<?xml version="1.0" encoding="UTF-8"?>
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<book id="V4LGuide">
<bookinfo>
<title>Video4Linux Programming</title>
<authorgroup>
<author>
<firstname>Alan</firstname>
<surname>Cox</surname>
<affiliation>
<address>
<email>alan@redhat.com</email>
</address>
</affiliation>
</author>
</authorgroup>
<copyright>
<year>2000</year>
<holder>Alan Cox</holder>
</copyright>
<legalnotice>
<para>
This documentation is free software; you can redistribute
it and/or modify it under the terms of the GNU General Public
License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later
version.
</para>
<para>
This program is distributed in the hope that it will be
useful, but WITHOUT ANY WARRANTY; without even the implied
warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
See the GNU General Public License for more details.
</para>
<para>
You should have received a copy of the GNU General Public
License along with this program; if not, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
MA 02111-1307 USA
</para>
<para>
For more details see the file COPYING in the source
distribution of Linux.
</para>
</legalnotice>
</bookinfo>
<toc></toc>
<chapter id="intro">
<title>Introduction</title>
<para>
Parts of this document first appeared in Linux Magazine under a
ninety day exclusivity.
</para>
<para>
Video4Linux is intended to provide a common programming interface
for the many TV and capture cards now on the market, as well as
parallel port and USB video cameras. Radio, teletext decoders and
vertical blanking data interfaces are also provided.
</para>
</chapter>
<chapter id="radio">
<title>Radio Devices</title>
<para>
There are a wide variety of radio interfaces available for PC's, and these
are generally very simple to program. The biggest problem with supporting
such devices is normally extracting documentation from the vendor.
</para>
<para>
The radio interface supports a simple set of control ioctls standardised
across all radio and tv interfaces. It does not support read or write, which
are used for video streams. The reason radio cards do not allow you to read
the audio stream into an application is that without exc
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