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• FMP4 moof box sequence number ordering

  15 avril 2024, par Daniel

  I wanted to do a basic fragmented mp4 broadcast program with avformat libs and HTML5 video and MSE.

  



  This is a live stream and I use avformat to copy h264 data to mp4 fragments.

  



  Here is my basic drawing of clients attaching to the stream :

  



  

  



  So, with words :

  



  

  1. C1J : First Client joins :


     

     • avformat process starts

     


     • ftyp, moov, moof, mdat boxes will be served to Client1

     


     • ftyp and moov atoms are both saved for later reuse

     


  


  2. C2J : Second Client joins (later in time) :


     

     • avformat process is ongoing (because it is still serving moof and mdat boxes for Client1)

     


     • previously saved ftyp and moov boxes will be served first to Client2

     


     • after ftyp and moov boxes were served, Client2 will join to the stream at the next moof box.

     


  


  



  I have saved an mp4 file to disk from both clients.

  



  Atoms' order within both files looks good : ftype, moov, moof, mdat, moof, mdat...

  



  Both files can be played by media players (like VLC) and also in browsers directly (Opera).

  



  Client1 can be played also via MSE in the browser (Opera), but Client2's stream is not displaying with MSE (Opera).

  



  No errors on the JS console, and media-internals looks also good (at least equivalent with Client1's one).

  



  Now I realized that every moof box contains an mfhd box (header) with a sequenceNumber field.

  



  Of course in Client1's first moof box this sequenceNumber is 1.
However in the later joined Client2's first moof box this sequenceNumber is always >= 1 (in my case it is 16).

  



  What do I need to modify in the moof boxes in Client2 to have a valid fmp4 from the beginning ?

  



  I think Opera's HTML5 video does not like if sequenceNumber does not start from 1, but there shall be other requirements for being it valid.

  


• avcodec/mips : Improve hevc bi hz and hv mc msa functions

  27 octobre 2017, par Kaustubh Raste

  avcodec/mips : Improve hevc bi hz and hv mc msa functions
  Align the mask buffer.
  Signed-off-by : Kaustubh Raste <kaustubh.raste@imgtec.com>
  
  Reviewed-by : Manojkumar Bhosale <Manojkumar.Bhosale@imgtec.com>
  
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavcodec/mips/hevc_mc_bi_msa.c

• 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.