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From:   Ricardo Ribalda <ribalda@chromium.org>
Date:   Tue, 19 Apr 2022 14:18:37 +0200
Message-ID: <CANiDSCv0BA5C8ijO-T_3c2rxGD_yC0LGuG77THkC7_52GZ-dtA@mail.gmail.com>
Subject: Re: [PATCH v3] media: usb: uvc: Add UVC_GUID_FORMAT_H265
To:     Laurent Pinchart <laurent.pinchart@ideasonboard.com>
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
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On Tue, 19 Apr 2022 at 14:17, Laurent Pinchart
<laurent.pinchart@ideasonboard.com> wrote:
>
> 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...

Thought that was the kernel codebase :)

>
> 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


-- 
Ricardo Ribalda