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• Error using pipe ffmpeg

  10 décembre 2016, par user3381786

  i am using ffmpeg to record video, but it doesn’t work..

      byte[] texBytes = tex.EncodeToPNG();//get byte[]
  
      proc = new System.Diagnostics.Process();
  
      proc.StartInfo.FileName = "ffmpeg.exe";
  
      proc.StartInfo.Arguments = " -y -r 30 -f rawvideo -codec rawvideo -s 512x512 -pixel_format rgba -i pipe:0 -vf \"transpose = 1\" -r 30 -threads 8 -c:v libx264 -preset slow -crf 18 -pix_fmt yuv420p test2.mp4";
  
      proc.StartInfo.CreateNoWindow = true;
  
      proc.StartInfo.UseShellExecute = false;
  
      proc.StartInfo.RedirectStandardError = true;
  
      proc.StartInfo.RedirectStandardInput = true;
  
      proc.Start();
  
  
  
      MemoryStream ms = new MemoryStream(texBytes);
  
      ms.WriteTo(proc.StandardInput.BaseStream);
  
      ms.Flush();
  
      ms.Close();

  the output file "test2.mp4" is only 1KB. Any problems in my codes ?
  thank you in advance.

• c# pipe using youtube-dl to ffmpeg

  1er janvier 2017, par lilscarecrow

  I am trying to pipe the audio stream from youtube-dl into ffmpeg for a program using discord.NET. I am not sure exactly how to achieve this in c#, though. Currently, I can play ffmpeg with a url or path from this code on the docs for discord.NET :

  var process = Process.Start(new ProcessStartInfo
  
          {                                                      
  
              FileName = "ffmpeg",
  
              Arguments = $"-i {outLine.Data}" +                                              
  
                          " -f s16le -ar 48000 -ac 2 pipe:1",                                         
  
              UseShellExecute = false,
  
              RedirectStandardOutput = true                                                                                   
  
          });
  
          Thread.Sleep(2000);                                                                                                                     
  
          int blockSize = 3840;                                                                                                         
  
          byte[] buffer = new byte[blockSize];
  
          int byteCount;
  
  
  
          while (!playing)                                                                                                  
  
          {
  
              byteCount = process.StandardOutput.BaseStream                                                  
  
                      .Read(buffer, 0, blockSize);                                                                          
  
  
  
              if (byteCount == 0)                                                                                                             
  
                  break;                                                                                                                          
  
  
  
              _vClient.Send(buffer, 0, byteCount);                                                                    
  
          }
  
          _vClient.Wait(); 

  So, I am trying to pipe the youtube-dl audio to this I assume. I just have no idea how to achieve piping in this format and for the file while it is downloading. Also, the program works on async if that helps.

• C++ Parse data from FFMPEG pipe output

  5 janvier 2017, par Simon

  I want to play around with data coming from an RTSP stream (e.g., do motion detection). Instead of using the cumbersome ffmpeg C API for decoding the stream, I decided to try something different. FFmpeg offers the possibility to pipe its output to stdout. Therefore, I wrote a C++ program which calls popen() to make an external call to ffmpeg and grabs the output. My aim is now to extract the YUV images from the resulting stream. As a first test, I decoded an h264 video file and wrote the stdout output coming from the ffmpeg call to a file.

  #include <iostream>
  
  #include <fstream>
  
  #include 
  
  
  
  using namespace std;
  
  
  
  int main()
  
  {
  
    FILE *in;
  
    char buff[512];
  
  
  
    if(!(in = popen("ffmpeg -i input.mp4 -c:v rawvideo -an -r 1 -f rawvideo pipe:1", "r")))
  
    {
  
      return 1;
  
    }
  
  
  
    ofstream outputFile("output.yuv");
  
    while(fgets(buff, sizeof(buff), in) != NULL)
  
    {
  
      outputFile &lt;&lt; buff;
  
    }
  
  
  
    outputFile.close();
  
    pclose(in);
  
    return 0;
  
  }
  
  </fstream></iostream>

  The resulting raw video can be played with vlc afterwards :

  vlc --rawvid-fps 1 --rawvid-width 1280 --rawvid-height 544 --rawvid-chroma I420 output.yuv

  Here, I chose the width and height from the video (a trailer of the Simpsons movie from http://www.dvdloc8.com/clip.php?movieid=12167&clipid=3). This first test worked very well. The resulting file is the same as when calling the ffmpeg binary directly with

  ffmpeg -i input.mp4 -c:v rawvideo -an -f output_ffmpeg.yuv

  Now I want to do some processing with the images coming from the ffmpeg output instead of dumping it to a file. My question is : Is there a clever way of parsing the stdout data from ffmpeg ? Ideally, I want to parse the stream into a sequence of instances of a YUVImage class (for example).