FFmpeg is frequently used by different studios for encoding their media, however the documentation for ffmpeg is often poor, or cryptic so its often harder than it should be to come up with a good starting point. We are aiming to come up with recommendations for different scenarios as well as document what the different flags are doing with the aim to make this easier to get to a good baseline.
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| Name | Source | ffmpeg flags | Description | Size |
|---|---|---|---|---|
| colorspace_yuv444p10le | https://trac.ffmpeg.org/wiki/colorspace | -c:v libx264 -preset placebo -qp 0 -x264-params "keyint=15:no-deblock=1" -pix_fmt yuv444p10le -sws_flags spline+accurate_rnd+full_chroma_int -vf "colorspace=bt709:iall=bt601-6-625:fast=1" -color_range 1 -colorspace 1 -color_primaries 1 -color_trc 1 | ||
| Prores 4444 | -c:v prores_ks -profile:v 4444 -qscale:v 1 -pix_fmt yuv444p10le -sws_flags spline+accurate_rnd+full_chroma_int -vf "colorspace=bt709:iall=bt601-6-625:fast=1" -color_range 1 -colorspace 1 -color_primaries 1 -color_trc 1 | |||
| -profile:v 4444 is equivalent to -profile:v 4 | ||||
| shotgun_diy_encode | https://support.shotgunsoftware.com/hc/en-us/articles/219030418-Do-it-yourself-DIY-transcoding', | -vcodec libx264 -pix_fmt yuv420p -g 30 -vprofile high -bf 0 -crf 2 | ||
| Prores 422 HQ | Some FFMpeg commands I need to remember for converting footage for video editing. http://bit.ly/vidsnippets · GitHub |
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Note the -profile:v 3 is equivalent to -profile:v hq | ||||
VMAF
I did explore using VMAF - Video Multi-Method Assessment Fusion as a way to quantify the compression, the notes for setting this up are below, however I think we are going with a fairly high compression factor , so I think this is probably not really going to help us much.
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Most windows laptops and most monitors typically default to a sRGB color space, the tricky part is that sRGB is sometimes interpreted as having exactly a 2.2 gamma, and sometimes a hybrid curve (based on the spec), for more details on this, see:
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Questions:
- On windows do any of the browsers read the color management settings flags for each monitor?
- Why does everybody set -color_trc 1 ? - it seems completely meaningless?
- Find the details about the firefox plugin for color management?
- What do ICC profiles for stills do on windows/linux boxes? - Are there situations where this is replicated for movies.
| Browser | Platform | Interpret NCLC flags | Color Managed | Tested |
|---|---|---|---|---|
| Firefox | OSX | No | ||
| Firefox | Windows | No | ||
| Firefox | Windows | |||
| Safari | OSX | Yes | Yes | |
| Chrome | OSX | Yes | Yes | |
| Chrome | Windows | No | ||
| Chrome | Linux |
Gamma 2.4
There is not a color_trc flag for gamma 2.4, the only option that exists for OSX is a cheat
using the flags "-color_trc 2 -movflags write_colr+write_gama -mov_gamma 2.4" but this only works for a full quicktime file, not a mp4 file. So the resulting file will not play correctly on windows.
ffmpeg -y -i chip-chart-1080.png -c:v libx264 -pix_fmt yuv444p -qscale:v 1 -sws_flags spline+accurate_rnd+full_chroma_int -vf "colorspace=bt709:iall=bt601-6-625:fast=1" -color_range 1 -colorspace 1 -color_primaries 1 -color_trc 2 -movflags write_colr+write_gama -mov_gamma 2.4 test2-h264-ffmpeg-yuv444p-gamma24.mp4