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• ffmpeg pass through video including Dolby Video

  11 janvier 2024, par cmjordan

  Given media that contains a video stream that includes Dolby Vision as one of the HDR metadata, how does one transcode the media and maintain the video stream as is (including the Dolby Vision and any other HDR metadata) ?

  


  Sample media mediainfo excerpt :

  


  Video
ID                                       : 1
Format                                   : HEVC
Format/Info                              : High Efficiency Video Coding
Format profile                           : Main 10@L5@High
HDR format                               : Dolby Vision, Version 1.0, dvhe.08.06, BL+RPU, HDR10 compatible / SMPTE ST 2094 App 4, Version 1, HDR10+ Profile B compatible
Codec ID                                 : V_MPEGH/ISO/HEVC
...


  


  -c:v:0 copy drops the Dolby Vision metadata from this and retains only the latter HDR metadata.

  


• Poor video quality in first few frames using video output options in gganimate

  27 janvier 2021, par Nautica

  I'm trying to export some animations I've made using gganimate through video format as the gifs I'm creating are quite large.

  


  Sample code :

  


  library(gganimate)

p <- ggplot(mtcars, aes(factor(cyl), mpg)) +
  theme_dark() +
  theme(panel.grid = element_line(colour = "white")) +
  geom_boxplot() +
  transition_states(
    gear,
    transition_length = 2,
    state_length = 1
  ) +
  enter_fade() +
  exit_shrink() +
  ease_aes('sine-in-out')

anim_save("example.mp4",
          animate(
            p,
            nframes = 450,
            fps = 25,
            width = 1280,
            height = 720,
            type = "cairo",
            start_pause = 50,
            end_pause = 50,
            renderer = av_renderer()
          ))


  


  Produces the video seen here : https://vimeo.com/505019987

  


  With the standard ggplot2 theme : https://vimeo.com/505020822

  


  This is another example of something I made using gganimate : https://www.youtube.com/watch?v=fHzjl_z_sSo

  


  You can see that the video quality in the first few frames are very bad. In the video with the standard ggplot2 theme and the YouTube video, the gridlines and watermark text are not visible at the start but fade in much later. I don't know much about video codecs but I assume it has something to do with the ffmpeg library the av package/av_renderer() is using. Has anyone experienced something like this ?

  


• Looking for video libraries for editing video on windows/ios/azure service [on hold]

  17 juillet 2015, par sanyam

  Which library would be a good bet in terms of ...
  1. Richness in features (I want to create a video from short clips and images with effects and filters). Think auto videos created from Google Photos.
  2. Extensibility - I would prefer using similar tech on IOS and Windows apps. Might have to offload some processing to a web service on Azure (windows or linux).
  3. Programmability - An API is preferred over command line as it gives more flexibility and better error handling.

  Given all these options, what is my best bet ? I’ve only looked at ffmpeg till now, is there a better alternative ?