[FFmpeg-devel] [PATCH] avcodec/options: Add options for inputing HDR10-related metadata

[Lynne]

Aug 11, 2020, 03:47 by kenny.mcclive at me.com:

> Previously, the only way to input the master display and content light metadata required for HDR10 was through x265-params. Obviously, that only worked with x265. If you wanted to use a different encoder like nvenc, you were out of luck. The options specified are written to the container (mov or matroska) only. Additional work would be required to write it to frames. The default values for the master display options may seem unorthodox, but it allows you to differentiate between 0 (which some movies use) and unspecified. The same was not done for content light metadata because 0 seems to mean unspecified in other systems such as x265.
>

I don't like this as-is.
For HDR transcoding/tonemapping we rely purely on frame side data atm. How would adding
new metadata to avcodeccontext work with this? Would the avcodec metadata overwrite the
avframe side data? We cannot break existing behavior as its actually used in production.
Furthermore, considering all codecs which support HDR carry data rather than rely on the
container, remuxing would break. Some ideas were discussed about adding a bsf to deal with this,
and if we were to add a bsf, it would make this patch largely redundant, apart from setting
the container fields, which is only somewhat useful.
For now, what's the problem with just using the AVFrame fields for the container as well?
Then you'll only need a filter to set the metadata.