155 lines
4.7 KiB
XML
155 lines
4.7 KiB
XML
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<refentry id="vidioc-g-audioout">
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<refmeta>
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<refentrytitle>ioctl VIDIOC_G_AUDOUT, VIDIOC_S_AUDOUT</refentrytitle>
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&manvol;
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</refmeta>
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<refnamediv>
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<refname>VIDIOC_G_AUDOUT</refname>
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<refname>VIDIOC_S_AUDOUT</refname>
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<refpurpose>Query or select the current audio output</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 v4l2_audioout *<parameter>argp</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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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>const struct v4l2_audioout *<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>&fd;</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>VIDIOC_G_AUDOUT, VIDIOC_S_AUDOUT</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 current audio output applications zero out the
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<structfield>reserved</structfield> array of a &v4l2-audioout; and
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call the <constant>VIDIOC_G_AUDOUT</constant> ioctl with a pointer
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to this structure. Drivers fill the rest of the structure or return an
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&EINVAL; when the device has no audio inputs, or none which combine
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with the current video output.</para>
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<para>Audio outputs have no writable properties. Nevertheless, to
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select the current audio output applications can initialize the
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<structfield>index</structfield> field and
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<structfield>reserved</structfield> array (which in the future may
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contain writable properties) of a
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<structname>v4l2_audioout</structname> structure and call the
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<constant>VIDIOC_S_AUDOUT</constant> ioctl. Drivers switch to the
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requested output or return the &EINVAL; when the index is out of
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bounds. This is a write-only ioctl, it does not return the current
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audio output attributes as <constant>VIDIOC_G_AUDOUT</constant>
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does.</para>
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<para>Note connectors on a TV card to loop back the received audio
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signal to a sound card are not audio outputs in this sense.</para>
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<table pgwide="1" frame="none" id="v4l2-audioout">
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<title>struct <structname>v4l2_audioout</structname></title>
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<tgroup cols="3">
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&cs-str;
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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>index</structfield></entry>
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<entry>Identifies the audio output, set by the
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driver or application.</entry>
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</row>
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<row>
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<entry>__u8</entry>
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<entry><structfield>name</structfield>[32]</entry>
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<entry>Name of the audio output, a NUL-terminated ASCII
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string, for example: "Line Out". This information is intended for the
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user, preferably the connector label on the device itself.</entry>
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</row>
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<row>
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<entry>__u32</entry>
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<entry><structfield>capability</structfield></entry>
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<entry>Audio capability flags, none defined yet. Drivers
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must set this field to zero.</entry>
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</row>
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<row>
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<entry>__u32</entry>
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<entry><structfield>mode</structfield></entry>
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<entry>Audio mode, none defined yet. Drivers and
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applications (on <constant>VIDIOC_S_AUDOUT</constant>) must set this
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field to zero.</entry>
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</row>
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<row>
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<entry>__u32</entry>
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<entry><structfield>reserved</structfield>[2]</entry>
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<entry>Reserved for future extensions. Drivers and
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applications must set the array to zero.</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>No audio outputs combine with the current video
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output, or the number of the selected audio output is out of bounds or
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it does not combine, or there are no audio outputs at all and the
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ioctl is not supported.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><errorcode>EBUSY</errorcode></term>
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<listitem>
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<para>I/O is in progress, the output cannot be
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switched.</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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<!--
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Local Variables:
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mode: sgml
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sgml-parent-document: "v4l2.sgml"
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indent-tabs-mode: nil
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End:
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-->
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