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• Saving animations using ffmpeg and matplotlib

  2 juillet 2015, par PedroLago

  im new in here and new in python, im doing some animations with animation.FuncAnimation of matplotliib. The animation works perfectly but i´m having problems saving the animations. here is the part of the code of the animation.

  import numpy as np 
  
  import matplotlib.pyplot as plt
  
  import matplotlib.animation as animation
  
  
  
  fig, ax = plt.subplots()
  
  
  
  line,  = ax.plot(range(N),sin(x[0,:]),'o-')
  
  ax.axis([0,1,-1,1])
  
  
  
  def animate(i):
  
      line.set_ydata(sin(x[i,:]))  # update the data
  
      return line,
  
  
  
  def init():
  
      line.set_ydata(np.ma.array(x[0,:], mask=True))
  
      return line,
  
  
  
  ani = animation.FuncAnimation(fig, animate, np.arange(1, 10000),
  
      interval=25, init_func=init, blit=True)
  
  ani.save('2osc.mp4', writer="ffmpeg")
  
  plt.show()

  where x[ :, :] is previously set. ani.save is saving every frame of the animation as a .npg image instade of saving the movie. I dont know if this is how it is suposed to work and i have to do the movie with the .npg with another program or if im doing something wrong.
  Obs : i’ve previously installed ffmpeg and it seems to be working just fine.

• lavu/riscv : helper macro for VTYPE encoding

  5 octobre 2022, par Rémi Denis-Courmont

  lavu/riscv : helper macro for VTYPE encoding
  On most cases, the vector type (VTYPE) for the RISC-V Vector extension
  
  is supplied as an immediate value, with either of the VSETVLI or
  
  VSETIVLI instructions. There is however a third instruction VSETVL
  
  which takes the vector type from a general purpose register. That is so
  
  the type can be selected at run-time.
  This introduces a macro to load a (valid) vector type into a register.
  
  The syntax follows that of VSETVLI and VSETIVLI, with element size,
  
  group multiplier, then tail and mask policies.
  

  • [DH] libavutil/riscv/asm.S

• Why are v0, v1, and v2 of ffmpeg still under active development ? What happened to ppa:jon-severinsson/ffmpeg ?

  12 avril 2015, par cxrodgers

  I know about the long history of ffmpeg and libav. Personally, I preferred to use Jon Severinsson’s PPA, as suggested in many answers here on stackoverflow or askubuntu. However, recently this PPA seems to have gone down recently (this page, which is the link everyone always gives, is dead). I don’t see if he put up a newer version, although I admit I find launchpad hard to navigate. Did it get replaced with this one from Doug McMahon or this one from Sam Rog ?

  Ok, so maybe I need to download it myself. I visit the releases page for ffmpeg, and there seems to be simultaneous development of releases from v2 (2.6.2), v1 (1.2.12, from February), and v0 (0.10.16, from March of this year). 0.10 isn’t even the newest of the v0 series, and yet it seems to be the most recently updated of that series, and (coincidentally ?) also the version that I most recently got from the PPA. Admittedly this was on a slightly older distribution (Linux Mint 16).

  ffmpeg -version
  
  ffmpeg version 0.10.12-7:0.10.12-1~saucy1

  So, which version should I download, now that the PPA is gone ? Does it depend on the distribution I’m using ?