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• Pause/resume ffmpeg transcoding process

  27 janvier 2014, par XXX

  In my Android application I use Ffmpeg library written in C++. I use ffmpeg command ffmpeg -y -i in.mp4 -s 320x240 -c:a copy out.mp4 to reduce the size of media files on Android. Everything works well. But if the file is too large, then the smartphone's battery heats up. And I have a question : is it possible to stop a ffmpeg process, and then continue it later on ? When I am converting a large file, I would like to be able to start from where I left off. Or is there any way to avoid heating the battery. May be this way : cut the file into pieces, reduce each separately and paste together ?

  UPDATE

  I found this Pause any process you want in Linux. So I decided to try to apply it on Android.

  public static void pause()
  
  {
  
      try
  
      {
  
          Process      sh = Runtime.getRuntime().exec("su", null,null);
  
          OutputStream os = sh.getOutputStream();
  
          os.write(("sudo -kill -STOP (pidof Thread-10)").getBytes("ASCII"));
  
          Log.e("!!", "process stopped!");
  
          os.flush();
  
          os.close();
  
          sh.waitFor();
  
      }
  
      catch(Throwable t){t.printStackTrace();}
  
  }

  But the process doesn't stop. Thread-10 it's the name of ffmpeg transcoding process. Whats wrong ?

• ffmpeg API encoding mpeg-4 Windows Media Player error

  9 juin 2017, par user1505129

  We have an app that uses the ffmpeg C API to encode mpeg-4 (AV_CODEC_ID_MPEG4) files in a mp4 container. The problem is that the files don’t play in Windows Media Player or the Windows 10 video player "Movies & TV" app. It plays in VLC, google chrome, Ubuntu’s video player, and all other video players I’ve tried.

  The two Windows players are able to play other files encoded with mpeg-4 in mp4 container. I also tested transcoding video files to the same format using the command line ’ffmpeg’ tool and was successfully able to play the video using the following command :

  ffmpeg input.avi -c:v mpeg4 output.mp4

  While I found the following commands do not work :

  ffmpeg input.avi -c:v mpeg4 -vtag xvid output.mp4

  ffmpeg input.avi -c:v libxvid output.mp4

  # the last command wont play with windows media player but VLC can still play it.  If the extension of the output file is changed to avi for the last two commands then Windows media player can play it.

  I started looking at the ffmpeg src code but it appears a bit large/complex, I tried using the simpler "encode_video.c" example, which was able to encode a video and play it in Ubuntu’s default video player but VLC nor Windows Media Player could play it.

  We need to encode these using the ffmpeg API, not the command line tool, so I am wondering what the ffmpeg command line tool is doing that I am not, or any ideas on what the problem could be and how to get this working.

  Thanks.

• How to do FFMPEG video conversion with a bash Timeout wrapped in shell_exec() properly ?

  30 juin 2022, par Avatar

  I am converting videos server side (with Ubuntu and PHP) with :

  


  $result = shell_exec("ffmpeg -i ".$filetmp." -vcodec h264 -filter:v fps=30 -acodec aac ".$filetmp.".mp4");


  


  Some video conversions take several minutes and I need to stop them.

  


  I have tried to give the ffmpeg command a timeout by using Ubuntu's timeout (in the following 30 seconds) :

  


  $result = shell_exec("timeout 30 ffmpeg -i ".$filetmp." -vcodec h264 -filter:v fps=30 -acodec aac ".$filetmp.".mp4 2>&1");


  


  But the output contains all the logs from FFmpeg.

  


  Even though the docs say :

  


  


  If the command times out, and —preserve-status is not set, then exit with status 124.

  


  


  I tried adding -loglevel quiet to the FFmpeg command (in hope I only get the timeout output 124) but then I get no logs.

  


  On PHP side I try to catch the timeout with :

  


  if ((int)$result == 124) { }


  


  How to get only the code 124 from the timeout command - without the FFmpeg logs ?

  

  


  Besides, do I need --kill-after=DURATION for the timeout ?