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Date:   Tue, 19 Apr 2022 15:17:38 +0300
From:   Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To:     Ricardo Ribalda <ribalda@chromium.org>
Cc:     James_Lin <Ping-lei.Lin@mediatek.com>,
        linux-kernel@vger.kernel.org,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Hans Verkuil <hverkuil-cisco@xs4all.nl>,
        Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>,
        Arnd Bergmann <arnd@arndb.de>,
        Sergey Senozhatsky <senozhatsky@chromium.org>,
        Alexandre Courbot <acourbot@chromium.org>,
        Sakari Ailus <sakari.ailus@linux.intel.com>,
        linux-media@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-mediatek@lists.infradead.org, sherlock.chang@mediatek.com,
        lecopzer.chen@mediatek.com, max.yan@mediatek.com,
        tm.wu@mediatek.com
Subject: Re: [PATCH v3] media: usb: uvc: Add UVC_GUID_FORMAT_H265
Message-ID: <Yl6oYlv+t63+5dVP@pendragon.ideasonboard.com>
References: <20220418090652.3156-1-Ping-lei.Lin@mediatek.com>
 <CANiDSCvLb785H7qyAzSfTSBRpO2eM-oJFF5SgVHXdL1O-GusLA@mail.gmail.com>
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Hello,

On Tue, Apr 19, 2022 at 01:46:15PM +0200, Ricardo Ribalda wrote:
> On Mon, 18 Apr 2022 at 11:07, James_Lin <Ping-lei.Lin@mediatek.com> wrote:
> >
> > This patch aims to add UVC_GUID_FORMAT_H265
> > High Efficiency Video Coding (HEVC), also known as H.265 and MPEG-H Part 2.
> > They describe the same video encoding method.
> > So for handling their behavior is the same.
> > However, when external camera device describes this encoding method,
> > some use hevc, some use h265.
> > There is no uniform specification to describe this encoding method.
> > So if an external camera device use h265 to describe this encoding method,
> > driver will not recognize it.
> > Therefore, this patch is to enable driver to read HEVC/H265
> > and convert it to V4L2_PIX_FMT_HEVC.
> >
> > Signed-off-by: James_Lin <Ping-lei.Lin@mediatek.com>
> 
> Reviewed-by: Ricardo Ribalda <ribalda@chromium.org>
> > ---
> >  drivers/media/usb/uvc/uvc_driver.c | 5 +++++
> >  drivers/media/usb/uvc/uvcvideo.h   | 3 +++
> >  2 files changed, 8 insertions(+)
> >
> > diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
> > index dda0f0aa78b8..e437e9f95890 100644
> > --- a/drivers/media/usb/uvc/uvc_driver.c
> > +++ b/drivers/media/usb/uvc/uvc_driver.c
> > @@ -154,6 +154,11 @@ static struct uvc_format_desc uvc_fmts[] = {
> >                 .guid           = UVC_GUID_FORMAT_H264,
> >                 .fcc            = V4L2_PIX_FMT_H264,
> >         },
> 
> Maybe I would add a comment here saying that some cameras represent
> hevc as h265.

I wish there would be a 4CC and GUID standard with a centralized
registry...

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

> > +       {
> > +               .name           = "H.265",
> > +               .guid           = UVC_GUID_FORMAT_H265,
> > +               .fcc            = V4L2_PIX_FMT_HEVC,
> > +       },
> >         {
> >                 .name           = "Greyscale 8 L/R (Y8I)",
> >                 .guid           = UVC_GUID_FORMAT_Y8I,
> > diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
> > index 143230b3275b..41f4d8c33f2a 100644
> > --- a/drivers/media/usb/uvc/uvcvideo.h
> > +++ b/drivers/media/usb/uvc/uvcvideo.h
> > @@ -139,6 +139,9 @@
> >  #define UVC_GUID_FORMAT_H264 \
> >         { 'H',  '2',  '6',  '4', 0x00, 0x00, 0x10, 0x00, \
> >          0x80, 0x00, 0x00, 0xaa, 0x00, 0x38, 0x9b, 0x71}
> > +#define UVC_GUID_FORMAT_H265 \
> > +       { 'H',  '2',  '6',  '5', 0x00, 0x00, 0x10, 0x00, \
> > +        0x80, 0x00, 0x00, 0xaa, 0x00, 0x38, 0x9b, 0x71}
> >  #define UVC_GUID_FORMAT_Y8I \
> >         { 'Y',  '8',  'I',  ' ', 0x00, 0x00, 0x10, 0x00, \
> >          0x80, 0x00, 0x00, 0xaa, 0x00, 0x38, 0x9b, 0x71}

-- 
Regards,

Laurent Pinchart