Commit 7a4b3770 authored by Jammy Huang's avatar Jammy Huang Committed by Hans Verkuil
Browse files

media: v4l: Add definition for the Aspeed JPEG format 



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. It 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: default avatarJammy Huang <jammy_huang@aspeedtech.com>
Signed-off-by: default avatarHans Verkuil <hverkuil-cisco@xs4all.nl>
parent c4d34416

Documentation/userspace-api/media/v4l/pixfmt-reserved.rst

+17 −0
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@@ -258,6 +258,23 @@ please make a proposal on the linux-media mailing list. 
        and it is used by various multimedia hardware blocks like GPU, display

        controllers, ISP and video accelerators.

        It contains four planes for progressive video.

    * .. _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.



        The implementation is based on AST2600 A3 datasheet, revision 0.9, which

        is not publicly available. Or you can reference Video stream data format

        – ASPEED mode compression of SDK_User_Guide which available on

        AspeedTech-BMC/openbmc/releases.



        Decoder's implementation can be found here,

        `aspeed_codec <https://github.com/AspeedTech-BMC/aspeed_codec/>`__

.. raw:: latex



    \normalsize

drivers/media/v4l2-core/v4l2-ioctl.c

+1 −0
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@@ -1497,6 +1497,7 @@ static void v4l_fill_fmtdesc(struct v4l2_fmtdesc *fmt) 
		case V4L2_PIX_FMT_MT21C:	descr = "Mediatek Compressed Format"; break;

		case V4L2_PIX_FMT_QC08C:	descr = "QCOM Compressed 8-bit Format"; break;

		case V4L2_PIX_FMT_QC10C:	descr = "QCOM Compressed 10-bit Format"; break;

		case V4L2_PIX_FMT_AJPG:		descr = "Aspeed JPEG"; break;

		default:

			if (fmt->description[0])

				return;

include/uapi/linux/videodev2.h

+1 −0
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@@ -775,6 +775,7 @@ struct v4l2_pix_format { 
#define V4L2_PIX_FMT_HI240    v4l2_fourcc('H', 'I', '2', '4') /* BTTV 8-bit dithered RGB */

#define V4L2_PIX_FMT_QC08C    v4l2_fourcc('Q', '0', '8', 'C') /* Qualcomm 8-bit compressed */

#define V4L2_PIX_FMT_QC10C    v4l2_fourcc('Q', '1', '0', 'C') /* Qualcomm 10-bit compressed */

#define V4L2_PIX_FMT_AJPG     v4l2_fourcc('A', 'J', 'P', 'G') /* Aspeed JPEG */



/* 10bit raw packed, 32 bytes for every 25 pixels, last LSB 6 bits unused */

#define V4L2_PIX_FMT_IPU3_SBGGR10	v4l2_fourcc('i', 'p', '3', 'b') /* IPU3 packed 10-bit BGGR bayer */