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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) ;
          
  

• How do I set ffmpeg pipe output ?

  5 décembre 2019, par mr_blond

  I need to read ffmpeg output as pipe.
  There is a code example :

      public static void PipeTest()
  
      {
  
          Process proc = new Process();
  
          proc.StartInfo.FileName = Path.Combine(WorkingFolder, "ffmpeg");
  
          proc.StartInfo.Arguments = String.Format("$ ffmpeg -i input.mp3 pipe:1");
  
          proc.StartInfo.UseShellExecute = false;
  
          proc.StartInfo.RedirectStandardInput = true;
  
          proc.StartInfo.RedirectStandardOutput = true;
  
          proc.Start();
  
  
  
          FileStream baseStream = proc.StandardOutput.BaseStream as FileStream;
  
          byte[] audioData;
  
          int lastRead = 0;
  
  
  
          using (MemoryStream ms = new MemoryStream())
  
          {
  
              byte[] buffer = new byte[5000];
  
              do
  
              {
  
                  lastRead = baseStream.Read(buffer, 0, buffer.Length);
  
                  ms.Write(buffer, 0, lastRead);
  
              } while (lastRead > 0);
  
  
  
              audioData = ms.ToArray();
  
          }
  
  
  
          using(FileStream s = new FileStream(Path.Combine(WorkingFolder, "pipe_output_01.mp3"), FileMode.Create))
  
          {
  
              s.Write(audioData, 0, audioData.Length);
  
          }
  
      }

  It’s log from ffmpeg, the first file is readed :

  Input #0, mp3, from ’norm.mp3’ :
  Metadata :
  encoder : Lavf58.17.103
  Duration : 00:01:36.22, start : 0.023021, bitrate : 128 kb/s
  Stream #0:0 : Audio : mp3, 48000 Hz, stereo, fltp, 128 kb/s
  Metadata :
  encoder : Lavc58.27

  Then pipe :

  [NULL @ 0x7fd58a001e00] Unable to find a suitable output format for ’$’
  $ : Invalid argument

  If I run "-i input.mp3 pipe:1", the log is :

  Unable to find a suitable output format for ’pipe:1’ pipe:1 : Invalid
  argument

  How do I set correct output ? And how should ffmpeg know what the output format is at all ?

• FFMPEG stream .mpg to windows pipe and display video in C#

  25 septembre 2018, par Przemysław

  i’ve got problem with streaming mpg video to windows pipe. I wang decode video with command ffmpeg.exe to windows pipe and connect to that pipe with c# and display video on winform. I’ve tried many commands but none of them worked.

  FFmpeg command :

  ffmpeg -i Day Flight.mpg -f image2pipe pipe:1 > //./pipe/ffpipe

  C# code :

  using System;
  
  using System.Drawing;
  
  using System.Windows.Forms;
  
  using System.IO;
  
  using System.IO.Pipes;
  
  using System.Threading;
  
  using System.Runtime.InteropServices;
  
  using System.Text;
  
  
  
  namespace WindowsFormsApplication1
  
  {
  
  
  
  public partial class Form1 : Form
  
  {
  
  
  
      String readLine_;
  
      private void readThread()
  
      {
  
  
  
          while (true)
  
          {
  
              readLine_ = reader_.ReadLine();
  
              if (readLine_ != null)
  
              {
  
  
  
                  byte[] bytes = Encoding.Unicode.GetBytes(readLine_);
  
                  //Console.WriteLine(readLine_);
  
                  //Console.ReadLine();
  
                  var ms = new MemoryStream(bytes);
  
                  // Bitmap bm = new Bitmap(ms);
  
                  Image im = (Bitmap)((new ImageConverter()).ConvertFrom(bytes));
  
              }
  
              else
  
                  Console.WriteLine("empty string");
  
  
  
              //
  
  
  
  
  
  
  
          }
  
      }
  
      private NamedPipeServerStream server_;
  
      StreamReader reader_;
  
  
  
  
  
      public Form1()
  
      {
  
          InitializeComponent();
  
      }
  
  
  
      private void Form1_Load(object sender, EventArgs e)
  
      {
  
          AllocConsole();
  
          server_ = new NamedPipeServerStream("ffpipe", PipeDirection.In, 1, PipeTransmissionMode.Byte);
  
          server_.WaitForConnection();
  
          reader_ = new StreamReader(server_);
  
          Thread t = new Thread(readThread);
  
          t.Start();
  
  
  
  
  
      }
  
  
  
  
  
      [DllImport("kernel32.dll", SetLastError = true)]
  
      [return: MarshalAs(UnmanagedType.Bool)]
  
      static extern bool AllocConsole();
  
  }

  }

  I can’t get image in C#, my program crashes in line
  Image im = (Bitmap)((new ImageConverter()).ConvertFrom(bytes)) ;

  And I don’t know where I make a mistake - in ffmpeg piping or in C# program
  https://image.ibb.co/eGDymp/Przechwytywanie.png
  https://image.ibb.co/hWpM6p/Przechwytywanie.png

  Example video :
  http://samples.ffmpeg.org/MPEG2/mpegts-klv/Day%20Flight.mpg