linux-kernel - Re: [PATCH v3 1/2] media: uapi: Add H264 low-level decoder API compound controls.

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Message-ID: <fb7e6bf4474583535961712bac5248b43dd47af0.camel@collabora.com>
Date:   Tue, 12 Feb 2019 18:17:52 -0300
From:   Ezequiel Garcia <ezequiel@...labora.com>
To:     Maxime Ripard <maxime.ripard@...tlin.com>,
        Hans Verkuil <hverkuil@...all.nl>
Cc:     hans.verkuil@...co.com, acourbot@...omium.org,
        sakari.ailus@...ux.intel.com,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        tfiga@...omium.org, posciak@...omium.org,
        Paul Kocialkowski <paul.kocialkowski@...tlin.com>,
        Chen-Yu Tsai <wens@...e.org>, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-media@...r.kernel.org,
        nicolas.dufresne@...labora.com, jenskuske@...il.com,
        jernej.skrabec@...il.com, jonas@...boo.se,
        linux-sunxi@...glegroups.com,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        Guenter Roeck <groeck@...omium.org>
Subject: Re: [PATCH v3 1/2] media: uapi: Add H264 low-level decoder API
 compound controls.

On Tue, 2019-02-12 at 14:05 +0100, Maxime Ripard wrote:
> Hi,
> 
> On Mon, Feb 11, 2019 at 04:21:47PM +0100, Hans Verkuil wrote:
> > > I think the API should be designed with 4k video in mind. So if some of
> > > these constants would be too small when dealing with 4k (even if the
> > > current HW doesn't support this yet), then these constants would have to
> > > be increased.
> > > 
> > > And yes, I know 8k video is starting to appear, but I think it is OK
> > > that additional control(s) would be needed to support 8k.
> > 
> > Hmm, 4k (and up) is much more likely to use HEVC. So perhaps designing this
> > for 4k is overkill.
> > 
> > Does anyone know if H.264 is used for 4k video at all? If not (or if very
> > rare), then just ignore this.
> 
> I don't know the state of it right now, but until quite recently
> youtube at least was encoding their 4k videos in both VP9 and
> H264. They might have moved to h265 since, but considering 4k doesn't
> seem unreasonable.
> 

Just asked the multimedia team here, and they say that 4k videos are in
fact widely used for both H264 and VP9 because of the HEVC licensing issues,
and because gains in compressions are not so impressive.

Regards,
Ezequiel