[FFmpeg-devel] [PATCH V5 1/2] avutil: add ROI (Region Of Interest) data struct and bump version

[Rostislav Pehlivanov]

On Fri, 4 Jan 2019 at 14:02, Nicolas George <george at nsup.org> wrote:

> Rostislav Pehlivanov (12019-01-04):
> > Which are in pixels, not bytes.
>
> And plain int, not uint32_t.
>
> > This is an encoder-only interface for now. For vp9 the denum would be 255
> > for example. They would warn on out of range qdelta.
> > I still don't get why this can't be an int.
>
> "For now" is the key. This is a new API, we should try to think of the
> likely future uses, not just what we have in mind right now.
>
> So: very likely use of ROI: -vf facedetect.
>
> Since the filter will not know the specifics of the encoder, it needs to
> be able to express things (and have default value) in an
> encoder-agnostic way.
>

Hence an AVRational is appropriate as you can have fractions between 0 and
1, the encoder can adjust it and it'll be agnostic.