Merge branch 'v4l_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab...
[linux-2.6.git] / Documentation / DocBook / media / v4l / pixfmt-m420.xml
1     <refentry id="V4L2-PIX-FMT-M420">
2       <refmeta>
3         <refentrytitle>V4L2_PIX_FMT_M420 ('M420')</refentrytitle>
4         &manvol;
5       </refmeta>
6       <refnamediv>
7         <refname><constant>V4L2_PIX_FMT_M420</constant></refname>
8         <refpurpose>Format with &frac12; horizontal and vertical chroma
9         resolution, also known as YUV 4:2:0. Hybrid plane line-interleaved
10         layout.</refpurpose>
11       </refnamediv>
12       <refsect1>
13         <title>Description</title>
14
15         <para>M420 is a YUV format with &frac12; horizontal and vertical chroma
16         subsampling (YUV 4:2:0). Pixels are organized as interleaved luma and
17         chroma planes. Two lines of luma data are followed by one line of chroma
18         data.</para>
19         <para>The luma plane has one byte per pixel. The chroma plane contains
20         interleaved CbCr pixels subsampled by &frac12; in the horizontal and
21         vertical directions. Each CbCr pair belongs to four pixels. For example,
22 Cb<subscript>0</subscript>/Cr<subscript>0</subscript> belongs to
23 Y'<subscript>00</subscript>, Y'<subscript>01</subscript>,
24 Y'<subscript>10</subscript>, Y'<subscript>11</subscript>.</para>
25
26         <para>All line lengths are identical: if the Y lines include pad bytes
27         so do the CbCr lines.</para>
28
29         <example>
30           <title><constant>V4L2_PIX_FMT_M420</constant> 4 &times; 4
31 pixel image</title>
32
33           <formalpara>
34             <title>Byte Order.</title>
35             <para>Each cell is one byte.
36                 <informaltable frame="none">
37                 <tgroup cols="5" align="center">
38                   <colspec align="left" colwidth="2*" />
39                   <tbody valign="top">
40                     <row>
41                       <entry>start&nbsp;+&nbsp;0:</entry>
42                       <entry>Y'<subscript>00</subscript></entry>
43                       <entry>Y'<subscript>01</subscript></entry>
44                       <entry>Y'<subscript>02</subscript></entry>
45                       <entry>Y'<subscript>03</subscript></entry>
46                     </row>
47                     <row>
48                       <entry>start&nbsp;+&nbsp;4:</entry>
49                       <entry>Y'<subscript>10</subscript></entry>
50                       <entry>Y'<subscript>11</subscript></entry>
51                       <entry>Y'<subscript>12</subscript></entry>
52                       <entry>Y'<subscript>13</subscript></entry>
53                     </row>
54                     <row>
55                       <entry>start&nbsp;+&nbsp;8:</entry>
56                       <entry>Cb<subscript>00</subscript></entry>
57                       <entry>Cr<subscript>00</subscript></entry>
58                       <entry>Cb<subscript>01</subscript></entry>
59                       <entry>Cr<subscript>01</subscript></entry>
60                     </row>
61                     <row>
62                       <entry>start&nbsp;+&nbsp;16:</entry>
63                       <entry>Y'<subscript>20</subscript></entry>
64                       <entry>Y'<subscript>21</subscript></entry>
65                       <entry>Y'<subscript>22</subscript></entry>
66                       <entry>Y'<subscript>23</subscript></entry>
67                     </row>
68                     <row>
69                       <entry>start&nbsp;+&nbsp;20:</entry>
70                       <entry>Y'<subscript>30</subscript></entry>
71                       <entry>Y'<subscript>31</subscript></entry>
72                       <entry>Y'<subscript>32</subscript></entry>
73                       <entry>Y'<subscript>33</subscript></entry>
74                     </row>
75                     <row>
76                       <entry>start&nbsp;+&nbsp;24:</entry>
77                       <entry>Cb<subscript>10</subscript></entry>
78                       <entry>Cr<subscript>10</subscript></entry>
79                       <entry>Cb<subscript>11</subscript></entry>
80                       <entry>Cr<subscript>11</subscript></entry>
81                     </row>
82                   </tbody>
83                 </tgroup>
84                 </informaltable>
85               </para>
86           </formalpara>
87
88           <formalpara>
89             <title>Color Sample Location.</title>
90             <para>
91                 <informaltable frame="none">
92                 <tgroup cols="7" align="center">
93                   <tbody valign="top">
94                     <row>
95                       <entry></entry>
96                       <entry>0</entry><entry></entry><entry>1</entry><entry></entry>
97                       <entry>2</entry><entry></entry><entry>3</entry>
98                     </row>
99                     <row>
100                       <entry>0</entry>
101                       <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry>
102                       <entry>Y</entry><entry></entry><entry>Y</entry>
103                     </row>
104                     <row>
105                       <entry></entry>
106                       <entry></entry><entry>C</entry><entry></entry><entry></entry>
107                       <entry></entry><entry>C</entry><entry></entry>
108                     </row>
109                     <row>
110                       <entry>1</entry>
111                       <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry>
112                       <entry>Y</entry><entry></entry><entry>Y</entry>
113                     </row>
114                     <row>
115                       <entry></entry>
116                     </row>
117                     <row>
118                       <entry>2</entry>
119                       <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry>
120                       <entry>Y</entry><entry></entry><entry>Y</entry>
121                     </row>
122                     <row>
123                       <entry></entry>
124                       <entry></entry><entry>C</entry><entry></entry><entry></entry>
125                       <entry></entry><entry>C</entry><entry></entry>
126                     </row>
127                     <row>
128                       <entry>3</entry>
129                       <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry>
130                       <entry>Y</entry><entry></entry><entry>Y</entry>
131                     </row>
132                   </tbody>
133                 </tgroup>
134                 </informaltable>
135               </para>
136           </formalpara>
137         </example>
138       </refsect1>
139     </refentry>