[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 11:22, Nicolas George <george at nsup.org> wrote:

> Rostislav Pehlivanov (12019-01-04):
> > > +typedef struct AVRegionOfInterest {
> > > +    size_t self_size;
> > > +    size_t top;
> > > +    size_t bottom;
> > > +    size_t left;
> > > +    size_t right;
> > I'd still much rather have uints with fixed sizes than these platform
> > dependent types.
>
> Guo, Yejun said:
>
> >> I usually choose 'size_t' for the meanings with length/size.
>
> But that is a mistake. size_t is for length/size of objects in memory,
> not any length/size.
>
> These numbers, unless I am mistaken, are coordinates within an AVFrame.
> In that case, the only correct type is the same as AVFrame.width and
> AVFrame.height.
>

Which are in pixels, not bytes.



>
> > Use an AVRational with a denum set to the max quantizer
>
> Can you explain "set to the max quantizer"? For decoders it makes sense,
> but what should the encoders do? Return EINVAL? Scale?
>

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.