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• Use animation.save with ffmpeg writer within a Python package

  16 janvier 2021, par Logan Yang

  I'm writing a Python package that produces some animated plots. I can successfully use matplotlib.animation.save to save gifs as such :

  


  anim.save(f"./{file}", writer="imagemagick", fps=15)


  


  But if I try to save it to mp4 like this, it doesn't work because I guess it can't find ffmpeg on my system (MacOS)

  


  anim.save(f"./{file}",writer=FFMpegWriter(fps=15))


  


  Error :

  


  MovieWriter stderr:
dyld: Library not loaded: /usr/local/opt/x265/lib/libx265.165.dylib
  Referenced from: /usr/local/bin/ffmpeg
  Reason: image not found
...


  


  My intention is to make it platform agnostic, since it's a Python package I'm writing, I would like it to be portable so that the user can use it out-of-the-box with pip install . Since gif is already working with imagemagick, I'm not sure how to make it work for ffmpeg writer.

  


  I tried pip install ffmpeg in my project but that didn't work. Any suggestion is appreciated !

  


• save matplotlib animation error

  27 juillet 2017, par Matt

  I created a program (see below) that takes position, force, and time from a pandas dataframe. The goal is to plot position vs force and animate it based on the time data associated with it.

  The animation is working well so far but I cannot save the animation, either as a gif or mp4. I have read countless solutions online for this sort of problem but none seem to work.

  I am using OS X El Capitan version 10.11.6 and python3.6. I used brew install ffmpeg and brew install mencoder. For both I get the error

   File "animation.py", line 73, in <module>
  
      ani.save('test.mp4', writer=writer)
  
    File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/matplotlib/animation.py", line 1009, in save
  
      for a in all_anim]):
  
    File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/matplotlib/animation.py", line 1009, in <listcomp>
  
      for a in all_anim]):
  
    File "/Library/Frameworks/Python.framework/Versions/3.6/lib/python3.6/site-packages/matplotlib/animation.py", line 1482, in new_saved_frame_seq
  
      return itertools.islice(self.new_frame_seq(), self.save_count)
  
  ValueError: Stop argument for islice() must be None or an integer: 0 &lt;= x &lt;= sys.maxsize.
  
  </listcomp></module>

  I used pip to install the rest of my packages so maybe that is the root of the problem ?

  import matplotlib.pyplot as plt
  
  import matplotlib.animation as animation
  
  import pandas
  
  import sys
  
  
  
  TABLE = pandas.read_csv("Data.csv")
  
  
  
  
  
  fig = plt.figure()
  
  ax1 = fig.add_subplot(1,1,1)
  
  
  
  xs=[]
  
  ys=[]
  
  
  
  def animate(interval):
  
  
  
      time = interval
  
  
  
      #convert to TIME series to int for handling purposes
  
      TABLE.TIME = TABLE.TIME.astype(int)
  
  
  
      if time in TABLE.TIME.unique(): 
  
  
  
          POSIT_series = TABLE[TABLE.TIME == time].POSIT
  
          POSIT_list = POSIT_series.tolist()
  
          x = POSIT_list[0]
  
  
  
          FORCE_series = TABLE[TABLE.TIME == time].FORCE
  
          FORCE_list = FORCE_series.tolist()
  
          y = FORCE_list[0]
  
  
  
          xs.append(x)
  
          ys.append(y)
  
  
  
          ax1.clear()
  
          ax1.plot(xs,ys)
  
      elif time > TABLE.TIME.max():
  
          sys.exit("Animation Done")
  
      return
  
  
  
  FRAMES= TABLE.TIME.astype(int).max()    
  
  plt.rcParams['animation.ffmpeg_path']='/usr/local/bin/ffmpeg'
  
  writer = animation.FFMpegWriter()
  
  ani = animation.FuncAnimation(fig, animate, interval=1, frames=FRAMES, repeat=False)
  
  plt.show()
  
  
  
  #same error for writer = 'mencoder' and writer ='ffpmeg
  
  ani.save('test.mp4', writer=writer)

• Is it possible to save an audio stream with pure JavaScript in the browser ?

  8 juin 2016, par Konstantin

  I would like to make a webpage where visitors can save audio streams by clicking on links (not live streams, but links from a radio archive which uses streams), I want to do this without a server backend with pure JavaScript in the browser.
  I read somewhere about the JavaScript port of FFMpeg, which can encode and save video / audio in the browser utilizing so called blobs. However download library is huge, as far as I remember 17 MB. In fact I would need only stream copying the audio streams, not a real encoding process.
  I usually use similar commands to save a programme :

  ffmpeg -i http://stream.example.com/stream_20160518_0630.mp3 -c copy -t 3600 programme.mp3

  I wonder, is it possible to compile a subset of FFMpeg into JavaScript which provides only the really needed stream copying ?