[FFmpeg-devel] [RFC] QP table API

[Lynne]

Mar 10, 2020, 17:45 by anton at khirnov.net:

> Hi,
> sending a proposed new API for exporting QP tables (and possibly other
> things in the future). It is based on a patch from Juan De León
> (cf. <20190819233655.171637-1-juandl at google.com>).
>
> The set is intended for dicussion, not merging at this point. It does
> not adapt the filters and thus breaks FATE.
>
> Some points to discuss:
> - should the per-block structure store the final per-block quantizer or
>  the delta from the per-frame value (each can be easily computed from
>  the other, so it's more of a convenience question)? deltas are used in
>  the current set as suggested by Lynne
>

I think I explained well why we can't use final block quantization values on IRC.
The most important point why we can't was because what do you do when it exceeds the max codec quantizer - clip or leave as is?
Just leave the delta values, I don't even know why you'd want anything else.



> - do we want per-plane quantizers in each block? The original patch
>  didn't have them. Do we want separate AC/DC quantizers? Anything else?
>

No per plane quantizers in each block.
You dropped the global ac/dc quant for the luma/chroma planes.
I'd like them back because with those you can completely express the quantizers of AV1.