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• Recording slow-motion video

  20 janvier 2016, par SharpAffair

  We have a camera that records videos with high FPS rate - 163.

  To capture from the camera in C#, we use AForge.Video library. The capture works fine.

  For saving the video to a file, we use AForge.Video.FFMPEG.VideoFileWriter as follows :

  FileWriter.Open("test.avi", eventArgs.Frame.Width, eventArgs.Frame.Height, 163, VideoCodec.MPEG4, 5000000);

  What we’re trying to figure out is how to use the VideoFileWriter to produce slow-motion video.

  Assuming we have to do something with frame rate of the video file output ? If so, what should we set the frame rate to ? And if not, what’s the correct approach to get the slow-motion output ?

  Thanks !

• How can I Recording a UDP stream in segments, FFmpeg

  25 octobre 2019, par A Person

  I’m looking for a way to record a UDP stream continuously in 30 minutes segments and encode live on the GPU. I want the recording to have the date and time burned into the clip and do it continuously (24/7).

  I have tried the following :

  ffmpeg -i udp://source:port -c copy -flags +global_header -f segment -segment_time 1800 -segment_format_options movflags=+faststart -reset_timestamps 1 show_{Date}_{Time}.mp4

  {Date} and {Time} are variable holding the time of when FFmpeg starts.

  This records my segments correctly, however, if there is a loss in signal in the stream, it FFmpeg crashes and doesn’t continue recording or start itself back up and this does not have the current time or date burned into the output video.

  I need it to be playable in html5, this is why I did mp4.

• PHP script works when called from command line, does not when called as background via web server

  6 juin 2014, par fNek

  I am facing a problem with a certain PHP script (CLI mode) I wrote. It should take certain arguments to convert a video with FFMPEG. When I call it from the command prompt, it works fine. However, I have to call it from a web server.

  The PHP script that handles the request calls the PHP script in the background via code I found here at SE :

  if (substr(php_uname(), 0, 7) == "Windows"){ 
  
      pclose(popen("start /B ". $cmd, "r"));  
  
  } 
  
  else { 
  
      exec("nohup " . $cmd . " > /dev/null &");
  
  }

  When run this way, however, the PHP script does not create the files, even after a much longer time than it took via the command prompt.

  The script runs, I have checked that by letting it insert dummy entries into the database. It also has the permission to create files, which I verified by letting it create a text file.

  What could be the difference that prevents my script from working properly ? I develop and test this code with XAMPP on Windows 7.

  //EDIT : I forgot to give you this link to the background PHP script : http://pastebin.com/pfTZMfwi

  //EDIT2 : I found out that the PHP process runs for a very short time (only until next refresh of the Windows task manager). Could it be that PHP kills its children when it exits ?

  //EDIT3 : No, that seems not to be the problem. I cannot execute programs via exec() when the script is called as background from the web server. What could the problem be, and what would be a solution/workaround ?

  //EDIT4 : The command that seems to cause the trouble is not exec()/etc. but the echo command I did before the exec(). I am going to remove it, but why does it cause a problem ?