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

Jammy Huang
2021-11-19T02:04:45Z

Hi Sakari,

On 2021/11/18 下午 08:33, Sakari Ailus wrote:
> 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?

Sorry, this datasheet is not publicly available.
Hans mentioned this as well in the discussion below:

https://lkml.org/lkml/2021/11/10/101

--
Best Regards
Jammy