Recherche avancée

Sur d’autres sites (12896)

• Possible bug in latest google chrome (v62) ?

  21 novembre 2017, par Jalal El-Shaer

  The following demo was working perfectly :

  http://jsfiddle.net/r6wz0nz6/2/

  The following is a sample of ’video-preview’ class in action :

  <a href="https://www.youtube.com/watch?v=v1uyQZNg2vE" target="_blank" class="video-preview" data-frames="100" data-source="http://i.imgur.com/BX0pV4J.jpg">
  
  </a>

  Now, if you use your mouse to scroll from left-to-right, somehow it is not working (shows thumbnail instead of current image position). This was working perfectly before v62. While, from right-to-left, it works normally.

  Updated Please watch how this looks here : https://www.youtube.com/watch?v=HvDP-YXJgOk

  Question : How can I overcome this bug/issue ?

  P.S. the demo is based on this blog post (https://www.binpress.com/tutorial/how-to-generate-video-previews-with-ffmpeg/138)

  Update 2
  Interesting, in the following part :

  elm.mousemove(function(e) {
  
  var left = e.clientX - elm.position().left;
  
  slider.show().css('left', left -1); // <<---------------------- this line
  
  img.css('left', -Math.floor((left / width) * frames) * width);

  if I remove the ’-1’ like so :
  slider.show().css('left', left);
  It works from Left-To-Right, but now from Right-To-Left is showing same bug !!

  Proposed Workaround by @A. Wollf
  Change the "mouseout" to "mouseleave" and it seems to fix it : http://jsfiddle.net/r6wz0nz6/388

• Python unknown file extension .mp4

  18 février 2024, par marlise23

  I am working on a simulation project, however I am unable to create a visual. I started out by running code from matplotlib's documentation (i.e. the code does not belong to me).
When I run the code, I get the error "unknown file extension : .mp4". 
I have installed ffmpeg and checked that it is an updated version.

  



  I am using a Windows computer and Python 3.

  



  import numpy as np
from matplotlib import pyplot as plt
from matplotlib import animation
plt.rcParams['animation.ffmpeg_path']='‪C:\\FFmpeg\bin\ffmpeg.exe'

# First set up the figure, the axis, and the plot element we want to animate
fig = plt.figure()
ax = plt.axes(xlim=(0, 2), ylim=(-2, 2))
line, = ax.plot([], [], lw=2)

# initialization function: plot the background of each frame
def init():
    line.set_data([], [])
    return line,

# animation function.  This is called sequentially
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,

# call the animator.  blit=True means only re-draw the parts that have changed.
anim = animation.FuncAnimation(fig, animate, init_func=init,
                               frames=200, interval=20, blit=True)

# save the animation as an mp4.  This requires ffmpeg or mencoder to be
# installed.  The extra_args ensure that the x264 codec is used, so that
# the video can be embedded in html5. 
anim.save('basic_animation.mp4', fps=30, extra_args=['-vcodec', 'libx264'])

plt.show()


  


• How to use timeline editing with a single image input in ffmpeg ?

  29 septembre 2017, par Serge

  Small image should be animated over a background video in a simple way :

  1. change position - move along a straight line, no easing. Starting at frame A, till frame B (i.e. frames 11 to 31) ;
  2. zoom in - between frames C and D (i.e. 45 and 55).

  Filters I intend to use :

  • overlay filter has x and y parameters for image position ;
  • zoompan filter allows zooming (preceeded with a static scale up to avoid jitter).

  My filtergraph :

  video.avi >----------------------------------->|-------|
  
                                                 |overlay|-> out.mp4
  
  image.png >-> scale >-> zoompan >-> zoompan >->|-------|

  ---

  The problem is with timeline editing. Both filter support the enable option. I thought I could add instructions like enable='between(n, 11, 31)' to "place" the animations at right times.

  Appears that the image input has only two values of n : zero and 1. Checked that by wrapping n with print(n) in zoompan filter to output during rendering.

  Inside overlay filter, in opposite, n outputs sequence of numbers as expected.

  ---

  Question : how can I make the single image input "look" like a normal video stream to ffmpeg filters – so that every generated frame has its unique number ?

  ---

  One of the latest tests. Video is hd720, image is 1000x200 transparent png with the logo occupying about 150x50 area in the center, not to be cropped out when zoomed in.

  ffmpeg -i $FOOTAGE -loop 1 -i $IMAGE -filter_complex \
  
  "
  
  [1:v]
  
    scale=10*iw:-2
  
    ,zoompan=
  
      z='1'
  
      :x='iw/2-(iw/zoom/2)+80'
  
      :y='ih/2-(ih/zoom/2)'
  
      :d=26
  
      :s=500x100
  
      :enable='lt(print(n),24)'
  
    ,zoompan=
  
      z='min(zoom+1.3/18,2.3)'
  
      :x='iw/2-(iw/zoom/2)'
  
      :y='ih/2-(ih/zoom/2)'
  
      :d=20
  
      :s=500x100
  
      :enable='between(n,24,42)'
  
  [name];
  
  [0:v][name]
  
    overlay=
  
      x=1005-250
  
      :y=406-50
  
      :enable='lte(n,173)'
  
  " -t 7 -y  -hide_banner  out.mp4