[英]VideoCapture is not working in OpenCV 2.4.2
I recently installed OpenCV 2.4.2 in Ubuntu 12.04. 我最近在Ubuntu 12.04中安装了OpenCV 2.4.2。
cap = VideoCapture(0)
is working. 正在工作。 but I can't grab frames from some video source.
但我无法从某些视频源中获取帧。
cap = VideoCapture("input.avi")
img = cap.read()
gives me a numpy with all zero elements. 给了我一个零元素的numpy。
I have also installed ffmpeg 0.11, Latest snapshot of x264, v4l-0.8.8 (All are latest stable versions) 我还安装了ffmpeg 0.11,x264的最新快照,v4l-0.8.8(所有都是最新的稳定版本)
cmake -D WITH_QT=ON -D WITH_FFMPEG=ON -D WITH_OPENGL=ON -D WITH_TBB=ON -D BUILD_EXAMPLES=OFF WITH_V4L=ON ..
make
sudo make install
When I do cmake, I get this 当我做cmake时,我明白了
-- Detected version of GNU GCC: 46 (406)
- 检测到的GNU GCC版本:46(406)
-- Found OpenEXR: /usr/lib/libIlmImf.so- 找到OpenEXR:/usr/lib/libIlmImf.so
-- Looking for linux/videodev.h- 寻找linux / videodev.h
-- Looking for linux/videodev.h - not found- 寻找linux / videodev.h - 找不到
-- Looking for linux/videodev2.h- 寻找linux / videodev2.h
-- Looking for linux/videodev2.h - found- 寻找linux / videodev2.h - 找到了
-- Looking for libavformat/avformat.h- 寻找libavformat / avformat.h
-- Looking for libavformat/avformat.h - found- 寻找libavformat / avformat.h - 找到了
-- Looking for ffmpeg/avformat.h- 寻找ffmpeg / avformat.h
-- Looking for ffmpeg/avformat.h - not found- 寻找ffmpeg / avformat.h - 未找到
-- checking for module 'tbb'- 检查模块'tbb'
-- package 'tbb' not found- 找不到包'tbb'
And 和
-- Video I/O:
-- DC1394 1.x: NO
-- DC1394 2.x: YES (ver 2.2.0)
-- FFMPEG: YES
-- codec: YES (ver 54.23.100)
-- format: YES (ver 54.6.100)
-- util: YES (ver 51.54.100)
-- swscale: YES (ver 2.1.100)
-- gentoo-style: YES
-- GStreamer:
-- base: YES (ver 0.10.36)
-- app: YES (ver 0.10.36)
-- video: YES (ver 0.10.36)
-- OpenNI: NO
-- OpenNI PrimeSensor Modules: NO
-- PvAPI: NO
-- UniCap: NO
-- UniCap ucil: NO
-- V4L/V4L2: Using libv4l (ver 0.8.8)
-- XIMEA: NO
-- Xine: NO
I looked for videodev.h, etc 我找了videodev.h等
But I couldn't find ffmpeg/avformat.h
但我找不到
ffmpeg/avformat.h
What's the problem here? 这有什么问题?
So, I realized there was some problem with ffmpeg. 所以,我意识到ffmpeg存在一些问题。 and I rebuilt and installed ffmpeg and then changed flags for cmake to make opencv.
然后我重建并安装了ffmpeg,然后为cmake更改了标志以生成opencv。
For ffmpeg, 对于ffmpeg,
./configure --enable-gpl --enable-libfaac --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libtheora --enable-libvorbis --enable-libx264 --enable-libxvid --enable-nonfree --enable-postproc --enable-version3 --enable-x11grab
make
sudo make install
For OpenCV, 对于OpenCV,
cmake -D CMAKE_BUILD_TYPE=RELEASE ..
make
sudo make install
Here's the complete script to install OpenCV 2.4.2 https://github.com/jayrambhia/Install-OpenCV/blob/master/Ubuntu/2.4/opencv2_4_2.sh 这是安装OpenCV 2.4.2的完整脚本https://github.com/jayrambhia/Install-OpenCV/blob/master/Ubuntu/2.4/opencv2_4_2.sh
and here's my blogpost about OpenCV 2.4.2 installation in detail http://jayrambhia.com/blog/install-opencv-2-4-in-ubuntu-12-04-precise-pangolin/ 这是我关于OpenCV 2.4.2安装的博文详情http://jayrambhia.com/blog/install-opencv-2-4-in-ubuntu-12-04-precise-pangolin/
To run a full installation of OpenCV try the following: 要运行OpenCV的完整安装,请尝试以下操作:
sudo apt-get install libopencv-dev python-opencv
For more details check out the following link http://milq.github.io/install-opencv-ubuntu-debian/ 有关更多详细信息,请查看以下链接http://milq.github.io/install-opencv-ubuntu-debian/
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