1 <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN""http://www.w3.org/TR/html4/loose.dtd"> 2 <HTML 3 ><HEAD 4 ><TITLE 5 >RDS Interface</TITLE 6 ><META 7 NAME="GENERATOR" 8 CONTENT="Modular DocBook HTML Stylesheet Version 1.79"><LINK 9 REL="HOME" 10 TITLE="Video for Linux Two API Specification" 11 HREF="book1.htm"><LINK 12 REL="UP" 13 TITLE="Interfaces" 14 HREF="c6488.htm"><LINK 15 REL="PREVIOUS" 16 TITLE="Radio Interface" 17 HREF="x7578.htm"><LINK 18 REL="NEXT" 19 TITLE="Function Reference" 20 HREF="r7624.htm"></HEAD 21 ><BODY 22 CLASS="SECTION" 23 BGCOLOR="#FFFFFF" 24 TEXT="#000000" 25 LINK="#0000FF" 26 VLINK="#840084" 27 ALINK="#0000FF" 28 ><DIV 29 CLASS="NAVHEADER" 30 ><TABLE 31 SUMMARY="Header navigation table" 32 WIDTH="100%" 33 BORDER="0" 34 CELLPADDING="0" 35 CELLSPACING="0" 36 ><TR 37 ><TH 38 COLSPAN="3" 39 ALIGN="center" 40 >Video for Linux Two API Specification: Revision 0.24</TH 41 ></TR 42 ><TR 43 ><TD 44 WIDTH="10%" 45 ALIGN="left" 46 VALIGN="bottom" 47 ><A 48 HREF="x7578.htm" 49 ACCESSKEY="P" 50 >Prev</A 51 ></TD 52 ><TD 53 WIDTH="80%" 54 ALIGN="center" 55 VALIGN="bottom" 56 >Chapter 4. Interfaces</TD 57 ><TD 58 WIDTH="10%" 59 ALIGN="right" 60 VALIGN="bottom" 61 ><A 62 HREF="r7624.htm" 63 ACCESSKEY="N" 64 >Next</A 65 ></TD 66 ></TR 67 ></TABLE 68 ><HR 69 ALIGN="LEFT" 70 WIDTH="100%"></DIV 71 ><DIV 72 CLASS="SECTION" 73 ><H1 74 CLASS="SECTION" 75 ><A 76 NAME="RDS" 77 >4.11. RDS Interface</A 78 ></H1 79 ><P 80 >The Radio Data System transmits supplementary 81 information in binary format, for example the station name or travel 82 information, on a inaudible audio subcarrier of a radio program. This 83 interface aims at devices capable of receiving and decoding RDS 84 information.</P 85 ><P 86 >The V4L API defines its RDS API as follows.</P 87 ><P 88 >From radio devices supporting it, RDS data can be read 89 with the <A 90 HREF="r14264.htm" 91 ><CODE 92 CLASS="FUNCTION" 93 >read()</CODE 94 ></A 95 > function. The data is packed in groups of three, 96 as follows:<P 97 ></P 98 ><OL 99 TYPE="1" 100 ><LI 101 ><P 102 >First Octet Least Significant Byte of RDS Block</P 103 ></LI 104 ><LI 105 ><P 106 >Second Octet Most Significant Byte of RDS Block</P 107 ></LI 108 ><LI 109 ><P 110 >Third Octet Bit 7: Error bit. Indicates that an 111 uncorrectable error occurred during reception of this block. Bit 6: 112 Corrected bit. Indicates that an error was corrected for this data 113 block. Bits 5-3: Received Offset. Indicates the offset received by the 114 sync system. Bits 2-0: Offset Name. Indicates the offset applied to 115 this data.</P 116 ></LI 117 ></OL 118 ></P 119 ><P 120 >It was argued the RDS API should be 121 extended before integration into V4L2, no new API has been devised yet. 122 Please write to the Video4Linux mailing list for discussion: <A 123 HREF="https://listman.redhat.com/mailman/listinfo/video4linux-list" 124 TARGET="_top" 125 >https://listman.redhat.com/mailman/listinfo/video4linux-list</A 126 >. 127 Meanwhile no V4L2 driver should set the 128 <CODE 129 CLASS="CONSTANT" 130 >V4L2_CAP_RDS_CAPTURE</CODE 131 > capability flag.</P 132 ></DIV 133 ><DIV 134 CLASS="NAVFOOTER" 135 ><HR 136 ALIGN="LEFT" 137 WIDTH="100%"><TABLE 138 SUMMARY="Footer navigation table" 139 WIDTH="100%" 140 BORDER="0" 141 CELLPADDING="0" 142 CELLSPACING="0" 143 ><TR 144 ><TD 145 WIDTH="33%" 146 ALIGN="left" 147 VALIGN="top" 148 ><A 149 HREF="x7578.htm" 150 ACCESSKEY="P" 151 >Prev</A 152 ></TD 153 ><TD 154 WIDTH="34%" 155 ALIGN="center" 156 VALIGN="top" 157 ><A 158 HREF="book1.htm" 159 ACCESSKEY="H" 160 >Home</A 161 ></TD 162 ><TD 163 WIDTH="33%" 164 ALIGN="right" 165 VALIGN="top" 166 ><A 167 HREF="r7624.htm" 168 ACCESSKEY="N" 169 >Next</A 170 ></TD 171 ></TR 172 ><TR 173 ><TD 174 WIDTH="33%" 175 ALIGN="left" 176 VALIGN="top" 177 >Radio Interface</TD 178 ><TD 179 WIDTH="34%" 180 ALIGN="center" 181 VALIGN="top" 182 ><A 183 HREF="c6488.htm" 184 ACCESSKEY="U" 185 >Up</A 186 ></TD 187 ><TD 188 WIDTH="33%" 189 ALIGN="right" 190 VALIGN="top" 191 >Function Reference</TD 192 ></TR 193 ></TABLE 194 ></DIV 195 ></BODY 196 ></HTML 197 > 198
