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