[FFmpeg-devel] [RFC PATCH 00/25] YUVJ removal + filter negotiation

[Niklas Haas]

Following up on the previous attempts at YUVJ removal, this series
implements full filter negotiation. It is WIP because I still need to go
through the remaining AVCodec (which are not covered by FATE) and
properly tag their colorspace and color range support. (See patch 19/25)

The rest should be good, though, so please feel free to review them with
scrutiny.

I decided to combine YUV range negotiation with YUV colorspace
negotiation. Several important points:

1. We now explicitly ignore YUV metadata for non-YUV (RGB/XYZ/PAL)
   formats, as these have no hope of being useful. In particular, we
   force the colorspace to AVCOL_SPC_RGB, mostly for sanity/consistency.

2. We currently continue treating GRAY formats as forced full range,
   which is the swscale status quo. I have a separate series that adds
   full range negotiation to grayscale formats, but it is out of scope
   of this already ominous series.

It was a delicate balancing act to get the new filter negotiation API
integrated into all core filters (in particular vf_scale and
vf_buffersrc) while maintaining forward and backward compatibility and
not breaking FATE, but I managed to find an order that works, by first
adding support to vf_buffersrc to make sure accurate metadata is
available downstream _before_ we insert any conversion filters.