On 15/07/2020 22:22, Ezequiel Garcia wrote:
> Commit 0b0393d59eb4a ("media: uapi: h264: clarify
> expected scaling_list_4x4/8x8 order") improved the
> documentation on H264 scaling lists order.
>
> This commit improves the documentation by clarifying
> that the lists themselves are expected in matrix order.
"matrix order" is not a well defined term. Especially since different
programming languages lay out matrices differently (e.g. fortran uses
column-major order). Perhaps something like this is more unambiguous:
"The values on each scaling list are in row-major order."
BTW, why not be explicit and use:
__u8 scaling_list_4x4[6][4][4];
__u8 scaling_list_8x8[6][8][8];
That makes it explicit and the order is just that of what the C language
uses.
Regards,
Hans
>
> Signed-off-by: Ezequiel Garcia <ezequiel@xxxxxxxxxxxxx>
> ---
> Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst b/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst
> index c2e17c02f77e..16bfc98ab2f6 100644
> --- a/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst
> +++ b/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst
> @@ -1725,12 +1725,14 @@ enum v4l2_mpeg_video_h264_hierarchical_coding_type -
> - ``scaling_list_4x4[6][16]``
> - Scaling matrix after applying the inverse scanning process.
> Expected list order is Intra Y, Intra Cb, Intra Cr, Inter Y,
> - Inter Cb, Inter Cr.
> + Inter Cb, Inter Cr. The values on each scaling list are
> + expected in matrix order.
> * - __u8
> - ``scaling_list_8x8[6][64]``
> - Scaling matrix after applying the inverse scanning process.
> Expected list order is Intra Y, Inter Y, Intra Cb, Inter Cb,
> - Intra Cr, Inter Cr.
> + Intra Cr, Inter Cr. The values on each scaling list are
> + expected in matrix order.
>
> ``V4L2_CID_MPEG_VIDEO_H264_SLICE_PARAMS (struct)``
> Specifies the slice parameters (as extracted from the bitstream)
>
