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• build : Allow generating dependencies as a side-effect of assembling

  13 octobre 2016, par Diego Biurrun

  build : Allow generating dependencies as a side-effect of assembling
  (Cherry-picked from libav commit 3c0efbd03349ae68d3a25a082222652a102e3fd4)
  Signed-off-by : James Almer <jamrial@gmail.com>
  

  • [DH] configure
  • [DH] ffbuild/common.mak

• Best way to record a HTML Canvas/WebGL animation server-side into a video ?

  19 novembre 2022, par Abhinav

  I have a set of animations which I can make in Canvas (fabric.js) or WebGL (three.js). I need to record them automatically, server-side, through a script and output a video file.

  



  The animations include :
  

  



  

  1. Pictures
     

  


  2. Videos (with audio)
     

  


  3. Other animations/effects

  


  



  I have researched a lot during last few months on this.

  



  Results
  
1. Use PhantomJS + FFMPEG
  
Run HTML Canvas animations on headless browser(PhantomJS) and record with FFMPEG. Here the issue is PhantomJS supports neither WebGL nor Video element. http://phantomjs.org/supported-web-standards.html

  
2. Use Websockets to send data back to server using DataURL
  
Here again, we will need to run the animations on browser (which we can't because we have to do everything on server).

  
3. Use node-canvas
  
This is a library by TJ Holowaychuk which allows rendering HTML Canvas on Node.js. But it has its own limitations plus I haven't really explored this field much. 
(If someone could shed more light on this library)

  



  If anyone has done it before or can guide me somewhere useful.
  
All we need to do is use some data to create animations and record it into a video, everything on server side.

  


• With apulsator in ffempeg - How do I make so one side does not completely become silent ?

  3 avril 2022, par corgrath

  I am trying to learn more about signal processing and the apulsator effect in ffmpeg.

  


  http://ffmpeg.org/ffmpeg-filters.html#apulsator

  


  With the most default example :

  


  ffmpeg -y -i input.mp3 -af "apulsator=hz=0.0625:timing=hz:mode=sine" output.mp3

  


  You can clearly hear that the sound travels from left to right and then back to left, as expected.

  


  However, I am trying to understand how/if it is possible that sound volume does not completely becomes silent, but perhaps 10% of the volume, while the other side gets 90%.

  


  What I am trying to achieve is that one side does not completely becomes silent.

  


  If this cannot be achieved solely by the apulsator settings, what other effects or ways can I achieve this using ffmpeg ?

  


  Any advice is appreciated !