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Commit 5deb1c04 authored by Niklas Söderlund's avatar Niklas Söderlund Committed by Mauro Carvalho Chehab
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[media] v4l: Define a pixel format for the R-Car VSP1 2-D histogram engine 



The format is used on the R-Car VSP1 video queues that carry
2-D histogram statistics data.

Signed-off-by: default avatarNiklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Reviewed-by: default avatarLaurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: default avatarLaurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@s-opensource.com>
parent f2421521

Documentation/media/uapi/v4l/meta-formats.rst

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@@ -13,3 +13,4 @@ These formats are used for the :ref:`metadata` interface only. 
    :maxdepth: 1



    pixfmt-meta-vsp1-hgo

    pixfmt-meta-vsp1-hgt

Documentation/media/uapi/v4l/pixfmt-meta-vsp1-hgt.rst

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.. -*- coding: utf-8; mode: rst -*-



.. _v4l2-meta-fmt-vsp1-hgt:



*******************************

V4L2_META_FMT_VSP1_HGT ('VSPT')

*******************************



Renesas R-Car VSP1 2-D Histogram Data





Description

===========



This format describes histogram data generated by the Renesas R-Car VSP1

2-D Histogram (HGT) engine.



The VSP1 HGT is a histogram computation engine that operates on HSV

data. It operates on a possibly cropped and subsampled input image and

computes the sum, maximum and minimum of the S component as well as a

weighted frequency histogram based on the H and S components.



The histogram is a matrix of 6 Hue and 32 Saturation buckets, 192 in

total. Each HSV value is added to one or more buckets with a weight

between 1 and 16 depending on the Hue areas configuration. Finding the

corresponding buckets is done by inspecting the H and S value independently.



The Saturation position **n** (0 - 31) of the bucket in the matrix is

found by the expression:



    n = S / 8



The Hue position **m** (0 - 5) of the bucket in the matrix depends on

how the HGT Hue areas are configured. There are 6 user configurable Hue

Areas which can be configured to cover overlapping Hue values:



::



         Area 0       Area 1       Area 2       Area 3       Area 4       Area 5

        ________     ________     ________     ________     ________     ________

   \   /|      |\   /|      |\   /|      |\   /|      |\   /|      |\   /|      |\   /

    \ / |      | \ / |      | \ / |      | \ / |      | \ / |      | \ / |      | \ /

     X  |      |  X  |      |  X  |      |  X  |      |  X  |      |  X  |      |  X

    / \ |      | / \ |      | / \ |      | / \ |      | / \ |      | / \ |      | / \

   /   \|      |/   \|      |/   \|      |/   \|      |/   \|      |/   \|      |/   \

  5U   0L      0U   1L      1U   2L      2U   3L      3U   4L      4U   5L      5U   0L

        <0..............................Hue Value............................255>



When two consecutive areas don't overlap (n+1L is equal to nU) the boundary

value is considered as part of the lower area.



Pixels with a hue value included in the centre of an area (between nL and nU

included) are attributed to that single area and given a weight of 16. Pixels

with a hue value included in the overlapping region between two areas (between

n+1L and nU excluded) are attributed to both areas and given a weight for each

of these areas proportional to their position along the diagonal lines

(rounded down).



The Hue area setup must match one of the following constrains:



::



    0L <= 0U <= 1L <= 1U <= 2L <= 2U <= 3L <= 3U <= 4L <= 4U <= 5L <= 5U



::



    0U <= 1L <= 1U <= 2L <= 2U <= 3L <= 3U <= 4L <= 4U <= 5L <= 5U <= 0L



**Byte Order.**

All data is stored in memory in little endian format. Each cell in the tables

contains one byte.



.. flat-table:: VSP1 HGT Data - (776 bytes)

    :header-rows:  2

    :stub-columns: 0



    * - Offset

      - :cspan:`4` Memory

    * -

      - [31:24]

      - [23:16]

      - [15:8]

      - [7:0]

    * - 0

      - -

      - S max [7:0]

      - -

      - S min [7:0]

    * - 4

      - :cspan:`4` S sum [31:0]

    * - 8

      - :cspan:`4` Histogram bucket (m=0, n=0) [31:0]

    * - 12

      - :cspan:`4` Histogram bucket (m=0, n=1) [31:0]

    * -

      - :cspan:`4` ...

    * - 132

      - :cspan:`4` Histogram bucket (m=0, n=31) [31:0]

    * - 136

      - :cspan:`4` Histogram bucket (m=1, n=0) [31:0]

    * -

      - :cspan:`4` ...

    * - 264

      - :cspan:`4` Histogram bucket (m=2, n=0) [31:0]

    * -

      - :cspan:`4` ...

    * - 392

      - :cspan:`4` Histogram bucket (m=3, n=0) [31:0]

    * -

      - :cspan:`4` ...

    * - 520

      - :cspan:`4` Histogram bucket (m=4, n=0) [31:0]

    * -

      - :cspan:`4` ...

    * - 648

      - :cspan:`4` Histogram bucket (m=5, n=0) [31:0]

    * -

      - :cspan:`4` ...

    * - 772

      - :cspan:`4` Histogram bucket (m=5, n=31) [31:0]

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

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@@ -1234,6 +1234,7 @@ static void v4l_fill_fmtdesc(struct v4l2_fmtdesc *fmt) 
	case V4L2_TCH_FMT_TU16:		descr = "16-bit unsigned touch data"; break;

	case V4L2_TCH_FMT_TU08:		descr = "8-bit unsigned touch data"; break;

	case V4L2_META_FMT_VSP1_HGO:	descr = "R-Car VSP1 1-D Histogram"; break;

	case V4L2_META_FMT_VSP1_HGT:	descr = "R-Car VSP1 2-D Histogram"; break;



	default:

		/* Compressed formats */

include/uapi/linux/videodev2.h

+2 −1
Original line number Diff line number Diff line
@@ -677,7 +677,8 @@ struct v4l2_pix_format { 
#define V4L2_TCH_FMT_TU08	v4l2_fourcc('T', 'U', '0', '8') /* 8-bit unsigned touch data */



/* Meta-data formats */

#define V4L2_META_FMT_VSP1_HGO    v4l2_fourcc('V', 'S', 'P', 'H') /* R-Car VSP1 Histogram */

#define V4L2_META_FMT_VSP1_HGO    v4l2_fourcc('V', 'S', 'P', 'H') /* R-Car VSP1 1-D Histogram */

#define V4L2_META_FMT_VSP1_HGT    v4l2_fourcc('V', 'S', 'P', 'T') /* R-Car VSP1 2-D Histogram */



/* priv field value to indicates that subsequent fields are valid. */

#define V4L2_PIX_FMT_PRIV_MAGIC		0xfeedcafe