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• Setting up OpenCV 2.4.6.1 on Ubuntu 12.04.02

  12 août 2013, par Damilola

  I had previously used OpenCV 2.4.5 with some certain configs and packages on Ubuntu 12.04.1 but had issues upgrading to OpenCV 2.4.6.1 on Ubuntu 12.04.2

  I would like to share some ideas (a compilation of noteworthy information gathered from several sources including SO, ubuntu.org, asklinux.org and many other ; and of course by trying several procedures)

  Below is what eventually got me through.

  NOTE : ensure you uninstall any previous installation of OpenCV, FFMpeg and other dependencies previously installed.

  STEP 1 (install ffmpeg and dependencies)

  ---

  # goto http://sourceforge.net/projects/opencvlibrary/files/opencv-unix/
  
  # download the latest stable opencv such as 2.4.6.1 (http://sourceforge.net/projects/opencvlibrary/files/opencv-unix/2.4.5/opencv-2.4.5.1.tar.gz/download) to current directory (such as home or ~/Document)
  
  # cd /opt
  
  # tar -xvf /OpenCV-2.4.6.1.tar.gz
  
  # cd OpenCV-2.4.6.1
  
  # create a foler under current dir (following previous step, this should be ), called prepare
  
  # cd prepare
  
  # Copy the following script to gedit and save as install.sh to current dir, this should be /prepare
  
  # Check corresponding url used in the script for latest versions of the package and replace as required
  
  # Open terminal and navigate to location used above
  
  # sudo chmod +x install.sh
  
  # ./install

  ---

  echo "Removing any pre-installed ffmpeg, x264, and other dependencies (not all the previously installed dependecies)"
  
  sudo apt-get remove ffmpeg x264 libx264-dev libvpx-dev librtmp0 librtmp-dev libopencv-dev
  
  sudo apt-get update
  
  
  
  arch=$(uname -m)
  
  if [ "$arch" == "i686" -o "$arch" == "i386" -o "$arch" == "i486" -o "$arch" == "i586" ]; then
  
  flag=0
  
  else
  
  flag=1
  
  fi
  
  
  
  echo "Installing Dependenices"
  
  sudo apt-get install autoconf automake make g++ curl cmake bzip2 python unzip \
  
    build-essential checkinstall git git-core libass-dev libgpac-dev \
  
    libsdl1.2-dev libtheora-dev libtool libva-dev libvdpau-dev libvorbis-dev libx11-dev \
  
    libxext-dev libxfixes-dev pkg-config texi2html zlib1g-dev
  
  
  
  echo "downloading yasm (assembler used by x264 and FFmpeg)"
  
  # use git or tarball (not both)
  
  wget http://www.tortall.net/projects/yasm/releases/yasm-1.2.0.tar.gz
  
  tar xzvf yasm-1.2.0.tar.gz
  
  cd yasm-1.2.0
  
  
  
  echo "installing yasm"
  
  ./configure
  
  make
  
  sudo make install
  
  cd ..
  
  
  
  echo 'READ NOTE BELOW which was extracted from http://wiki.serviio.org/doku.php?id=build_ffmpeg_linux'
  
  echo 'New version of x264 contains by default support of OpenCL. If not installed or without sense (example Ubuntu 12.04LTS on VMWare) add to configure additional option --disable-opencl. Without this option ffmpeg could not be configured (ERROR: libx264 not found).'
  
  
  
  echo "downloading x264 (H.264 video encoder)"
  
  # use git or tarball (not both)
  
  # git clone http://repo.or.cz/r/x264.git or
  
  git clone git://git.videolan.org/x264.git
  
  cd x264
  
  # wget ftp://ftp.videolan.org/pub/videolan/x264/snapshots/x264-snapshot-20130801-2245-stable.tar.bz2
  
  # tar -xvjf x264-snapshot-20130801-2245-stable.tar.bz2
  
  # cd x264-snapshot-20130801-2245-stable/
  
  
  
  echo "Installing x264"
  
  if [ $flag -eq 0 ]; then
  
  ./configure --enable-static --disable-opencl
  
  else
  
  ./configure --enable-shared --enable-pic --disable-opencl
  
  fi
  
  make
  
  sudo make install
  
  cd ..
  
  
  
  echo "downloading fdk-aac (AAC audio encoder)"
  
  # use git or tarball (not both)
  
  git clone --depth 1 git://github.com/mstorsjo/fdk-aac.git
  
  cd fdk-aac
  
  
  
  echo "installing fdk-aac"
  
  autoreconf -fiv
  
  ./configure --disable-shared
  
  make
  
  sudo make install
  
  cd ..
  
  
  
  echo "installing libmp3lame-dev (MP3 audio encoder.)"
  
  sudo apt-get install libmp3lame-dev
  
  
  
  echo "downloading libopus (Opus audio decoder and encoder.)
  
  wget http://downloads.xiph.org/releases/opus/opus-1.0.3.tar.gz
  
  tar xzvf opus-1.0.3.tar.gz
  
  cd opus-1.0.3
  
  
  
  echo "installing libopus"
  
  ./configure --disable-shared
  
  make
  
  sudo make install
  
  cd ..
  
  
  
  echo "downloading libvpx VP8/VP9 video encoder and decoder)
  
  # use git or tarball (not both)
  
  git clone --depth 1 http://git.chromium.org/webm/libvpx.git
  
  cd libvpx
  
  # wget http://webm.googlecode.com/files/libvpx-v1.1.0.tar.bz2 (this seems not to be update, but can still be used if the fedoraproject link below is not available))
  
  # wget http://pkgs.fedoraproject.org/repo/pkgs/libvpx/libvpx-v1.2.0.tar.bz2/400d7c940c5f9d394893d42ae5f463e6/libvpx-v1.2.0.tar.bz2
  
  # tar xvjf libvpx-v1.2.0.tar.bz2
  
  # cd libvpx-v1.2.0
  
  
  
  echo "installing libvpx"
  
  ./configure --disable-examples
  
  make
  
  sudo make install
  
  cd ..
  
  
  
  sudo ldconfig
  
  
  
  echo "downloading ffmpeg"
  
  # git clone http://repo.or.cz/r/ffmpeg.git
  
  git clone git://source.ffmpeg.org/ffmpeg.git
  
  cd ffmpeg/
  
  # wget http://ffmpeg.org/releases/ffmpeg-2.0.tar.bz2
  
  # tar -xvjf ffmpeg-2.0.tar.bz2
  
  # cd ffmpeg-2.0/
  
  
  
  echo "installing ffmpeg" 
  
  if [ $flag -eq 0 ]; then
  
  ./configure --enable-gpl --enable-libass --enable-libfdk-aac --enable-libopus --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 --enable-libvpx
  
  else
  
  ./configure --enable-gpl --enable-libass --enable-libfdk-aac --enable-libopus --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 --enable-libvpx --enable-shared
  
  fi
  
  
  
  make
  
  sudo make install
  
  hash -r
  
  
  
  cd .. # move up one level to prepare folder
  
  cd .. # move up one level to opencv folder
  
  
  
  echo "Checking to see if you're using your new ffmpeg"
  
  ffmpeg 2>&1 | head -n1
  
  
  
  sudo ldconfig

  STEP 2 (Install OpenCV and necessary packages)

  echo "Installing Dependenices"
  
  sudo apt-get install libopencv-dev
  
  sudo apt-get install libtiff4-dev libjpeg-dev libjasper-dev
  
  
  
  echo "installing Video I/O libraries, support for Firewire video cameras and video streaming libraries"
  
  sudo apt-get install libav-tools libavcodec-dev libavformat-dev libswscale-dev libdc1394-22-dev libxine-dev libgstreamer0.10-dev libgstreamer-plugins-base0.10-dev libv4l-dev v4l-utils v4l-conf
  
  
  
  echo "installing the Python development environment and the Python Numerical library"
  
  sudo apt-get install python-dev python-numpy
  
  
  
  echo "installing the parallel code processing library (the Intel tbb library)"
  
  sudo apt-get install libtbb-dev
  
  
  
  echo "installing the Qt dev library"
  
  sudo apt-get install libqt4-dev libgtk2.0-dev
  
  
  
  echo "installing other dependencies (if need be it would upgrade current version of the packages)"
  
  sudo apt-get install patch subversion ruby librtmp0 librtmp-dev libfaac-dev libmp3lame-dev libopencore-amrnb-dev libopencore-amrwb-dev libvpx-dev libxvidcore-dev
  
  
  
  echo installing optional packages"
  
  sudo apt-get install libdc1394-utils libdc1394-22-dev libdc1394-22 libjpeg-dev libpng-dev libtiff-dev libjasper-dev

  STEP 3 (run ldconfig)

  # Open a new terminal window
  
  # Open /etc/ld.so.conf and check, 
  
  # if the paths "/usr/lib" and "/usr/local/lib" including the quote exist in the file. If not, add them manually or by
  
      sudo echo "/usr/local/lib" >> /etc/ld.so.conf
  
      sudo echo "/usr/lib" >> /etc/ld.so.conf
  
  # execute the following
  
      sudo ldconfig

  STEP 4

  # still ensure you haven't close the new terminal window open in STEP 3
  
  # execute the following
  
      mkdir build
  
      cd build
  
      cmake -D CMAKE_BUILD_TYPE=RELEASE -D CMAKE_INSTALL_PREFIX=/usr/local -D BUILD_SHARED_LIBS=OFF -D WITH_TBB=ON -D BUILD_NEW_PYTHON_SUPPORT=ON -D WITH_V4L=ON -D INSTALL_C_EXAMPLES=ON -D INSTALL_PYTHON_EXAMPLES=ON -D BUILD_EXAMPLES=ON -D WITH_QT=ON -D WITH_OPENGL=ON ..
  
  
  
      make
  
      sudo make install
  
  
  
  # add the following to user environment variable ~/.bashrc
  
      export LD_LIBRARY_PATH=${LD_LIBRARY_PATH}:/usr/local/lib
  
      export PKG_CONFIG_PATH=${PKG_CONFIG_PATH}:/usr/local/lib/pkgconfig
  
  # execute the following
  
      sudo ldconfig
  
  # start to use and enjoy opencv, it should have been install into these locations
  
  #   /usr/local/include/, /usr/local/share/, /usr/local/lib/

  STEP 5 (install v4l : Note : installing v4l-utils after opencv installation works for Ubuntu 12.04.2 & OpenCV 2.4.6.1)

  # still ensure you haven't close the new terminal window open in STEP 3
  
  # goto http://www.linuxtv.org/downloads/v4l-utils
  
  # download the latest v4l such as v4l-utils-0.9.5.tar.bz2
  
  # copy the downloaded file to the current terminal dir (following previous step, this should be /prepare)
  
  # execute the following
  
      tar -xvjf v4l-utils-0.9.5.tar.bz2
  
      cd v4l-utils-0.9.5/
  
      ./configure
  
      make
  
      sudo make install
  
      cd ..
  
      cd .. # (to go to )
  
      sudo ldconfig

  Worth Noting

  # To check the path where opencv & other lib files are stored, do:
  
  
  
  
  
  pkg-config --cflags opencv
  
  
  
      (output will come as)
  
      -I/usr/include/opencv
  
  
  
  
  
  
  
  pkg-config --libs opencv
  
  
  
      (output will come as)
  
      -lopencv_core -lopencv_imgproc -lopencv_highgui -lopencv_ --ml -lopencv_video -lopencv_features2d -lopencv_calib3d -lopencv_objdetect -lopencv_contrib -lopencv_legacy -lopencv_flann
  
  
  
  # The above paths are needed to compile your opencv programs, as given in the next illustration.
  
  
  
  # write a simple C program to test, by saving below program in a file named DisplayImage.c
  
  
  
  #include 
  
      #include <opencv2></opencv2>highgui/highgui.hpp>
  
  
  
      int main(int argc, char *argv[]) {
  
          IplImage* img=0; /* pointer to an image */
  
          printf("Hello\n");
  
  
  
          if(argv[1] != 0)
  
              img = cvLoadImage(argv[1], 0); // 1 for color
  
          else
  
              printf("Enter filename\n");
  
  
  
          if(img != 0) {
  
              cvNamedWindow("Display", CV_WINDOW_AUTOSIZE); // create a window
  
              cvShowImage("Display", img); // show image in window
  
              cvWaitKey(0); // wait until user hits a key
  
              cvDestroyWindow("Display");
  
          }
  
          else
  
              printf("File not found\n");
  
  
  
          return 0;
  
      }
  
  
  
  # write a simple C++ program to test, by saving below program in a file named DisplayImage.cpp
  
  
  
  #include 
  
  #include <opencv2></opencv2>opencv.hpp>
  
  #include <opencv2></opencv2>highgui/highgui.hpp>
  
  
  
  using namespace cv;
  
  
  
  int main( int argc, char** argv )
  
  {
  
    Mat image;
  
    image = imread( argv[1], 1 );
  
  
  
    if( argc != 2 || !image.data )
  
      {
  
        printf( "No image data \n" );
  
        return -1;
  
      }
  
  
  
    namedWindow( "Display Image", CV_WINDOW_AUTOSIZE );
  
    imshow( "Display Image", image );
  
  
  
    waitKey(0);
  
  
  
    return 0;
  
  }
  
  
  
  # To compile &amp; run :
  
  
  
  
  
  
  
  g++  `pkg-config --cflags --libs opencv` &amp;&amp; ./a.out img
  
  
  
  or
  
  
  
  
  
  
  
  g++ -I/usr/include/opencv -I/usr/local/include -lopencv_core -lopencv_highgui -lopencv_ml -lopencv_imgproc -lopencv_video -lopencv_features2d -lopencv_calib3d -lopencv_objdetect -lopencv_contrib -lopencv_legacy -lopencv_flann -lopencv_nonfree  &amp;&amp; ./a.out img
  
  
  
  where “img” is the name of any image with extension within the same folder .
  
  You should be able to see “Hello” and the image in a different window.
  
  
  
  If this runs, Congrats! now you can run any C/C++ program with opencv lib.
  
  
  
  
  
  # Now lets simplify the above big command by making a shortcut for it:
  
  go to your local home directory(cd /home/) and open the .bashrc file using gedit(the file will be hidden). Append the following to the file:
  
  
  
  
  
  
  
  alias gcv="g++ -I/usr/include/opencv -I/usr/local/include -lopencv_core -lopencv_highgui -lopencv_ml -lopencv_imgproc -lopencv_video -lopencv_features2d -lopencv_calib3d -lopencv_objdetect -lopencv_contrib -lopencv_legacy -lopencv_flann -lopencv_nonfree"
  
  
  
  and save. Close the terminal and open it again.(as this process requires relogin of the terminal)
  
  
  
  # Now, go to directory containing a sample program &amp; do
  
  
  
  
  
  
  
  gcv  &amp;&amp; ./a.out
  
  
  
  or
  
  
  
  
  
  
  
  gcv 
  
      ./a.out input_img.jpg

  As you can see the commands now become similar to $cc filename.c, $./a.out which are used normally for compiling and executing C/C++ programs.

  ---

  Some ways to check whether all lib files are installed-

  apt-cache search opencv

  returns :

  libcv-dev - Translation package for libcv-dev
  
  libcv2.3 - computer vision library - libcv* translation package
  
  libcvaux-dev - Translation package for libcvaux-dev
  
  libcvaux2.3 - computer vision library - libcvaux translation package
  
  libhighgui-dev - Translation package for libhighgui-dev
  
  libhighgui2.3 - computer vision library - libhighgui translation package
  
  libopencv-calib3d-dev - development files for libopencv-calib3d
  
  libopencv-calib3d2.3 - computer vision Camera Calibration library
  
  libopencv-contrib-dev - development files for libopencv-contrib
  
  libopencv-contrib2.3 - computer vision contrib library
  
  libopencv-core-dev - development files for libopencv-core
  
  libopencv-core2.3 - computer vision core library
  
  libopencv-dev - development files for opencv
  
  libopencv-features2d-dev - development files for libopencv-features2d
  
  libopencv-features2d2.3 - computer vision Feature Detection and Descriptor Extraction library
  
  libopencv-flann-dev - development files for libopencv-flann
  
  libopencv-flann2.3 - computer vision Clustering and Search in Multi-Dimensional spaces library
  
  libopencv-gpu-dev - development files for libopencv-gpu
  
  libopencv-gpu2.3 - computer vision GPU Processing library
  
  libopencv-highgui-dev - development files for libopencv-highgui
  
  libopencv-highgui2.3 - computer vision High-level GUI and Media I/O library
  
  libopencv-imgproc-dev - development files for libopencv-imgproc
  
  libopencv-imgproc2.3 - computer vision Image Processing library
  
  libopencv-legacy-dev - development files for libopencv-legacy
  
  libopencv-legacy2.3 - computer vision legacy library
  
  libopencv-ml-dev - development files for libopencv-ml
  
  libopencv-ml2.3 - computer vision Machine Learning library
  
  libopencv-objdetect-dev - development files for libopencv-objdetect
  
  libopencv-objdetect2.3 - computer vision Object Detection library
  
  libopencv-video-dev - development files for libopencv-video
  
  libopencv-video2.3 - computer vision Video analysis library
  
  opencv-doc - OpenCV documentation and examples
  
  python-opencv - Python bindings for the computer vision library

• FFmpeg.Autogen : Issue with Zero-Sized Atom Boxes in MP4 Output

  16 juin 2024, par Alexander Jansson

  I just started learning ffmpeg using ffmpeg.autogen wrapper version 5.1 in c#, and ffmpeg shared libs version 5.1. Im trying to facilitate a class which screenrecords using gdigrab and produces streamable mp4 to a/an buffer/event. Everything seems to work as suposed to with no error except that the outputstream produces atom boxes with 0 in size thus small file size aswell, no data seems to be produced in the boxes, the "debug test mp4 file" is analyzed with MP4Box and the box info is provided in the thread.

  


  To be more specific why does this code produce empty atomboxes, is someone able to make the data produced actually contain any frame data from the gdigrab editing my code ?

  


  `code :

  


   public unsafe class ScreenStreamer : IDisposable
 {
     private readonly AVCodec* productionCodec;
     private readonly AVCodec* screenCaptureAVCodec;
     private readonly AVCodecContext* productionAVCodecContext;
     private readonly AVFormatContext* productionFormatContext;
     private readonly AVCodecContext* screenCaptureAVCodecContext;
     private readonly AVDictionary* productionAVCodecOptions;
     private readonly AVInputFormat* screenCaptureInputFormat;
     private readonly AVFormatContext* screenCaptureInputFormatContext;
     private readonly int gDIGrabVideoStreamIndex;
     private readonly System.Drawing.Size screenBounds;
     private readonly int _produceAtleastAmount;
     public EventHandler OnNewVideoDataProduced;
     private MemoryStream unsafeToManagedBridgeBuffer;
     private CancellationTokenSource cancellationTokenSource;
     private Task recorderTask;

     public ScreenStreamer(int fps, int bitrate, int screenIndex, int produceAtleastAmount = 1000)
     {
         ffmpeg.avdevice_register_all();
         ffmpeg.avformat_network_init();
         recorderTask = Task.CompletedTask;
         cancellationTokenSource = new CancellationTokenSource();
         unsafeToManagedBridgeBuffer = new MemoryStream();
         _produceAtleastAmount = produceAtleastAmount;

         // Allocate and initialize production codec and context
         productionCodec = ffmpeg.avcodec_find_encoder(AVCodecID.AV_CODEC_ID_H264);
         if (productionCodec == null) throw new ApplicationException("Could not find encoder for codec ID H264.");

         productionAVCodecContext = ffmpeg.avcodec_alloc_context3(productionCodec);
         if (productionAVCodecContext == null) throw new ApplicationException("Could not allocate video codec context.");

         // Set codec parameters
         screenBounds = RetrieveScreenBounds(screenIndex);
         productionAVCodecContext->width = screenBounds.Width;
         productionAVCodecContext->height = screenBounds.Height;
         productionAVCodecContext->time_base = new AVRational() { den = fps, num = 1 };
         productionAVCodecContext->pix_fmt = AVPixelFormat.AV_PIX_FMT_YUV420P;
         productionAVCodecContext->bit_rate = bitrate;

         int result = ffmpeg.av_opt_set(productionAVCodecContext->priv_data, "preset", "veryfast", 0);
         if (result != 0)
         {
             throw new ApplicationException($"Failed to set options with error code {result}.");
         }

         // Open codec
         fixed (AVDictionary** pm = &productionAVCodecOptions)
         {
             result = ffmpeg.av_dict_set(pm, "movflags", "frag_keyframe+empty_moov+default_base_moof", 0);
             if (result < 0)
             {
                 throw new ApplicationException($"Failed to set dictionary with error code {result}.");
             }

             result = ffmpeg.avcodec_open2(productionAVCodecContext, productionCodec, pm);
             if (result < 0)
             {
                 throw new ApplicationException($"Failed to open codec with error code {result}.");
             }
         }

         // Allocate and initialize screen capture codec and context
         screenCaptureInputFormat = ffmpeg.av_find_input_format("gdigrab");
         if (screenCaptureInputFormat == null) throw new ApplicationException("Could not find input format gdigrab.");

         fixed (AVFormatContext** ps = &screenCaptureInputFormatContext)
         {
             result = ffmpeg.avformat_open_input(ps, "desktop", screenCaptureInputFormat, null);
             if (result < 0)
             {
                 throw new ApplicationException($"Failed to open input with error code {result}.");
             }

             result = ffmpeg.avformat_find_stream_info(screenCaptureInputFormatContext, null);
             if (result < 0)
             {
                 throw new ApplicationException($"Failed to find stream info with error code {result}.");
             }
         }

         gDIGrabVideoStreamIndex = -1;
         for (int i = 0; i < screenCaptureInputFormatContext->nb_streams; i++)
         {
             if (screenCaptureInputFormatContext->streams[i]->codecpar->codec_type == AVMediaType.AVMEDIA_TYPE_VIDEO)
             {
                 gDIGrabVideoStreamIndex = i;
                 break;
             }
         }

         if (gDIGrabVideoStreamIndex < 0)
         {
             throw new ApplicationException("Failed to find video stream in input.");
         }

         AVCodecParameters* codecParameters = screenCaptureInputFormatContext->streams[gDIGrabVideoStreamIndex]->codecpar;
         screenCaptureAVCodec = ffmpeg.avcodec_find_decoder(codecParameters->codec_id);
         if (screenCaptureAVCodec == null)
         {
             throw new ApplicationException("Could not find decoder for screen capture.");
         }

         screenCaptureAVCodecContext = ffmpeg.avcodec_alloc_context3(screenCaptureAVCodec);
         if (screenCaptureAVCodecContext == null)
         {
             throw new ApplicationException("Could not allocate screen capture codec context.");
         }

         result = ffmpeg.avcodec_parameters_to_context(screenCaptureAVCodecContext, codecParameters);
         if (result < 0)
         {
             throw new ApplicationException($"Failed to copy codec parameters to context with error code {result}.");
         }

         result = ffmpeg.avcodec_open2(screenCaptureAVCodecContext, screenCaptureAVCodec, null);
         if (result < 0)
         {
             throw new ApplicationException($"Failed to open screen capture codec with error code {result}.");
         }
     }

     public void Start()
     {
         recorderTask = Task.Run(() =>
         {
             AVPacket* packet = ffmpeg.av_packet_alloc();
             AVFrame* rawFrame = ffmpeg.av_frame_alloc();
             AVFrame* compatibleFrame = null;
             byte* dstBuffer = null;

             try
             {
                 while (!cancellationTokenSource.Token.IsCancellationRequested)
                 {
                     if (ffmpeg.av_read_frame(screenCaptureInputFormatContext, packet) >= 0)
                     {
                         if (packet->stream_index == gDIGrabVideoStreamIndex)
                         {
                             int response = ffmpeg.avcodec_send_packet(screenCaptureAVCodecContext, packet);
                             if (response < 0)
                             {
                                 throw new ApplicationException($"Error while sending a packet to the decoder: {response}");
                             }

                             response = ffmpeg.avcodec_receive_frame(screenCaptureAVCodecContext, rawFrame);
                             if (response == ffmpeg.AVERROR(ffmpeg.EAGAIN) || response == ffmpeg.AVERROR_EOF)
                             {
                                 continue;
                             }
                             else if (response < 0)
                             {
                                 throw new ApplicationException($"Error while receiving a frame from the decoder: {response}");
                             }

                             compatibleFrame = ConvertToCompatiblePixelFormat(rawFrame, out dstBuffer);

                             response = ffmpeg.avcodec_send_frame(productionAVCodecContext, compatibleFrame);
                             if (response < 0)
                             {
                                 throw new ApplicationException($"Error while sending a frame to the encoder: {response}");
                             }

                             while (response >= 0)
                             {
                                 response = ffmpeg.avcodec_receive_packet(productionAVCodecContext, packet);
                                 if (response == ffmpeg.AVERROR(ffmpeg.EAGAIN) || response == ffmpeg.AVERROR_EOF)
                                 {
                                     break;
                                 }
                                 else if (response < 0)
                                 {
                                     throw new ApplicationException($"Error while receiving a packet from the encoder: {response}");
                                 }

                                 using var packetStream = new UnmanagedMemoryStream(packet->data, packet->size);
                                 packetStream.CopyTo(unsafeToManagedBridgeBuffer);
                                 byte[] managedBytes = unsafeToManagedBridgeBuffer.ToArray();
                                 OnNewVideoDataProduced?.Invoke(this, managedBytes);
                                 unsafeToManagedBridgeBuffer.SetLength(0);
                             }
                         }
                     }
                     ffmpeg.av_packet_unref(packet);
                     ffmpeg.av_frame_unref(rawFrame);
                     if (compatibleFrame != null)
                     {
                         ffmpeg.av_frame_unref(compatibleFrame);
                         ffmpeg.av_free(dstBuffer);
                     }
                 }
             }
             finally
             {
                 ffmpeg.av_packet_free(&packet);
                 ffmpeg.av_frame_free(&rawFrame);
                 if (compatibleFrame != null)
                 {
                     ffmpeg.av_frame_free(&compatibleFrame);
                 }
             }
         });
     }

     public AVFrame* ConvertToCompatiblePixelFormat(AVFrame* srcFrame, out byte* dstBuffer)
     {
         AVFrame* dstFrame = ffmpeg.av_frame_alloc();
         int buffer_size = ffmpeg.av_image_get_buffer_size(productionAVCodecContext->pix_fmt, productionAVCodecContext->width, productionAVCodecContext->height, 1);
         byte_ptrArray4 dstData = new byte_ptrArray4();
         int_array4 dstLinesize = new int_array4();
         dstBuffer = (byte*)ffmpeg.av_malloc((ulong)buffer_size);
         ffmpeg.av_image_fill_arrays(ref dstData, ref dstLinesize, dstBuffer, productionAVCodecContext->pix_fmt, productionAVCodecContext->width, productionAVCodecContext->height, 1);

         dstFrame->format = (int)productionAVCodecContext->pix_fmt;
         dstFrame->width = productionAVCodecContext->width;
         dstFrame->height = productionAVCodecContext->height;
         dstFrame->data.UpdateFrom(dstData);
         dstFrame->linesize.UpdateFrom(dstLinesize);

         SwsContext* swsCtx = ffmpeg.sws_getContext(
             srcFrame->width, srcFrame->height, (AVPixelFormat)srcFrame->format,
             productionAVCodecContext->width, productionAVCodecContext->height, productionAVCodecContext->pix_fmt,
             ffmpeg.SWS_BILINEAR, null, null, null);

         if (swsCtx == null)
         {
             throw new ApplicationException("Could not initialize the conversion context.");
         }

         ffmpeg.sws_scale(swsCtx, srcFrame->data, srcFrame->linesize, 0, srcFrame->height, dstFrame->data, dstFrame->linesize);
         ffmpeg.sws_freeContext(swsCtx);
         return dstFrame;
     }

     private System.Drawing.Size RetrieveScreenBounds(int screenIndex)
     {
         return new System.Drawing.Size(1920, 1080);
     }

     public void Dispose()
     {
         cancellationTokenSource?.Cancel();
         recorderTask?.Wait();
         cancellationTokenSource?.Dispose();
         recorderTask?.Dispose();
         unsafeToManagedBridgeBuffer?.Dispose();

         fixed (AVCodecContext** p = &productionAVCodecContext)
         {
             if (*p != null)
             {
                 ffmpeg.avcodec_free_context(p);
             }
         }
         fixed (AVCodecContext** p = &screenCaptureAVCodecContext)
         {
             if (*p != null)
             {
                 ffmpeg.avcodec_free_context(p);
             }
         }

         if (productionFormatContext != null)
         {
             ffmpeg.avformat_free_context(productionFormatContext);
         }

         if (screenCaptureInputFormatContext != null)
         {
             ffmpeg.avformat_free_context(screenCaptureInputFormatContext);
         }

         if (productionAVCodecOptions != null)
         {
             fixed (AVDictionary** p = &productionAVCodecOptions)
             {
                 ffmpeg.av_dict_free(p);
             }
         }
     }
 }


  


  I call Start method and wait 8 econds, out of scope I write the bytes to an mp4 file without using the write trailer just to debug the atomboxes. and the mp4 debugging box output I got :

  


  (Full OUTPUT)
https://pastebin.com/xkM4MfG7

  


  ---

  


  (Not full)

  


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• FFmpeg.Autogen Wrapper : Issue with Zero-Sized Atom Boxes in MP4 Output

  11 juin 2024, par Alexander Jansson

  I just started learning ffmpeg using ffmpeg.autogen wrapper version 5.1 in c#, and ffmpeg shared libs version 5.1. Im trying to facilitate a class which screenrecords using gdigrab and produces streamable mp4 to a/an buffer/event. Everything seems to work as suposed to with no error except that the outputstream produces atom boxes with 0 in size thus small file size aswell, no data seems to be produced in the boxes, the "debug test mp4 file" is analyzed with MP4Box and the box info is provided in the thread.

  


  To be more specific why does this code produce empty atomboxes, is someone able to make the data produced actually contain any frame data from the gdigrab editing my code ?

  


  `code :

  


   public unsafe class ScreenStreamer : IDisposable
 {
     private readonly AVCodec* productionCodec;
     private readonly AVCodec* screenCaptureAVCodec;
     private readonly AVCodecContext* productionAVCodecContext;
     private readonly AVFormatContext* productionFormatContext;
     private readonly AVCodecContext* screenCaptureAVCodecContext;
     private readonly AVDictionary* productionAVCodecOptions;
     private readonly AVInputFormat* screenCaptureInputFormat;
     private readonly AVFormatContext* screenCaptureInputFormatContext;
     private readonly int gDIGrabVideoStreamIndex;
     private readonly System.Drawing.Size screenBounds;
     private readonly int _produceAtleastAmount;
     public EventHandler OnNewVideoDataProduced;
     private MemoryStream unsafeToManagedBridgeBuffer;
     private CancellationTokenSource cancellationTokenSource;
     private Task recorderTask;

     public ScreenStreamer(int fps, int bitrate, int screenIndex, int produceAtleastAmount = 1000)
     {
         ffmpeg.avdevice_register_all();
         ffmpeg.avformat_network_init();
         recorderTask = Task.CompletedTask;
         cancellationTokenSource = new CancellationTokenSource();
         unsafeToManagedBridgeBuffer = new MemoryStream();
         _produceAtleastAmount = produceAtleastAmount;

         // Allocate and initialize production codec and context
         productionCodec = ffmpeg.avcodec_find_encoder(AVCodecID.AV_CODEC_ID_H264);
         if (productionCodec == null) throw new ApplicationException("Could not find encoder for codec ID H264.");

         productionAVCodecContext = ffmpeg.avcodec_alloc_context3(productionCodec);
         if (productionAVCodecContext == null) throw new ApplicationException("Could not allocate video codec context.");

         // Set codec parameters
         screenBounds = RetrieveScreenBounds(screenIndex);
         productionAVCodecContext->width = screenBounds.Width;
         productionAVCodecContext->height = screenBounds.Height;
         productionAVCodecContext->time_base = new AVRational() { den = fps, num = 1 };
         productionAVCodecContext->pix_fmt = AVPixelFormat.AV_PIX_FMT_YUV420P;
         productionAVCodecContext->bit_rate = bitrate;

         int result = ffmpeg.av_opt_set(productionAVCodecContext->priv_data, "preset", "veryfast", 0);
         if (result != 0)
         {
             throw new ApplicationException($"Failed to set options with error code {result}.");
         }

         // Open codec
         fixed (AVDictionary** pm = &productionAVCodecOptions)
         {
             result = ffmpeg.av_dict_set(pm, "movflags", "frag_keyframe+empty_moov+default_base_moof", 0);
             if (result < 0)
             {
                 throw new ApplicationException($"Failed to set dictionary with error code {result}.");
             }

             result = ffmpeg.avcodec_open2(productionAVCodecContext, productionCodec, pm);
             if (result < 0)
             {
                 throw new ApplicationException($"Failed to open codec with error code {result}.");
             }
         }

         // Allocate and initialize screen capture codec and context
         screenCaptureInputFormat = ffmpeg.av_find_input_format("gdigrab");
         if (screenCaptureInputFormat == null) throw new ApplicationException("Could not find input format gdigrab.");

         fixed (AVFormatContext** ps = &screenCaptureInputFormatContext)
         {
             result = ffmpeg.avformat_open_input(ps, "desktop", screenCaptureInputFormat, null);
             if (result < 0)
             {
                 throw new ApplicationException($"Failed to open input with error code {result}.");
             }

             result = ffmpeg.avformat_find_stream_info(screenCaptureInputFormatContext, null);
             if (result < 0)
             {
                 throw new ApplicationException($"Failed to find stream info with error code {result}.");
             }
         }

         gDIGrabVideoStreamIndex = -1;
         for (int i = 0; i < screenCaptureInputFormatContext->nb_streams; i++)
         {
             if (screenCaptureInputFormatContext->streams[i]->codecpar->codec_type == AVMediaType.AVMEDIA_TYPE_VIDEO)
             {
                 gDIGrabVideoStreamIndex = i;
                 break;
             }
         }

         if (gDIGrabVideoStreamIndex < 0)
         {
             throw new ApplicationException("Failed to find video stream in input.");
         }

         AVCodecParameters* codecParameters = screenCaptureInputFormatContext->streams[gDIGrabVideoStreamIndex]->codecpar;
         screenCaptureAVCodec = ffmpeg.avcodec_find_decoder(codecParameters->codec_id);
         if (screenCaptureAVCodec == null)
         {
             throw new ApplicationException("Could not find decoder for screen capture.");
         }

         screenCaptureAVCodecContext = ffmpeg.avcodec_alloc_context3(screenCaptureAVCodec);
         if (screenCaptureAVCodecContext == null)
         {
             throw new ApplicationException("Could not allocate screen capture codec context.");
         }

         result = ffmpeg.avcodec_parameters_to_context(screenCaptureAVCodecContext, codecParameters);
         if (result < 0)
         {
             throw new ApplicationException($"Failed to copy codec parameters to context with error code {result}.");
         }

         result = ffmpeg.avcodec_open2(screenCaptureAVCodecContext, screenCaptureAVCodec, null);
         if (result < 0)
         {
             throw new ApplicationException($"Failed to open screen capture codec with error code {result}.");
         }
     }

     public void Start()
     {
         recorderTask = Task.Run(() =>
         {
             AVPacket* packet = ffmpeg.av_packet_alloc();
             AVFrame* rawFrame = ffmpeg.av_frame_alloc();
             AVFrame* compatibleFrame = null;
             byte* dstBuffer = null;

             try
             {
                 while (!cancellationTokenSource.Token.IsCancellationRequested)
                 {
                     if (ffmpeg.av_read_frame(screenCaptureInputFormatContext, packet) >= 0)
                     {
                         if (packet->stream_index == gDIGrabVideoStreamIndex)
                         {
                             int response = ffmpeg.avcodec_send_packet(screenCaptureAVCodecContext, packet);
                             if (response < 0)
                             {
                                 throw new ApplicationException($"Error while sending a packet to the decoder: {response}");
                             }

                             response = ffmpeg.avcodec_receive_frame(screenCaptureAVCodecContext, rawFrame);
                             if (response == ffmpeg.AVERROR(ffmpeg.EAGAIN) || response == ffmpeg.AVERROR_EOF)
                             {
                                 continue;
                             }
                             else if (response < 0)
                             {
                                 throw new ApplicationException($"Error while receiving a frame from the decoder: {response}");
                             }

                             compatibleFrame = ConvertToCompatiblePixelFormat(rawFrame, out dstBuffer);

                             response = ffmpeg.avcodec_send_frame(productionAVCodecContext, compatibleFrame);
                             if (response < 0)
                             {
                                 throw new ApplicationException($"Error while sending a frame to the encoder: {response}");
                             }

                             while (response >= 0)
                             {
                                 response = ffmpeg.avcodec_receive_packet(productionAVCodecContext, packet);
                                 if (response == ffmpeg.AVERROR(ffmpeg.EAGAIN) || response == ffmpeg.AVERROR_EOF)
                                 {
                                     break;
                                 }
                                 else if (response < 0)
                                 {
                                     throw new ApplicationException($"Error while receiving a packet from the encoder: {response}");
                                 }

                                 using var packetStream = new UnmanagedMemoryStream(packet->data, packet->size);
                                 packetStream.CopyTo(unsafeToManagedBridgeBuffer);
                                 byte[] managedBytes = unsafeToManagedBridgeBuffer.ToArray();
                                 OnNewVideoDataProduced?.Invoke(this, managedBytes);
                                 unsafeToManagedBridgeBuffer.SetLength(0);
                             }
                         }
                     }
                     ffmpeg.av_packet_unref(packet);
                     ffmpeg.av_frame_unref(rawFrame);
                     if (compatibleFrame != null)
                     {
                         ffmpeg.av_frame_unref(compatibleFrame);
                         ffmpeg.av_free(dstBuffer);
                     }
                 }
             }
             finally
             {
                 ffmpeg.av_packet_free(&packet);
                 ffmpeg.av_frame_free(&rawFrame);
                 if (compatibleFrame != null)
                 {
                     ffmpeg.av_frame_free(&compatibleFrame);
                 }
             }
         });
     }

     public AVFrame* ConvertToCompatiblePixelFormat(AVFrame* srcFrame, out byte* dstBuffer)
     {
         AVFrame* dstFrame = ffmpeg.av_frame_alloc();
         int buffer_size = ffmpeg.av_image_get_buffer_size(productionAVCodecContext->pix_fmt, productionAVCodecContext->width, productionAVCodecContext->height, 1);
         byte_ptrArray4 dstData = new byte_ptrArray4();
         int_array4 dstLinesize = new int_array4();
         dstBuffer = (byte*)ffmpeg.av_malloc((ulong)buffer_size);
         ffmpeg.av_image_fill_arrays(ref dstData, ref dstLinesize, dstBuffer, productionAVCodecContext->pix_fmt, productionAVCodecContext->width, productionAVCodecContext->height, 1);

         dstFrame->format = (int)productionAVCodecContext->pix_fmt;
         dstFrame->width = productionAVCodecContext->width;
         dstFrame->height = productionAVCodecContext->height;
         dstFrame->data.UpdateFrom(dstData);
         dstFrame->linesize.UpdateFrom(dstLinesize);

         SwsContext* swsCtx = ffmpeg.sws_getContext(
             srcFrame->width, srcFrame->height, (AVPixelFormat)srcFrame->format,
             productionAVCodecContext->width, productionAVCodecContext->height, productionAVCodecContext->pix_fmt,
             ffmpeg.SWS_BILINEAR, null, null, null);

         if (swsCtx == null)
         {
             throw new ApplicationException("Could not initialize the conversion context.");
         }

         ffmpeg.sws_scale(swsCtx, srcFrame->data, srcFrame->linesize, 0, srcFrame->height, dstFrame->data, dstFrame->linesize);
         ffmpeg.sws_freeContext(swsCtx);
         return dstFrame;
     }

     private System.Drawing.Size RetrieveScreenBounds(int screenIndex)
     {
         return new System.Drawing.Size(1920, 1080);
     }

     public void Dispose()
     {
         cancellationTokenSource?.Cancel();
         recorderTask?.Wait();
         cancellationTokenSource?.Dispose();
         recorderTask?.Dispose();
         unsafeToManagedBridgeBuffer?.Dispose();

         fixed (AVCodecContext** p = &productionAVCodecContext)
         {
             if (*p != null)
             {
                 ffmpeg.avcodec_free_context(p);
             }
         }
         fixed (AVCodecContext** p = &screenCaptureAVCodecContext)
         {
             if (*p != null)
             {
                 ffmpeg.avcodec_free_context(p);
             }
         }

         if (productionFormatContext != null)
         {
             ffmpeg.avformat_free_context(productionFormatContext);
         }

         if (screenCaptureInputFormatContext != null)
         {
             ffmpeg.avformat_free_context(screenCaptureInputFormatContext);
         }

         if (productionAVCodecOptions != null)
         {
             fixed (AVDictionary** p = &productionAVCodecOptions)
             {
                 ffmpeg.av_dict_free(p);
             }
         }
     }
 }


  


  I call Start method and wait 8 econds, out of scope I write the bytes to an mp4 file without using the write trailer just to debug the atomboxes. and the mp4 debugging box output I got :

  


  (Full OUTPUT)
https://pastebin.com/xkM4MfG7

  


  ---

  


  (Not full)

  


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