Recherche avancée

Sur d’autres sites (9356)

• How to use fig.show=animate in knitr without administrator privileges

  23 mai 2013, par Stéphane Laurent

  I use Windows without administrator privileges hence I cannot set a path in the Windows PATH variable.

  The ffmpeg.exe file is in my "U:/ProgramFiles/ImageMagick-6.8.5-5/" folder.

  I have found how to use the saveVideo() function of the animate package :

  ani.options(ffmpeg = shQuote('U:/ProgramFiles/ImageMagick-6.8.5-5/ffmpeg.exe'))
  
  saveVideo({
  
    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()
  
    }
  
  },
  
          video.name="mavideo.mp4",
  
          outdir="U:/Data/Rtests/Animation")

  But I haven't find how to knit a Rmd file with the option fig.show=animate in a chunk, for instance :

  ```{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 have tried to modifiy the hook_ffmpeg_html() function by only changing the ffmpeg.cmd variable :

  ```{r}
  
   hook_ffmpeg_html2 <- function (x, options) 
  
  { 
  
      ........ 
  
      ffmpeg.cmd = paste("-y", "-r", 1/options$interval, 
  
          "-i", fig.fname, mov.fname) 
  
      ffmpeg.cmd <-  paste('"U:/ProgramFiles/ImageMagick-6.8.5-5/ffmpeg"', ffmpeg.cmd) 
  
     ...... 
  
  } 
  
  opts_knit$set(animation.fun = hook_ffmpeg_html2) 
  
  ```

  But this chunk does not work, below is the error message :

  label: unnamed-chunk-1 
  
  Warning in block_exec(params) : 
  
    failed to tidy R code in chunk  
  
  reason: Error in base::parse(text = text, srcfile = NULL) : 
  
    21:14: unexpected symbol 
  
  20: options$out.height), if ("controls" %in% mov.opts) 
  
  21: "controls=\\"controls 

• h264 RTP timestamp

  26 octobre 2024, par user269090

  I have a confusion about the timestamp of h264 RTP packet. I know the wall clock rate of video is 90KHz which I defined in the SIP SDP. The frame rate of my encoder is not exactly 30 FPS, it is variable. It varies from 15 FPS to 30 FPS on the fly. So, I cannot use any fixed timestamp.

  



  Could any one tell me the timestamp of the following encoded packet.
  
After 0 milisecond encoded RTP timestamp = 0 (Let the starting timestamp 0)
  
After 50 milisecond encoded RTP timestamp = ?
  
After 40 milisecond encoded RTP timestamp = ?
  
After 33 milisecond encoded RTP timestamp = ?
  

  



  What is the formula when the encoded frame rate is variable ?

  



  Thank you in advance.

  


• watermark image get rotated on video using ffmpeg- android

  24 avril 2017, par Pratik Deogade

  I am trying to add water mark on my video in android, i am successfull in adding it but the problem is water image get rotated by 90 degree clock wise

  here is my command

  String[] complexCommand = "ffmpeg","-y" ,"-i", "/sdcard/Vid.mp4","-strict","experimental", "-vf", "movie=/sdcard/watermarka.png [watermark] ; [in][watermark] overlay=main_w-overlay_w-10:10 [out]","-s", "320x2400","-r", "30", "-b", "15496k", "-vcodec", "mpeg4","-ab", "48000", "-ac", "2", "-ar", "22050", "/sdcard/out.mp4" ;

  the output i am getting is :