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Diffstat (limited to 'Documentation/DocBook/v4l/pixfmt-nv12.xml')
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1 | <refentry> | ||
2 | <refmeta> | ||
3 | <refentrytitle>V4L2_PIX_FMT_NV12 ('NV12'), V4L2_PIX_FMT_NV21 ('NV21')</refentrytitle> | ||
4 | &manvol; | ||
5 | </refmeta> | ||
6 | <refnamediv> | ||
7 | <refname id="V4L2-PIX-FMT-NV12"><constant>V4L2_PIX_FMT_NV12</constant></refname> | ||
8 | <refname id="V4L2-PIX-FMT-NV21"><constant>V4L2_PIX_FMT_NV21</constant></refname> | ||
9 | <refpurpose>Formats with ½ horizontal and vertical | ||
10 | chroma resolution, also known as YUV 4:2:0. One luminance and one | ||
11 | chrominance plane with alternating chroma samples as opposed to | ||
12 | <constant>V4L2_PIX_FMT_YVU420</constant></refpurpose> | ||
13 | </refnamediv> | ||
14 | <refsect1> | ||
15 | <title>Description</title> | ||
16 | |||
17 | <para>These are two-plane versions of the YUV 4:2:0 format. | ||
18 | The three components are separated into two sub-images or planes. The | ||
19 | Y plane is first. The Y plane has one byte per pixel. For | ||
20 | <constant>V4L2_PIX_FMT_NV12</constant>, a combined CbCr plane | ||
21 | immediately follows the Y plane in memory. The CbCr plane is the same | ||
22 | width, in bytes, as the Y plane (and of the image), but is half as | ||
23 | tall in pixels. Each CbCr pair belongs to four pixels. For example, | ||
24 | Cb<subscript>0</subscript>/Cr<subscript>0</subscript> belongs to | ||
25 | Y'<subscript>00</subscript>, Y'<subscript>01</subscript>, | ||
26 | Y'<subscript>10</subscript>, Y'<subscript>11</subscript>. | ||
27 | <constant>V4L2_PIX_FMT_NV21</constant> is the same except the Cb and | ||
28 | Cr bytes are swapped, the CrCb plane starts with a Cr byte.</para> | ||
29 | |||
30 | <para>If the Y plane has pad bytes after each row, then the | ||
31 | CbCr plane has as many pad bytes after its rows.</para> | ||
32 | |||
33 | <example> | ||
34 | <title><constant>V4L2_PIX_FMT_NV12</constant> 4 × 4 | ||
35 | pixel image</title> | ||
36 | |||
37 | <formalpara> | ||
38 | <title>Byte Order.</title> | ||
39 | <para>Each cell is one byte. | ||
40 | <informaltable frame="none"> | ||
41 | <tgroup cols="5" align="center"> | ||
42 | <colspec align="left" colwidth="2*" /> | ||
43 | <tbody valign="top"> | ||
44 | <row> | ||
45 | <entry>start + 0:</entry> | ||
46 | <entry>Y'<subscript>00</subscript></entry> | ||
47 | <entry>Y'<subscript>01</subscript></entry> | ||
48 | <entry>Y'<subscript>02</subscript></entry> | ||
49 | <entry>Y'<subscript>03</subscript></entry> | ||
50 | </row> | ||
51 | <row> | ||
52 | <entry>start + 4:</entry> | ||
53 | <entry>Y'<subscript>10</subscript></entry> | ||
54 | <entry>Y'<subscript>11</subscript></entry> | ||
55 | <entry>Y'<subscript>12</subscript></entry> | ||
56 | <entry>Y'<subscript>13</subscript></entry> | ||
57 | </row> | ||
58 | <row> | ||
59 | <entry>start + 8:</entry> | ||
60 | <entry>Y'<subscript>20</subscript></entry> | ||
61 | <entry>Y'<subscript>21</subscript></entry> | ||
62 | <entry>Y'<subscript>22</subscript></entry> | ||
63 | <entry>Y'<subscript>23</subscript></entry> | ||
64 | </row> | ||
65 | <row> | ||
66 | <entry>start + 12:</entry> | ||
67 | <entry>Y'<subscript>30</subscript></entry> | ||
68 | <entry>Y'<subscript>31</subscript></entry> | ||
69 | <entry>Y'<subscript>32</subscript></entry> | ||
70 | <entry>Y'<subscript>33</subscript></entry> | ||
71 | </row> | ||
72 | <row> | ||
73 | <entry>start + 16:</entry> | ||
74 | <entry>Cb<subscript>00</subscript></entry> | ||
75 | <entry>Cr<subscript>00</subscript></entry> | ||
76 | <entry>Cb<subscript>01</subscript></entry> | ||
77 | <entry>Cr<subscript>01</subscript></entry> | ||
78 | </row> | ||
79 | <row> | ||
80 | <entry>start + 20:</entry> | ||
81 | <entry>Cb<subscript>10</subscript></entry> | ||
82 | <entry>Cr<subscript>10</subscript></entry> | ||
83 | <entry>Cb<subscript>11</subscript></entry> | ||
84 | <entry>Cr<subscript>11</subscript></entry> | ||
85 | </row> | ||
86 | </tbody> | ||
87 | </tgroup> | ||
88 | </informaltable> | ||
89 | </para> | ||
90 | </formalpara> | ||
91 | |||
92 | <formalpara> | ||
93 | <title>Color Sample Location.</title> | ||
94 | <para> | ||
95 | <informaltable frame="none"> | ||
96 | <tgroup cols="7" align="center"> | ||
97 | <tbody valign="top"> | ||
98 | <row> | ||
99 | <entry></entry> | ||
100 | <entry>0</entry><entry></entry><entry>1</entry><entry></entry> | ||
101 | <entry>2</entry><entry></entry><entry>3</entry> | ||
102 | </row> | ||
103 | <row> | ||
104 | <entry>0</entry> | ||
105 | <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry> | ||
106 | <entry>Y</entry><entry></entry><entry>Y</entry> | ||
107 | </row> | ||
108 | <row> | ||
109 | <entry></entry> | ||
110 | <entry></entry><entry>C</entry><entry></entry><entry></entry> | ||
111 | <entry></entry><entry>C</entry><entry></entry> | ||
112 | </row> | ||
113 | <row> | ||
114 | <entry>1</entry> | ||
115 | <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry> | ||
116 | <entry>Y</entry><entry></entry><entry>Y</entry> | ||
117 | </row> | ||
118 | <row> | ||
119 | <entry></entry> | ||
120 | </row> | ||
121 | <row> | ||
122 | <entry>2</entry> | ||
123 | <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry> | ||
124 | <entry>Y</entry><entry></entry><entry>Y</entry> | ||
125 | </row> | ||
126 | <row> | ||
127 | <entry></entry> | ||
128 | <entry></entry><entry>C</entry><entry></entry><entry></entry> | ||
129 | <entry></entry><entry>C</entry><entry></entry> | ||
130 | </row> | ||
131 | <row> | ||
132 | <entry>3</entry> | ||
133 | <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry> | ||
134 | <entry>Y</entry><entry></entry><entry>Y</entry> | ||
135 | </row> | ||
136 | </tbody> | ||
137 | </tgroup> | ||
138 | </informaltable> | ||
139 | </para> | ||
140 | </formalpara> | ||
141 | </example> | ||
142 | </refsect1> | ||
143 | </refentry> | ||
144 | |||
145 | <!-- | ||
146 | Local Variables: | ||
147 | mode: sgml | ||
148 | sgml-parent-document: "pixfmt.sgml" | ||
149 | indent-tabs-mode: nil | ||
150 | End: | ||
151 | --> | ||