[FFmpeg-user] HDR 4K support in ffmpeg

Kevin Wheatley kevin.j.wheatley at gmail.com
Thu Dec 17 10:17:45 CET 2015


On Wed, Dec 16, 2015 at 11:27 PM, Rens Dijkshoorn <rens at offlinemedia.nl> wrote:
> Currently there is no agreed standard how this
> curve should be defined. The NHK/BBC proposal
> seems to be the most promising
>
> If the input file already has an OETF applied encoding
> with ffmpeg should be straight forward in 10 bit x264
> or x265.
>
> If you need to apply an OETF or EOTF then the 3dlut filter
> i.c with the right 3dlut might be the way to go..

If you have correctly ranged OpenEXR files, then the OpenEXR reader
can apply most of the standard "OETF"/transfer characteristics for
encoding using '-apply_trc', however the NHK/BBC proposal is not one
of them as I did not have a good reference/standard document for the
required values to use in encoded files. It does include SMPTE ST2084
for instance - though you can be at the whims of the downstream
conversion functions doing the correct thing.

You will need to flag which ever image state you have using
'-color_trc' as well - using color_trc would apply if you have already
correctly encoded images in the cases when ffmpeg is unable to
determine the correct value (like when fileformats do not support this
metadata).

Kevin


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