linux-kernel - Re: [PATCH v5 1/2] media: uapi: Add H264 low-level decoder API compound controls.

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Date:   Tue, 19 Mar 2019 13:03:58 +0900
From:   Tomasz Figa <tfiga@...omium.org>
To:     Maxime Ripard <maxime.ripard@...tlin.com>
Cc:     Hans Verkuil <hans.verkuil@...co.com>,
        Alexandre Courbot <acourbot@...omium.org>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Pawel Osciak <posciak@...omium.org>,
        Paul Kocialkowski <paul.kocialkowski@...tlin.com>,
        Chen-Yu Tsai <wens@...e.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "list@....net:IOMMU DRIVERS <iommu@...ts.linux-foundation.org>, Joerg
        Roedel <joro@...tes.org>," <linux-arm-kernel@...ts.infradead.org>,
        Linux Media Mailing List <linux-media@...r.kernel.org>,
        Nicolas Dufresne <nicolas.dufresne@...labora.com>,
        jenskuske@...il.com, Jernej Skrabec <jernej.skrabec@...il.com>,
        Jonas Karlman <jonas@...boo.se>,
        Ezequiel Garcia <ezequiel@...labora.com>,
        linux-sunxi@...glegroups.com,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        Guenter Roeck <groeck@...omium.org>
Subject: Re: [PATCH v5 1/2] media: uapi: Add H264 low-level decoder API
 compound controls.

On Tue, Mar 19, 2019 at 12:47 AM Maxime Ripard
<maxime.ripard@...tlin.com> wrote:
>
> On Thu, Mar 14, 2019 at 01:13:33PM +0900, Tomasz Figa wrote:
> > On Thu, Mar 14, 2019 at 12:31 AM Maxime Ripard
> > <maxime.ripard@...tlin.com> wrote:
> > >
> > > Hi Tomasz,
> > >
> > > On Fri, Mar 08, 2019 at 03:12:18PM +0900, Tomasz Figa wrote:
> > > > > +.. _v4l2-mpeg-h264:
> > > > > +
> > > > > +``V4L2_CID_MPEG_VIDEO_H264_SPS (struct)``
> > > > > +    Specifies the sequence parameter set (as extracted from the
> > > > > +    bitstream) for the associated H264 slice data. This includes the
> > > > > +    necessary parameters for configuring a stateless hardware decoding
> > > > > +    pipeline for H264.  The bitstream parameters are defined according
> > > > > +    to :ref:`h264`. Unless there's a specific comment, refer to the
> > > > > +    specification for the documentation of these fields, section 7.4.2.1.1
> > > > > +    "Sequence Parameter Set Data Semantics".
> > > >
> > > > I don't see this section being added by this patch. Where does it come from?
> > >
> > > This is referring to the the H264 spec itself, as I was trying to
> > > point out with the reference in that paragraph. How would you write
> > > this down to make it more obvious?
> > >
> >
> > Aha, somehow it didn't come to my mind when reading it. How about
> > something like below?
> >
> > Unless there is a specific comment, refer to the ITU-T Rec. H.264
> > specification, section "7.4.2.1.1 Sequence parameter set data semantics"
> > (as of the 04/2017 edition).
>
> The :ref:`h264` currently expands to "ITU H.264", which means in the
> documentation, in the case above, it ends up as
>
>  The bitstream parameters are defined according to ITU H.264. Unless
>  there’s a specific comment, refer to the specification for the
>  documentation of these fields, section 7.4.2.1.1 “Sequence Parameter
>  Set Data Semantics”.
>
> I could change the reference to have "ITU-T Rec. H.264 Specification
> (04/2017 Edition)". Would that work for you?
>

Sounds good to me.

How about tweaking the text a bit too?

The bitstream parameters are defined according to ITU-T Rec. H.264
Specification (04/2017 Edition), section 7.4.2.1.1 “Sequence Parameter
Set Data Semantics”. For further documentation, refer to the above
specification, unless there is an explicit comment stating otherwise.

Best regards,
Tomasz