mirror of https://gitee.com/openkylin/linux.git
319 lines
9.6 KiB
XML
319 lines
9.6 KiB
XML
<refentry id="media-ioc-enum-entities">
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<refmeta>
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<refentrytitle>ioctl MEDIA_IOC_ENUM_ENTITIES</refentrytitle>
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&manvol;
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</refmeta>
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<refnamediv>
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<refname>MEDIA_IOC_ENUM_ENTITIES</refname>
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<refpurpose>Enumerate entities and their properties</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<funcsynopsis>
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<funcprototype>
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<funcdef>int <function>ioctl</function></funcdef>
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<paramdef>int <parameter>fd</parameter></paramdef>
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<paramdef>int <parameter>request</parameter></paramdef>
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<paramdef>struct media_entity_desc *<parameter>argp</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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</refsynopsisdiv>
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<refsect1>
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<title>Arguments</title>
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<variablelist>
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<varlistentry>
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<term><parameter>fd</parameter></term>
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<listitem>
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<para>File descriptor returned by
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<link linkend='media-func-open'><function>open()</function></link>.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>request</parameter></term>
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<listitem>
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<para>MEDIA_IOC_ENUM_ENTITIES</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>argp</parameter></term>
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<listitem>
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<para></para>
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</listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1>
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<title>Description</title>
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<para>To query the attributes of an entity, applications set the id field
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of a &media-entity-desc; structure and call the MEDIA_IOC_ENUM_ENTITIES
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ioctl with a pointer to this structure. The driver fills the rest of the
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structure or returns an &EINVAL; when the id is invalid.</para>
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<para>Entities can be enumerated by or'ing the id with the
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<constant>MEDIA_ENT_ID_FLAG_NEXT</constant> flag. The driver will return
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information about the entity with the smallest id strictly larger than the
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requested one ('next entity'), or the &EINVAL; if there is none.</para>
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<para>Entity IDs can be non-contiguous. Applications must
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<emphasis>not</emphasis> try to enumerate entities by calling
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MEDIA_IOC_ENUM_ENTITIES with increasing id's until they get an error.</para>
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<para>Two or more entities that share a common non-zero
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<structfield>group_id</structfield> value are considered as logically
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grouped. Groups are used to report
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<itemizedlist>
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<listitem><para>ALSA, VBI and video nodes that carry the same media
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stream</para></listitem>
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<listitem><para>lens and flash controllers associated with a sensor</para></listitem>
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</itemizedlist>
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</para>
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<table pgwide="1" frame="none" id="media-entity-desc">
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<title>struct <structname>media_entity_desc</structname></title>
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<tgroup cols="5">
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<colspec colname="c1" />
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<colspec colname="c2" />
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<colspec colname="c3" />
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<colspec colname="c4" />
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<colspec colname="c5" />
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<tbody valign="top">
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<row>
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<entry>__u32</entry>
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<entry><structfield>id</structfield></entry>
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<entry></entry>
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<entry></entry>
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<entry>Entity id, set by the application. When the id is or'ed with
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<constant>MEDIA_ENT_ID_FLAG_NEXT</constant>, the driver clears the
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flag and returns the first entity with a larger id.</entry>
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</row>
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<row>
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<entry>char</entry>
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<entry><structfield>name</structfield>[32]</entry>
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<entry></entry>
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<entry></entry>
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<entry>Entity name as an UTF-8 NULL-terminated string.</entry>
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</row>
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<row>
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<entry>__u32</entry>
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<entry><structfield>type</structfield></entry>
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<entry></entry>
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<entry></entry>
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<entry>Entity type, see <xref linkend="media-entity-type" /> for details.</entry>
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</row>
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<row>
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<entry>__u32</entry>
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<entry><structfield>revision</structfield></entry>
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<entry></entry>
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<entry></entry>
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<entry>Entity revision in a driver/hardware specific format.</entry>
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</row>
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<row>
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<entry>__u32</entry>
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<entry><structfield>flags</structfield></entry>
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<entry></entry>
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<entry></entry>
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<entry>Entity flags, see <xref linkend="media-entity-flag" /> for details.</entry>
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</row>
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<row>
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<entry>__u32</entry>
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<entry><structfield>group_id</structfield></entry>
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<entry></entry>
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<entry></entry>
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<entry>Entity group ID</entry>
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</row>
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<row>
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<entry>__u16</entry>
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<entry><structfield>pads</structfield></entry>
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<entry></entry>
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<entry></entry>
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<entry>Number of pads</entry>
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</row>
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<row>
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<entry>__u16</entry>
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<entry><structfield>links</structfield></entry>
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<entry></entry>
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<entry></entry>
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<entry>Total number of outbound links. Inbound links are not counted
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in this field.</entry>
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</row>
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<row>
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<entry>union</entry>
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</row>
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<row>
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<entry></entry>
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<entry>struct</entry>
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<entry><structfield>v4l</structfield></entry>
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<entry></entry>
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<entry>Valid for V4L sub-devices and nodes only.</entry>
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</row>
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<row>
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<entry></entry>
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<entry></entry>
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<entry>__u32</entry>
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<entry><structfield>major</structfield></entry>
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<entry>V4L device node major number. For V4L sub-devices with no
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device node, set by the driver to 0.</entry>
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</row>
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<row>
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<entry></entry>
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<entry></entry>
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<entry>__u32</entry>
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<entry><structfield>minor</structfield></entry>
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<entry>V4L device node minor number. For V4L sub-devices with no
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device node, set by the driver to 0.</entry>
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</row>
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<row>
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<entry></entry>
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<entry>struct</entry>
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<entry><structfield>fb</structfield></entry>
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<entry></entry>
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<entry>Valid for frame buffer nodes only.</entry>
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</row>
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<row>
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<entry></entry>
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<entry></entry>
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<entry>__u32</entry>
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<entry><structfield>major</structfield></entry>
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<entry>Frame buffer device node major number.</entry>
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</row>
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<row>
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<entry></entry>
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<entry></entry>
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<entry>__u32</entry>
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<entry><structfield>minor</structfield></entry>
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<entry>Frame buffer device node minor number.</entry>
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</row>
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<row>
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<entry></entry>
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<entry>struct</entry>
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<entry><structfield>alsa</structfield></entry>
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<entry></entry>
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<entry>Valid for ALSA devices only.</entry>
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</row>
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<row>
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<entry></entry>
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<entry></entry>
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<entry>__u32</entry>
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<entry><structfield>card</structfield></entry>
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<entry>ALSA card number</entry>
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</row>
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<row>
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<entry></entry>
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<entry></entry>
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<entry>__u32</entry>
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<entry><structfield>device</structfield></entry>
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<entry>ALSA device number</entry>
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</row>
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<row>
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<entry></entry>
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<entry></entry>
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<entry>__u32</entry>
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<entry><structfield>subdevice</structfield></entry>
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<entry>ALSA sub-device number</entry>
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</row>
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<row>
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<entry></entry>
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<entry>int</entry>
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<entry><structfield>dvb</structfield></entry>
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<entry></entry>
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<entry>DVB card number</entry>
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</row>
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<row>
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<entry></entry>
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<entry>__u8</entry>
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<entry><structfield>raw</structfield>[180]</entry>
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<entry></entry>
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<entry></entry>
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</row>
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</tbody>
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</tgroup>
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</table>
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<table frame="none" pgwide="1" id="media-entity-type">
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<title>Media entity types</title>
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<tgroup cols="2">
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<colspec colname="c1"/>
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<colspec colname="c2"/>
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<tbody valign="top">
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<row>
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<entry><constant>MEDIA_ENT_T_DEVNODE</constant></entry>
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<entry>Unknown device node</entry>
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</row>
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<row>
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<entry><constant>MEDIA_ENT_T_DEVNODE_V4L</constant></entry>
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<entry>V4L video, radio or vbi device node</entry>
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</row>
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<row>
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<entry><constant>MEDIA_ENT_T_DEVNODE_FB</constant></entry>
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<entry>Frame buffer device node</entry>
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</row>
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<row>
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<entry><constant>MEDIA_ENT_T_DEVNODE_ALSA</constant></entry>
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<entry>ALSA card</entry>
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</row>
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<row>
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<entry><constant>MEDIA_ENT_T_DEVNODE_DVB</constant></entry>
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<entry>DVB card</entry>
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</row>
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<row>
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<entry><constant>MEDIA_ENT_T_V4L2_SUBDEV</constant></entry>
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<entry>Unknown V4L sub-device</entry>
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</row>
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<row>
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<entry><constant>MEDIA_ENT_T_V4L2_SUBDEV_SENSOR</constant></entry>
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<entry>Video sensor</entry>
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</row>
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<row>
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<entry><constant>MEDIA_ENT_T_V4L2_SUBDEV_FLASH</constant></entry>
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<entry>Flash controller</entry>
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</row>
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<row>
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<entry><constant>MEDIA_ENT_T_V4L2_SUBDEV_LENS</constant></entry>
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<entry>Lens controller</entry>
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</row>
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<row>
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<entry><constant>MEDIA_ENT_T_V4L2_SUBDEV_DECODER</constant></entry>
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<entry>Video decoder, the basic function of the video decoder is to
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accept analogue video from a wide variety of sources such as
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broadcast, DVD players, cameras and video cassette recorders, in
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either NTSC, PAL or HD format and still occasionally SECAM, separate
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it into its component parts, luminance and chrominance, and output
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it in some digital video standard, with appropriate embedded timing
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signals.</entry>
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</row>
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</tbody>
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</tgroup>
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</table>
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<table frame="none" pgwide="1" id="media-entity-flag">
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<title>Media entity flags</title>
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<tgroup cols="2">
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<colspec colname="c1"/>
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<colspec colname="c2"/>
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<tbody valign="top">
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<row>
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<entry><constant>MEDIA_ENT_FL_DEFAULT</constant></entry>
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<entry>Default entity for its type. Used to discover the default
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audio, VBI and video devices, the default camera sensor, ...</entry>
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</row>
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</tbody>
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</tgroup>
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</table>
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</refsect1>
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<refsect1>
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&return-value;
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<variablelist>
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<varlistentry>
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<term><errorcode>EINVAL</errorcode></term>
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<listitem>
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<para>The &media-entity-desc; <structfield>id</structfield> references
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a non-existing entity.</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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</refentry>
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