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• How to save animations with tight layout, transparency and in high quality with matplotlib ?

  29 novembre 2019, par mapf

  I am trying to implement an option in my GUI to save an image sequence displayed using matplotlib. The code looks something like this :

  import matplotlib.pyplot as plt
  
  from matplotlib.backends.backend_qt5agg import \
  
      FigureCanvasQTAgg as FigureCanvas
  
  from matplotlib.animation import FuncAnimation
  
  from PIL import Image
  
  
  
  
  
  plt.rcParams['savefig.bbox'] = 'tight' 
  
  
  
  
  
  class Printer:
  
      def __init__(self, data):
  
          self.fig, self.ax = plt.subplots()
  
          self.canvas = FigureCanvas(self.fig)
  
  
  
          # some irrelevant color adjustment here
  
          #self.ax.spines['bottom'].set_color('#f9f2d7')
  
          #self.ax.spines['top'].set_color('#f9f2d7')
  
          #self.ax.spines['right'].set_color('#f9f2d7')
  
          #self.ax.spines['left'].set_color('#f9f2d7')
  
          #self.ax.tick_params(axis='both', colors='#f9f2d7')
  
          #self.ax.yaxis.label.set_color('#f9f2d7')
  
          #self.ax.xaxis.label.set_color('#f9f2d7')
  
          #self.fig.subplots_adjust(left=0.1, right=0.975, bottom=0.09, top=0.98)
  
          self.fig.patch.set_alpha(0)
  
          self.fig.patch.set_visible(False)
  
          self.canvas.setStyleSheet("background-color:transparent;")
  
          self.fig.set_size_inches(10, 10, True)
  
          self.fig.tight_layout()
  
  
  
          self.data = data
  
          self.image_artist = self.ax.imshow(data[0])
  
  
  
      def animate(self, i):
  
          self.image_artist.set_data(self.data[i])
  
          self.canvas.draw()
  
  
  
  
  
  def save_animation():
  
      data = [
  
          Image.open("test000.png"),
  
          Image.open("test001.png"),
  
      ]
  
      file = 'test.gif'
  
      printer = Printer(data)
  
  
  
      ani = FuncAnimation(
  
          printer.fig, printer.animate, interval=100, frames=len(data),
  
      )
  
      # writer = animation.writers['pillow'](bitrate=1000)
  
      ani.save(
  
          file, writer='pillow', savefig_kwargs={'transparent': True, 'bbox_inches': 'tight'}
  
      )
  
  
  
  
  
  save_animation()

  Transparency :

  As you can see I have already tried several different approaches as suggested elsewhere (1, 2), but didn’t manage to find a solution. All of the settings and arguments patch.set_alpha(0), patch.set_visible(False), canvas.setStyleSheet("background-color:transparent;"), savefig_kwargs={'transparent': True} seem to have no effect at all on the transparency. I found this post but I didn’t get the code to work (for one I had to comment out this %matplotlib inline, but then I ended up getting some error during the MovieWriter.cleanup out = TextIOWrapper(BytesIO(out)).read() TypeError: a bytes-like object is required, not 'str'). Here, it was suggested that this is actually a bug, but the proposed workaroud doesn’t work for me since I would have to rely on third-party software. There also exists this bug report which was supposedly solved, so maybe it is unrelated.

  Tight layout

  I actually couldn’t really find much on this, but all the things I tried (plt.rcParams['savefig.bbox'] = 'tight', fig.tight_layout(), savefig_kwargs={'bbox_inches': 'tight'}) don’t have any effect or are even actively discarded in the case of the bbox_inches argument. How does this work ?

  High quality

  Since I cannot use ImageMagick and can’t get ffmpeg to work (more on this below), I rely on pillow to save my animation. But the only argument in terms of quality that I can pass on seems to be the bitrate, which doesn’t have any effect. The files still have the same size and the animation still looks like mush. The only way that I found to increase the resolution was to use fig.set_size_inches(10, 10, True), but this still doesn’t improve the overall quality of the animation. It still looks bad. I saw that you can pass on codec and extra_args so maybe that is something that might help, but I have no idea how to use these because I couldn’t find a list with allowed arguments.

  ffmpeg

  I can’t get ffmpeg to work. I installed the python package from here and can import it into a python session but I don’t know how I can get matplotlib to use that. I also got ffmpeg from here (Windows 64-bit version) and set the plt.rcParams['animation.ffmpeg_path'] to where I saved the files (there was no intaller to run, not sure if I did it correctly). But this didn’t help either. Also this is of course also third-party software, so if somebody else were to use my code/program it wouldn’t work.

• Put image over video and save video to sd card Android

  29 août 2018, par Ronak Thakkar

  I’m working on a feature in which I want to add picture over the video and save it to sd card.

  in general, the user selects an image with semi-transparent background and puts that image above the video, after the user presses the save button he gets a new video but already with the image above the video.

  I have heard about ffmpeg, and saw some commands that are provided by ffmpeg. but I don’t know where I should initialize. can anyone provide me an example for the same ?

  Thank you.

• Put image over video and save video to sd card Android

  25 juillet 2016, par Ronak Thakkar

  I’m working on a feature in which I want to add picture over the video and save it to sd card.

  in general, user selects an image with semi transparent background and puts that image above the video, after user presses the save button he gets a new video but already with image above the video.

  I have heard about ffmpeg, and saw some commands that are provided by ffmpeg. but i don’t know from where I should initialize. can anyone provide me any example for the same.

  Thank you.