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 >Codec 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="Video Output Overlay Interface" 17 HREF="x6909.htm"><LINK 18 REL="NEXT" 19 TITLE="Effect Devices Interface" 20 HREF="x7002.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="x6909.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="x7002.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="CODEC" 77 >4.5. Codec Interface</A 78 ></H1 79 ><DIV 80 CLASS="NOTE" 81 ><BLOCKQUOTE 82 CLASS="NOTE" 83 ><P 84 ><B 85 >Suspended: </B 86 >This interface has been be suspended from the V4L2 API 87 implemented in Linux 2.6 until we have more experience with codec 88 device interfaces.</P 89 ></BLOCKQUOTE 90 ></DIV 91 ><P 92 >A V4L2 codec can compress, decompress, transform, or otherwise 93 convert video data from one format into another format, in memory. 94 Applications send data to be converted to the driver through a 95 <A 96 HREF="r14496.htm" 97 ><CODE 98 CLASS="FUNCTION" 99 >write()</CODE 100 ></A 101 > call, and receive the converted data through a 102 <A 103 HREF="r14264.htm" 104 ><CODE 105 CLASS="FUNCTION" 106 >read()</CODE 107 ></A 108 > call. For efficiency a driver may also support streaming 109 I/O.</P 110 ><P 111 >[to do]</P 112 ></DIV 113 ><DIV 114 CLASS="NAVFOOTER" 115 ><HR 116 ALIGN="LEFT" 117 WIDTH="100%"><TABLE 118 SUMMARY="Footer navigation table" 119 WIDTH="100%" 120 BORDER="0" 121 CELLPADDING="0" 122 CELLSPACING="0" 123 ><TR 124 ><TD 125 WIDTH="33%" 126 ALIGN="left" 127 VALIGN="top" 128 ><A 129 HREF="x6909.htm" 130 ACCESSKEY="P" 131 >Prev</A 132 ></TD 133 ><TD 134 WIDTH="34%" 135 ALIGN="center" 136 VALIGN="top" 137 ><A 138 HREF="book1.htm" 139 ACCESSKEY="H" 140 >Home</A 141 ></TD 142 ><TD 143 WIDTH="33%" 144 ALIGN="right" 145 VALIGN="top" 146 ><A 147 HREF="x7002.htm" 148 ACCESSKEY="N" 149 >Next</A 150 ></TD 151 ></TR 152 ><TR 153 ><TD 154 WIDTH="33%" 155 ALIGN="left" 156 VALIGN="top" 157 >Video Output Overlay Interface</TD 158 ><TD 159 WIDTH="34%" 160 ALIGN="center" 161 VALIGN="top" 162 ><A 163 HREF="c6488.htm" 164 ACCESSKEY="U" 165 >Up</A 166 ></TD 167 ><TD 168 WIDTH="33%" 169 ALIGN="right" 170 VALIGN="top" 171 >Effect Devices Interface</TD 172 ></TR 173 ></TABLE 174 ></DIV 175 ></BODY 176 ></HTML 177 > 178
