Re: [PATCH v3] media: usb: uvc: Add UVC_GUID_FORMAT_H265

[Nicolas Dufresne <nicolas@ndufresne.ca>]

Le mardi 19 avril 2022 à 14:18 +0200, Ricardo Ribalda a écrit :
> 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 :)

You'll find multiple fourcc for the same thing in the linux kernel ;-P

> 
> > 
> > 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
> 
> 
>