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• using ffmpeg for silence detect with input pipe

  24 août 2018, par Moharrer

  I am trying to detect silence from audio file with ffmpeg in c#.
  i want to pipe input from c# memory stream and get silence duration like following command

  ffmpeg -hide_banner -i pipe:0 -af silencedetect=noise=-50dB:d=0.5 -f null - 

  but there is a problem, when input stream pump in pipe, ffmpeg waiting in p.WaitForExit() line.
  when i change p.WaitForExit() to p.WaitForExit(1000) and set force timeout the following result is displayed.
  

  [mp3 @ 00000163818da580] invalid concatenated file detected - using bitrate for durationInput #0, mp3, from ’pipe:0’ :  
  Metadata :    encoder : Lavf57.71.100  Duration : N/A, start : 0.023021, bitrate : 86 kb/s    
  Stream #0:0 : Audio : mp3, 48000 Hz, mono, fltp, 86 kb/sStream mapping :  Stream #0:0 -> #0:0 (mp3 (mp3float) -> pcm_s16le (native))Output #0, null, to ’pipe :’ :  
  Metadata :    encoder : Lavf58.17.101    Stream #0:0 : Audio : pcm_s16le, 48000 Hz, mono, s16, 768 kb/s   
   Metadata :      encoder : Lavc58.21.105 pcm_s16le
  [silencedetect @ 0000023df1786840] silence_start : 50.1098
  
  [silencedetect @ 0000023df1786840] silence_end : 51.5957 | silence_duration : 1.48588
  
  [silencedetect @ 0000023df1786840] silence_start : 51.5959
  
  [silencedetect @ 0000023df1786840] silence_end : 52.127 | silence_duration : 0.531062
  
  [silencedetect @ 0000023df1786840] silence_start : 52.8622
  
  [silencedetect @ 0000023df1786840] silence_end : 54.0096 | silence_duration : 1.14733
  
  [silencedetect @ 0000023df1786840] silence_start : 54.6804
  

  as you can see in result silence detection done but with error at the first.
  this mean input file pumped correctly in ffmpg but waiting.
  how can i solve problem without set time out for p.WaitForExit()

  private void Execute(string exePath, string parameters, Stream inputStream)
          
              byte[] Data = new byte[5000] ;
              var p = new Process() ;
  
              var sti = p.StartInfo ;
  
              sti.CreateNoWindow = true ;
  
              sti.UseShellExecute = false ;
  
              sti.FileName = exePath ;
  
              sti.Arguments = arg ;
  
              sti.LoadUserProfile = false ;
  
              sti.RedirectStandardInput = true ;
  
              sti.RedirectStandardOutput = true ;
              sti.RedirectStandardError = true ;
              p.ErrorDataReceived += P_ErrorDataReceived ;
  
              p.OutputDataReceived += P_OutputDataReceived ;
              p.Start() ;
              p.BeginOutputReadLine() ;
  
              p.BeginErrorReadLine() ;
              var spInput = new StreamPump(inputStream, p.StandardInput.BaseStream, 4064) ;
  
              spInput.Pump((pump, result) =>
  
              
  
                  pump.Output.Flush() ;
  
                  inputStream.Dispose() ;
  
              ) ;
              //unlimited waiting
  
              //p.WaitForExit() ;
              p.WaitForExit(1000) ;
          
  

• Artifact while streaming multicast with ffmpeg

  17 août 2018, par Nicosmik

  Locally, from my windows machine with ffmpeg 3.3.2 from Zeranoe

  ffmpeg version 3.2.2 Copyright (c) 2003-2016 the FFmpeg developers
  built with gcc 5.4.0 (GCC)
  configuration : —enable-gpl
  —enable-version3 —enable-dxva2 —enable-libmfx —enable-nvenc —enable-avisynth —enable-bzlib —enable-fontconfig —enable-frei0r —enable-gnutls —enable-iconv —enable-libass —enable-libbluray —enable-libbs2b —enable-libcaca —enable-libfreetype —enable-libgme —enable-libgsm —enable-libilbc —enable-libmodplug —enable-libmp3lame —enable-libopencore-amrnb —enable-libopencore-amrwb —enable-libopenh264 —enable-libopenjpeg —enable-libopus —enable-librtmp —enable-libsnappy —enable-libsoxr —enable-libspeex —enable-libtheora —enable-libtwolame —enable-libvidstab —enable-libvo-amrwbenc —enable-libvorbis —enable-libvpx —enable-libwavpack —enable-libwebp —enable-libx264 —enable-libx265 —enable-libxavs —enable-libxvid —enable-libzimg —enable-lzma —enable-decklink —enable-zlib

  Server side

  Launch udp multicast streaming.

   ffmpeg -re -i video.ts -an -f mpegts -c copy udp://224.1.1.1:5000

  Client side

  Playing with ffplay is correct, no artifacts displayed

  ffplay udp://224.1.1.1:5000

  Playing after decoding cause artifacts

  ffmpeg -i udp://224.1.1.1:5000 -pix_fmt gray -f avi - | ffplay -

  or

  ffmpeg -f mpegts -i udp://224.1.1.1:5000 -pix_fmt gray -c:v rawvideo -f avi out.avi

  Does someone has an explanation ?

• How to get output from ffmpeg process in c#

  13 juillet 2018, par Anirudha Gupta

  In the code I written in WPF, I run some filter in FFmpeg, If I run the command in terminal (PowerShell or cmd prompt) It will give me information line by line what’s going on.

  I am calling the process from C# code and it’s work fine. The problem I have with my code is actually I am not able to get any output from the process I run.

  I have tried some answers from StackOverflow for FFmpeg process. I see 2 opportunities in my code. I can either fix it by Timer approach or secondly hook an event to OutputDataReceived.

  I tried OutputDataReceived event, My code never got it worked. I tried Timer Approach but still, it’s not hitting my code. Please check the code below

          _process = new Process
  
          {
  
              StartInfo = new ProcessStartInfo
  
              {
  
                  FileName = ffmpeg,
  
                  Arguments = arguments,
  
                  UseShellExecute = false,
  
                  RedirectStandardOutput = true,
  
                  RedirectStandardError = true,
  
                  CreateNoWindow = true,
  
              },
  
              EnableRaisingEvents = true
  
          };
  
  
  
          _process.OutputDataReceived += Proc_OutputDataReceived;
  
  
  
          _process.Exited += (a, b) =>
  
          {
  
              System.Threading.Tasks.Task.Run(() =>
  
              {
  
                  System.Threading.Tasks.Task.Delay(5000);
  
                  System.IO.File.Delete(newName);
  
              });
  
  
  
              //System.IO.File.Delete()
  
          };
  
  
  
          _process.Start();
  
          _timer = new Timer();
  
          _timer.Interval = 500;
  
          _timer.Start();
  
          _timer.Tick += Timer_Tick;
  
      }
  
  
  
  
  
      private void Timer_Tick(object sender, EventArgs e)
  
      {
  
          while (_process.StandardOutput.EndOfStream)
  
          {
  
             string line = _process.StandardOutput.ReadLine();
  
          }
  
          // Check the process.
  
  
  
      }