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