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• Error opening video file with openCV cv2VideoCapture

  19 mai 2017, par kollo

  I have a video file here /data/out.mp4 and its copy /data/out.
  I’m on Osx Sierra with Xcode 8.

  Open video with mp4 extension is ok but get error with no extension or any other format.

  I tryed opencv 2.4 and latest 3.2 from git.
  Compiled with ffmpeg release/2.0 and also tryed release/3.0

  With opencv version 3.2 :

  Python 2.7.10 (default, Jul 30 2016, 19:40:32)
  
  [GCC 4.2.1 Compatible Apple LLVM 8.0.0 (clang-800.0.34)] on darwin
  
  Type "help", "copyright", "credits" or "license" for more information.
  
  >>> import cv2
  
  >>> cv2.__version__
  
  '3.2.0-dev'
  
  >>> cv2.__file__
  
  '/Users/johndoe/work/myproject/venv/local/lib/python2.7/site-packages/cv2.so'

  If video have extension :

  >>> v=cv2.VideoCapture('/data/out.mp4')
  
  >>> v.get(cv2.CAP_PROP_FRAME_COUNT)
  
  61117.0

  If video have no extension :

  >>> v=cv2.VideoCapture('/data/out')
  
  VIDEOIO(cvCreateFileCapture_AVFoundation (filename)): raised unknown C++ exception!
  
  
  
  >>> v.get(cv2.CAP_PROP_FRAME_COUNT)
  
  0.0

  My FFmpeg configure :

  ./configure --prefix=/usr \
  
  --bindir=/usr/local/bin/ \
  
  --shlibdir=/usr/lib64 \
  
  --datadir=/usr/share/ffmpeg \
  
  --incdir=/usr/include/ffmpeg \
  
  --libdir=/usr/lib64 \
  
  --mandir=/usr/share/man \
  
  --extra-cflags='-O2 -g' \
  
  --extra-version=rpmfusion \
  
  --enable-bzlib  \
  
  --enable-nonfree \
  
  --enable-libopenjpeg \
  
  --enable-libx264  \
  
  --enable-avfilter \
  
  --enable-postproc \
  
  --enable-pthreads \
  
  --disable-static \
  
  --enable-shared \
  
  --enable-gpl \
  
  --enable-runtime-cpudetect \
  
  --arch=x86_64

  My opencv CMAKE :

  cmake -D CMAKE_BUILD_TYPE=RELEASE \
  
  -D CMAKE_INSTALL_PREFIX=/Users/johndoe/work/myproject/venv/local/ \
  
  -D INSTALL_C_EXAMPLES=OFF \
  
  -D PYTHON_PACKAGES_PATH=/Users/johndoe/work/myproject/venv/lib/python2.7/site-packages \
  
  -D INSTALL_PYTHON_EXAMPLES=ON \
  
  -D PYTHON_EXECUTABLE=/Users/johndoe/work/myproject/venv/bin/python \
  
  -D WITH_CUDA=OFF ..

  I tryed various other formats reencoding my original video (ie : ffmpeg -i out.mp4 out.asf) :

  >>> v=cv2.VideoCapture('/data/out.avi')
  
  VIDEOIO(cvCreateFileCapture_AVFoundation (filename)): raised unknown C++ exception!
  
  
  
  >>> v=cv2.VideoCapture('/data/out.flv')
  
  VIDEOIO(cvCreateFileCapture_AVFoundation (filename)): raised unknown C++ exception!
  
  
  
  >>> v=cv2.VideoCapture('/data/out.asf')
  
  VIDEOIO(cvCreateFileCapture_AVFoundation (filename)): raised unknown C++ exception!

• Why does OpenCV not compile with ffmpeg support ?

  19 février 2017, par kollo

  I ran the following command to compile opencv :

  cmake -D CMAKE_BUILD_TYPE=RELEASE -D CMAKE_INSTALL_PREFIX=/Users/user/work/repo/venv/local/ -D INSTALL_C_EXAMPLES=OFF -D PYTHON_PACKAGES_PATH=/Users/user/work/repo/venv/lib/python2.7/site-packages -D INSTALL_PYTHON_EXAMPLES=ON -D PYTHON_EXECUTABLE=/Users/user/work/repo/venv/bin/python -D WITH_CUDA=OFF -D FFMPEG_INCLUDE_DIR=/usr/include/ffmpeg -D FFMPEG_LIB_DIR=/usr/lib64 -D WITH_FFMPEG=YES ..

  Which resulted in :

  --   Video I/O:
  
  --     DC1394 1.x:                  NO
  
  --     DC1394 2.x:                  NO
  
  --     FFMPEG:                      NO
  
  --       avcodec:                   YES (ver 57.75.100)
  
  --       avformat:                  YES (ver 57.63.100)
  
  --       avutil:                    YES (ver 55.45.100)
  
  --       swscale:                   YES (ver 4.3.101)
  
  --       avresample:                NO

  Then any Python call to opencv using ffmpeg as a capture source will fail.

  I though I had the proper paths setup, since calling the ffmpeg command line returns :

  $ ffmpeg
  
  ffmpeg version n3.0.5-19-ga71d22d-rpmfusion Copyright (c) 2000-2016 the FFmpeg developers
  
    built with Apple LLVM version 8.0.0 (clang-800.0.42.1)
  
    configuration: --prefix=/usr --bindir=/usr/local/bin/ --shlibdir=/usr/lib64 --datadir=/usr/share/ffmpeg --incdir=/usr/include/ffmpeg --libdir=/usr/lib64 --mandir=/usr/share/man --extra-cflags='-O2 -g' --extra-version=rpmfusion --enable-bzlib --enable-nonfree --enable-libopenjpeg --enable-libx264 --enable-avfilter --enable-postproc --enable-pthreads --disable-static --enable-shared --enable-gpl --enable-runtime-cpudetect --arch=x86_64

  And looking up in those dirs indeed give me the list of codecs listed in the cmakeoutput.

  I’m on OSX Sierra, and both opencv and ffmpeg are compiled manually.

  I can run the ffmpeg command line fine to convert any video file I need. I also can fire a Python shell and import using opencv and opening videos works correctly as long as I used the default capture source instead of cv2.CAP_FFMPEG. This means I can only open mp4 files right now.

• Getting RTSP stream with Opencv and python

  2 mai 2017, par magicleon

  I know this could be the 100th question of this kind, but I dug up google and everything, and I could not find anything working.
  I need to get an RTSP stream with opencv in python, and I’m out of ideas.
  Here’s what I tried so far :

  • Tried to stream with ffserver and ffmpeg but even when I got it working, I could see the stream only in the browser with very high latency, and not working in opencv
  • Tried to stream directly to udp with ffmpeg but again, no luck
  • Tried this script, but all I got was corrupted and unusable images.

  Any ideas ? I’m running on Mac OSX Sierra, I have compiled OpenCV 3.2.0 with ffmpeg support and I’m using Python 2.7.
  My cam is a Sricam SP09 and my RTSP url is the following :

  rtsp://973704:888888@192.168.1.78:554/onvif1