| Hans de Goede | 0e59fd0 | 2011-05-11 09:56:20 -0300 | [diff] [blame] | 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 ½ 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 ½ 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 ½ 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 × 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 + 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 + 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 + 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 + 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 + 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 + 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> |