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• 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

• OpenCV 3.2 + Python 2.7 + Windows 7 GETTING STARTED

  8 mai 2017, par Arantxa

  I’m having several problems to start working with OpenCV and Python in a Windows environment.

  After doing many of the instructions given on the internet, I haven’t found the correct way yet.

  I was wondering to use Highgui in order to do image processing. But after opening the camera, the frame is totally black, I tried to put the ffmpeg codecs correctly but it looks like it wasnt because of that, so I tried to save a frame just to see if the frame was totally empty too, and I can’t use cv2.SaveImage() method, because, as it says, ’module’ object has no attribute ’SaveImage’

  I have tried to :

  • Install it with Anaconda. After no success...I
  • Install OpenCV from Sourceforge, and after that copy the cv2.pyd file inside Pyton27/Lib/site-packages/
  • Install the next packages from Python oficial page :
    • opencv-python
    • opencv-contrib-python

  How do you use OpenCV with Python ?

• Anomalie #2840 : #LESAUTEURS

  7 septembre 2012, par Paolo -

  Aië ! J’ai fait cela trop vite : c’est à dire j’ai dit ce que je pensais être la source du bug au lieu d’examiner vraiment ce qui le cause. Pardon. Fermons ce bug-ci et je vais ouvrir une autre pour mieux décrire. (Je ne trouve pas comment le fermer d’ailleurs (...)