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• HEVC File bigger after converting from h264

  26 janvier 2019, par Aaroknight

  I’m currently working an an automated Python script for indexing and converting all my movies and episodes with ffmpeg. I use subprocess.call() for running the ffmpeg command and tested this command with some movies. As expected the big h264 files were converted to merely one third of what they used to have.

  But now that I was testing the method I found that a converted episode (about 400MB in h264) had over 1,6GB in hevc. I have absolutely no idea why the new file would be that much bigger in hevc.
  This is my code :

  def convert(path):
  
      outvid = path.strip(".mkv") + "h265.mkv"
  
  
  
      cmd = ["ffmpeg", "-i", path, "-map", "0", "-map_metadata", "0", "-map_chapters", "0", "-c:v", "libx265",
  
             "-c:a", "copy", "-c:s", "copy", "-preset", "ultrafast", "-x265-params", "lossless=1", outvid]
  
      subprocess.call(cmd)
  
  
  
  convert("/Volumes/2TB/Black Butler/Season 1/Black Butler S01E01.mkv")

  I don’t have that much experience with ffmpeg, nor with subprocess. This is one of my first bigger projects. I hope someone can tell me what the problem might be.

  UPDATE
  Problem applies only for small video files. I now just check for the file size and skip the small files. Wouldn’t have made much of a difference anyway.

  

• My (FFMPEG issue ) RTMP server(freebsd) wont let me hear video when I play a huge file over the server itself :/

  19 avril 2021, par Engi Gang

  Hey my name is Alisha from Norway im trying to get my RTMP server working the thing is that it works just fine but I just cant stream over it with ffmpeg I can stream to it on OBS and it works fine, but I am trying to a website where people could watch old public domain movies from the 1950 some of the films are actually pretty big lol.... anyways I detailed bellow more

  


  rm -rf /mnt/hls/loool && ffmpeg -re -i "$file" -c:v libx264 -c:a aac -b:v 300k -b:a 95k -f flv -flvflags no_duration_filesize rtmp ://lambright.xyz:1935/live/loool

  


  any work around I literally cant play the audio :( I can only hear (my source file is an MKV and 3gb )

  


  Note I had a smaller mp4 file and it did played the audio, the video isnt even playable in chrome but on VLC it is, but only a small file worked fine... its fine when I stream from my pc, but whats the point I am trying to set up my vintage 1950 serverbox :') trying to build a nice website where users could watch neat and decent old movies that are public domain if you wonder :/

  


  Another note when I am trying to play it on my iphone safari browser it does actually play parts but audio is super corrupted like you hear the audio sometimes :((

  


  rtmp {
    server {
        listen 1935; # Listen on standard RTMP port
        chunk_size 4000;

        application live {
            allow play all;
            live on;
            record off;
            hls on;
            hls_nested on;
            hls_path /mnt/hls/;
            hls_fragment 2s;
        }
        
    }
}


  


• How to make high smooth, high resolution particle motion animations

  5 décembre 2019, par algae

  For some time I have been having trouble with producing short movies/animations/gifs which are of sufficiently high resolution. I’m going to use R to generate some frames as a random example, but if there is somewhere else I should be creating frames from to give better results I would be interested in that too.

  Creating frames

  The kinds of animations I’m interested involve some cloud of ’particles’ moving about the page. There are usually a large number of particles and I would like their motion be as smooth as possible. As a random example, consider the R code (using base graphics and not ggplot2 as it is far quicker for saving a large number of frames)

  N <- 500
  
  nFrames <- 250
  
  points <- pracma::randp(n=N, r=1)
  
  rot <- function(p, a) { return(cbind(p[,1]*cos(a) - p[,2]*sin(a), p[,1]*sin(a) + p[,2]*cos(a))) }
  
  cols <- colorRampPalette(c("red", "green", "blue"))(nFrames)
  
  ang <- seq(0, pi, length=N)
  
  
  
  # Save frames
  
  png(filename="%d.png")
  
  par(mar=c(0,0,0,0))
  
  for (i in seq(1,N,length=nFrames)) 
  
          plot(sqrt(i)*rot(points, ang[i]), xlim=sqrt(N)*c(-1,1),  ylim=sqrt(N)*c(-1,1), cex=0.5, pch=19, col=cols[i], asp=1, xaxs="i")
  
  
  
  dev.off()

  Frames to animation

  There are a number of tools available to chain each frame together into an animation (in R there are also things like gganimate which I have tried but did not find convenient or better than the following). I also don’t have any requirements for the resulting file size or time taken to get everything looking as crisp as possible.

  convert

  For short gif style animations a common solution is to do something like convert -delay 1 -loop 0 *.png g.gif which gives

  

  gifski

  Running gifski -o g.gif *.png produces

  

  There is an annoying amount of ’jitter’ happening in the transition between frames in both of the above (though less noticeable with gifski).

  ffmpeg

  Being gifs, the above will be have limited options for tweaking so I suspect part of the solution lies in using ffmpeg. All I would like to know is how to make the animation appear totally smooth without any kind of noticeable blurriness. Here the resulting movies tend to be quite smooth, but resolution is lacking.. e.g. after setting height=1080 and width=1080 in png() of the above code we can run

  fmpeg -i %d.png -s 1080x1080 -c:v libx264 -vf fps=250 -pix_fmt yuv444p out.mp4

  If the particles move on a time/space scale smaller than is visible to the naked eye, and we set the frames per second to be the total number of frames, the transition between frames should be seamless, right ? At around the 2 second mark in out.mp4 you will see some kind of frame drop and similarly right at the beginning. Why does this happen ?

  Questions

  1. Is there a standard documented approach to generating high quality animations/movies involving large numbers of ’point-like’ particles ? Do we need more an more frames ?
  2. How to improve resolution of movies using ffmpeg ? Should I change from .png format to something vectorised (if so, how) ?

  Running Fedora v31.