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

  14 décembre 2016, 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. User 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.

• Why can I not change the number of frames (nframes) in a gganimate animation ?

  26 décembre 2022, par Gekin

  I have produced an animation per gganimate and rendered it per ffmpeg. It works just fine, but only, if I do not change the number of frames. If I do set the number of frames, I get this error message :

  


  nframes and fps adjusted to match transition
Error parsing framerate 8,4.                           
Error: Rendering with ffmpeg failed


  


  I produced the gganim MonthlyAveragePrecipitationMap the following way :

  


  options(scipen = 999, OutDec  =  ",")

MonthlyAveragePrecipitationMap = ggplot(MonthlyAverageExtremePrecipitation) + 
  geom_path(data = map_data("world","Germany"),
            aes(x = long, y = lat, group = group)) +
  coord_fixed(xlim = c(6,15),
              ylim = c(47,55)) + 
  geom_point(aes(x=lon, y=lat, 
                 colour = ShareOfExtremePrecipitationEvents,
                 group = MonthOfYear),
             size = 3) + 
  scale_color_gradient(low="blue", high="yellow") + 
  xlab("Longitude (degree)") +
  ylab("Latitude (degree)") + 
  theme_bw() +
  transition_manual(frames = MonthOfYear) + 
  labs(title = '{unique(MonthlyAverageExtremePrecipitation$MonthOfYear)[as.integer(frame)]}', 
       color = paste0("Share of Extreme Precipitation Events \namong all Precipitation Events")) 


  


  I call the animation the following way :

  


  animate(MonthlyAveragePrecipitationMap,
        nframes = 300,
        renderer =
          ffmpeg_renderer(
            format = "auto",
            ffmpeg = NULL,
            options = list(pix_fmt = "yuv420p")))



  


  I used this exact code just a few days ago and it worked fine.

  


  Has someone had similar experiences ?
Thanks in advance.

  


• 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.