Hi Jammy, On Fri, Nov 19, 2021 at 10:02:40AM +0800, Jammy Huang wrote: > 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@xxxxxxxxxxxxxx> > > > --- > > > 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 If the vendor documentation is not publicly available, you'll need to have the format documented here. Alternatively an open source implementation (e.g. LGPL) is presumably fine, too. -- Regards, Sakari Ailus
