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• Anomalie #4513 (Fermé) : Undefined au post d’un message de forum public

  6 juillet 2021, par cedric -

  Corrigé par https://git.spip.net/spip/forum/commit/e9a254c4638853e0cde99391adfdebec94c20017 donc

• using ffmpeg to convert a mkv or mp4 suitable for a DVD player that supports MPEG-4 / DivX [closed]

  17 juillet 2022, par Neil Telford

  I got a DVD Player with USB support. It is a recent player (DVD-225), but the documentation is sparse, but it does claim MPEG-4 and DivX support.

  


  Now, I have got certain AVI files to play via USB, but everything else fails. I looked at the metadata of an AVI file that worked via ffprobe, and got the following :

  


  Metadata:
    encoder         : Lavf58.17.101   Duration: 00:58:30.94, start: 0.000000, bitrate: 1336 kb/s
    Stream #0:0: Video: mpeg4 (Simple Profile) (xvid / 0x64697678), yuv420p, 640x290 [SAR 1:1 DAR 64:29], 1196 kb/s, 23.98 fps, 23.98 tbr,
23.98 tbn, 23.98 tbc
    Stream #0:1: Audio: mp3 (U[0][0][0] / 0x0055), 48000 Hz, stereo, fltp, 128 kb/s


  


  Now, I figured that if I can replicate the above, I can convert most things to play via USB, even if it isn't the most up to date codecs.

  


  I've tried various combinations, but they all fail. The closest I got was by using the following shell script :

  


  for i in *.avi; do ffmpeg -i "$i" -c:v mpeg4 -vtag divx -qscale:v 3 -c:a libmp3lame -qscale:a 4 "_${i%.*}.avi"; done


  


  This has a strange result that it will play the audio track, but not the video track. The metadata I got from this was :

  


  Metadata:
    encoder         : Lavf58.45.100
  Duration: 00:58:07.99, start: 0.000000, bitrate: 3026 kb/s
    Stream #0:0: Video: mpeg4 (Simple Profile) (divx / 0x78766964), yuv420p, 1280x720 [SAR 3:4 DAR 4:3], 2901 kb/s, 23.98 fps, 23.98 tbr, 23.98 tbn, 24k tbc
    Metadata:
      title           : ******************
    Stream #0:1: Audio: mp3 (U[0][0][0] / 0x0055), 48000 Hz, stereo, fltp, 109 kb/s
    Metadata:
      title           : ******************


  


  Does anyone know where I am going wrong with this ? I've converted AVI, MKV and MP4 files, and while they work on my computer, the DVD player seems to be very picky.

  


  Any suggestions ?

  


  Thanks
Neil

  


• matplotlib.animate saves only one still frame

  22 août 2015, par dim_voly

  EDIT

  Changed the presented code so that another person can take it away and reproduce the error. The data for the below code can be found here, including the code and the animation produced.

  import os
  
  import numpy as np
  
  import matplotlib as mpl
  
  mpl.use("Agg")
  
  import matplotlib.pyplot as plt
  
  import matplotlib.animation as animation
  
  
  
  
  
  if __name__ == '__main__':
  
      print "Plotting Clevis LVDT Displacements"
  
      os.chdir(r"F:\BrokenAnimation")
  
      animation_data = np.loadtxt("animation_data.csv", delimiter=",")
  
      time = animation_data[:,0] 
  
      L10 = animation_data[:,1]
  
      L11 = animation_data[:,2]
  
      L12 = animation_data[:,3]
  
  
  
      def data_gen():
  
          t = data_gen.t
  
          cnt = 0
  
          L10_iter = data_gen.L10_iter
  
          L11_iter = data_gen.L11_iter
  
          L12_iter = data_gen.L12_iter
  
          while cnt < 35000:
  
              cnt+=1
  
              t += 10.0
  
              yield [-10.25, L10_iter.next()], [10.1875, L11_iter.next()],
  
                    [L12_iter.next(), -9.0] 
  
      data_gen.t = 0
  
      data_gen.L10_iter = iter(np.array(L10))
  
      data_gen.L11_iter = iter(np.array(L11))
  
      data_gen.L12_iter = iter(np.array(L12))
  
  
  
      fig, ax = plt.subplots()
  
      scat = ax.scatter([0.0, 0.0, 0.0], [0.0, 0.0, 0.0])
  
  
  
      ax.set_xlim(-15, 15)
  
      ax.set_ylim(-10.0, 0.5)
  
      ax.set_ylim(-0.5, 0.5)
  
      ax.grid()
  
  
  
  
  
      def run(data):
  
          # update the data
  
          x, y, z = data
  
          scat.set_offsets([x, y, z])
  
          return scat,
  
  
  
      ani = animation.FuncAnimation(fig, run, data_gen,
  
                                    blit=True, interval=40, # 40msec? implying 25fps?
  
                                    )
  
  
  
      # This works
  
      plt.show()
  
  
  
      # Doesn't really save what I see in plt.show()
  
      ani.save('South_Clevis.mp4') # 435kb file 4 sec long, 25 fps 800x600 887Kbps

  I’m trying to plot a time history of the displacements of the dots below :

  

  The dots at y = 0.0 are the original positions and the animation moves the dots up and down. For context, the dots represent LVDT displacements over a time history of 35,000 sec with a sample rate of 1 per second. So each "second" the plot should be updated.

  Bitrate does not appear to be a keyword that actually does anything. I have ffmpeg installed and it is on the Windows path. Using the basic writer example (but without the line matplotlib.use("Agg"), because python complained) works fine and produces an animation that can be played back.