1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
|
.. Permission is granted to copy, distribute and/or modify this
.. document under the terms of the GNU Free Documentation License,
.. Version 1.1 or any later version published by the Free Software
.. Foundation, with no Invariant Sections, no Front-Cover Texts
.. and no Back-Cover Texts. A copy of the license is included at
.. Documentation/media/uapi/fdl-appendix.rst.
..
.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections
.. _V4L2-PIX-FMT-YUV420M:
.. _v4l2-pix-fmt-yvu420m:
************************************************************
V4L2_PIX_FMT_YUV420M ('YM12'), V4L2_PIX_FMT_YVU420M ('YM21')
************************************************************
V4L2_PIX_FMT_YVU420M
Variation of ``V4L2_PIX_FMT_YUV420`` and ``V4L2_PIX_FMT_YVU420`` with
planes non contiguous in memory.
Description
===========
This is a multi-planar format, as opposed to a packed format. The three
components are separated into three sub-images or planes.
The Y plane is first. The Y plane has one byte per pixel. For
``V4L2_PIX_FMT_YUV420M`` the Cb data constitutes the second plane which
is half the width and half the height of the Y plane (and of the image).
Each Cb belongs to four pixels, a two-by-two square of the image. For
example, Cb\ :sub:`0` belongs to Y'\ :sub:`00`, Y'\ :sub:`01`,
Y'\ :sub:`10`, and Y'\ :sub:`11`. The Cr data, just like the Cb plane,
is in the third plane.
``V4L2_PIX_FMT_YVU420M`` is the same except the Cr data is stored in the
second plane and the Cb data in the third plane.
If the Y plane has pad bytes after each row, then the Cb and Cr planes
have half as many pad bytes after their rows. In other words, two Cx
rows (including padding) is exactly as long as one Y row (including
padding).
``V4L2_PIX_FMT_YUV420M`` and ``V4L2_PIX_FMT_YVU420M`` are intended to be
used only in drivers and applications that support the multi-planar API,
described in :ref:`planar-apis`.
**Byte Order.**
Each cell is one byte.
.. flat-table::
:header-rows: 0
:stub-columns: 0
* - start0 + 0:
- Y'\ :sub:`00`
- Y'\ :sub:`01`
- Y'\ :sub:`02`
- Y'\ :sub:`03`
* - start0 + 4:
- Y'\ :sub:`10`
- Y'\ :sub:`11`
- Y'\ :sub:`12`
- Y'\ :sub:`13`
* - start0 + 8:
- Y'\ :sub:`20`
- Y'\ :sub:`21`
- Y'\ :sub:`22`
- Y'\ :sub:`23`
* - start0 + 12:
- Y'\ :sub:`30`
- Y'\ :sub:`31`
- Y'\ :sub:`32`
- Y'\ :sub:`33`
* -
* - start1 + 0:
- Cb\ :sub:`00`
- Cb\ :sub:`01`
* - start1 + 2:
- Cb\ :sub:`10`
- Cb\ :sub:`11`
* -
* - start2 + 0:
- Cr\ :sub:`00`
- Cr\ :sub:`01`
* - start2 + 2:
- Cr\ :sub:`10`
- Cr\ :sub:`11`
**Color Sample Location:**
.. flat-table::
:header-rows: 0
:stub-columns: 0
* -
- 0
-
- 1
-
- 2
-
- 3
* - 0
- Y
-
- Y
-
- Y
-
- Y
* -
-
- C
-
-
-
- C
-
* - 1
- Y
-
- Y
-
- Y
-
- Y
* -
* - 2
- Y
-
- Y
-
- Y
-
- Y
* -
-
- C
-
-
-
- C
-
* - 3
- Y
-
- Y
-
- Y
-
- Y
|
