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• FFMPEG video encoding time increases over time

  8 août 2018, par NStof

  I am creating a fairly basic DVR in C# using the FFMPEG wrapper in Accord.net. Essentially it works by getting the raw frames from the on-board frame grabber, displays the frame on screen and places it in a buffer. In a Separate thread in 20 second intervals, the frames are taken from the buffer and using Accord.Video.FFMPEG.VideoFileWriter.WriteVideoFrame(Bitmap bmp) the frame is encoded and saved to disk. Video is saved in two minute file chunks.
  This works happily for about 24-30 hours, however after that it looks like the average time it takes to encode/save each frame increases to the point where it gets new frames faster than they can be saved. This causes buffer to grow and ends in tears.

  What I would like to know is why does the time it takes to complete the WriteVideoFrame(Bitmap bmp) function increase over time.

  What I think I know so far :
  I do not know if this problem is caused by something in FFMPEG or in the Accord.net wrapper.
  I am reasonably sure it is not caused by hardware. Neither CPU usage nor HDD are working particularly hard. In fact, when I monitor the CPU usage, it does not work any harder or less hard when the encoding time increases.
  When I stop recording (close and dispose all Accord.net objects) and start again, it does not reset the encoding speed. Only when I close the software and start it again does it fix the problem.
  Any thoughts and help with this will be greatly appreciated. If more information is required, please let me know.

• FFMPEG DirectShow AJA Audio capture

  15 août 2018, par NiCO

  I have an AJA board with an SDI input cable connected to it.
  The input signal has video and audio embeded.

  The video is accesible through the "Vid" Pin and the audio is accesible through the "Aud 1-2" pin.

  Well running DirectShow filter graphs :

  

  

  "No Direct Show Audio Devices" :

  

  I cannot get FFMPEG to correctly map the audio part.

  This is what I tried without success to record the audio :

  ffmpeg -y -rtbufsize 2048M -f dshow -i audio="AJA S-Capture KonaLHi- 0"  -acodec pcm_s24le -ar 48000 output.wav
  
  
  
  ffmpeg -y -rtbufsize 2048M -f dshow -audio_pin_name "Aud 1-2" -i audio="AJA S-Capture KonaLHi- 0"  -acodec pcm_s24le -ar 48000 output.wav

  this is the return error I get
  return error :

  

  The filter is NOT being used by any other software.
  I have no problems recording the video.

• DirectShow AJA Audio capture with FFMPEG

  29 septembre 2021, par NiCO

  I have an AJA board with an SDI input cable connected to it.
The input signal has video and audio embeded.

  



  The video is accesible through the "Vid" Pin and the audio is accesible through the "Aud 1-2" pin.

  



  Well running DirectShow filter graphs :

  



  

  



  

  



  "No Direct Show Audio Devices" :

  



  

  



  I cannot get FFMPEG to correctly map the audio part.

  



  This is what I tried without success to record the audio :

  



  ffmpeg -y -rtbufsize 2048M -f dshow -i audio="AJA S-Capture KonaLHi- 0"  -acodec pcm_s24le -ar 48000 output.wav

ffmpeg -y -rtbufsize 2048M -f dshow -audio_pin_name "Aud 1-2" -i audio="AJA S-Capture KonaLHi- 0"  -acodec pcm_s24le -ar 48000 output.wav


  



  this is the return error I get
return error :

  



  

  



  The filter is NOT being used by any other software.
I have no problems recording the video.