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• Why opencv videowriter is so slow ?

  22 février 2021, par user2267367

  Hi stackoverflow community,
I have a tricky problem and I need your help to understand what is going on here.
My program captures frames from a video grabber card (Blackmagic) which just works fine so far, at the same time I display the captured images with opencv (cv::imshow) which works good as well (But pretty cpu wasting).
The captured images are supposed to be stored on the disk as well, for this I put the captured Frames (cv::Mat) on a stack, to finally write them async with opencv :

  


  cv::VideoWriter videoWriter(path, cv::CAP_FFMPEG, fourcc, fps, *size);
videoWriter.set(cv::VIDEOWRITER_PROP_QUALITY, 100);

int id = metaDataWriter.insertNow(path);

while (this->isRunning) {

    while (!this->stackFrames.empty()) {

        cv:Mat m = this->stackFrames.pop();

        videoWriter << m;
    }
    
}

videoWriter.release();


  


  This code is running in an additional thread and will be stopped from outside.
The code is working so far, but it is sometimes pretty slow, which means my stack size increases and my system runs out of ram and get killed by the OS.

  


  Currently it is running on my developing system :

  


  

  • Ubuntu 18.04.05

  


  • OpenCV 4.4.0 compiled with Cuda

  


  • Intel i7 10. generation 32GB RAM, GPU Nvidia p620, M.2 SSD

  


  


  Depending on the codec (fourcc) this produces a high CPU load. So far I used mainly "MJPG", "x264". Sometimes even MJPG turns one core of the CPU to 100% load, and my stack raises until the programs run out of run. After a restart, sometimes, this problem is fixed, and it seems the load is distributed over all cores.

  


  Regarding to the Intel Doc. for my CPU, it has integrated hardware encoding/decoding for several codecs. But I guess opencv is not using them. Opencv even uses its own ffmpeg and not the one of my system. Here is my build command of opencv :

  


  cmake -D CMAKE_BUILD_TYPE=RELEASE \
-D CMAKE_INSTALL_PREFIX=/usr/local \
-D WITH_TBB=ON \
-D WITH_CUDA=ON \
-D BUILD_opencv_cudacodec=OFF \
-D ENABLE_FAST_MATH=1 \
-D CUDA_FAST_MATH=1 \
-D WITH_CUBLAS=1 \
-D WITH_V4L=ON \
-D WITH_QT=OFF \
-D WITH_OPENGL=ON \
-D WITH_GSTREAMER=ON \
-D OPENCV_GENERATE_PKGCONFIG=ON \
-D OPENCV_ENABLE_NONFREE=ON \
-D WITH_FFMPEG=1 \
-D OPENCV_EXTRA_MODULES_PATH=../../opencv_contrib/modules \
-D WITH_CUDNN=ON \
-D OPENCV_DNN_CUDA=ON \
-D CUDA_ARCH_BIN=6.1 ..


  


  I just started development with linux and C++, before I was working with Java/Maven, so the use of cmake is still a work in progress, pls go easy on me.

  


  Basically my question is, how can I make the video encoding/writing faster, use the hardware acceleration at best ?
Or if you think there is something else fishy, pls let me know.

  


  BR Michael

  


• Piwik PRO is hiring a Project Coordinator (Job description)

  18 février 2015, par Matthieu Aubry — Jobs

  At Piwik and Piwik PRO we develop the leading open source web analytics platform, used by more than one million websites worldwide. Our vision is to build the best open alternative to Google Universal Analytics. We are growing and now looking for a Project Coordinator !

  What will you be doing ?

  • Participating in calls with Piwik PRO clients and analyzing requirements for enterprise customers
  • Planning and coordinating the implementation of projects
  • Helping customers to improve and adjust data reporting methods to suit their needs
  • Functioning as the voice of the customer and provide internal feedback on how Piwik PRO can better serve our customers

  What do we expect from you ?

  • Fluent command of English (both in writing and speaking), confidence to communicate in formal conversations and a good knowledge of business English
  • Previous experience in working with corporate clients
  • Great communication skills
  • A proactive attitude and the ability to use your initiative
  • Ability to achieve goals without detailed instructions

  Possessing these assets would be an advantage :

  • Technical knowledge associated with using data analytics platforms
  • Data analysis and interpretation skills
  • Knowledge of German or French
  • Knowledge of Piwik Analytics

  What can you expect from us ?

  • Flexible cooperation
  • An attractive salary
  • The opportunity to develop your skills and gain more experience by working on exceptional projects
  • Multisport Card
  • Access to a regularly updated resource library and the opportunity to contribute to it
  • Flexible working hours
  • Unforgettable parties and integration trips
  • A completely unique work atmosphere – we really like to keep things informal

  Location

  We have offices in Poland and New Zealand, and Remote work is possible.

  Ideally you will be located in the USA or in Europe where most of our clients are based.

  Apply online

  To apply for this position, please Apply online here. We look forward to receiving your applications !

• Piwik PRO is hiring a Project Coordinator (Job description)

  18 février 2015, par Matthieu Aubry — Jobs

  At Piwik and Piwik PRO we develop the leading open source web analytics platform, used by more than one million websites worldwide. Our vision is to build the best open alternative to Google Universal Analytics. We are growing and now looking for a Project Coordinator !

  What will you be doing ?

  • Participating in calls with Piwik PRO clients and analyzing requirements for enterprise customers
  • Planning and coordinating the implementation of projects
  • Helping customers to improve and adjust data reporting methods to suit their needs
  • Functioning as the voice of the customer and provide internal feedback on how Piwik PRO can better serve our customers

  What do we expect from you ?

  • Fluent command of English (both in writing and speaking), confidence to communicate in formal conversations and a good knowledge of business English
  • Previous experience in working with corporate clients
  • Great communication skills
  • A proactive attitude and the ability to use your initiative
  • Ability to achieve goals without detailed instructions

  Possessing these assets would be an advantage :

  • Technical knowledge associated with using data analytics platforms
  • Data analysis and interpretation skills
  • Knowledge of German or French
  • Knowledge of Piwik Analytics

  What can you expect from us ?

  • Flexible cooperation
  • An attractive salary
  • The opportunity to develop your skills and gain more experience by working on exceptional projects
  • Multisport Card
  • Access to a regularly updated resource library and the opportunity to contribute to it
  • Flexible working hours
  • Unforgettable parties and integration trips
  • A completely unique work atmosphere – we really like to keep things informal

  Location

  We have offices in Poland and New Zealand, and Remote work is possible.

  Ideally you will be located in the USA or in Europe where most of our clients are based.

  Apply online

  To apply for this position, please Apply online here. We look forward to receiving your applications !