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• Powershell script finishes after the first ffmpeg call

  25 mars 2014, par sk904861

  The following Powershell script only executes the first ffmpeg call, no matter which one is first. Both the ffmpeg and the powershell processes never finish. Stopping the server, however, leads to the processes finishing and suddenly the second picture also appears.

  Param($InputFile, $OutputFile, $Thumbnail, $Sprites)
  
  
  
  $ThumbnailWidth = 120
  
  $ThumbnailHeight = 120
  
  
  
  # Thumbnail
  
  ffmpeg -i $InputFile -f image2 -vframes 1 -filter:v "crop=min(iw\,ih):min(iw\,ih), scale=$($ThumbnailWidth):$($ThumbnailHeight)" -crf 18 "$($Thumbnail)\150x150.png"
  
  
  
  # Poster
  
  ffmpeg -i $InputFile -f image2 -vframes 1 -filter:v "crop=min(iw\,ih):min(iw\,ih), scale=$($PosterWidth):$($PosterHeight)" -crf 18 "$($Thumbnail)\1000x1000.png"

  The script gets called within an ASP.NET application as follows :

  ProcessStartInfo startInfo = new ProcessStartInfo();
  
  startInfo.FileName = "powershell.exe";
  
  startInfo.Arguments = String.Format("-executionpolicy RemoteSigned -file \"{0}\" \"{1}\" \"{2}\" \"{3}\" \"{4}\"", scriptPath, fullPath, videoPath, thumbnailPath, sprites);
  
  startInfo.RedirectStandardOutput = true;
  
  startInfo.RedirectStandardError = true;
  
  startInfo.UseShellExecute = false;
  
  startInfo.CreateNoWindow = true;
  
  Process process = new Process();
  
  process.StartInfo = startInfo;
  
  
  
  process.EnableRaisingEvents = true;
  
  process.Exited += delegate
  
  {
  
       // Do some cleaning up
  
  };
  
  
  
  process.Start();

  Does anyone have a clue, why only the first the two ffmpeg calls is working, while each call seems to be correct ?

  Adding process.StandardError.ReadToEnd(); makes the script finish as expected, but also makes it block, which is not acceptable.

• Enocding user uploaded video stream ?

  20 septembre 2014, par Nine

  Goal : I’m creating a video sharing website. I would like to encode a user uploaded video stream to mp4. (I’m assuming this in turn would also verify that the user uploaded a video file and not an exe.)

  Current Code :

      [HttpPost]
  
      public async Task<actionresult> Upload(HttpPostedFileBase video)
  
      {
  
          using (var ffmpeg = new Process())
  
          {
  
              ffmpeg.StartInfo.FileName = "ffmpeg.exe";
  
              ffmpeg.StartInfo.Arguments = "-i - {0} -f mp4 - ";
  
              ffmpeg.StartInfo.UseShellExecute = false;
  
              ffmpeg.StartInfo.RedirectStandardError = true;
  
              ffmpeg.StartInfo.RedirectStandardInput = true;
  
              ffmpeg.StartInfo.RedirectStandardOutput = true;
  
              ffmpeg.StartInfo.CreateNoWindow = true;
  
  
  
              ffmpeg.Start();
  
  
  
              video.InputStream.Position = 0;
  
  
  
              var buffer = new byte[video.InputStream.Length];
  
              await video.InputStream.ReadAsync(buffer, 0, buffer.Length);
  
  
  
              await ffmpeg.StandardInput.BaseStream.WriteAsync(buffer, 0, buffer.Length);
  
  
  
              var stdoutLength = Convert.ToInt32(ffmpeg.StandardOutput.BaseStream.Length);
  
              var encodedVideo = new byte[stdoutLength];
  
              await ffmpeg.StandardOutput.BaseStream.ReadAsync(encodedVideo, 0, stdoutLength);
  
          }
  
  
  
          // Upload encoded video to Azure block blob storage
  
  
  
          // Return
  
      }
  
  </actionresult>

  Error : Currently I’m getting "The pipe has been ended" when trying write to StandardInput. However I’m sure there is even more issues with this code.

  Thank you in advanced.

• Recording with python librtmp RTMP shrinks. Please help because i´m asking for solution for 2 months and i cant solve this

  21 décembre 2022, par Yojuan

  The code for capturing a video stream using python librtmp is this :

  


  import librtmp

conn = librtmp.RTMP('rtmp://some_program', live=True)
conn.connect()
stream = conn.create_stream(update_buffer=True)
        
f = open("my_program.flv", 'wb')
while True:
    try:
        data=stream.read(1024)
        if data:
            f.write(data)
            f.flush()
    except:
        print("Error during stream")


  


  The duration of the program is of 1 hour, but when i play the video, the duration becomes in 59 min and 52 secs or 59 min and 56 secs.... but in the most cases the duration is 1 hour exactly.

  


  I noticed that the first record always is perfect but in some cases the second shrinks. (when i use the function for second time or more)

  


  First i thought the problem was on ffmpeg because i use it to encode the video but it isnt because the video without encoding (the raw capture) shrinks anyway and i have other program that capture the same video with duration of 1 hour every time.

  


  I want to know if somebody knows what happends. I suppose that there is a buffer that is not being emptied correctly or something like that. Please help !