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+<title>Introduction</title>
+
+<section id="requisites">
+<title>What you need to know</title>
+
+<para>The reader of this document is required to have some knowledge in
+the area of digital video broadcasting (DVB) and should be familiar with
+part I of the MPEG2 specification ISO/IEC 13818 (aka ITU-T H.222), i.e
+you should know what a program/transport stream (PS/TS) is and what is
+meant by a packetized elementary stream (PES) or an I-frame.</para>
+
+<para>Various DVB standards documents are available from
+<ulink url="http://www.dvb.org" /> and/or
+<ulink url="http://www.etsi.org" />.</para>
+
+<para>It is also necessary to know how to access unix/linux devices and
+how to use ioctl calls. This also includes the knowledge of C or C++.
+</para>
+</section>
+
+<section id="history">
+<title>History</title>
+
+<para>The first API for DVB cards we used at Convergence in late 1999
+was an extension of the Video4Linux API which was primarily developed
+for frame grabber cards. As such it was not really well suited to be
+used for DVB cards and their new features like recording MPEG streams
+and filtering several section and PES data streams at the same time.
+</para>
+
+<para>In early 2000, we were approached by Nokia with a proposal for a
+new standard Linux DVB API. As a commitment to the development of
+terminals based on open standards, Nokia and Convergence made it
+available to all Linux developers and published it on
+<ulink url="http://www.linuxtv.org/" /> in September 2000.
+Convergence is the maintainer of the Linux DVB API. Together with the
+LinuxTV community (i.e. you, the reader of this document), the Linux DVB
+API will be constantly reviewed and improved. With the Linux driver for
+the Siemens/Hauppauge DVB PCI card Convergence provides a first
+implementation of the Linux DVB API.</para>
+</section>
+
+<section id="overview">
+<title>Overview</title>
+
+<figure id="stb_components">
+<title>Components of a DVB card/STB</title>
+<mediaobject>
+<imageobject>
+<imagedata fileref="dvbstb.pdf" format="PS" />
+</imageobject>
+<imageobject>
+<imagedata fileref="dvbstb.png" format="PNG" />
+</imageobject>
+</mediaobject>
+</figure>
+
+<para>A DVB PCI card or DVB set-top-box (STB) usually consists of the
+following main hardware components: </para>
+
+<itemizedlist>
+ <listitem>
+
+<para>Frontend consisting of tuner and DVB demodulator</para>
+
+<para>Here the raw signal reaches the DVB hardware from a satellite dish
+or antenna or directly from cable. The frontend down-converts and
+demodulates this signal into an MPEG transport stream (TS). In case of a
+satellite frontend, this includes a facility for satellite equipment
+control (SEC), which allows control of LNB polarization, multi feed
+switches or dish rotors.</para>
+
+</listitem>
+ <listitem>
+
+<para>Conditional Access (CA) hardware like CI adapters and smartcard slots
+</para>
+
+<para>The complete TS is passed through the CA hardware. Programs to
+which the user has access (controlled by the smart card) are decoded in
+real time and re-inserted into the TS.</para>
+
+</listitem>
+ <listitem>
+ <para>Demultiplexer which filters the incoming DVB stream</para>
+
+<para>The demultiplexer splits the TS into its components like audio and
+video streams. Besides usually several of such audio and video streams
+it also contains data streams with information about the programs
+offered in this or other streams of the same provider.</para>
+
+</listitem>
+<listitem>
+
+<para>MPEG2 audio and video decoder</para>
+
+<para>The main targets of the demultiplexer are the MPEG2 audio and
+video decoders. After decoding they pass on the uncompressed audio and
+video to the computer screen or (through a PAL/NTSC encoder) to a TV
+set.</para>
+
+
+</listitem>
+</itemizedlist>
+
+<para><xref linkend="stb_components" /> shows a crude schematic of the control and data flow
+between those components.</para>
+
+<para>On a DVB PCI card not all of these have to be present since some
+functionality can be provided by the main CPU of the PC (e.g. MPEG
+picture and sound decoding) or is not needed (e.g. for data-only uses
+like &#8220;internet over satellite&#8221;). Also not every card or STB
+provides conditional access hardware.</para>
+
+</section>
+
+<section id="dvb_devices">
+<title>Linux DVB Devices</title>
+
+<para>The Linux DVB API lets you control these hardware components
+through currently six Unix-style character devices for video, audio,
+frontend, demux, CA and IP-over-DVB networking. The video and audio
+devices control the MPEG2 decoder hardware, the frontend device the
+tuner and the DVB demodulator. The demux device gives you control over
+the PES and section filters of the hardware. If the hardware does not
+support filtering these filters can be implemented in software. Finally,
+the CA device controls all the conditional access capabilities of the
+hardware. It can depend on the individual security requirements of the
+platform, if and how many of the CA functions are made available to the
+application through this device.</para>
+
+<para>All devices can be found in the <emphasis role="tt">/dev</emphasis>
+tree under <emphasis role="tt">/dev/dvb</emphasis>. The individual devices
+are called:</para>
+
+<itemizedlist>
+<listitem>
+
+<para><emphasis role="tt">/dev/dvb/adapterN/audioM</emphasis>,</para>
+</listitem>
+<listitem>
+<para><emphasis role="tt">/dev/dvb/adapterN/videoM</emphasis>,</para>
+</listitem>
+<listitem>
+<para><emphasis role="tt">/dev/dvb/adapterN/frontendM</emphasis>,</para>
+</listitem>
+ <listitem>
+
+<para><emphasis role="tt">/dev/dvb/adapterN/netM</emphasis>,</para>
+</listitem>
+ <listitem>
+
+<para><emphasis role="tt">/dev/dvb/adapterN/demuxM</emphasis>,</para>
+</listitem>
+ <listitem>
+
+<para><emphasis role="tt">/dev/dvb/adapterN/caM</emphasis>,</para></listitem></itemizedlist>
+
+<para>where N enumerates the DVB PCI cards in a system starting
+from&#x00A0;0, and M enumerates the devices of each type within each
+adapter, starting from&#x00A0;0, too. We will omit the &#8220;<emphasis
+role="tt">/dev/dvb/adapterN/</emphasis>&#8221; in the further dicussion
+of these devices. The naming scheme for the devices is the same wheter
+devfs is used or not.</para>
+
+<para>More details about the data structures and function calls of all
+the devices are described in the following chapters.</para>
+
+</section>
+
+<section id="include_files">
+<title>API include files</title>
+
+<para>For each of the DVB devices a corresponding include file exists.
+The DVB API include files should be included in application sources with
+a partial path like:</para>
+
+
+<programlisting>
+        #include &#x003C;linux/dvb/frontend.h&#x003E;
+</programlisting>
+
+<para>To enable applications to support different API version, an
+additional include file <emphasis
+role="tt">linux/dvb/version.h</emphasis> exists, which defines the
+constant <emphasis role="tt">DVB_API_VERSION</emphasis>. This document
+describes <emphasis role="tt">DVB_API_VERSION&#x00A0;3</emphasis>.
+</para>
+
+</section>
+