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• How to change the colour of pixels in videos with OpenGL in C++ [closed]

  8 juin 2020, par Dennio

  I would like to overlay a specifically coloured pattern or matrix over every frame of a video, so that every pixel changes it's color slightly corresponding to a data-matrix which I generate from a bitstream. It would begin with the upper left pixel and would go on till the end of the "line" and so on. I would like to change the red and blue values which means if the bitstream begins with a "1" the amount of red should be raised by 5 and if it begins with a "0" the amount of blue should be raised by 5. That would be done for every pixel of the frame.

  



  I can already open a video using FFmpeg in a selfmade videoplayer, I can also generate the data-matrix but I just don't know which way is suitable to manipulate the videoframes in c++. I already successfully compiled some OpenGL and OpenGL ES triangles on my RaspberryPi 4. Is it possible to convert the frames and pixels into textures and go from there to display everything ? Or is there maybe a better way to do this ? I would like to use the GPU of the RaspberryPi for the tasks to get a good performance out of this.

  


• checkasm : disable unaligned access emulation

  1er juin 2024, par Rémi Denis-Courmont

  checkasm : disable unaligned access emulation
  The OS may silently fix (emulate) unaligned hardware access exceptions.
  
  This is extremely slow and code should be fixed not to rely on unaligned
  
  access on affected hardware. Accordingly this requests that the OS
  
  disable emulation and instead throw Bus error, which will be caught by
  
  checkasm's signal handler.
  This has no effects if the hardware supports unaligned access in
  
  hardware, since no exceptions are generated. prctl() will fail safe in
  
  that case.
  

  • [DH] tests/checkasm/checkasm.c

• Nginx allow only my domain to access a video url

  4 septembre 2019, par Bruno F

  i’m setting up a web server that contains live video streaming embed into the html5 video tag. My workflow is to grab the rtsp video from an ip camera, decode it to a HLS format using ffmpeg and send the video to my server.
  Nginx allows access to the video through a url, which I put in my video tag as a source.

  Everything works perfectly, the only problem is that anyone can access the URL of the video and put that URL on their website without my permission.

  Is there any way to only allow my domain to access, and block for example www.domain2.com to put it into their video tag or other framework thath they use ? i’m think Nginx can do the job maybe.

  Here are the codes of Nginx and my html in case is needed.

  HTML :

  <video class="video-js vjs-default-skin vjs-big-play-centered vjs-fluid" controls="controls" preload="none">
  
  <source src="//mydomain.com/live/stream.m3u8" type="application/x-mpegURL"></source>
  
  </video>

  Nginx :

  location /live {
  
              types {
  
                      application/vnd.apple.mpegurl m3u8;
  
              }
  
              limit_conn addr 5;
  
              alias /home/stream;
  
              add_header Cache-Control no-cache;
  
              add_header 'Access-Control-Allow-Origin' '*';
  
      }

  Many thanks guys !