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• Running "FFMPEG" for several times in winfoms

  13 novembre 2015, par Ahmad

  In a C# Windows application, I try to call "ffmpeg" to multiplex video and audio. It may be called several times. In the first call, everything is fine, but in the next call I have some problems. One problem is that the earlier "ffmpeg" process isn’t closed. So, I tried to kill it if it exists. but now I got an error for a disposed object in the following code :

     public static void FFMPEG3(string exe_path, string avi_path, string mp3_path, string output_file)
  
      {
  
          const int timeout = 2000;
  
          Kill(exe_path);
  
          using (Process process = new Process())
  
          {
  
              process.StartInfo.FileName = exe_path;
  
              process.StartInfo.Arguments = string.Format(@"-i ""{0}"" -i ""{1}"" -acodec copy -vcodec copy ""{2}""",
  
                                             avi_path, mp3_path, output_file);
  
              process.StartInfo.UseShellExecute = false;
  
              process.StartInfo.CreateNoWindow = true;
  
              process.StartInfo.RedirectStandardOutput = true;
  
              process.StartInfo.RedirectStandardError = true;
  
  
  
              StringBuilder output = new StringBuilder();
  
              StringBuilder error = new StringBuilder();
  
  
  
              using (AutoResetEvent outputWaitHandle = new AutoResetEvent(false))
  
              using (AutoResetEvent errorWaitHandle = new AutoResetEvent(false))
  
              {
  
                  process.OutputDataReceived += (sender, e) =>
  
                  {
  
                      if (e.Data == null)
  
                      {
  
                          outputWaitHandle.Set();
  
                      }
  
                      else
  
                      {
  
                          output.AppendLine(e.Data);
  
                      }
  
                  };
  
                  process.ErrorDataReceived += (sender, e) =>
  
                  {
  
                      if (e.Data == null)
  
                      {
  
                          errorWaitHandle.Set();
  
                      }
  
                      else
  
                      {
  
                          error.AppendLine(e.Data);
  
                      }
  
                  };
  
  
  
                  process.Start();
  
  
  
                  process.BeginOutputReadLine();
  
                  process.BeginErrorReadLine();
  
  
  
                  if (process.WaitForExit(timeout) &&
  
                      outputWaitHandle.WaitOne(timeout) &&
  
                      errorWaitHandle.WaitOne(timeout))
  
                  {
  
                      // Process completed. Check process.ExitCode here.
  
                      process.Close();
  
                  }
  
                  else
  
                  {
  
                      // Timed out.
  
                      process.Close();
  
                  }
  
              }
  
          }
  
      }

  I get ObjectDisposedException for ErrorDataRecieved event on errorWaitHandle.Set();

  First, I want to resolve this error, but if you know any better solution to run the "ffmpeg" for several times please suggest me.

• FFmpeg - Multiple videos with 4 areas and different play times

  25 mai 2018, par Robert Smith

  I have videos as follows

  video   time
  
  ======= =========
  
  Area 1:
  
  video1a    0-2000
  
  video1b 2500-3000
  
  video1c 3000-4000
  
  
  
  Area 2:
  
  video2a  300- 400
  
  video2b  800- 900
  
  
  
  Area 3:
  
  video3a  400- 500
  
  video3b  700- 855
  
  
  
  Area 4:
  
  video4a  400- 500
  
  video4b  800- 900

  Basically these are security camera outputs and should display in 4 areas :

  So far I have the following :

  ffmpeg
  
      -i 1.avi -i 2.avi -i 3.avi -i 4.avi
  
      -filter_complex "
  
          nullsrc=size=640x480 [base];
  
          [0:v] setpts=PTS-STARTPTS, scale=320x240 [upperleft];
  
          [1:v] setpts=PTS-STARTPTS, scale=320x240 [upperright];
  
          [2:v] setpts=PTS-STARTPTS, scale=320x240 [lowerleft];
  
          [3:v] setpts=PTS-STARTPTS, scale=320x240 [lowerright];
  
          [base][upperleft] overlay=shortest=1 [tmp1];
  
          [tmp1][upperright] overlay=shortest=1:x=320 [tmp2];
  
          [tmp2][lowerleft] overlay=shortest=1:y=240 [tmp3];
  
          [tmp3][lowerright] overlay=shortest=1:x=320:y=240
  
      "
  
      -c:v libx264 output.mp4

  But there are two things I am missing :

  • The above is only for 4 video files, I need a way to add additional files to each area (for example video1b should play at its corresponding time after video1a in the same area)
  • How do I specify the beginning/ending time as shown above for each file ?

• Insert Random silence multiple times between Audios in ffmpeg

  23 septembre 2021, par Gracie williams

  suppose I have MP3 of around 1 minute duration and increase its duration longer.Duration can be any.

  


  I want to randomly add N seconds of silence to that audio.

  


  I can generate the silence like below

  


  ffmpeg -f lavfi -i anullsrc=r=44100:cl=mono -t <seconds> -q:a 9 -acodec libmp3lame out.mp3&#xA;</seconds>

  


  And I can insert silence to audio like below

  


  ffmpeg -i in.wav -filter_complex "anullsrc,atrim=0:4[s];[0]atrim=0:14[a];[0]atrim=14,asetpts=N/SR/TB[b];[a][s][b]concat=3:v=0:a=1" out.wav


  


  Is there anyway to insert silence at multiple areas.With php I can generate random time to insert based on 60 seconds audio like below.

  


  $arr = [];
$arr[3] = 2; //here 3 is original audio insert time and 2 is the duration of silence
$arr[6] = 3;  //here 6 is original audio insert time and 3 is the duration of silence
$arr[10] = 1;
$arr[12] = 3;


  


  Now I want to insert silence between seconds based on above array like

  


  2 seconds silence at 3rd second
3 seconds silence at 6th second
1 second silence at 10th second


  


  and son on..