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• Graph-based video processing for .NET

  23 octobre 2016, par Borv

  Does anyone know a good object-oriented library (preferably high-level, like C# or Java) for working with video and audio streams ?

  I wrote an app which fiddles with video and audio streams, feeds and such. The original task was simple :

  • grab an RTSP feed
  • display original feed(s) on the display
  • convert it to a series of h264 ts files
  • extract audio into separate MP3 files
  • upload videos and audio to the web site (preferably in real time, few minute delay is acceptable)

  As you may have already guessed it is about recording events (e.g. lectures) and publishing them on the web.

  To pull this out I needed some graph-based non-linear editing for media. Two weeks in, I tried ffmpeg, vlc and WMF. The only library I got to work is ffmpeg, and that comes with lots of "however". WMF required a lot of coding (and I abandoned this path), vlc looked great on paper, but I stumbled across some bugs with input splitting I could not get around (e.g. transcode:es combination flat out refused to work).

  So, the question. What are good non-linear editing libraries besides ffmpeg, vlc and wmf/directshow that allow for building video processing graphs with sources, sinks and filters ? Or perhaps good bindings over ffmpeg and vlc allowing to build such graphs ?

• FFMPEG - C# - Audio and Video out of sync on certain videos after concatenation

  10 décembre 2016, par iamanoob

  Hey guys I’ve been trying to make this work for a while now and I can’t seem to find how to make the audio/video synced after the concatenation, I’ve searched and tested some solutions but couldn’t get it working.

  Here is what I do right now, Everything is working but I must be doing something wrong.

  So First, I split the videos into the video that I want

  System.Diagnostics.Process.Start(ffmpegPath, "-i " + 
  
  video.Path + " -ss " + StartTime + " -t " + Duration + " " + video.Output);

  After "cutting/splitting" the videos that I want like I want, I tried concatenating the videos together ( using -safe 0 to use the absolute path, else it wasn’t working ) :

  System.Diagnostics.Process.Start(ffmpegPath, 
  
  "-f concat -safe 0 -i " + txtFile + " C:\\Downloads\\Build\\" + rdn.Next(0,1000) + ".mp4");

  After that , I’ve noticed the audio/video was sometime out of sync so I searched and found this

  so I decided to Pad all the videos after splitting them :

  System.Diagnostics.Process.Start(ffmpegPath, 
  
  "-i " + video.Output + " -af apad -c:v libx264 -shortest -avoid_negative_ts make_zero -fflags +genpts -report " + padding);

  and then building it again, but it ended up having the same audio desync.

  It’s my first time working with mp4s and with FFMPEG and I’m sure I’m missing something.

• FFmpeg - feed raw frames via pipe - FFmpeg does not detect pipe closure

  8 septembre 2018, par Rumble

  Im trying to follow these examples from C++ in Windows. Phyton Example C# Example

  I have an application that produces raw frames that shall be encoded with FFmpeg.
  The raw frames are transfered via IPC pipe to FFmpegs STDIN. That is working as expected, FFmpeg even displays the number of frames currently available.

  The problem occours when we are done sending frames. When I close the write end of the pipe I would expect FFmpeg to detect that, finish up and output the video. But that does not happen. FFmpeg stays open and seems to wait for more data.

  I made a small test project in VisualStudio.

  #include "stdafx.h" 
  
  //// stdafx.h 
  
  //#include "targetver.h"
  
  //#include 
  
  //#include 
  
  //#include <iostream>
  
  
  
  #include "Windows.h"
  
  #include <cstdlib>
  
  
  
  using namespace std;
  
  
  
  bool WritePipe(void* WritePipe, const UINT8 *const Buffer, const UINT32 Length)
  
  {
  
      if (WritePipe == nullptr || Buffer == nullptr || Length == 0)
  
      {
  
          cout &lt;&lt; __FUNCTION__ &lt;&lt; ": Some input is useless";
  
          return false;
  
      }
  
  
  
      // Write to pipe
  
      UINT32 BytesWritten = 0;
  
      UINT8 newline = '\n';
  
      bool bIsWritten = WriteFile(WritePipe, Buffer, Length, (::DWORD*)&amp;BytesWritten, nullptr);
  
      cout &lt;&lt; __FUNCTION__ &lt;&lt; " Bytes written to pipe " &lt;&lt; BytesWritten &lt;&lt; endl;
  
      //bIsWritten = WriteFile(WritePipe, &amp;newline, 1, (::DWORD*)&amp;BytesWritten, nullptr); // Do we need this? Actually this should destroy the image.
  
  
  
      FlushFileBuffers(WritePipe); // Do we need this?
  
  
  
      return bIsWritten;
  
  }
  
  
  
  #define PIXEL 80 // must be multiple of 8. Otherwise we get warning: Bytes are not aligned
  
  
  
  int main()
  
  {
  
      HANDLE PipeWriteEnd = nullptr;
  
      HANDLE PipeReadEnd = nullptr;
  
      {
  
          // create us a pipe for inter process communication
  
          SECURITY_ATTRIBUTES Attr = { sizeof(SECURITY_ATTRIBUTES), NULL, true };
  
          if (!CreatePipe(&amp;PipeReadEnd, &amp;PipeWriteEnd, &amp;Attr, 0))
  
          {
  
              cout &lt;&lt; "Could not create pipes" &lt;&lt; ::GetLastError() &lt;&lt; endl;
  
              system("Pause");
  
              return 0;
  
          }
  
      }
  
  
  
      // Setup the variables needed for CreateProcess
  
      // initialize process attributes
  
      SECURITY_ATTRIBUTES Attr;
  
      Attr.nLength = sizeof(SECURITY_ATTRIBUTES);
  
      Attr.lpSecurityDescriptor = NULL;
  
      Attr.bInheritHandle = true;
  
  
  
      // initialize process creation flags
  
      UINT32 CreateFlags = NORMAL_PRIORITY_CLASS;
  
      CreateFlags |= CREATE_NEW_CONSOLE;
  
  
  
      // initialize window flags
  
      UINT32 dwFlags = 0;
  
      UINT16 ShowWindowFlags = SW_HIDE;
  
  
  
      if (PipeWriteEnd != nullptr || PipeReadEnd != nullptr)
  
      {
  
          dwFlags |= STARTF_USESTDHANDLES;
  
      }
  
  
  
      // initialize startup info
  
      STARTUPINFOA StartupInfo = {
  
          sizeof(STARTUPINFO),
  
          NULL, NULL, NULL,
  
          (::DWORD)CW_USEDEFAULT,
  
          (::DWORD)CW_USEDEFAULT,
  
          (::DWORD)CW_USEDEFAULT,
  
          (::DWORD)CW_USEDEFAULT,
  
          (::DWORD)0, (::DWORD)0, (::DWORD)0,
  
          (::DWORD)dwFlags,
  
          ShowWindowFlags,
  
          0, NULL,
  
          HANDLE(PipeReadEnd),
  
          HANDLE(nullptr),
  
          HANDLE(nullptr)
  
      };
  
  
  
      LPSTR ffmpegURL = "\"PATHTOFFMPEGEXE\" -y -loglevel verbose -f rawvideo -vcodec rawvideo -framerate 1 -video_size 80x80 -pixel_format rgb24 -i - -vcodec mjpeg -framerate 1/4 -an \"OUTPUTDIRECTORY\"";
  
  
  
      // Finally create the process
  
      PROCESS_INFORMATION ProcInfo;
  
      if (!CreateProcessA(NULL, ffmpegURL, &amp;Attr, &amp;Attr, true, (::DWORD)CreateFlags, NULL, NULL, &amp;StartupInfo, &amp;ProcInfo))
  
      {
  
          cout &lt;&lt; "CreateProcess failed " &lt;&lt; ::GetLastError() &lt;&lt; endl;
  
      }
  
      //CloseHandle(ProcInfo.hThread);
  
  
  
  
  
          // Create images and write to pipe
  
  #define MYARRAYSIZE (PIXEL*PIXEL*3) // each pixel has 3 bytes
  
  
  
      UINT8* Bitmap = new UINT8[MYARRAYSIZE];
  
  
  
      for (INT32 outerLoopIndex = 9; outerLoopIndex >= 0; --outerLoopIndex)   // frame loop
  
      {
  
          for (INT32 innerLoopIndex = MYARRAYSIZE - 1; innerLoopIndex >= 0; --innerLoopIndex) // create the pixels for each frame
  
          {
  
              Bitmap[innerLoopIndex] = (UINT8)(outerLoopIndex * 20); // some gray color
  
          }
  
          system("pause");
  
          if (!WritePipe(PipeWriteEnd, Bitmap, MYARRAYSIZE))
  
          {
  
              cout &lt;&lt; "Failed writing to pipe" &lt;&lt; endl;
  
          }
  
      }
  
  
  
      // Done sending images. Tell the other process. IS THIS NEEDED? HOW TO TELL FFmpeg WE ARE DONE?
  
      //UINT8 endOfFile = 0xFF; // EOF = -1 == 1111 1111 for uint8
  
      //if (!WritePipe(PipeWriteEnd, &amp;endOfFile, 1))
  
      //{
  
      //  cout &lt;&lt; "Failed writing to pipe" &lt;&lt; endl;
  
      //}
  
      //FlushFileBuffers(PipeReadEnd); // Do we need this?
  
  
  
      delete Bitmap;
  
  
  
  
  
      system("pause");
  
  
  
      // clean stuff up
  
      FlushFileBuffers(PipeWriteEnd); // Do we need this?
  
  
  
      if (PipeWriteEnd != NULL &amp;&amp; PipeWriteEnd != INVALID_HANDLE_VALUE)
  
      {
  
          CloseHandle(PipeWriteEnd);
  
      }
  
  
  
      // We do not want to destroy the read end of the pipe? Should not as that belongs to FFmpeg
  
      //if (PipeReadEnd != NULL &amp;&amp; PipeReadEnd != INVALID_HANDLE_VALUE)
  
      //{
  
      //  ::CloseHandle(PipeReadEnd);
  
      //}
  
  
  
  
  
      return 0;
  
  
  
  }
  
  </cstdlib></iostream>

  And here the output of FFmpeg

  ffmpeg version 3.4.1 Copyright (c) 2000-2017 the FFmpeg developers
  
    built with gcc 7.2.0 (GCC)
  
    configuration: --enable-gpl --enable-version3 --enable-sdl2 --enable-bzlib --enable-fontconfig --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libfreetype --enable-libmp3lame --enable-libopenjpeg --enable-libopus --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libtheora --enable-libtwolame --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libzimg --enable-lzma --enable-zlib --enable-gmp --enable-libvidstab --enable-libvorbis --enable-cuda --enable-cuvid --enable-d3d11va --enable-nvenc --enable-dxva2 --enable-avisynth --enable-libmfx
  
    libavutil      55. 78.100 / 55. 78.100
  
    libavcodec     57.107.100 / 57.107.100
  
    libavformat    57. 83.100 / 57. 83.100
  
    libavdevice    57. 10.100 / 57. 10.100
  
    libavfilter     6.107.100 /  6.107.100
  
    libswscale      4.  8.100 /  4.  8.100
  
    libswresample   2.  9.100 /  2.  9.100
  
    libpostproc    54.  7.100 / 54.  7.100
  
  [rawvideo @ 00000221ff992120] max_analyze_duration 5000000 reached at 5000000 microseconds st:0
  
  Input #0, rawvideo, from 'pipe:':
  
    Duration: N/A, start: 0.000000, bitrate: 153 kb/s
  
      Stream #0:0: Video: rawvideo, 1 reference frame (RGB[24] / 0x18424752), rgb24, 80x80, 153 kb/s, 1 fps, 1 tbr, 1 tbn, 1 tbc
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (rawvideo (native) -> mjpeg (native))
  
  [graph 0 input from stream 0:0 @ 00000221ff999c20] w:80 h:80 pixfmt:rgb24 tb:1/1 fr:1/1 sar:0/1 sws_param:flags=2
  
  [auto_scaler_0 @ 00000221ffa071a0] w:iw h:ih flags:'bicubic' interl:0
  
  [format @ 00000221ffa04e20] auto-inserting filter 'auto_scaler_0' between the filter 'Parsed_null_0' and the filter 'format'
  
  [swscaler @ 00000221ffa0a780] deprecated pixel format used, make sure you did set range correctly
  
  [auto_scaler_0 @ 00000221ffa071a0] w:80 h:80 fmt:rgb24 sar:0/1 -> w:80 h:80 fmt:yuvj444p sar:0/1 flags:0x4
  
  Output #0, mp4, to 'c:/users/vr3/Documents/Guenni/sometest.mp4':
  
    Metadata:
  
      encoder         : Lavf57.83.100
  
      Stream #0:0: Video: mjpeg, 1 reference frame (mp4v / 0x7634706D), yuvj444p(pc), 80x80, q=2-31, 200 kb/s, 1 fps, 16384 tbn, 1 tbc
  
      Metadata:
  
        encoder         : Lavc57.107.100 mjpeg
  
      Side data:
  
        cpb: bitrate max/min/avg: 0/0/200000 buffer size: 0 vbv_delay: -1
  
  frame=   10 fps=6.3 q=1.6 size=       0kB time=00:00:09.00 bitrate=   0.0kbits/s speed=5.63x

  As you can see in the last line of te FFmpeg output, the images got trough. 10 frames are available. But after closing the pipe, FFmpeg does not close, still expecting input.

  As the linked examples show, this should be a valid method.

  Trying for a week now...