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• Extract individual frames from video and pipe them to StandardOutput in FFmpeg

  13 novembre 2019, par Nicke Manarin

  I’m trying to extract frames from a video using FFmpeg. But instead of letting FFmpeg write the files to disk, I’m trying to get the frames directly from StandardOutput.

  I’m not sure if it’s feasible. I’m expecting to get each frame individually as they get decoded by reading and waiting until all frames are extracted.

  With the current code, I think that I’m getting all frames at once.

  ---

  Command

  ffmpeg -i "C:\video.mp4" -r 30 -ss 00:00:10.000 -to 00:01:20.000 -hide_banner -c:v png -f image2pipe -

  Code

  var start = TimeSpan.FromMilliseconds(SelectionSlider.LowerValue);
  
  var end = TimeSpan.FromMilliseconds(SelectionSlider.UpperValue);
  
  
  
  var info = new ProcessStartInfo(UserSettings.All.FfmpegLocation)
  
  {
  
      Arguments = $" -i \"{VideoPath}\" -r {fps} -ss {start:hh\\:mm\\:ss\\.fff} " +
  
          "-to {end:hh\\:mm\\:ss\\.fff} -hide_banner -c:v png -f image2pipe -",
  
      CreateNoWindow = true,
  
      ErrorDialog = false,
  
      UseShellExecute = false,
  
      RedirectStandardError = true,
  
      RedirectStandardOutput = true
  
  };
  
  
  
  var process = new Process();
  
  process.StartInfo = info;
  
  process.Start();
  
  
  
  while (!process.StandardOutput.EndOfStream)
  
  {
  
      if (_cancelled)
  
      {
  
          process.Kill();
  
          return;
  
      }
  
  
  
      //This returns me the entire byte array, of all frames.
  
      var bytes = default(byte[]);
  
      using (var memstream = new MemoryStream())
  
      {
  
          process.StandardOutput.BaseStream.CopyTo(memstream);
  
          bytes = memstream.ToArray();
  
      }
  
  }

  ---

  I also tried to use process.BeginOutputReadLine() and wait for each frame in OutputDataReceived. But it returns parts of each frame, like the 10 first bytes, than other 50 bytes, it’s erratic.

  Is there any way to get the frames separately via the output stream ?

• How to run FFMPEG at my web host server

  26 avril 2013, par user1978421

  I want to perform some video process at my web host server. I don't think the web host server will allow me to execute an exe file for security reasons.

  Should I use SharpFFMpeg ?

  I have downloaded SharpFFMpeg. But it's lacking a proper documentation.

  Can someone give one example how to perform a conversion from one video format to another ?

  I have written my execution program, but the compiler says it cannot file the file specified. What's wrong with it ?

          string command = @"D:\Recorded TV\ffmpeg.exe -i ""Australia's Toughest Police_QUEST_2013_04_17_21_57_00.wtv"" -s 800x400 throughCS.mp4";
  
          try
  
          {
  
              ProcessStartInfo psi = new ProcessStartInfo("\"" + command + "\"");
  
              psi.RedirectStandardOutput = true;
  
              psi.UseShellExecute = false;
  
              psi.CreateNoWindow = true;
  
              Process proc = new Process();
  
              proc.StartInfo = psi;
  
              proc.Start();
  
              string result = proc.StandardOutput.ReadToEnd();
  
              tb1.Text = result;
  
              Debug.WriteLine(result);
  
          }

• FFMPEG - errors when combining videos

  1er décembre 2012, par ethrbunny

  I have two .OGG files of similar size, FPS and duration. My goal is to combine them into a side-by-side presentation using FFMPEG. To this end I've tried the following cmd :

  ffmpeg -i subject.ogg -vf "[in]pad=3*iw:3*ih[left] ;movie=clinician.ogg[right] ;[left] [right]overlay=100:0[out]" combined.ogg

  Suffice to say that the resultant video is non-playable. During the combination process FFMPEG prints lots of errors that read like :

  [Parsed_overlay_2 @ 0x1eb7d3e0] Buffer queue overflow, dropping

  What is this telling me ?

  Note :

  • both source files are playable
  • I padded the 'output' to be rather large in an attempt to understand the params
  • the placement of the 2nd video at 100:0 is arbitrary. Once I get the cmd working I'll move it to a better location in the output.
  • both videos began life as .FLV recorded from web cameras. I converted them to .ogg as FFMPEG didn't want to combine two .FLV files. If there is a better route to this, please let me know.

  So - what's wrong with my parameters and what am I doing to cause these FFMPEG errors ?

  EDIT :
  ffmpeg -i clinician.ogg

  Input #0, ogg, from 'clinician.ogg' :
  Duration : 00:05:20.98, start : 0.001000, bitrate : 2273 kb/s
  Stream #0:0 : Video : theora, yuv420p, 500x500 [SAR 1:1 DAR 1:1], 1k tbr, 1k tbn, 1k tbc
  Metadata :
  SERVER : Red5 Server 1.0.0 RC1 $Rev : 4193 $
  CANSEEKTOEND : true
  ENCODER : Lavf54.31.100
  Stream #0:1 : Audio : vorbis, 8000 Hz, stereo, s16
  Metadata :
  SERVER : Red5 Server 1.0.0 RC1 $Rev : 4193 $
  CANSEEKTOEND : true
  ENCODER : Lavf54.31.100

  ffmpeg -i subject.ogg

  Input #0, ogg, from 'subject.ogg' :
  Duration : 00:05:17.60, start : 0.001000, bitrate : 1341 kb/s
  Stream #0:0 : Video : theora, yuv420p, 300x300 [SAR 1:1 DAR 1:1], 83.33 tbr, 1k tbn, 1k tbc
  Metadata :
  SERVER : Red5 Server 1.0.0 RC1 $Rev : 4193 $
  CANSEEKTOEND : true
  ENCODER : Lavf54.31.100
  Stream #0:1 : Audio : vorbis, 8000 Hz, stereo, s16
  Metadata :
  SERVER : Red5 Server 1.0.0 RC1 $Rev : 4193 $
  CANSEEKTOEND : true
  ENCODER : Lavf54.31.100