Re: [PATCH v5 05/10] media: v4l: Add definition for the Aspeed JPEG format

Sakari Ailus
2021-11-18T12:33:27Z

Hi Jammy,

On Thu, Nov 18, 2021 at 03:40:26PM +0800, Jammy Huang wrote:
> This introduces support for the Aspeed JPEG format, where the new frame
> can refer to previous frame to reduce the amount of compressed data. The
> concept is similar to I/P frame of video compression. I will compare the
> new frame with previous one to decide which macroblock's data is
> changed, and only the changed macroblocks will be compressed.
>
> This Aspeed JPEG format is used by the video engine on Aspeed platforms,
> which is generally adapted for remote KVM.
>
> Signed-off-by: Jammy Huang <jammy_huang@aspeedtech.com>
> ---
> v5:
> - no update
> v4:
> - new
> ---
> Documentation/media/uapi/v4l/pixfmt-reserved.rst | 12 ++++++++++++
> drivers/media/v4l2-core/v4l2-ioctl.c | 1 +
> include/uapi/linux/videodev2.h | 1 +
> 3 files changed, 14 insertions(+)
>
> diff --git a/Documentation/media/uapi/v4l/pixfmt-reserved.rst b/Documentation/media/uapi/v4l/pixfmt-reserved.rst
> index b2cd155e691b..23c05063133d 100644
> --- a/Documentation/media/uapi/v4l/pixfmt-reserved.rst
> +++ b/Documentation/media/uapi/v4l/pixfmt-reserved.rst
> @@ -264,6 +264,18 @@ 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-AJPG:
> +
> + - ``V4L2_PIX_FMT_AJPG``
> + - 'AJPG'
> + - ASPEED JPEG format used by the aspeed-video driver on Aspeed platforms,
> + which is generally adapted for remote KVM.
> + On each frame compression, I will compare the new frame with previous
> + one to decide which macroblock's data is changed, and only the changed
> + macroblocks will be compressed.
> +
> + You could reference to chapter 36, Video Engine, of AST2600's datasheet
> + for more information.

Is this datasheet publicly available? Do you have a URL?

--
Regards,

Sakari Ailus