THE LAST STABLE VERSION)
sudo apt-get install -y unzip wget
# opencv contrib
wget https://github.com/opencv/opencv_contrib/archive/3.2.0.zip -O opencv_contrib-3.2.0.zip
unzip opencv_contrib-3.2.0.zip
rm opencv_contrib-3.2.0.zip
# opencv
wget https://github.com/opencv/opencv/archive/3.2.0.zip
unzip 3.2.0.zip
rm 3.2.0.zip
mv opencv-3.2.0 OpenCV-3.2.0
cd OpenCV-3.2.0
mkdir build
cd build
cmake -D WITH_QT=ON \
-D WITH_OPENGL=ON \
-D FORCE_VTK=ON \
-D WITH_TBB=ON \
-D WITH_GDAL=ON \
-D WITH_XINE=ON \
-D BUILD_EXAMPLES=ON \
-D INSTALL_PYTHON_EXAMPLES=ON \
-D ENABLE_PRECOMPILED_HEADERS=OFF \
-D BUILD_NEW_PYTHON_SUPPORT=ON \
..
make -j4
sudo make install
sudo ldconfig
# 4. EXECUTE SOME OPENCV EXAMPLES AND COMPILE A DEMONSTRATION
# To complete this step, please visit 'http://milq.github.io/install-opencv-ubuntu-debian'.
以下脚本适用于系统范围的安装：
import cv2
img = cv2.imread('some_img.jpg')
虽然这个没有 - 甚至系统Python也不能出于某种原因阅读视频...
import cv2
video_capture = cv2.VideoCapture(0)
ret, frame = video_capture.read()
print ret # always False
但我想让它与我的virtualenv一起工作。所以我用：
重新编译了OpenCVcmake -D WITH_QT=ON \
-D WITH_OPENGL=ON \
-D FORCE_VTK=ON \
-D WITH_TBB=ON \
-D WITH_GDAL=ON \
-D WITH_XINE=ON \
-D BUILD_EXAMPLES=ON \
-D INSTALL_PYTHON_EXAMPLES=ON \
-D ENABLE_PRECOMPILED_HEADERS=OFF \
-D BUILD_NEW_PYTHON_SUPPORT=ON \
-D OPENCV_EXTRA_MODULES_PATH=/home/me/code/myproject/opencv_contrib-3.2.0/modules \
-D PYTHON_EXECUTABLE=~/.envs/myenv/bin/python \
..
make -j4
sudo make install
sudo ldconfig
这是CMake日志：
-- Found VTK ver. 6.2.0 (usefile: /usr/lib/cmake/vtk-6.2/UseVTK.cmake)
-- Caffe: NO
-- Protobuf: YES
-- Glog: NO
-- freetype2: YES
-- harfbuzz: YES
-- Module opencv_sfm disabled because the following dependencies are not found: Glog/Gflags
-- freetype2: YES
-- harfbuzz: YES
-- Checking for modules 'tesseract;lept'
-- No package 'tesseract' found
-- No package 'lept' found
-- Tesseract: NO
-- Check contents of vgg_generated_48.i ...
-- Check contents of vgg_generated_64.i ...
-- Check contents of vgg_generated_80.i ...
-- Check contents of vgg_generated_120.i ...
-- Check contents of boostdesc_bgm.i ...
-- Check contents of boostdesc_bgm_bi.i ...
-- Check contents of boostdesc_bgm_hd.i ...
-- Check contents of boostdesc_binboost_064.i ...
-- Check contents of boostdesc_binboost_128.i ...
-- Check contents of boostdesc_binboost_256.i ...
-- Check contents of boostdesc_lbgm.i ...
--
-- General configuration for OpenCV 3.2.0 =====================================
-- Version control: 817bd7b-dirty
--
-- Extra modules:
-- Location (extra): /home/me/code/myproject/opencv_contrib-3.2.0/modules
-- Version control (extra): 817bd7b-dirty
--
-- Platform:
-- Timestamp: 2017-07-20T18:25:26Z
-- Host: Linux 4.8.0-58-generic x86_64
-- CMake: 3.5.1
-- CMake generator: Unix Makefiles
-- CMake build tool: /usr/bin/make
-- Configuration: Release
--
-- C/C++:
-- Built as dynamic libs?: YES
-- C++ Compiler: /usr/bin/c++ (ver 5.4.0)
-- C++ flags (Release): -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 -Wno-narrowing -Wno-delete-non-virtual-dtor -Wno-comment -fdiagnostics-show-option -Wno-long-long -pthread -fomit-frame-pointer -msse -msse2 -mno-avx -msse3 -mno-ssse3 -mno-sse4.1 -mno-sse4.2 -ffunction-sections -fvisibility=hidden -fvisibility-inlines-hidden -O3 -DNDEBUG -DNDEBUG
-- C++ flags (Debug): -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 -Wno-narrowing -Wno-delete-non-virtual-dtor -Wno-comment -fdiagnostics-show-option -Wno-long-long -pthread -fomit-frame-pointer -msse -msse2 -mno-avx -msse3 -mno-ssse3 -mno-sse4.1 -mno-sse4.2 -ffunction-sections -fvisibility=hidden -fvisibility-inlines-hidden -g -O0 -DDEBUG -D_DEBUG
-- C Compiler: /usr/bin/cc
-- C flags (Release): -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 -Wno-narrowing -Wno-comment -fdiagnostics-show-option -Wno-long-long -pthread -fomit-frame-pointer -msse -msse2 -mno-avx -msse3 -mno-ssse3 -mno-sse4.1 -mno-sse4.2 -ffunction-sections -fvisibility=hidden -O3 -DNDEBUG -DNDEBUG
-- C flags (Debug): -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 -Wno-narrowing -Wno-comment -fdiagnostics-show-option -Wno-long-long -pthread -fomit-frame-pointer -msse -msse2 -mno-avx -msse3 -mno-ssse3 -mno-sse4.1 -mno-sse4.2 -ffunction-sections -fvisibility=hidden -g -O0 -DDEBUG -D_DEBUG
-- Linker flags (Release):
-- Linker flags (Debug):
-- ccache: NO
-- Precompiled headers: NO
-- Extra dependencies: Qt5::Test Qt5::Concurrent Qt5::OpenGL /usr/lib/x86_64-linux-gnu/libwebp.so /usr/lib/x86_64-linux-gnu/libjasper.so /usr/lib/x86_64-linux-gnu/libImath.so /usr/lib/x86_64-linux-gnu/libIlmImf.so /usr/lib/x86_64-linux-gnu/libIex.so /usr/lib/x86_64-linux-gnu/libHalf.so /usr/lib/x86_64-linux-gnu/libIlmThread.so /usr/lib/libgdal.so dc1394 xine avcodec-ffmpeg avformat-ffmpeg avutil-ffmpeg swscale-ffmpeg Qt5::Core Qt5::Gui Qt5::Widgets /usr/lib/x86_64-linux-gnu/hdf5/serial/lib/libhdf5.so /usr/lib/x86_64-linux-gnu/libpthread.so /usr/lib/x86_64-linux-gnu/libsz.so /usr/lib/x86_64-linux-gnu/libdl.so /usr/lib/x86_64-linux-gnu/libm.so vtkRenderingOpenGL vtkImagingHybrid vtkIOImage vtkCommonDataModel vtkCommonMath vtkCommonCore vtksys vtkCommonMisc vtkCommonSystem vtkCommonTransforms vtkCommonExecutionModel vtkDICOMParser vtkIOCore /usr/lib/x86_64-linux-gnu/libz.so vtkmetaio /usr/lib/x86_64-linux-gnu/libjpeg.so /usr/lib/x86_64-linux-gnu/libpng.so /usr/lib/x86_64-linux-gnu/libtiff.so vtkImagingCore vtkRenderingCore vtkCommonColor vtkFiltersExtraction vtkFiltersCore vtkFiltersGeneral vtkCommonComputationalGeometry vtkFiltersStatistics vtkImagingFourier vtkalglib vtkFiltersGeometry vtkFiltersSources vtkInteractionStyle vtkRenderingLOD vtkFiltersModeling vtkIOPLY vtkIOGeometry /usr/lib/x86_64-linux-gnu/libjsoncpp.so vtkFiltersTexture vtkRenderingFreeType /usr/lib/x86_64-linux-gnu/libfreetype.so vtkftgl vtkIOExport vtkRenderingAnnotation vtkImagingColor vtkRenderingContext2D vtkRenderingGL2PS vtkRenderingContextOpenGL /usr/lib/libgl2ps.so vtkRenderingLabel dl m pthread rt /usr/lib/x86_64-linux-gnu/libGLU.so /usr/lib/x86_64-linux-gnu/libGL.so tbb
-- 3rdparty dependencies: libprotobuf
--
-- OpenCV modules:
-- To be built: core flann hdf imgproc ml photo reg surface_matching video viz dnn freetype fuzzy imgcodecs shape videoio highgui objdetect plot superres ts xobjdetect xphoto bgsegm bioinspired dpm face features2d line_descriptor saliency text calib3d ccalib cvv datasets rgbd stereo tracking videostab xfeatures2d ximgproc aruco optflow phase_unwrapping stitching structured_light java python2 python3
-- Disabled: world contrib_world
-- Disabled by dependency: -
-- Unavailable: cudaarithm cudabgsegm cudacodec cudafeatures2d cudafilters cudaimgproc cudalegacy cudaobjdetect cudaoptflow cudastereo cudawarping cudev cnn_3dobj matlab sfm
--
-- GUI:
-- QT 5.x: YES (ver 5.5.1)
-- QT OpenGL support: YES (Qt5::OpenGL 5.5.1)
-- OpenGL support: YES (/usr/lib/x86_64-linux-gnu/libGLU.so /usr/lib/x86_64-linux-gnu/libGL.so)
-- VTK support: YES (ver 6.2.0)
--
-- Media I/O:
-- ZLib: /usr/lib/x86_64-linux-gnu/libz.so (ver 1.2.8)
-- JPEG: /usr/lib/x86_64-linux-gnu/libjpeg.so (ver )
-- WEBP: /usr/lib/x86_64-linux-gnu/libwebp.so (ver encoder: 0x0202)
-- PNG: /usr/lib/x86_64-linux-gnu/libpng.so (ver 1.2.54)
-- TIFF: /usr/lib/x86_64-linux-gnu/libtiff.so (ver 42 - 4.0.6)
-- JPEG 2000: /usr/lib/x86_64-linux-gnu/libjasper.so (ver 1.900.1)
-- OpenEXR: /usr/lib/x86_64-linux-gnu/libImath.so /usr/lib/x86_64-linux-gnu/libIlmImf.so /usr/lib/x86_64-linux-gnu/libIex.so /usr/lib/x86_64-linux-gnu/libHalf.so /usr/lib/x86_64-linux-gnu/libIlmThread.so (ver 2.2.0)
-- GDAL: /usr/lib/libgdal.so
-- GDCM: NO
--
-- Video I/O:
-- DC1394 1.x: NO
-- DC1394 2.x: YES (ver 2.2.4)
-- FFMPEG: YES
-- avcodec: YES (ver 56.60.100)
-- avformat: YES (ver 56.40.101)
-- avutil: YES (ver 54.31.100)
-- swscale: YES (ver 3.1.101)
-- 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/YES
-- XIMEA: NO
-- Xine: YES (ver 1.2.6)
-- gPhoto2: NO
--
-- Parallel framework: TBB (ver 4.4 interface 9002)
--
-- Other third-party libraries:
-- Use IPP: 9.0.1 [9.0.1]
-- at: /home/me/code/myproject/OpenCV-3.2.0/build/3rdparty/ippicv/ippicv_lnx
-- Use IPP Async: NO
-- Use VA: NO
-- Use Intel VA-API/OpenCL: NO
-- Use Lapack: NO
-- Use Eigen: YES (ver 3.2.92)
-- Use Cuda: NO
-- Use OpenCL: YES
-- Use OpenVX: NO
-- Use custom HAL: NO
--
-- OpenCL: <Dynamic loading of OpenCL library>
-- Include path: /home/me/code/myproject/OpenCV-3.2.0/3rdparty/include/opencl/1.2
-- Use AMDFFT: NO
-- Use AMDBLAS: NO
--
-- Python 2:
-- Interpreter: /home/me/.envs/myenv/bin/python (ver 2.7.12)
-- Libraries: /usr/lib/x86_64-linux-gnu/libpython2.7.so (ver 2.7.12)
-- numpy: /home/me/.envs/myenv/local/lib/python2.7/site-packages/numpy/core/include (ver 1.13.1)
-- packages path: lib/python2.7/site-packages
--
-- Python 3:
-- Interpreter: /usr/bin/python3 (ver 3.5.2)
-- Libraries: /usr/lib/x86_64-linux-gnu/libpython3.5m.so (ver 3.5.2)
-- numpy: /usr/lib/python3/dist-packages/numpy/core/include (ver 1.11.0)
-- packages path: lib/python3.5/dist-packages
--
-- Python (for build): /home/me/.envs/myenv/bin/python
--
-- Java:
-- ant: /usr/bin/ant (ver 1.9.6)
-- JNI: /usr/lib/jvm/default-java/include /usr/lib/jvm/default-java/include/linux /usr/lib/jvm/default-java/include
-- Java wrappers: YES
-- Java tests: YES
--
-- Matlab: Matlab not found or implicitly disabled
--
-- Documentation:
-- Doxygen: /usr/bin/doxygen (ver 1.8.11)
--
-- Tests and samples:
-- Tests: YES
-- Performance tests: YES
-- C/C++ Examples: YES
--
-- Install path: /usr/local
--
-- cvconfig.h is in: /home/me/code/myproject/OpenCV-3.2.0/build
-- -----------------------------------------------------------------
--
不幸的是，虽然这有效但我可以在shell中导入cv2，但它无法使用上述脚本读取视频，可能是因为ffmpeg的编译或链接不正确？令人困惑的部分是OpenCV的系统范围安装工作正常，即使没有安装ffmpeg！
我做错了什么？我怎样才能让OpenCV使用virtualenv？
====
编辑：运行C ++视频写作示例有以下结果：
$ cd /home/me/code/myproject/OpenCV-3.2.0/build/bin
$ ./cpp-tutorial-video-write ../../samples/data/vtest.avi R Y
------------------------------------------------------------------------------
This program shows how to write video files.
You can extract the R or G or B color channel of the input video.
Usage:
./video-write <input_video_name> [ R | G | B] [Y | N]
------------------------------------------------------------------------------
OpenCV: FFMPEG: tag 0xffffffff/'����' is not found (format 'avi / AVI (Audio Video Interleaved)')'
(cpp-tutorial-video-write:19523): GStreamer-CRITICAL **: gst_element_make_from_uri: assertion 'gst_uri_is_valid (uri)' failed
OpenCV Error: Unsupported format or combination of formats (Gstreamer Opencv backend does not support this codec.) in CvVideoWriter_GStreamer::open, file /home/me/code/myproject/OpenCV-3.2.0/modules/videoio/src/cap_gstreamer.cpp, line 1388
VIDEOIO(cvCreateVideoWriter_GStreamer(filename, fourcc, fps, frameSize, is_color)): raised OpenCV exception:
/home/me/code/myproject/OpenCV-3.2.0/modules/videoio/src/cap_gstreamer.cpp:1388: error: (-210) Gstreamer Opencv backend does not support this codec. in function CvVideoWriter_GStreamer::open
Could not open the output video for write: ../../samples/data/vtest.avi
opencv_test_videoio单元测试会报告以下内容：https://pastebin.com/q4mf224Q
但是，运行c ++视频启动器示例可以正常工作，使用以下命令和输出，我可以在highgui界面中看到网络摄像头工作和流视频：
$ ./cpp-example-videocapture_starter 0
VIDEOIO ERROR: V4L: device 0: Unable to query number of channels
(ERROR)icvOpenAVI_XINE(): Unable to initialize video driver.
GStreamer: Error opening bin: no element "0"
press space to save a picture. q or esc to quit
init done
opengl support available
答案 0 :(得分：2)
根据指南，您安装了libavcodec-dev libavformat-dev libswscale-dev libv4l-dev，这是使用相机和解码音频/视频流所必需的。
我认为CMake输出/日志应该给你一些提示，我建议你提供一个关于这个日志的pastebin / gist的链接。
例如，你在CMake日志中的这一行下面有什么？ （你应该有很多是的）
-- Video I/O:
在这一个：
-- OpenCV modules:
-- To be built: <list of opencv modules>
<list of opencv modules>是否包含＆＃34; videoio＆＃34; ？
另一个愚蠢的测试：你的相机有效吗？你有/ dev / video0文件吗？你能看到vlc或者奶酪的视频流吗？
修改
我看到你没有gstreamer，
您可以尝试安装以下库：libgstreamer1.0-dev libgstreamer-plugins-base1.0-dev并重新编译吗？
V4L2应该足够了，但是你拥有它，但是according to the sources gstreamer也可以用于视频捕获。 因此，解决问题的概率很低但不可忽略。
其他问题：
cpp-example-videocapture_basic还是cpp-example-videocapture_starter，他们会给您一个错误吗？