Re: [PATCH 03/10] media: uapi: h264: Split prediction weight parameters

[Nicolas Dufresne]

Le samedi 25 juillet 2020 Ã 22:30 +0900, Alexandre Courbot a Ãcrit :
> On Thu, Jul 16, 2020 at 5:23 AM Ezequiel Garcia <ezequiel@xxxxxxxxxxxxx> wrote:
> > The prediction weight parameters are only required under
> > certain conditions, which depend on slice header parameters.
> > 
> > The slice header syntax specifies that the prediction
> > weight table is present if:
> > 
> > ((weighted_pred_flag && (slice_type == P || slice_type == SP)) || \
> > (weighted_bipred_idc == 1 && slice_type == B))
> 
> This is a pretty important bit - how about mentioning in the documentation when
> this new control is expected to be present, so both drivers and
> userspace submit it
> or omit it in a consistent manner?

This is copy paste from the spec. We can add a reference to the syntax
chapter in the spec that express exactly this if condition (syntax is
express in pseudo code). The bitstream works exactly the same. Note
that it's not a fault to provide the control even if not needed,
drivers will kindly ignore it.

Reference: 7.3.3 Slice header syntax

Nicolas

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