Recherche avancée

Sur d’autres sites (14083)

• Can't save process's output stream to file

  10 octobre 2018, par Wahid Masud

  I’m using ffmpeg.exe as a process and output the converted video to memory, then from memory I’m saving the data to a video file (this is the requirement I can’t directly save the converted video to a file). But the conversion is not working for some reason, Here is what I’ve tried,

  var ffmpeg = HttpContext.Current.Server.MapPath("~/FFMpeg/ffmpeg.exe");
  
  var outputDir = HttpContext.Current.Server.MapPath("~/Uploads/converted.mp4");
  
  var inputDir = "https://www.sample-videos.com/video/mp4/720/big_buck_bunny_720p_10mb.mp4";
  
  var args = "-i " + inputDir + " -c:v libx264 -preset veryslow -crf 26 " +
  
              "-ar 44100 -ac 2 -c:a aac -strict -2 -b:a 128k -";
  
  
  
  var process = new Process();
  
  process.StartInfo.UseShellExecute = false;
  
  process.StartInfo.FileName = ffmpeg;
  
  process.StartInfo.WorkingDirectory = ffmpeg.Replace("\\ffmpeg.exe", "");
  
  process.StartInfo.Arguments = args;
  
  process.StartInfo.RedirectStandardOutput = true;
  
  process.Start();
  
  process.EnableRaisingEvents = true;
  
  //process.WaitForExit();
  
  Stream output = process.StandardOutput.BaseStream;
  
  process.Exited += (sender, e) =>
  
  {
  
      using (var fileStream = File.Create(outputDir))
  
      {
  
          output.Seek(0, SeekOrigin.Begin);
  
          output.CopyTo(fileStream);
  
      }
  
  };  

  The output file converted.mp4 is created but its 0 kb.

• Error during the compilation of OpenCV with CUDA and FFMpeg on Ubuntu 18.04

  19 juillet 2019, par Karthik

  I have a requirement to install OpenCV compiled with CUDA and FFMpeg for an optical flow calculation.

  I followed this post to install on Ubuntu 18.04, but I am getting the following error shown in the below screenshot when I am trying to execute the following command :

    cmake -D CMAKE_BUILD_TYPE=RELEASE \
  
              -D CMAKE_INSTALL_PREFIX=/usr/local \
  
              -D INSTALL_C_EXAMPLES=ON \
  
              -D INSTALL_PYTHON_EXAMPLES=ON \
  
              -D OPENCV_EXTRA_MODULES_PATH=../../opencv_contrib/modules \
  
              -D BUILD_EXAMPLES=ON \
  
              -D BUILD_opencv_python2=OFF \
  
              -D WITH_FFMPEG=1 \
  
              -D WITH_CUDA=ON \
  
              -D CUDA_GENERATION=Pascal \
  
              -D ENABLE_FAST_MATH=1 \
  
              -D CUDA_FAST_MATH=1 \
  
              -D WITH_CUBLAS=1 \
  
              -D PYTHON_DEFAULT_EXECUTABLE=/opt/anaconda/bin/python \
  
              -D PYTHON3_INCLUDE_DIR=/opt/anaconda/include/python3.5m \
  
              -D PYTHON3_LIBRARY=/opt/anaconda/lib/libpython3.5m.so \
  
              -D PYTHON3_PACKAGES_PATH=/opt/anaconda/lib/python3.5 \
  
              -D WITH_LAPACK=OFF \
  
              -D PYTHON3_NUMPY_INCLUDE_DIRS=/opt/anaconda/lib/python3.5/site-packages/numpy/core/include ..

  

  I have installed the CUDA version 10.0

  It would be of a great help, if you can guide me to fix this error or suggest me a different procedure to install OpenCV compiled with CUDA and FFMpeg on Ubuntu 18.04.

  Thanks !

• ffmpeg choose exact frame from long film strip

  28 novembre 2018, par Tech Aimley

  I’m working with ffmpeg to choose the better thumbnail for my video. and the selection would be based on the slider.
  as per the requirement multiple thumbnails not needed just a single long film image and with the help of slider select the thumbnail and save it.

  i used below command to get the long strip thumbnail.

  ffmpeg -loglevel panic -y -i "video.mp4" -frames 1 -q:v 1 -vf "select=not(mod(n\,40)),scale=-1:120,tile=100x1" video_preview.jpg

  I followed the instructions from this tutorial

  I’m able to get the long film image :
  

  This is working fine, they moving the image in slider which is fine.

  My question is how can I select a particular frame from that slider / film strip. How can I calculate the exact time duration from the slider and then execute a command to extract that frame ?