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

    pixfmt-meta-vsp1-hgo
    pixfmt-meta-vsp1-hgt
+120 −0
Original line number Diff line number Diff line
.. -*- 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]
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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 */
+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