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• Extracting audio from video command fails for some videos

  16 juin 2018, par Java Android

  I am using below FFmpeg command for extracting audio from video-

  String[] complexCommand = new String[]"-y","-ss", "" +
  startMs / 1000, "-t", "" + (endMs - startMs) / 1000, "-i",
  inputFileAbsolutePath, "-vn", "-ar", "44100", "-ac", "2", "-b:a",
  "256k", "-f", "mp3", outputFileAbsolutePath ;

  It works fine in my device but through analytics I came to know that its failing for many users or for many videos.I failed to understand whats wrong with the command and why its failing many times ?

• Converting mp4 to webm , ogg formats

  24 août 2016, par user2943893

  Currently i need to convert mp4 video to webm and ogg . To convert mp4 to webm i have used "ffmpeg.exe". I am running following code to convert video mp4 to webm.

  [DllImport("User32.dll")]
  
  public static extern bool SetForegroundWindow(IntPtr hWnd);
  
  public void mciConvertWavMP3(string fileName, bool waitFlag)
  
  {
  
  
  
      string savepath = Server.MapPath(fileName);
  
      string destpath = Server.MapPath(fileName);
  
      string pworkingDir = Server.MapPath("~/ffmpeg/");
  
  
  
   // string outfile = "-b:a 16 --resample 24 -m j " + savepath + " " + savepath.Replace(".wav", ".mp3") + ""; //--- lame code
  
    //  string outfile = "-b 192k -i " + savepath + " " + destpath.Replace(".mp4", ".webm");
  
     // string outfile = "ffmpeg -i " + savepath + " -acodec libvorbis -ac 2 -ab 96k -ar 44100 -b 345k -s 640x360 " + Server.MapPath("output-file.webm");
  
  
  
      string outfile = "ffmpeg -i \"test7.mp4\" -c:v libvpx -crf 10 -b:v 1M -c:a libvorbis \"" + Server.MapPath("output-file.webm") + "\"";
  
     // string outfile = "ffmpeg -i \""+fileName+"\" -codec:v libvpx -quality good -cpu-used 0 -b:v 600k -qmin 10 -qmax 42 -maxrate 500k -bufsize 1000k -threads 2 -vf scale=-1:480 -an -pass 1 -f webm /dev/null";
  
  
  
      System.Diagnostics.ProcessStartInfo psi = new System.Diagnostics.ProcessStartInfo();
  
      psi.FileName = pworkingDir+"ffmpeg.exe";
  
      psi.Arguments = outfile;
  
      psi.UseShellExecute = true;
  
      psi.CreateNoWindow = false;
  
      System.Diagnostics.Process p = System.Diagnostics.Process.Start(psi);
  
      Thread.Sleep(1000);// utput.webm
  
      if (waitFlag)
  
      {
  
          p.WaitForExit();
  
          // wait for exit of called application 
  
      }
  
  }

  I kept my project folder in D :/ drive

  When i am running from Command promt its working fine. But when i am running this code its not working fine.

  Formal errors which i am getting are :

  " unable to find a suitable output format for ’ffmpeg’ " kind of errors. SO please can any one help to solve this issue.

  Thank & Regards

• latency when streaming x264

  18 novembre 2013, par tobsen

  I would like to produce a zerolatency live video stream and play it in VLC player with as little latency as possible.

  This are the settings I currently use :

  x264_param_default_preset( &m_Params, "veryfast", "zerolatency" );
  
  
  
  m_Params.i_threads              =   2;
  
  m_Params.b_sliced_threads       =   true;
  
  m_Params.i_width                =   m_SourceWidth;
  
  m_Params.i_height               =   m_SourceHeight;
  
  
  
  m_Params.b_intra_refresh        =   1;
  
  
  
  m_Params.b_vfr_input            =   true;
  
  m_Params.i_timebase_num         =   1;
  
  m_Params.i_timebase_den         =   1000;
  
  
  
  m_Params.i_fps_num              =   1;
  
  m_Params.i_fps_den              =   60;
  
  
  
  m_Params.rc.i_vbv_max_bitrate   =   512;
  
  m_Params.rc.i_vbv_buffer_size   =   256;
  
  m_Params.rc.f_vbv_buffer_init   =   1.1f;
  
  
  
  m_Params.rc.i_rc_method         =   X264_RC_CRF;
  
  m_Params.rc.f_rf_constant       =   24;
  
  m_Params.rc.f_rf_constant_max   =   35;
  
  
  
  m_Params.b_annexb               =   0;
  
  m_Params.b_repeat_headers       =   0;
  
  m_Params.b_aud                  =   0;
  
  
  
  x264_param_apply_profile( &m_Params, "high" );

  Using those settings, I have the following issues :

  • VLC shows lots of missing frames (see screenshot, "verloren"). I am not sure if this is an issue.
  • If I set a value <200ms for the network stream delay in VLC, VLC renders a few frames and than stops to decode/render frames.
  • If I set a value >= 200ms for the network stream delay in VLC, everything looks good so far but the latency is, obviously, 200ms, which is too high.

  Question :
  Which settings (x264lib and VLC) should I use in order to encode and stream with as little latency as possible ?