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1 <refentry> 2 <refmeta> 3 <refentrytitle>V4L2_PIX_FMT_NV12M ('NM12'), V4L2_PIX_FMT_NV21M ('NM21'), V4L2_PIX_FMT_NV12MT_16X16</refentrytitle> 4 &manvol; 5 </refmeta> 6 <refnamediv> 7 <refname id="V4L2-PIX-FMT-NV12M"><constant>V4L2_PIX_FMT_NV12M</constant></refname> 8 <refname id="V4L2-PIX-FMT-NV21M"><constant>V4L2_PIX_FMT_NV21M</constant></refname> 9 <refname id="V4L2-PIX-FMT-NV12MT-16X16"><constant>V4L2_PIX_FMT_NV12MT_16X16</constant></refname> 10 <refpurpose>Variation of <constant>V4L2_PIX_FMT_NV12</constant> and <constant>V4L2_PIX_FMT_NV21</constant> with planes 11 non contiguous in memory. </refpurpose> 12 </refnamediv> 13 <refsect1> 14 <title>Description</title> 15 16 <para>This is a multi-planar, two-plane version of the YUV 4:2:0 format. 17 The three components are separated into two sub-images or planes. 18 <constant>V4L2_PIX_FMT_NV12M</constant> differs from <constant>V4L2_PIX_FMT_NV12 19 </constant> in that the two planes are non-contiguous in memory, i.e. the chroma 20 plane do not necessarily immediately follows the luma plane. 21 The luminance data occupies the first plane. The Y plane has one byte per pixel. 22 In the second plane there is a chrominance data with alternating chroma samples. 23 The CbCr plane is the same width, in bytes, as the Y plane (and of the image), 24 but is half as tall in pixels. Each CbCr pair belongs to four pixels. For example, 25 Cb<subscript>0</subscript>/Cr<subscript>0</subscript> belongs to 26 Y'<subscript>00</subscript>, Y'<subscript>01</subscript>, 27 Y'<subscript>10</subscript>, Y'<subscript>11</subscript>. 28 <constant>V4L2_PIX_FMT_NV12MT_16X16</constant> is the tiled version of 29 <constant>V4L2_PIX_FMT_NV12M</constant> with 16x16 macroblock tiles. Here pixels 30 are arranged in 16x16 2D tiles and tiles are arranged in linear order in memory. 31 <constant>V4L2_PIX_FMT_NV21M</constant> is the same as <constant>V4L2_PIX_FMT_NV12M</constant> 32 except the Cb and Cr bytes are swapped, the CrCb plane starts with a Cr byte.</para> 33 34 <para><constant>V4L2_PIX_FMT_NV12M</constant> is intended to be 35 used only in drivers and applications that support the multi-planar API, 36 described in <xref linkend="planar-apis"/>. </para> 37 38 <para>If the Y plane has pad bytes after each row, then the 39 CbCr plane has as many pad bytes after its rows.</para> 40 41 <example> 42 <title><constant>V4L2_PIX_FMT_NV12M</constant> 4 × 4 pixel image</title> 43 44 <formalpara> 45 <title>Byte Order.</title> 46 <para>Each cell is one byte. 47 <informaltable frame="none"> 48 <tgroup cols="5" align="center"> 49 <colspec align="left" colwidth="2*" /> 50 <tbody valign="top"> 51 <row> 52 <entry>start0 + 0:</entry> 53 <entry>Y'<subscript>00</subscript></entry> 54 <entry>Y'<subscript>01</subscript></entry> 55 <entry>Y'<subscript>02</subscript></entry> 56 <entry>Y'<subscript>03</subscript></entry> 57 </row> 58 <row> 59 <entry>start0 + 4:</entry> 60 <entry>Y'<subscript>10</subscript></entry> 61 <entry>Y'<subscript>11</subscript></entry> 62 <entry>Y'<subscript>12</subscript></entry> 63 <entry>Y'<subscript>13</subscript></entry> 64 </row> 65 <row> 66 <entry>start0 + 8:</entry> 67 <entry>Y'<subscript>20</subscript></entry> 68 <entry>Y'<subscript>21</subscript></entry> 69 <entry>Y'<subscript>22</subscript></entry> 70 <entry>Y'<subscript>23</subscript></entry> 71 </row> 72 <row> 73 <entry>start0 + 12:</entry> 74 <entry>Y'<subscript>30</subscript></entry> 75 <entry>Y'<subscript>31</subscript></entry> 76 <entry>Y'<subscript>32</subscript></entry> 77 <entry>Y'<subscript>33</subscript></entry> 78 </row> 79 <row> 80 <entry></entry> 81 </row> 82 <row> 83 <entry>start1 + 0:</entry> 84 <entry>Cb<subscript>00</subscript></entry> 85 <entry>Cr<subscript>00</subscript></entry> 86 <entry>Cb<subscript>01</subscript></entry> 87 <entry>Cr<subscript>01</subscript></entry> 88 </row> 89 <row> 90 <entry>start1 + 4:</entry> 91 <entry>Cb<subscript>10</subscript></entry> 92 <entry>Cr<subscript>10</subscript></entry> 93 <entry>Cb<subscript>11</subscript></entry> 94 <entry>Cr<subscript>11</subscript></entry> 95 </row> 96 </tbody> 97 </tgroup> 98 </informaltable> 99 </para> 100 </formalpara> 101 102 <formalpara> 103 <title>Color Sample Location.</title> 104 <para> 105 <informaltable frame="none"> 106 <tgroup cols="7" align="center"> 107 <tbody valign="top"> 108 <row> 109 <entry></entry> 110 <entry>0</entry><entry></entry><entry>1</entry><entry></entry> 111 <entry>2</entry><entry></entry><entry>3</entry> 112 </row> 113 <row> 114 <entry>0</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 <entry></entry><entry>C</entry><entry></entry><entry></entry> 121 <entry></entry><entry>C</entry><entry></entry> 122 </row> 123 <row> 124 <entry>1</entry> 125 <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry> 126 <entry>Y</entry><entry></entry><entry>Y</entry> 127 </row> 128 <row> 129 <entry></entry> 130 </row> 131 <row> 132 <entry>2</entry> 133 <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry> 134 <entry>Y</entry><entry></entry><entry>Y</entry> 135 </row> 136 <row> 137 <entry></entry> 138 <entry></entry><entry>C</entry><entry></entry><entry></entry> 139 <entry></entry><entry>C</entry><entry></entry> 140 </row> 141 <row> 142 <entry>3</entry> 143 <entry>Y</entry><entry></entry><entry>Y</entry><entry></entry> 144 <entry>Y</entry><entry></entry><entry>Y</entry> 145 </row> 146 </tbody> 147 </tgroup> 148 </informaltable> 149 </para> 150 </formalpara> 151 </example> 152 </refsect1> 153 </refentry>
