linux-kernel - Re: [PATCH 0/2] Document memory-to-memory video codec interfaces

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Date:   Tue, 11 Sep 2018 12:52:43 +0900
From:   Tomasz Figa <tfiga@...omium.org>
To:     Hans Verkuil <hverkuil@...all.nl>
Cc:     Linux Media Mailing List <linux-media@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Stanimir Varbanov <stanimir.varbanov@...aro.org>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Pawel Osciak <posciak@...omium.org>,
        Alexandre Courbot <acourbot@...omium.org>, kamil@...as.org,
        a.hajda@...sung.com, Kyungmin Park <kyungmin.park@...sung.com>,
        jtp.park@...sung.com, Philipp Zabel <p.zabel@...gutronix.de>,
        Tiffany Lin (林慧珊) 
        <tiffany.lin@...iatek.com>,
        Andrew-CT Chen (陳智迪) 
        <andrew-ct.chen@...iatek.com>, todor.tomov@...aro.org,
        nicolas@...fresne.ca,
        Paul Kocialkowski <paul.kocialkowski@...tlin.com>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        dave.stevenson@...pberrypi.org,
        Ezequiel Garcia <ezequiel@...labora.com>
Subject: Re: [PATCH 0/2] Document memory-to-memory video codec interfaces

On Mon, Sep 10, 2018 at 6:14 PM Hans Verkuil <hverkuil@...all.nl> wrote:
>
> Hi Tomasz,
>
> On 07/24/2018 04:06 PM, Tomasz Figa wrote:
> > This series attempts to add the documentation of what was discussed
> > during Media Workshops at LinuxCon Europe 2012 in Barcelona and then
> > later Embedded Linux Conference Europe 2014 in Düsseldorf and then
> > eventually written down by Pawel Osciak and tweaked a bit by Chrome OS
> > video team (but mostly in a cosmetic way or making the document more
> > precise), during the several years of Chrome OS using the APIs in
> > production.
> >
> > Note that most, if not all, of the API is already implemented in
> > existing mainline drivers, such as s5p-mfc or mtk-vcodec. Intention of
> > this series is just to formalize what we already have.
> >
> > It is an initial conversion from Google Docs to RST, so formatting is
> > likely to need some further polishing. It is also the first time for me
> > to create such long RST documention. I could not find any other instance
> > of similar userspace sequence specifications among our Media documents,
> > so I mostly followed what was there in the source. Feel free to suggest
> > a better format.
> >
> > Much of credits should go to Pawel Osciak, for writing most of the
> > original text of the initial RFC.
>
> I'm adding this here as a result of an irc discussion, since it applies
> to both encoders and decoders:
>
> How to handle non-square pixel aspect ratios?
>
> Decoders would have to report it through VIDIOC_CROPCAP, so this needs
> to be documented when the application should call this, but I don't
> think we can provide this information today for encoders.

Thanks for heads up. Will document that VIDIOC_CROPCAP needs to return it.

Best regards,
Tomasz