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• 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.
  
  
  
      }

• Force ffmpeg to generate WebVTT for each subtitle track

  14 juin 2018, par Rogue

  I use the following ffmpeg command to generate an HLS stream from a video :

  ffmpeg -i pipe:0 \
  
      -y -b:a 64k -acodec aac -vcodec copy \
  
      -hls_time 10 -hls_playlist_type vod -start_number 0 -hls_base_url http://127.0.0.1:5000/ -hls_list_size 0 \
  
      -f hls -crf 20 -hls_flags split_by_time -force_key_frames "expr:gte(t,n_forced*3)"\
  
      -threads 4 \
  
      target/stream.m3u8

  It works perfectly, and to my pleasure and surprise ffmpeg generates a second m3u8 file corresponding to the subtitles that are embeded in the video file, with the appropriate .vtt files.
  The problem is that when i input a video file with more than one subtitle tracks, i only get files for the first one.
  How can i force ffmpeg to output ALL tracks as m3u8 / .vtt files ?

  Thanks a lot