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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.

  


• avcodec/dovi_rpu{enc,dec} : fix ms_weight handling

  25 mai 2024, par Niklas Haas

  avcodec/dovi_rpuenc,dec : fix ms_weight handling
  The code as written was wrong. In the spec, these fields are treated
  
  merely as plain integers in the range 0 to 4095. The only difference
  
  between L2 and L8 is that L2.ms_weight also accepts an additional value
  
  of -1, hence the extra sign bit. While it's likely that these are still
  
  shifted integers in disguise, since all real-world samples seem to use
  
  a value of 2048 here, the offset used in the code was wrong.
  In addition, because the l8.ms_weight struct member is unsigned, these
  
  wrong shifting semantics ended up overflowing the field, leading to
  
  undefined behavior when transcoding. Fortunately, the damage was
  
  relatively contained in practice, because it just corrupts the coding of
  
  this field, which is ignored in practice in all implementations I have
  
  seen.
  

  • [DH] libavcodec/dovi_rpudec.c
  • [DH] libavcodec/dovi_rpuenc.c

• How to restrict fetching hls segment files on pause in Safari (MacOS and iOS)

  24 juillet 2021, par Charan Kumar

  We generate hls files with segment size of 3 seconds. We use hlsjs for non Safari browsers and Safari has native hls support.

  


  In hlsjs world we were able to restrict how much ahead we should be in terms of buffer using maxMaxBufferLength, where as we are unable to find similar solution for Safari. In Safari, after loading video m3u8, even if I pause after a second, in the network tab I can see that all the segments are being fetched which I would like to restrict.

  


  I'll not be able to share our examples due to company polices. But, a public example file by hls.js is attached below :

  


  https://test-streams.mux.dev/x36xhzz/url_6/193039199_mp4_h264_aac_hq_7.m3u8 try opening this url in Safari, and try pausing the video, you'll see that it continues to download. Where as if you open same one using https://hls-js.netlify.app/demo/ with maxMaxBufferLength : 5 it won't happen.

  


  Is there an option at ffmpeg to make it controlled buffer or some solution that we should do for Safari by listening to events ?

  


  Found the same question here -> https://developer.apple.com/forums/thread/121074