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• Running matplotlib animation on Mac using Spyder : says to install ffmpeg

  28 avril 2017, par Addem

  I installed Anaconda on a new Mac, made a simple animation with matplotlib like

  import numpy as np
  
  from matplotlib import pyplot as plt
  
  from matplotlib import animation
  
  
  
  fig = plt.figure()
  
  ax = plt.axes(xlim=(0, 2), ylim=(-2, 2))
  
  line, = ax.plot([], [], lw=2)
  
  
  
  def init():
  
      line.set_data([], [])
  
      return line,
  
  
  
  def animate(i):
  
      x = np.linspace(0, 2, 1000)
  
      y = np.sin(2 * np.pi * (x - 0.01 * i))
  
      line.set_data(x, y)
  
      return line,
  
  
  
  anim = animation.FuncAnimation(fig, animate, init_func=init,
  
                                 frames=200, interval=20, blit=True)
  
  
  
  
  
  anim.save('basic_animation.mp4', fps=30, extra_args=['-vcodec', 'libx264'])
  
  
  
  plt.show()

  When I run it, it tells me to install ffmpeg. I tried using these instructions : http://stephenjungels.com/jungels.net/articles/ffmpeg-howto.html But the instructions were unclear about what I was supposed to download, especially when it got to the part about a "patch". This also just feels insanely complicated for something that seems like it should be much simpler. I also tried following some instructions for installing ffmpeg using Homebrew but the instructions were again poorly written so that some of the buttons it said should be there weren’t. I tried to figure it out by guessing what I should do, and it seemed to work but with a lot of warning messages. By the end of the process, when I type into a terminal

  which ffmpeg

  it returns /usr/local/bin/ffmpeg. However, even after restarting Spyder and re-running the code, it still tells me to install ffmpeg. I also navigated to /usr/local/bin and it doesn’t have a folder ffmpeg. So my guess is that ffmpeg didn’t install.

  I read in the matplotlib documentation that Anaconda doesn’t give a build for Python that is appropriate, something about a "framework" build (http://matplotlib.org/faq/osx_framework.html). But it says that in Anaconda you can install it easily by running conda install python.app which I did and it worked. It then says to use pythonw rather than python. I’m not really sure what this means, because in Spyder I don’t run scripts from the terminal. I tried navigating to the file anyway and running it with

  pythonw anim.py

  and it mysteriously gave me an I/O error.

  Do I really need to install ffmpeg or is there some simpler fix ?

  If I do need to install ffmpeg, where get I get up-to-date instructions that make the process clear ?

• FFMPEG GIF without loop, without transparency

  4 janvier 2019, par Wallie

  I use the following bash file in Terminal to transcode video files to high quality gifs.

  #!/bin/sh
  
  
  
  palette="/tmp/palette.png"
  
  
  
  filters="fps=25,scale=576:-1.78:flags=lanczos"
  
  
  
  ffmpeg -v warning -i $1 -vf "$filters,palettegen" -y $palette
  
  ffmpeg -v warning -i $1 -i $palette -lavfi "$filters [x]; [x][1:v] 
  
  paletteuse" -y $2

  Right now a 6 second video ends up as a 10 second gif. Which is a bit odd since the framerate matches. I guess it’s due to looping.

  Is it possible to add a simple filter that prevents looping.

  And also a filter that prevents transparency ?

  Source is a prores422 file.

• subtitles dont show ffmpeg issue

  30 septembre 2016, par Bilal Shahid

  I’m using below command to burn subtitles to a video. I have successfully done it via terminal in ubuntu. I’ve used this library in android android library and I’ve run the same command to do the same task but it wont work the command executes successfully but in result video I don’t see any subtitle.

  fmpeg -i /home/s9iper1/a.mp4 -vf "subtitles=/home/s9iper1/titles.srt:force_style='Fontsize=24,PrimaryColour=&H0000ff&'" -c:a copy /home/s9iper1/out.mp4