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• 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


  


• 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 Windows Batch - Recursive Convert based and settings based on Frame Height

  3 avril 2017, par Vahid Jamali

  So I’m trying to make a batch file to use FFMPEG to convert around 1000 MP4 video files.

  I want to recursively go through these folders, possibly use ffprobe to discover the frame height, and then based on the frame height options (360, 480, 720, or 1080 frame height) give them individually different ffmpeg commands.

  I’ve been reading up on various approaches to this just as far as batch processing goes.

  So far I’m at this stage :

  for %%a in ("*.*") do C:\ffinstall\local64\bin-video\ffmpeg -i "%%a"  -c:v libx264 -crf 18 -preset veryslow -tune film -refs 8 -bf 6 -aq-mode 2 -filter_complex "[0:v][1:v]overlay=30:main_h-overlay_h-30,subtitles='D:\add.ass'" -c:a copy "encoded\%%~na.mp4"

  pause

  Code to discover the frame height :

  ffprobe -v error -show_entries stream=height -of default=noprint_wrappers=1 inputfile.mp4

  Trying to figure out conditionals and how their syntax is. Also I’m getting a Unable to parse option value "add.ass" as image size error. Which I believe is due to not being to see the subtitle file.

  Any suggestions on where I can start ? Thanks for any help.