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• RMarkdown Plot Animation - disappearing output files

  20 avril 2015, par tcs

  I downloaded the latest ffmpeg (exe version), unzipped the files, renamed the directory to ffmpeg, copied the directory into c :\Program Files. I appended my PATH variable to include c :\Program Files\ffmpeg\bin. Finally, I restarted Rstudio.

  While attempting to run the following code chunk :

  ```{r clock, fig.width=7, fig.height=6, fig.show='animate'}
  
  par(mar = rep(3, 4))
  
  for (i in seq(pi/2, -4/3 * pi, length = 12)) {
  
      plot(0, 0, pch = 20, ann = FALSE, axes = FALSE)
  
      arrows(0, 0, cos(i), sin(i))
  
      axis(1, 0, "VI"); axis(2, 0, "IX")
  
      axis(3, 0, "XII"); axis(4, 0, "III"); box()
  
  }
  
  
  
  ```

  I see within the output in in my RMarkdown window that the ffmpeg call seems to be successfully run, but while watching the directory where my code is located the png that is attempted to be created can often disappear, or not appear at all. Strangeness.

  Any ideas on what might be happening ? I’ve tried adding in other graphs, and I see this random behavior of the file folder appearing disappearing, sometimes the file is created, other times not.

• How to stitch videos to one 360 video without 3rd party software ?

  6 janvier 2017, par Basset hound

  I am using a 3D software, something like GTA.
  I wanted to create a 360 video.
  What I did was create 84 videos automatically by C#.
  
  Set camera orientation to, (Step = 30 degree)
  

  1. (Rx, Ry, Rz) = (0.0, -90.0, 0.0)
  
  2. (Rx, Ry, Rz) = (0.0, -90.0, 30.0)
  
  3. (Rx, Ry, Rz) = (0.0, -90.0, 60.0)
  
  ...
  
  12. (Rx, Ry, Rz) = (0.0, -90.0, 330.0) 
  
  
  
  13. (Rx, Ry, Rz) = (0.0, -60.0, 0.0) 
  
  14. (Rx, Ry, Rz) = (0.0, -60.0, 30.0)
  
  15. (Rx, Ry, Rz) = (0.0, -60.0, 60.0) 
  
  ...
  
  83. (Rx, Ry, Rz) = (0.0, 90.0, 300.0) 
  
  84. (Rx, Ry, Rz) = (0.0, 90.0, 330.0) 

  After created 84 videos, I used Kolor Autopano Video to stitch the video.
  The result is good.
  
  However, I was wondering, each video has precise camera orientation.
  I think I don’t really need Kolor Autopano Video to create 360 video.
  Is it possible to stitch 84 videos by FFmpeg or C# ?
  Do you have any hint about this ?
  
  Thank you.

• lowpass filter Q factor online simulator (bode plot)

  5 novembre 2016, par user1320370

  I like to add a low pass filter on a audio file myfile.flac with ffmpeg.

  The parameters to choose are the frequency and Q-factor or slope.

  ffmpeg -i myfile.flac -af "highpass=f=9000:width_type=q:width=0.707" output.flac

  The default q-factor is 0.707.

  I like to increase the q-factor but a too high value can cause excessive resonance.

  For this reason before do it can be useful to test with a bode plot simular (online if exist) that can accept filter type (lowpass, highpass) , frequency and Q-factor.

  Someone can please send a link of a bode plot that show a simulator like this ?

  thank you !!