Re: [PATCH v5 02/14] media:Add nt8 and nt10 video format.

From: Ezequiel Garcia
Date: Tue Jul 27 2021 - 14:04:06 EST


On Tue, 27 Jul 2021 at 14:58, Nicolas Dufresne <nicolas@xxxxxxxxxxxx> wrote:
>
> Le mardi 27 juillet 2021 à 11:20 +0800, Ming Qian a écrit :
> > NT8 is 8-bit tiled nv12 format used by amphion decoder.
> > NT10 is 10-bit tiled format used by amphion decoder.
> > The tile size is 8x128
> >
> > Signed-off-by: Ming Qian <ming.qian@xxxxxxx>
> > Signed-off-by: Shijie Qin <shijie.qin@xxxxxxx>
> > Signed-off-by: Zhou Peng <eagle.zhou@xxxxxxx>
> > ---
> > .../userspace-api/media/v4l/pixfmt-reserved.rst | 15 +++++++++++++++
> > drivers/media/v4l2-core/v4l2-ioctl.c | 2 ++
> > include/uapi/linux/videodev2.h | 2 ++
> > 3 files changed, 19 insertions(+)
> >
> > diff --git a/Documentation/userspace-api/media/v4l/pixfmt-reserved.rst b/Documentation/userspace-api/media/v4l/pixfmt-reserved.rst
> > index c9231e18859b..2deae49210a7 100644
> > --- a/Documentation/userspace-api/media/v4l/pixfmt-reserved.rst
> > +++ b/Documentation/userspace-api/media/v4l/pixfmt-reserved.rst
> > @@ -256,3 +256,18 @@ please make a proposal on the linux-media mailing list.
> > of tiles, resulting in 32-aligned resolutions for the luminance plane
> > and 16-aligned resolutions for the chrominance plane (with 2x2
> > subsampling).
> > + * .. _V4L2-PIX-FMT-NT8:
> > +
> > + - ``V4L2_PIX_FMT_NT8``
> > + - 'NA12'
> > + - Two-planar NV12-based format used by the video engine found on Amphion decoder,
> > + with 8x128 tiles for the luminance plane and chrominance plane.
> > + The number of bytes in one luminance or chrominance row must be divisible by 256.
> > + * .. _V4L2-PIX-FMT-NT10:
>
> There is a large spread of "vendor specific" format that aren't really specific,
> or complex enough to be worth being marked as vendor format. As per my reading
> of this description, this is linearly layout 8x128 tiled format, with no
> compression or anything (well unless you forgot to mention). As a side effect,
> we should give that format an explicit name (NT8 is cryptic). What about
> V4L2_PIX_FMT_NV12_8L128, my colleague is about to send a proposal in that
> direction. That would be NV12 with plane tiled 8x128 bytes and layout linearly,
> row by row, left to right. We already have cryptic formats like SUNXI, HM12 that
> are literally just that, simple tiling, and we endup having to use obscure
> vendor name whenever other HW uses the same.
>
> (this comment extends to the other formats here)
>

Here's the proposal Nicolas is talking about:

https://lore.kernel.org/linux-media/20210727145745.25203-1-ezequiel@xxxxxxxxxxxxx/T/#t

V4L2_PIX_FMT_NV12_8L128 makes sense, please also add support for this
format in GStreamer. I think that makes it easier to confirm the
layout of the format.

Thanks!
Ezequiel