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• Batch file - Using pipe command after opening a cmd prompt

  20 janvier 2021, par Julien nist

  I am currently trying to create a batch file which will do the following :

  


  

  1. Open a cmd prompt

  


  2. Execute a ffmpeg | sox (audio shenanigans for my project)

  


  3. Open another cmd prompt

  


  4. Execute the same ffmpeg | sox with different parameters

  


  5. ...

  


  


  My current script is as follow :

  


  start /min cmd /k "ffmpeg -i http://localhost:8000/xxx -f flac - | sox - -t flac E:\Extracts\xxx.flac silence 1 0.50 0.1% 1 2.0 0.1% : newfile : restart"


  


  But when executing this, only the first ffmpeg part will be effectively executed in the new prompt. The command is working well if launched manually though.

  


  Any idea on why the redirection doesn't work ? I tried to split the cmd with variable names, and a couple workaround but no solution atm.

  


  Thanks a lot

  


  Julien

  


• avformat/img2dec : remove functions from image pipe which are unneeded for image pipes

  4 juillet 2014, par Michael Niedermayer

  avformat/img2dec : remove functions from image pipe which are unneeded for image pipes
  Signed-off-by : Michael Niedermayer <michaelni@gmx.at>
  

  • [DH] libavformat/img2dec.c

• FFmpeg with Pipe - how can I periodically grab real-time frames out of live streams in C# ?

  2 mars 2020, par BBy

  I am new to FFmpeg and C# and I want grab frames to do image processing with IP Camera.

  I have made the following C# class and I could get a single frame from IP Camera.

  class FFmpegHandler
  
      {
  
          public Process ffmpeg = new Process();
  
          public Image image;
  
  
  
          public Image init()
  
          {
  
              ffmpeg = new Process()
  
              {
  
                  StartInfo =
  
                  {
  
                      FileName = @"./ffmpeg/ffmpeg.exe",
  
                      //Arguments = "-i http://admin:@192.168.10.1/videostream.asf -an -f image2pipe -preset ultrafast -tune zerolatency -s 320x240 pipe:1", // Hangs
  
                      Arguments = "-i http://admin:@192.168.10.1/videostream.asf -vframes 1 -an -f image2pipe -preset ultrafast -tune zerolatency -s 320x240 pipe:1",
  
                      UseShellExecute = false,
  
                      RedirectStandardOutput = true,
  
                      RedirectStandardError = true,
  
                      CreateNoWindow = true,
  
                      WorkingDirectory = "./ffmpeg/"
  
                  }
  
              };
  
  
  
              ffmpeg.EnableRaisingEvents = true;
  
              ffmpeg.Start();
  
  
  
              var stream = ffmpeg.StandardOutput.BaseStream;
  
              var img = Image.FromStream(stream);
  
              //ffmpeg.WaitForExit();
  
  
  
              return img;
  
          }
  
      }   

  The problem is that I want to grab real-time (latest) images when I request.

  If I run FFmpegHandler.init(), it will take 2 seconds to give me delayed image output.

  I have tried removing argument -vframes 1, then it will hang after image = Image.FromStream(stream) ;.

  When I check the ffmpeg output directly, it looks like ffmpeg is keep building the stream

  frame=    6 fps=0.0 q=2.2 size=      25kB time=00:00:00.24 bitrate= 861.9kbits/s dup=4 drop=0 speed=0.435x    
  
  frame=   65 fps= 60 q=24.8 size=     140kB time=00:00:02.60 bitrate= 440.9kbits/s dup=4 drop=0 speed=2.41x    
  
  frame=   77 fps= 49 q=24.8 size=     161kB time=00:00:03.08 bitrate= 428.0kbits/s dup=4 drop=0 speed=1.95x    
  
  frame=   89 fps= 43 q=24.8 size=     182kB time=00:00:03.56 bitrate= 418.6kbits/s dup=4 drop=0 speed= 1.7x    
  
  frame=  102 fps= 39 q=24.8 size=     205kB time=00:00:04.08 bitrate= 410.7kbits/s dup=4 drop=0 speed=1.57x    
  
  frame=  116 fps= 37 q=24.8 size=     229kB time=00:00:04.64 bitrate= 404.2kbits/s dup=4 drop=0 speed=1.49x    
  
  frame=  128 fps= 35 q=24.8 size=     250kB time=00:00:05.12 bitrate= 399.8kbits/s dup=4 drop=0 speed=1.41x    
  
  frame=  142 fps= 34 q=24.8 size=     274kB time=00:00:05.68 bitrate= 395.7kbits/s dup=4 drop=0 speed=1.36x    
  
  frame=  156 fps= 33 q=24.8 size=     299kB time=00:00:06.24 bitrate= 392.3kbits/s dup=4 drop=0 speed=1.32x    
  
  frame=  169 fps= 32 q=24.8 size=     322kB time=00:00:06.76 bitrate= 389.7kbits/s dup=4 drop=0 speed=1.29x    
  
  frame=  182 fps= 32 q=24.8 size=     344kB time=00:00:07.28 bitrate= 387.4kbits/s dup=4 drop=0 speed=1.26x    
  
  frame=  195 fps= 31 q=24.8 size=     367kB time=00:00:07.80 bitrate= 385.5kbits/s dup=4 drop=0 speed=1.24x    
  
  frame=  208 fps= 31 q=24.8 size=     390kB time=00:00:08.32 bitrate= 383.8kbits/s dup=4 drop=0 speed=1.22x    
  
  frame=  221 fps= 30 q=24.8 size=     413kB time=00:00:08.84 bitrate= 382.3kbits/s dup=4 drop=0 speed=1.21x   

  How can I grab the latest frames out of this live-stream image ? (OR is there a thread-safe way to clean the stream and only get the latest frame when I request ?)