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• C# Process in loop reading error output, causes "No async read operation is in progress on the stream" error

  29 mai 2023, par TSLee

  I am trying to read the format of multiple video files using ffmpeg in an asynchronous operation of Process and facing an error, "No async read operation is in progress on the stream". According to https://social.msdn.microsoft.com/Forums/vstudio/en-US/c961f461-7afb-4a92-b0ae-f78c2003b5de/help-an-asynchronous-read-operation-is-already-in-progress-on-the-standardoutput-stream?forum=csharpgeneral, I think I have to use CancelErrorRead(), as BeginErrorReadLine() can't be launched more than once. I also wonder if I use this function in the wrong place, because the read operation has ended in process1.exited() ? But the operation can't proceed to the second index with this error.

  


  How could I use CancelErrorRead()/CancelOutputRead() properly and where should I place them on the code ? I also did an experiment in that I commented these two CancelRead(), and a different error "async read operation has been started on the stream" will appear.

  


              Process process1 = new Process();
            process1.StartInfo.WindowStyle = ProcessWindowStyle.Hidden;
            process1.StartInfo.CreateNoWindow = true;
            process1.StartInfo.UseShellExecute = false;
            process1.StartInfo.FileName = ".\\ffmpeg.exe";
            process1.StartInfo.WorkingDirectory = ".\\";
            process1.EnableRaisingEvents = true;
            process1.StartInfo.RedirectStandardOutput = true; //if this is true, UseShellExecute must be false. true if output should be written to StandardOutput
            process1.StartInfo.RedirectStandardError = true;
            //indicates that the associated Process has written a line that's terminated with a newline
            process1.ErrorDataReceived += new DataReceivedEventHandler(inputHandler);
            process1.Exited += (ending, p) =>
            {
                flag = true;
                process1.CancelOutputRead();
                process1.CancelErrorRead();//
            };
            foreach (String file in inputList)
            {
                if (flag == true)
                {
                    flag = false;
                    process1.StartInfo.Arguments = "-i " + " \"" + file + "\"";
                    Console.WriteLine(process1.StartInfo.Arguments);
                    process1.Start();
                    process1.BeginOutputReadLine();//
                    process1.BeginErrorReadLine();
                    process1.WaitForExit(); //for asynchronous output
                }


            }
        }
        private void inputHandler(object sender, DataReceivedEventArgs l)
        {
             cba.Append(l.Data + "\n");
             videoInput = l.Data;
             //Console.WriteLine(cba);
             //Process p = sender as Process;
             Console.WriteLine(videoInput);

             this.BeginInvoke(new MethodInvoker(() =>
             {

              if (!String.IsNullOrEmpty(videoInput))
              {
                    if (videoInput.Contains("Stream #0:0"))
                    {
                        String subvideoInput1 = 
                        videoInput.Substring(videoInput.IndexOf("Stream #0:0"));
                        String video_inputType = subvideoInput1;
                        textBox1.Text += video_inputType + System.Environment.NewLine;
                        Console.WriteLine(video_inputType);
                     }
                     if (videoInput.Contains("Stream #0:1"))
                     {
                         String subvideoInput2 = 
                         videoInput.Substring(videoInput.IndexOf("Stream #0:1"));
                         Console.WriteLine(subvideoInput2.IndexOf("\n"));
                         Console.WriteLine(subvideoInput2);
                         String audio_inputType = subvideoInput2;
                         textBox1.AppendText(audio_inputType + System.Environment.NewLine);
                         Console.WriteLine(audio_inputType);
                     }
                     if (videoInput.Contains("Duration:"))
                     {
                         String videoinputDuration = 
                         videoInput.Substring(videoInput.IndexOf("Duration:"));
                         String subvideo_inputDuration = videoinputDuration.Substring(9);
                         String inputvideoDuration = 
                     subvideo_inputDuration.Remove(subvideo_inputDuration.IndexOf("."));
                         Console.WriteLine(inputvideoDuration);
                         double totalseconds = 
                         TimeSpan.Parse(inputvideoDuration).TotalSeconds;
                    
                    

                }
            }

        }));


    }


  


• FFMPEG Streaming Issue - "Connection Failed : I/O Error"

  25 avril 2023, par 1080Jake

  For a fun project I wanted to see if I could create an SRT stream from an active SDI input (1080i59.94) on a BMD Decklink Quad card. Whenever I try to execute my syntax, I get the following prompt "Connection to srt ://127.0.0.1:1234 failed : I/O error"
Is there anyway to use a debug mode and get more details about what is causing this ? I am very new to FFMPEG and obviously clueless. This is the syntax I am trying to execute -

  


  C:\Users\01>ffmpeg -f decklink -i "DeckLink Quad (8)" -c:v libx265 -preset ultrafast -b:v 5000k -f mpegts srt://127.0.0.1:1234


  


  Full printout here -

  


  C:\Users\01>ffmpeg -f decklink -i "DeckLink Quad (8)" -c:v libx265 -preset ultrafast -b:v 5000k -bufsize 3000k -f mpegts srt://127.0.0.1:1234
ffmpeg version n6.0-ffmpeg-windows-build-helpers Copyright (c) 2000-2023 the FFmpeg developers
  built with gcc 10.2.0 (GCC)
  configuration: --pkg-config=pkg-config --pkg-config-flags=--static --extra-version=ffmpeg-windows-build-helpers --enable-version3 --disable-debug --disable-w32threads --arch=x86_64 --target-os=mingw32 --cross-prefix=/home/runner/work/ffmpeg-stable-autobuild/ffmpeg-stable-autobuild/sandbox/cross_compilers/mingw-w64-x86_64/bin/x86_64-w64-mingw32- --enable-libcaca --enable-gray --enable-libtesseract --enable-fontconfig --enable-gmp --enable-libass --enable-libbluray --enable-libbs2b --enable-libflite --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libilbc --enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopus --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvo-amrwbenc --enable-libvorbis --enable-libwebp --enable-libzimg --enable-libzvbi --enable-libmysofa --enable-libopenjpeg --enable-libopenh264 --enable-libvmaf --enable-libsrt --enable-libxml2 --enable-opengl --enable-libdav1d --enable-cuda-llvm --enable-gnutls --enable-libsvtav1 --enable-libvpx --enable-libaom --enable-nvenc --enable-nvdec --extra-libs=-lharfbuzz --extra-libs=-lm --extra-libs=-lshlwapi --extra-libs=-lmpg123 --extra-libs=-lpthread --extra-cflags=-DLIBTWOLAME_STATIC --extra-cflags=-DMODPLUG_STATIC --extra-cflags=-DCACA_STATIC --enable-amf --enable-libmfx --enable-gpl --enable-frei0r --enable-librubberband --enable-libvidstab --enable-libx264 --enable-libx265 --enable-avisynth --enable-libaribb24 --enable-libxvid --enable-libdavs2 --enable-libxavs2 --enable-libxavs --extra-cflags='-mtune=generic' --extra-cflags=-O3 --enable-static --disable-shared --prefix=/home/runner/work/ffmpeg-stable-autobuild/ffmpeg-stable-autobuild/sandbox/cross_compilers/mingw-w64-x86_64/x86_64-w64-mingw32 --enable-nonfree --enable-libfdk-aac --enable-decklink
  libavutil      58.  2.100 / 58.  2.100
  libavcodec     60.  3.100 / 60.  3.100
  libavformat    60.  3.100 / 60.  3.100
  libavdevice    60.  1.100 / 60.  1.100
  libavfilter     9.  3.100 /  9.  3.100
  libswscale      7.  1.100 /  7.  1.100
  libswresample   4. 10.100 /  4. 10.100
  libpostproc    57.  1.100 / 57.  1.100
[decklink @ 000002ad2785a6c0] Autodetected the input mode
[decklink @ 000002ad2785a6c0] Found Decklink mode 1920 x 1080 with rate 29.97(i)
Guessed Channel Layout for Input Stream #0.0 : stereo
Input #0, decklink, from 'DeckLink Quad (8)':
  Duration: N/A, start: 0.000000, bitrate: 995869 kb/s
  Stream #0:0: Audio: pcm_s16le, 48000 Hz, 2 channels, s16, 1536 kb/s
  Stream #0:1: Video: rawvideo (UYVY / 0x59565955), uyvy422(top first), 1920x1080, 994333 kb/s, 29.97 tbr, 1000k tbn
[srt @ 000002ad2a870dc0] Connection to srt://127.0.0.1:1234 failed: I/O error
srt://127.0.0.1:1234: I/O error


  


  Instead of using an SDI input from my BMD card, I also tried to use a local mp4 file on my PC but I get the same prompt. Note - I am running FFMPEG on a Windows 10 PC.

  


• A ffplay Error :"Failed to set value 'yuv420p' for option 'pix_fmt' : Option not found"

  3 novembre 2023, par DavisTao

  I was trying to play a video by ffplay. Here’s my command :

  


  ffplay -f rawvideo -pix_fmt yuv420p -video_size 640x360 Resources/video.h264

  


  but I got this error :
Failed to set value 'yuv420p’ for option 'pix_fmt: Option not found

  


  So l used another command to make the video playing correctly, and this is the command :

  


  ffplay -f rawvideo -video_size 640x360 Resources/video.h264

  


  I wonder why the first command reported the error, because I used ffplav -pix_fmts and found that yuv420p is supported.

  


  By the way the pixel format of the video file is yuv420p exactly.