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• 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.

  


• lavu/timer : use time for AV_READ_TIME on RISC-V

  15 août 2023, par Rémi Denis-Courmont

  lavu/timer : use time for AV_READ_TIME on RISC-V
  So far, AV_READ_TIME would return the cycle counter. This posed two
  
  problems :
  
  1) On recent systems, it would just raise an illegal instruction
  
     exception. Indeed RDCYCLE is blocked in user space to ward off some
  
     side channel attacks. In particular, this would cause the random
  
     number generator to crash.
  
  2) It does not match the x86 behaviour and the apparent original intent
  
     of AV_READ_TIME in the functional code base (outside test cases).
  So this replaces the cycle counter with the time counter. The unit is
  
  a platform-dependent constant fraction of time, and the value should be
  
  stable across harts (RISC-V lingo for physical CPU thread).
  

  • [DH] libavutil/riscv/timer.h

• FFMPEG - why zoompan causes unexpected stretching ?

  14 septembre 2020, par Sarmad S.

  I have two images as input, both are 1600x1066. I am vertically stacking them. Then I am drawing a box and vertically stacking that box under both of the image. Inside of the box I write text, then I output a video that is 1080x1920. Everything works well, until I use zoompan to zoom in on the images, I get weird behavior. basically all input images including the box stretchs (shrink) vertically and no longer fit the entire height of the video which is 1920.

  


  The command (removed some drawtext commands from it) :

  


  -filter_complex 
"color=s=1600x1066:color=blue, drawtext=fontfile=font.otf: text='My Text':fontcolor=white: fontsize=30: x=50: y=50[box]; 
[0]scale=4000x4000,zoompan=z='min(zoom+0.0015,1.5)':x='iw/2-(iw/zoom/2)':y='ih/2-(ih/zoom/2)':d=125:s=1600x1066[z0];
[1]scale=4000x4000,zoompan=z='min(zoom+0.0015,1.5)':x='iw/2-(iw/zoom/2)':y='ih/2-(ih/zoom/2)':d=125:s=1600x1066[z1];
[z0][z1][box]vstack=inputs=3"


  


  How do I fix this ? I want to zoom in without stretching the images

  


  Before using zoompan this is how the video looks like (I want to keep it this way while zooming in the images) :


  


  After using zoompan this is how the video looks like :