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• Why does ffmpeg could only record the first 100 frames of the animation ?

  9 février 2020, par jack fang

  I am using the following Python code to make an animation and want to save it as a video through FFmpeg (in PyCharm) :

  import numpy as np
  
  import matplotlib.pyplot as plt
  
  import matplotlib.animation as animation
  
  from matplotlib.animation import FFMpegWriter
  
  
  
  def func():
  
      for j in range(1, len(t)):
  
          time = j * 0.01
  
          print('time:{:2}'.format(time))
  
          yield time
  
  
  
  def animate(data):
  
      time = data
  
      ax2.plot(time, time, **{'marker':'o'})
  
      ax2.set_title('t = {:.2}'.format(time))
  
      return  ax2
  
  
  
  def init():
  
      ax2.plot(0, 0)
  
      return ax2
  
  
  
  dt = 0.01
  
  t = np.arange(0, 50, dt)
  
  
  
  fig2 = plt.figure()
  
  ax2 = fig2.add_subplot(111, autoscale_on=True)
  
  ax2.grid()
  
  
  
  ani = animation.FuncAnimation(fig2, animate, func, interval=dt*1000, blit=False, init_func=init, repeat=False)
  
  
  
  plt.rcParams['animation.ffmpeg_path'] = 'C:\Program Files\\ffmpeg\\bin\\ffmpeg.exe'
  
  writer = FFMpegWriter(fps=15, metadata=dict(artist='Me'), bitrate=1800)
  
  ani.save("movie.mp4", writer=writer)
  
  
  
  #plt.show()

  But when time reaches 1.0, the process stopped but it is supposed to stop when time reaches 50.0. The following picture shows when the process stopped. The PyCharm Run console
  I then check movie.mp4 and find that the video ends when time reaches 1.0.
  That is to say, only the first 100 frames of the animation were converted into the .mp4 file, so I was very confused where did the rest of the frames went ?

  I tried to run the code through windows cmd but got the same result.
  I then uncomment the line #plt.show() and found that the process stopped when time reaches 50.0 and the animation could be displayed properly but still only the first 100 frames was converted.

  I am now very confused about this problem and don’t know how to solve it. Appreciated for your help. :)

• FFMpeg kmsgrab record pixels wrong

  21 avril 2020, par Alex Joel

  ffmpeg -f kmsgrab -i - -framerate 60 -vf 'hwdownload,format=bgr0' -preset ultrafast out.mkv

  



  This is how a video frame should look like

This is how it is recorded by ffmpeg
https://drive.google.com/file/d/11jOUTk3ZxOfwnfd7zS4d4qBLApTS3Vmx/view?usp=sharing

  


• FFMPEG : Converting chapter points when converting PAL to NTSC

  26 février 2020, par koberulz

  I have a batch file converting my PAL TV series DVDs to the correct NTSC frame rates :

  for %%F in (*.mkv) do (
  
  echo A = LWLibAvVideoSource("%%F"^) > script.avs
  
  echo B = LWLibAvAudioSource("%%F"^) >> script.avs
  
  echo AudioDub(A,B^) >> script.avs
  
  echo AssumeFPS(24000,1001,sync_audio=true^) >> script.avs
  
  echo ResampleAudio(48000^) >> script.avs
  
  ffmpeg\ffmpeg.exe -i script.avs -aspect 16:9 -acodec ac3 -vcodec libx264 -preset slow -qp 16 "Output\%%F"
  
  del "%%F.lwi"
  
  del script.avs
  
  )
  
  
  
  pause

  But this removes the chapter points. I’m assuming map_chapters, if I figured out how to use it, would just shift in the chapters at the old PAL timestamps, so they wouldn’t match up to the correct times in the actual NTSC video ? Is there a way to get the chapters in the right spots other than manually opening each episode, finding the equivalent points, and manually creating each chapter ?