and may change in the future.</para>
<itemizedlist>
- <listitem>
- <para>Video Output Overlay (OSD) Interface, <xref
- linkend="osd" />.</para>
- </listitem>
<listitem>
<para>&VIDIOC-DBG-G-REGISTER; and &VIDIOC-DBG-S-REGISTER;
ioctls.</para>
<listitem>
<para>&VIDIOC-DBG-G-CHIP-INFO; ioctl.</para>
</listitem>
- <listitem>
- <para>&VIDIOC-ENUM-DV-TIMINGS;, &VIDIOC-QUERY-DV-TIMINGS; and
- &VIDIOC-DV-TIMINGS-CAP; ioctls.</para>
- </listitem>
- <listitem>
- <para>Flash API. <xref linkend="flash-controls" /></para>
- </listitem>
- <listitem>
- <para>&VIDIOC-CREATE-BUFS; and &VIDIOC-PREPARE-BUF; ioctls.</para>
- </listitem>
- <listitem>
- <para>Selection API. <xref linkend="selection-api" /></para>
- </listitem>
- <listitem>
- <para>Sub-device selection API: &VIDIOC-SUBDEV-G-SELECTION;
- and &VIDIOC-SUBDEV-S-SELECTION; ioctls.</para>
- </listitem>
- <listitem>
- <para>Support for frequency band enumeration: &VIDIOC-ENUM-FREQ-BANDS; ioctl.</para>
- </listitem>
- <listitem>
- <para>Vendor and device specific media bus pixel formats.
- <xref linkend="v4l2-mbus-vendor-spec-fmts" />.</para>
- </listitem>
- <listitem>
- <para>Importing DMABUF file descriptors as a new IO method described
- in <xref linkend="dmabuf" />.</para>
- </listitem>
- <listitem>
- <para>Exporting DMABUF files using &VIDIOC-EXPBUF; ioctl.</para>
- </listitem>
- <listitem>
- <para>Software Defined Radio (SDR) Interface, <xref linkend="sdr" />.</para>
- </listitem>
</itemizedlist>
</section>
<section id="flash-controls">
<title>Flash Control Reference</title>
- <note>
- <title>Experimental</title>
-
- <para>This is an <link linkend="experimental">experimental</link>
-interface and may change in the future.</para>
- </note>
-
<para>
The V4L2 flash controls are intended to provide generic access
to flash controller devices. Flash controller devices are
<section id="image-source-controls">
<title>Image Source Control Reference</title>
- <note>
- <title>Experimental</title>
-
- <para>This is an <link
- linkend="experimental">experimental</link> interface and may
- change in the future.</para>
- </note>
-
<para>
The Image Source control class is intended for low-level
control of image source devices such as image sensors. The
<section id="image-process-controls">
<title>Image Process Control Reference</title>
- <note>
- <title>Experimental</title>
-
- <para>This is an <link
- linkend="experimental">experimental</link> interface and may
- change in the future.</para>
- </note>
-
<para>
The Image Process control class is intended for low-level control of
image processing functions. Unlike
<section id="dv-controls">
<title>Digital Video Control Reference</title>
- <note>
- <title>Experimental</title>
-
- <para>This is an <link
- linkend="experimental">experimental</link> interface and may
- change in the future.</para>
- </note>
-
<para>
The Digital Video control class is intended to control receivers
and transmitters for <ulink url="http://en.wikipedia.org/wiki/Vga">VGA</ulink>,
<title>Software Defined Radio Interface (SDR)</title>
- <note>
- <title>Experimental</title>
- <para>This is an <link linkend="experimental"> experimental </link>
- interface and may change in the future.</para>
- </note>
-
<para>
SDR is an abbreviation of Software Defined Radio, the radio device
which uses application software for modulation or demodulation. This interface
<title>Sub-device Interface</title>
- <note>
- <title>Experimental</title>
- <para>This is an <link linkend="experimental">experimental</link>
- interface and may change in the future.</para>
- </note>
-
<para>The complex nature of V4L2 devices, where hardware is often made of
several integrated circuits that need to interact with each other in a
controlled way, leads to complex V4L2 drivers. The drivers usually reflect
<section id="dmabuf">
<title>Streaming I/O (DMA buffer importing)</title>
- <note>
- <title>Experimental</title>
- <para>This is an <link linkend="experimental">experimental</link>
- interface and may change in the future.</para>
- </note>
-
<para>The DMABUF framework provides a generic method for sharing buffers
between multiple devices. Device drivers that support DMABUF can export a DMA
buffer to userspace as a file descriptor (known as the exporter role), import a
<section id="selection-api">
- <title>Experimental API for cropping, composing and scaling</title>
-
- <note>
- <title>Experimental</title>
-
- <para>This is an <link linkend="experimental">experimental</link>
-interface and may change in the future.</para>
- </note>
+ <title>API for cropping, composing and scaling</title>
<section>
<title>Introduction</title>
<section id="v4l2-mbus-vendor-spec-fmts">
<title>Vendor and Device Specific Formats</title>
- <note>
- <title>Experimental</title>
- <para>This is an <link linkend="experimental">experimental</link>
-interface and may change in the future.</para>
- </note>
-
<para>This section lists complex data formats that are either vendor or
device specific.
</para>
<refsect1>
<title>Description</title>
- <note>
- <title>Experimental</title>
- <para>This is an <link linkend="experimental"> experimental </link>
- interface and may change in the future.</para>
- </note>
-
<para>This ioctl is used to create buffers for <link linkend="mmap">memory
mapped</link> or <link linkend="userp">user pointer</link> or <link
linkend="dmabuf">DMA buffer</link> I/O. It can be used as an alternative or in
<refsect1>
<title>Description</title>
- <note>
- <title>Experimental</title>
- <para>This is an <link linkend="experimental"> experimental </link>
- interface and may change in the future.</para>
- </note>
-
<para>To query the capabilities of the DV receiver/transmitter applications initialize the
<structfield>pad</structfield> field to 0, zero the reserved array of &v4l2-dv-timings-cap;
and call the <constant>VIDIOC_DV_TIMINGS_CAP</constant> ioctl on a video node
<refsect1>
<title>Description</title>
- <note>
- <title>Experimental</title>
- <para>This is an <link linkend="experimental"> experimental </link>
- interface and may change in the future.</para>
- </note>
-
<para>While some DV receivers or transmitters support a wide range of timings, others
support only a limited number of timings. With this ioctl applications can enumerate a list
of known supported timings. Call &VIDIOC-DV-TIMINGS-CAP; to check if it also supports other
<refsect1>
<title>Description</title>
- <note>
- <title>Experimental</title>
- <para>This is an <link linkend="experimental"> experimental </link>
- interface and may change in the future.</para>
- </note>
-
<para>Enumerates the frequency bands that a tuner or modulator supports.
To do this applications initialize the <structfield>tuner</structfield>,
<structfield>type</structfield> and <structfield>index</structfield> fields,
<refsect1>
<title>Description</title>
- <note>
- <title>Experimental</title>
- <para>This is an <link linkend="experimental"> experimental </link>
- interface and may change in the future.</para>
- </note>
-
<para>This ioctl is an extension to the <link linkend="mmap">memory
mapping</link> I/O method, therefore it is available only for
<constant>V4L2_MEMORY_MMAP</constant> buffers. It can be used to export a
<refsect1>
<title>Description</title>
- <note>
- <title>Experimental</title>
- <para>This is an <link linkend="experimental"> experimental </link>
- interface and may change in the future.</para>
- </note>
-
<para>The ioctls are used to query and configure selection rectangles.</para>
<para>To query the cropping (composing) rectangle set &v4l2-selection;
<refsect1>
<title>Description</title>
- <note>
- <title>Experimental</title>
- <para>This is an <link linkend="experimental"> experimental </link>
- interface and may change in the future.</para>
- </note>
-
<para>Applications can optionally call the
<constant>VIDIOC_PREPARE_BUF</constant> ioctl to pass ownership of the buffer
to the driver before actually enqueuing it, using the
<refsect1>
<title>Description</title>
- <note>
- <title>Experimental</title>
- <para>This is an <link linkend="experimental"> experimental </link>
- interface and may change in the future.</para>
- </note>
-
<para>The hardware may be able to detect the current DV timings
automatically, similar to sensing the video standard. To do so, applications
call <constant>VIDIOC_QUERY_DV_TIMINGS</constant> with a pointer to a
<refsect1>
<title>Description</title>
- <note>
- <title>Experimental</title>
- <para>This is an <link linkend="experimental">experimental</link>
- interface and may change in the future.</para>
- </note>
-
<para>This ioctl lets applications enumerate available frame intervals on a
given sub-device pad. Frame intervals only makes sense for sub-devices that
can control the frame period on their own. This includes, for instance,
<refsect1>
<title>Description</title>
- <note>
- <title>Experimental</title>
- <para>This is an <link linkend="experimental">experimental</link>
- interface and may change in the future.</para>
- </note>
-
<para>This ioctl allows applications to enumerate all frame sizes
supported by a sub-device on the given pad for the given media bus format.
Supported formats can be retrieved with the &VIDIOC-SUBDEV-ENUM-MBUS-CODE;
<refsect1>
<title>Description</title>
- <note>
- <title>Experimental</title>
- <para>This is an <link linkend="experimental">experimental</link>
- interface and may change in the future.</para>
- </note>
-
<para>To enumerate media bus formats available at a given sub-device pad
applications initialize the <structfield>pad</structfield>, <structfield>which</structfield>
and <structfield>index</structfield> fields of &v4l2-subdev-mbus-code-enum; and
<refsect1>
<title>Description</title>
- <note>
- <title>Experimental</title>
- <para>This is an <link linkend="experimental">experimental</link>
- interface and may change in the future.</para>
- </note>
-
<para>These ioctls are used to negotiate the frame format at specific
subdev pads in the image pipeline.</para>
<refsect1>
<title>Description</title>
- <note>
- <title>Experimental</title>
- <para>This is an <link linkend="experimental">experimental</link>
- interface and may change in the future.</para>
- </note>
-
<para>These ioctls are used to get and set the frame interval at specific
subdev pads in the image pipeline. The frame interval only makes sense for
sub-devices that can control the frame period on their own. This includes,
<refsect1>
<title>Description</title>
- <note>
- <title>Experimental</title>
- <para>This is an <link linkend="experimental">experimental</link>
- interface and may change in the future.</para>
- </note>
-
<para>The selections are used to configure various image
processing functionality performed by the subdevs which affect the
image size. This currently includes cropping, scaling and
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