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• Starting and stopping a system command in C++ based on whether the main program is running

  3 juillet 2018, par zach

  I’m writing a program and I want to use ffmpeg’s x11grab to record the users actions on screen while they interact with the program. I am able to set up the system call to ffmpeg, but I’m not sure how I get it to stop once the program has finished running ?

  Ideally, I would like for the user to hit start (which begins the recording), interact with the main part of the program, hit end, and then have a video file of their session placed somewhere.

  Here’s the code I have so far. This just finds the screen resolution, then calls ffmpeg’s x11grab.

  QRect screen = QApplication::desktop()->screen(QApplication::desktop()->primaryScreen())->geometry();
  
  
  
  int width = screen.width();
  
  int height = screen.height();
  
  
  
  std::string resolution = std::to_string(width) + "x" + std::to_string(height);
  
  std::string record_command = "ffmpeg -f x11grab -s  -r 30 -i :0.0 -qscale 0.1 -vcodec huffyuv grab.avi";
  
  //insert screen resolution into bash command
  
  record_command.insert(21, resolution);
  
  std::cout << record_command;
  
  //bash command to record 
  
  system(record_command.c_str());

• FFMPEG : Creating video using drawtext along with word wrap and padding

  11 octobre 2022, par Chaitanya Sai

  I'm working to create a video from text with drawtext filter. Output video i can see the text is overflowing instead of coming in new line.

  



  Is there any way i can archive word wrapping and also set the internal padding to video ?

  



  Below is the snippet I'm using to generate video from text

  



  ffmpeg.exe -f lavfi -i color=c=white:s=640x480:d=5.396 -vf "[in] drawtext=fontfile=font.ttf:fontsize=20:fontcolor=black:x=0+0*print(tw):y=0+0*print(th):text='this is new whiteboard te':enable='between(t,6.634,6.818)',drawtext=fontfile=font.ttf:fontsize=20:fontcolor=black:x=0+0*print(tw):y=0+0*print(th):text='this is new whiteboard testing':enable='between(t,0.0,2.032)',drawtext=fontfile=font.ttf:fontsize=20:fontcolor=black:x=0+0*print(tw):y=0+0*print(th):text='this is new whiteboard testing no padding and the text is overflowing from the video frame check this  need to acheve word wrapping':enable='between(t,2.032,5.396)'"[out] -c:v libx264 -t 30 -crf 30 ../output.mp4


  



  Output looks like this


  


• Add unit tests for word-wise CRC16 functions

  20 mai 2018, par Robert Kausch

  Add unit tests for word-wise CRC16 functions
  Update FLAC__BitReader structure in unit test.
  

  • [DH] src/test_libFLAC/bitreader.c
  • [DH] src/test_libFLAC/crc.c