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authorMauro Carvalho Chehab <mchehab@redhat.com>2011-05-31 15:27:44 -0400
committerMauro Carvalho Chehab <mchehab@redhat.com>2011-07-27 16:52:05 -0400
commit4266129964b8238526936d723de65b419d8069c6 (patch)
tree38c6b5cd3dc99b8599391ffad3b87e399bef56a2 /Documentation/DocBook/media/v4l/pixfmt-nv12.xml
parent04893043ae9ea8aa82b712491ed25ba6c4ffbca3 (diff)
[media] DocBook: Move all media docbook stuff into its own directory
This patch addresses several issues pointed by Randy Dunlap <rdunlap@xenotime.net> at changeset ece722c: - In the generated index.html file, "media" is listed first, but it should be listed in alphabetical order, not first. - The generated files are (hidden) in .tmpmedia/ - The link from the top-level index.html file to "media" is to media/index.html, but the file is actually in .tmpmedia/media/index.html - Please build docs with and without using "O=builddir" and test that. - Would it be possible for media to have its own Makefile instead of merging into this one? Due to the way cleandocs target works, I had to rename the media DocBook to media_api, otherwise cleandocs would remove the /media directory. Thanks-to: Randy Dunlap <rdunlap@xenotime.net> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
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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 &frac12; horizontal and vertical
10chroma resolution, also known as YUV 4:2:0. One luminance and one
11chrominance 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.
18The three components are separated into two sub-images or planes. The
19Y plane is first. The Y plane has one byte per pixel. For
20<constant>V4L2_PIX_FMT_NV12</constant>, a combined CbCr plane
21immediately follows the Y plane in memory. The CbCr plane is the same
22width, in bytes, as the Y plane (and of the image), but is half as
23tall in pixels. Each CbCr pair belongs to four pixels. For example,
24Cb<subscript>0</subscript>/Cr<subscript>0</subscript> belongs to
25Y'<subscript>00</subscript>, Y'<subscript>01</subscript>,
26Y'<subscript>10</subscript>, Y'<subscript>11</subscript>.
27<constant>V4L2_PIX_FMT_NV21</constant> is the same except the Cb and
28Cr 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
31CbCr plane has as many pad bytes after its rows.</para>
32
33 <example>
34 <title><constant>V4L2_PIX_FMT_NV12</constant> 4 &times; 4
35pixel 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&nbsp;+&nbsp;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&nbsp;+&nbsp;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&nbsp;+&nbsp;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&nbsp;+&nbsp;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&nbsp;+&nbsp;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&nbsp;+&nbsp;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 <!--
146Local Variables:
147mode: sgml
148sgml-parent-document: "pixfmt.sgml"
149indent-tabs-mode: nil
150End:
151 -->
generated by cgit v1.2.2 (git 2.25.0) at 2024-11-28 16:50:22 -0500