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• Difficulties saving an animation (matplotlib)

  14 avril 2020, par Ben C.

  I have a simple animation that I want to save. I followed the example : https://matplotlib.org/examples/animation/basic_example_writer.html

  



  But I get the following error : RuntimeError : Requested MovieWriter (ffmpeg) not available

  



  I installed ffmpeg and checked via ffmpeg -version that it really is installed and the path correct.

  



  Here is my code :

  



  import numpy as np
import matplotlib.animation as animation
import matplotlib.pyplot as plt

# Set up formatting for the movie files
Writer = animation.writers['ffmpeg']
writer = Writer(fps=15, metadata=dict(artist='Me'), bitrate=1800)

fig, ax = plt.subplots()

x = np.random.uniform(0,1)
y = np.random.uniform(0,1)


scat = ax.scatter(x,y, color= 'blue')
circle = plt.Circle((x,y), radius=0.1, color='blue', fill=False, lw=0.5)
ax.add_patch(circle)

def init():
    scat = ax.scatter(x, y, color = 'blue')
    circle = plt.Circle((x,y), radius=0.1, color='blue', fill=False, lw=0.5)

def animate(i):
    random = np.random.uniform(0,1)
    if random < 0.5:
        scat.set_color('red')
        circle.set_edgecolor('blue')
    else:
        scat.set_color('blue')
        circle.set_edgecolor('red')
    return circle, scat,


ani = animation.FuncAnimation(fig, animate, init_func=init(), interval=1000, blit=True)
ani.save('test.mp4', writer=writer)


  



  None of the proposed solution in RuntimeError : No MovieWriters available in Matplotlib animation worked for me. Any ideas ?

  



  Edit : I am using Windows (10)

  


• Saving raw YUV420P frame FFmpeg/Libav

  14 mars 2016, par Sir DrinksCoffeeALot

  Previously i successfully opened, decoded and saved frames from .mp4 file. Raw frames were in YUV420P format which i converted to RGB24 using sws_scale() function and saved them into a .ppm file. What i’m trying to do now is to keep raw decoded frames in YUV420P, or convert frames that i get to YUV420P just to make sure they are in YUV420P. But the problem is that i don’t know which type of file should i use, i’m guessing .yuv ? And another problem is that i also don’t know how to save YUV420P data.

  I used to save RGB24 in .ppmlike this :

  for (y = 0; y < height; y++)
  
  {
  
  fwrite(frame->data[0] + y*frame->linesize[0], 1, width * 3, pf);
  
  }

  which worked fine since i was using only 1 plane. But YUV420P uses 3 planes (Y,Cb,Cr). What i tried to do is to save Y component first, and Cb/Cr after that.

  for (y = 0; y < height; y++)
  
  {
  
      fwrite(frame->data[0] + y*frame->linesize[0], 1, width, pf);
  
  }
  
  
  
  for (y = 0; y < height / 2; y++)
  
  {
  
      fwrite(frame->data[1] + y*frame->linesize[1], 1, width, pf);
  
      fwrite(frame->data[2] + y*frame->linesize[2], 1, width, pf);
  
  }

  But as you can guess that is not working at all. Actually it does, but it saves only Y component. Could anyone guide me to right direction please ?

  EDIT
  I’ve changed mine saveFrame() function like you said, but instead of interleaved chroma writing i used planar. But, i’m still getting only Y component picture (black-white).

  fprintf(pf, "P5\n%d %d\n255\n", width, height);
  
  
  
  for (y = 0; y < height; y++)
  
  {
  
      fwrite(frame->data[0] + y*frame->linesize[0], 1, width, pf);
  
  }
  
  
  
  for (y = 0; y < height / 2; y++)
  
  {
  
      fwrite(frame->data[1] + y*frame->linesize[1], 1, width / 2, pf);
  
  }
  
  
  
  for (y = 0; y < height / 2; y++)
  
  {
  
      fwrite(frame->data[2] + y*frame->linesize[2], 1, width / 2, pf);
  
  }

• Trouble saving matplotlib animation with ffmpeg

  21 avril 2017, par kevinkayaks

  I installed ffmpeg and would like to save an animation.

  My code is

  #evo is the dataset composed of sequence of images
  
  
  
  evo = np.load('bed_evolution_3000iter_2.npy')
  
  fig = plt.figure(figsize=(15,15*2*width/length))
  
  # make axesimage object
  
  # the vmin and vmax here are very important to get the color map correct
  
  im = plt.imshow(np.transpose(evo[0]), cmap=plt.get_cmap('jet'), vmin=0, vmax=1300)
  
  cbar_ax = fig.add_axes([0.85, 0.15, 0.05, 0.7])
  
  fig.colorbar(im, cax=cbar_ax)
  
  fig.subplots_adjust(right=0.8)
  
  
  
  def updatefig(j):    
  
      # set the data in the axesimage object
  
      im.set_array(np.transpose(evo[j]))
  
      # return the artists set
  
      return im,
  
  # kick off the animation
  
  ani = animation.FuncAnimation(fig, updatefig, frames=range(len(evo)), 
  
                            interval=100, blit=True)
  
  
  
  #now just need to get the ability to save... this uses 
  
  
  
  FFwriter = animation.FFMpegWriter()
  
  ani.save('basic_animation.mp4', writer = FFwriter, fps=30, extra_args =([vcodec', 'libx264'])

  The animation runs and it looks good, but I just can’t get it to save. The error message (at this stage) is

  

  I am not sure what’s going wrong. Any help is appreciated.

  EDIT :
  Following Can’t save matplotlib animation I added

  plt.rcParams['animation.ffmpeg_path'] ='C:\\Program Files\\ffmpeg  \\bin\\ffmpeg.exe'

  Which returns
  Warning : Cannot change to a different GUI toolkit : qt. Using qt4 instead.
  ERROR : execution aborted