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 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 × 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 + 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 <!-- 146Local Variables: 147mode: sgml 148sgml-parent-document: "pixfmt.sgml" 149indent-tabs-mode: nil 150End: 151 --> 152