Opencv 2.4 Videocapture Not Working on Windows

OpenCV 2.4 VideoCapture not working on Windows

Add C:\OpenCV\3rdparty\ffmpeg\ to the Windows PATH environment variable or copy opencv_ffmpeg.dll from that directory to C:\Python27\ or to a directory that is in the PATH. Alternatively, use the OpenCV binaries from http://www.lfd.uci.edu/~gohlke/pythonlibs/#opencv.

Renaming the opencv_ffmpeg.dll file may also be necessary.

For OpenCV version X.Y.Z

opencv_ffmpeg.dll ==> opencv_ffmpegXYZ.dll

For 64-bit OpenCV version X.Y.Z

opencv_ffmpeg.dll ==> opencv_ffmpegXYZ_64.dll

VideoCapture OpenCV 2.4.2 error in windows

In my case, the same problem was resolved after deleting all opencv_***.dll files in C:\Windows\System32. So, I use the dll files just through the path like "%PATH%;C: \Program Files \OpenCV2.4.2\build\x86\vc10/bin". Please try it.

OpenCV VideoCapture not read any video File in Windows 7 32bit

For some unknown reason in a system 32bit the building created a dll called opencv_ffmpeg248_64.dll and the installation of opencv was in a folder "x64", so i think that dll was for 64bit system. I download the pre built version of openCV and i use the dll included in that package.

VideoCapture is not working in OpenCV 2.4.2

So, I realized there was some problem with ffmpeg. and I rebuilt and installed ffmpeg and then changed flags for cmake to make opencv.

For 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,

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

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/

Can't open video using opencv

It's a codec problem

I converted that mp4 file to an avi file with ffmpeg. Then the above opencv code can play that avi file well.

Therefore I am sure that this is a codec problem.

(I then converted that mp4 file to another mp4 file using ffmpeg, thinking maybe ffmpeg would help turning that original unreadable .mp4 codec into a readable .mp4 codec, but the resulting .mp4 file ended up broken. This fact may or may not relate to this problem, just mentioning, in case anybody needs this information.)

The answer to it - Rebuild FFmpeg then Rebuild Opencv

Despite knowing this is a codec problem, I tried many other ways but still couldn't solve it. At last I tried rebuilding ffmpeg and opencv, then the problem was solved!

Following is my detailed rebuilding procedure.

(1) Build ffmpeg

1. Download ffmpeg-2.7.1.tar.bz2
   
   

   FFmpeg website: https://www.ffmpeg.org/download.html

   ffmpeg-2.7.1.tar.bz2 link: http://ffmpeg.org/releases/ffmpeg-2.7.1.tar.bz2

2. tar -xvf ffmpeg-2.7.1.tar.bz2
3. cd ffmpeg-2.7.1
4. ./configure --enable-pic --extra-ldexeflags=-pie
   

   From http://www.ffmpeg.org/platform.html#Advanced-linking-configuration

   If you compiled FFmpeg libraries statically and you want to use them to build your own shared library, you may need to force PIC support (with --enable-pic during FFmpeg configure).

   If your target platform requires position independent binaries, you should pass the correct linking flag (e.g. -pie) to --extra-ldexeflags.

   ---

   
   

   If you encounter error:
   yasm/nasm not found or too old. Use --disable-yasm for a crippled build.

   Just sudo apt-get install yasm

   ---

   
   

   Further building options: https://trac.ffmpeg.org/wiki/CompilationGuide/Ubuntu

   e.g. Adding option --enable-libmp3lame enables png encoder. (Before ./configure you need to sudo apt-get install libmp3lame-dev with version ≥ 3.98.3)

5. make -j5 (under ffmpeg folder)
6. sudo make install

(2) Build Opencv

1. wget http://downloads.sourceforge.net/project/opencvlibrary/opencv-unix/2.4.9/opencv-2.4.9.zip
2. unzip opencv-2.4.9.zip
3. cd opencv-2.4.9
4. mkdir build
5. cd build
6. cmake -D CMAKE_BUILD_TYPE=RELEASE -D CMAKE_INSTALL_PREFIX=/usr/local -D BUILD_NEW_PYTHON_SUPPORT=ON -D WITH_QT=OFF -D WITH_V4L=ON -D CMAKE_SHARED_LINKER_FLAGS=-Wl,-Bsymbolic ..
   

   You can change those options depend on your needs. Only the last one -D CMAKE_SHARED_LINKER_FLAGS=-Wl,-Bsymbolic is the key option. If you omit this one then the make will jump out errors.

   This is also from http://www.ffmpeg.org/platform.html#Advanced-linking-configuration (the same link of step 4 above)

   If you compiled FFmpeg libraries statically and you want to use them to build your own shared library, you may need to ... and add the following option to your project LDFLAGS: -Wl,-Bsymbolic

7. make -j5
8. sudo make install
9. sudo sh -c 'echo "/usr/local/lib" > /etc/ld.so.conf.d/opencv.conf'
10. sudo ldconfig

Now the opencv code should play a mp4 file well!

Methods I tried but didn't work

1. Try add WITH_UNICAP=ON WITH_V4L=ON when cmake opencv. But didn't work at all.
2. Try changing codec inside the python opencv code. But in vain.
   
   

   cap = cv2.VideoCapture("MOV_0006.mp4")

   print cap.get(cv2.cv.CV_CAP_PROP_FOURCC)

   I tested this in two environment. In the first environment the opencv works, and in the other the opencv fails to play a video. But both printed out same codec 828601953.0.

   I tried to change their codec by cap.set(cv2.cv.CV_CAP_PROP_FOURCC, cv2.cv.CV_FOURCC(*'H264')) but didn't work at all.

3. Try changing the libraries under opencv-2.4.8/3rdparty/lib/ into libraries in my workable environment. But couldn't even successfully build.
   
   

   I grep AVC: nal size and find the libraries contain this error message are opencv-2.4.8/3rdparty/lib/libavcodec.a etc. That's why I tried to replace them. But it turns out that this is a bad idea.

4. sudo apt-get -y install libopencv-dev build-essential cmake git libgtk2.0-dev pkg-config python-dev python-numpy libdc1394-22 libdc1394-22-dev libjpeg-dev libpng12-dev libtiff4-dev libjasper-dev libavcodec-dev libavformat-dev libswscale-dev libxine-dev libgstreamer0.10-dev libgstreamer-plugins-base0.10-dev libv4l-dev libtbb-dev libqt4-dev libfaac-dev libmp3lame-dev libopencore-amrnb-dev libopencore-amrwb-dev libtheora-dev libvorbis-dev libxvidcore-dev x264 v4l-utils unzip
   

   Try to install some that thing and some this thing. But it was totally useless.

Problems Related

I've searched the web and there are many similar problems, but NONE of them had a solution!

Below are problems I think the same as mine.

• OpenCV/ffmpeg does not play my mp4 video. —
  from opencv-users.nabble.com

• VideoCapture is not working in OpenCV 2.4.2 —
  from answers.opencv.org

  This one mentions rebuilding ffmpeg! But the arguments weren't enough for me.

• Mp4 reading problem - I installed OpenCV 2.4.1 and python 2.7 and made a short program that reads the avi file successfully. However it fails to read mp4 file. —
  from answers.opencv.org

• Cannot open “.mp4” video files using OpenCV 2.4.3, Python 2.7 in _Windows 7 machine —
  from Stack Overflow

• OpenCV 2.4 VideoCapture not working on Windows —
  from Stack Overflow

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