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• AccessViolationException occurred in AForge.Video.FFMPEG.dll

  4 août 2018, par Prakash M

  I have a camera class, in this class I used a timer and in its tick event I am saving video using AForge.Net’s VideoFileWriter in C++/Cli (x86, .net framework : v4.6).
  This is not supposed to happen, as this is managed code. But even if I wrap in try catch block, program crashes because of AccessViolationException. I have verified that Image is not null. Something to do with VideoFileWriter. This happens anytime between app start to 30 minutes of running.

  An unhandled exception of type ’System.AccessViolationException’
  occurred in AForge.Video.FFMPEG.dll
  Additional information : Attempted to read or write protected memory.
  This is often an indication that other memory is corrupt.

  In Visual Studio’s output I see

  Exception thrown at 0x0C4D689F (swscale-2.dll) in test.exe : 0xC0000005 : Access violation writing location 0x09F83D80.
  Exception thrown : ’System.AccessViolationException’ in
  AForge.Video.FFMPEG.dll

  code :

   private: System::Void Video_Recorder_Tick(System::Object^  sender, System::Timers::ElapsedEventArgs^  e)
  
    {
  
        Bitmap^ save = ConvertMatToBitmap(image); //function to convert opencv's Mat to .net's Bitmap        
  
        if(writer!= nullptr)
  
         writer->WriteVideoFrame(save);
  
         delete save;
  
     }
  
  
  
    VideoFileWriter ^writer = gcnew VideoFileWriter();
  
  
  
    private: Void load_VideoWriter()
  
    {
  
      writer->Open("C:/video.avi", 640, 480, 10, VideoCodec::Default);        
  
    }

  Visual Studio showed few values for writer

  BitRate 400000
  Codec Default
  FrameRate 10
  Height 480
  IsOpen true
  Width 640
  

  Let me know if anybody needs more info.
  call stack didn’t help much

  

  To my surprise no one on internet is having this issue !
  Code seems straight forward, what could possibly be the issue ?

• Modify video frames but keep their timestamp in python skvideo ffmpeg

  3 août 2018, par bendaf

  I have .ts videos with variable frame rate and I would like to modify the frames of the videos and keep the timestamps belonging to the frames. I am using python and experiencing with ffmpeg, but I am open to any solution.

  The output of

  $ffmpeg -i myvideo.ts -hide_banner

  Input #0, mpegts, from 'myvideo.ts':
  
    Duration: 00:02:37.84, start: 1.400000, bitrate: 13799 kb/s
  
    Program 1 
  
      Metadata:
  
        service_name    : Service01
  
        service_provider: FFmpeg
  
      Stream #0:0[0x100]: Video: h264 (High) ([27][0][0][0] / 0x001B), yuv420p, 3840x1080, 25 fps, 25 tbr, 90k tbn, 50 tbc

  What I have tried so far is :

  import skvideo.io
  
  
  
  outpudict = {"-map": "0",
  
               "-vcodec": "libx264",
  
               "-pix_fmt": "yuv420p",
  
               "-f": "mpegts"
  
               }
  
  
  
  videogen = skvideo.io.vreader(args.input_video)
  
  writer = skvideo.io.FFmpegWriter(filename + file_extension, outputdict=outpudict)
  
  for i, frame in enumerate(videogen):
  
      # modify the frame
  
      writer.writeFrame(frame)
  
  
  
  writer.close()

  But so far I am not able to keep the pts and dts parameters of the frames only the format and encoding.

  Note : I have tried to use skvideo.io.FFmpegReader or pass the outputdict parameter also to vreader but the script crashed because of this bug.

  Note2 : I am checking the pts of the frames with

  $ffprobe -hide_banner -show_entries packet=pts,dts myvideo.ts

  Thank you for reading through my question, any idea would be appreciated !

• Modify video frames but keep their timestamp in python (maybe with ffmpeg ?)

  3 août 2018, par bendaf

  I have .ts videos with variable frame rate and I would like to modify the frames of the videos and keep the timestamps belonging to the frames. I am using python and experiencing with ffmpeg, but I am open to any solution.

  The output of

  $ffmpeg -i myvideo.ts -hide_banner

  Input #0, mpegts, from 'myvideo.ts':
  
    Duration: 00:02:37.84, start: 1.400000, bitrate: 13799 kb/s
  
    Program 1 
  
      Metadata:
  
        service_name    : Service01
  
        service_provider: FFmpeg
  
      Stream #0:0[0x100]: Video: h264 (High) ([27][0][0][0] / 0x001B), yuv420p, 3840x1080, 25 fps, 25 tbr, 90k tbn, 50 tbc

  What I have tried so far is :

  import skvideo.io
  
  
  
  outpudict = {"-map": "0",
  
               "-vcodec": "libx264",
  
               "-pix_fmt": "yuv420p",
  
               "-f": "mpegts"
  
               }
  
  
  
  videogen = skvideo.io.vreader(args.input_video)
  
  writer = skvideo.io.FFmpegWriter(filename + file_extension, outputdict=outpudict)
  
  for i, frame in enumerate(videogen):
  
      # modify the frame
  
      writer.writeFrame(frame)
  
  
  
  writer.close()

  But so far I am not able to keep the pts and dts parameters of the frames only the format and encoding.

  Note : I have tried to use skvideo.io.FFmpegReader or pass the outputdict parameter also to vreader but the script crashed because of this bug.

  Note2 : I am checking the pts of the frames with

  $ffprobe -hide_banner -show_entries packet=pts,dts myvideo.ts

  Thank you for reading through my question, any idea would be appreciated !