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• ffmpeg change video stream resolution

  10 décembre 2014, par skorpionet

  I have an MKV with a video stream with wrong resolution of 1920x800, but the inside film is 1920x1080 so my main video player, an LG Smart TV, shows a flattened image. I can easily change resolution in container metadata but LG TV ignores this data and read only video stream data.

  First question : only way to change video stream resolution data is scale the video ?

  To scale with ffmpeg I used this command :

  ffmpeg -i input.mkv -map 0 -c:a copy -c:s copy -c:v libx264 -preset slow -crf 17 -vf scale=1920:1080,setdar=16/9 output.mkv

  Now the mkv is fine, my LG TV read it, looks awesome but..... size went from 3,3Gb to 12Gb !!
  Overall bit rate of 3,3Gb video is 2.704 Kbps, 12Gb is 9.829 Kbps. I think that 7000Kbps more are useless, in original video there aren’t info to raise quality.

  Second question : Why this huge size change ? What is my mistake ?

  Best Regards

• FFmpeg encoding slow for 4K HDR content

  1er mars 2023, par Geno Diaz

  When processing 4K input with the following configuration it is taking upwards of 2 minutes to process a 35s, 60fps, 4K HDR clip recorded from an iPhone. Is this the expected performance or is there an inefficiency within the configuration that is causing this ?

  


  In comparison, running this configuration on a 35s, 30fps, 4K non-HDR clip, only takes about 20 seconds.

  


  ffmpeg 
-i "input path" 
-y 
-filter:v scale=w=2160:h=3840 
-threads 4 
-r 59.94 
-c:v libx264 
-preset veryfast 
-vsync 1 
-tune film 
-maxrate 6000k 
-bufsize 5400k 
-g 60 
-x264opts no-scenecut 
-c:a aac 
-af aresample=async=1:min_hard_comp=0.100000:first_pts=0 
-ac 2 
-b:a 128k 
-ar 44100 
-vf zscale=transfer=linear:npl=100,
  format=gbrpf32le,
  zscale=primaries=bt709,
  tonemap=tonemap=hable:desat=0,
  zscale=transfer=bt709:matrix=bt709:range=tv,
  format=yuv420p 
-sws_flags full_chroma_int+full_chroma_inp 
-pix_fmt yuv420p 
"outputfile".mp4


  


• php-ffmpeg too slow - generating thumbnails ?

  25 avril 2013, par Wiggler Jtag

  first time I am trying to create thumbnail preview from video file, uploaded 700mb .avi film with 209747 frames. Now I am trying to create 1 thumbnail, but it takes 4.7 seconds, because I've set frame 10000, if I set it just to 1000, it takes only 0.4 seconds to generate thumbnail.

  How could I generate like 5-10 thumbnails from different frames on-the-go in less than a second ? Is it even possible ? Is it different to use exec(ffmpeg) or php-ffmpeg ?
  Using 0.6-svn ffmpeg, Debian 6.0.7, php 5.4.14 on machine 2x Xeon L5420 and still slow... Any ideas ? How about to use ffmpeg + time of the video instead of frame ?

  $movie = 'ai.avi';
  
  $thumbnail = 'thumbnail.jpg';
  
  
  
  $mov = new ffmpeg_movie($movie);
  
  $frame = 10000;
  
  $frame = $mov->getFrame($frame);
  
  
  
  if($frame) { 
  
    $gd_image = $frame->toGDImage();
  
    if($gd_image) {
  
      imagejpeg($gd_image, $thumbnail, 100);
  
      imagedestroy($gd_image);
  
    }
  
  }
  
  echo &#39;<img src="http://stackoverflow.com/feeds/tag/&#39;.$thumbnail.&#39;" style='max-width: 300px; max-height: 300px' /><br />&#39;;