2024-09-09 08:52:07 +00:00
|
|
|
<refentry id="vidioc-querycap">
|
|
|
|
|
<refmeta>
|
|
|
|
|
<refentrytitle>ioctl VIDIOC_QUERYCAP</refentrytitle>
|
|
|
|
|
&manvol;
|
|
|
|
|
</refmeta>
|
|
|
|
|
|
|
|
|
|
<refnamediv>
|
|
|
|
|
<refname>VIDIOC_QUERYCAP</refname>
|
|
|
|
|
<refpurpose>Query device capabilities</refpurpose>
|
|
|
|
|
</refnamediv>
|
|
|
|
|
|
|
|
|
|
<refsynopsisdiv>
|
|
|
|
|
<funcsynopsis>
|
|
|
|
|
<funcprototype>
|
|
|
|
|
<funcdef>int <function>ioctl</function></funcdef>
|
|
|
|
|
<paramdef>int <parameter>fd</parameter></paramdef>
|
|
|
|
|
<paramdef>int <parameter>request</parameter></paramdef>
|
|
|
|
|
<paramdef>struct v4l2_capability *<parameter>argp</parameter></paramdef>
|
|
|
|
|
</funcprototype>
|
|
|
|
|
</funcsynopsis>
|
|
|
|
|
</refsynopsisdiv>
|
|
|
|
|
|
|
|
|
|
<refsect1>
|
|
|
|
|
<title>Arguments</title>
|
|
|
|
|
|
|
|
|
|
<variablelist>
|
|
|
|
|
<varlistentry>
|
|
|
|
|
<term><parameter>fd</parameter></term>
|
|
|
|
|
<listitem>
|
|
|
|
|
<para>&fd;</para>
|
|
|
|
|
</listitem>
|
|
|
|
|
</varlistentry>
|
|
|
|
|
<varlistentry>
|
|
|
|
|
<term><parameter>request</parameter></term>
|
|
|
|
|
<listitem>
|
|
|
|
|
<para>VIDIOC_QUERYCAP</para>
|
|
|
|
|
</listitem>
|
|
|
|
|
</varlistentry>
|
|
|
|
|
<varlistentry>
|
|
|
|
|
<term><parameter>argp</parameter></term>
|
|
|
|
|
<listitem>
|
|
|
|
|
<para></para>
|
|
|
|
|
</listitem>
|
|
|
|
|
</varlistentry>
|
|
|
|
|
</variablelist>
|
|
|
|
|
</refsect1>
|
|
|
|
|
|
|
|
|
|
<refsect1>
|
|
|
|
|
<title>Description</title>
|
|
|
|
|
|
|
|
|
|
<para>All V4L2 devices support the
|
|
|
|
|
<constant>VIDIOC_QUERYCAP</constant> ioctl. It is used to identify
|
|
|
|
|
kernel devices compatible with this specification and to obtain
|
|
|
|
|
information about driver and hardware capabilities. The ioctl takes a
|
|
|
|
|
pointer to a &v4l2-capability; which is filled by the driver. When the
|
|
|
|
|
driver is not compatible with this specification the ioctl returns an
|
|
|
|
|
&EINVAL;.</para>
|
|
|
|
|
|
|
|
|
|
<table pgwide="1" frame="none" id="v4l2-capability">
|
|
|
|
|
<title>struct <structname>v4l2_capability</structname></title>
|
|
|
|
|
<tgroup cols="3">
|
|
|
|
|
&cs-str;
|
|
|
|
|
<tbody valign="top">
|
|
|
|
|
<row>
|
|
|
|
|
<entry>__u8</entry>
|
|
|
|
|
<entry><structfield>driver</structfield>[16]</entry>
|
|
|
|
|
<entry><para>Name of the driver, a unique NUL-terminated
|
|
|
|
|
ASCII string. For example: "bttv". Driver specific applications can
|
|
|
|
|
use this information to verify the driver identity. It is also useful
|
|
|
|
|
to work around known bugs, or to identify drivers in error reports.</para>
|
|
|
|
|
<para>Storing strings in fixed sized arrays is bad
|
|
|
|
|
practice but unavoidable here. Drivers and applications should take
|
|
|
|
|
precautions to never read or write beyond the end of the array and to
|
|
|
|
|
make sure the strings are properly NUL-terminated.</para></entry>
|
|
|
|
|
</row>
|
|
|
|
|
<row>
|
|
|
|
|
<entry>__u8</entry>
|
|
|
|
|
<entry><structfield>card</structfield>[32]</entry>
|
2024-09-09 08:57:42 +00:00
|
|
|
<entry>Name of the device, a NUL-terminated UTF-8 string.
|
2024-09-09 08:52:07 +00:00
|
|
|
For example: "Yoyodyne TV/FM". One driver may support different brands
|
|
|
|
|
or models of video hardware. This information is intended for users,
|
|
|
|
|
for example in a menu of available devices. Since multiple TV cards of
|
|
|
|
|
the same brand may be installed which are supported by the same
|
|
|
|
|
driver, this name should be combined with the character device file
|
|
|
|
|
name (⪚ <filename>/dev/video2</filename>) or the
|
|
|
|
|
<structfield>bus_info</structfield> string to avoid
|
|
|
|
|
ambiguities.</entry>
|
|
|
|
|
</row>
|
|
|
|
|
<row>
|
|
|
|
|
<entry>__u8</entry>
|
|
|
|
|
<entry><structfield>bus_info</structfield>[32]</entry>
|
|
|
|
|
<entry>Location of the device in the system, a
|
2024-09-09 08:57:42 +00:00
|
|
|
NUL-terminated ASCII string. For example: "PCI:0000:05:06.0". This
|
2024-09-09 08:52:07 +00:00
|
|
|
information is intended for users, to distinguish multiple
|
2024-09-09 08:57:42 +00:00
|
|
|
identical devices. If no such information is available the field must
|
|
|
|
|
simply count the devices controlled by the driver ("platform:vivi-000").
|
|
|
|
|
The bus_info must start with "PCI:" for PCI boards, "PCIe:" for PCI Express boards,
|
|
|
|
|
"usb-" for USB devices, "I2C:" for i2c devices, "ISA:" for ISA devices,
|
|
|
|
|
"parport" for parallel port devices and "platform:" for platform devices.</entry>
|
2024-09-09 08:52:07 +00:00
|
|
|
</row>
|
|
|
|
|
<row>
|
|
|
|
|
<entry>__u32</entry>
|
|
|
|
|
<entry><structfield>version</structfield></entry>
|
|
|
|
|
<entry><para>Version number of the driver.</para>
|
|
|
|
|
<para>Starting on kernel 3.1, the version reported is provided per
|
|
|
|
|
V4L2 subsystem, following the same Kernel numberation scheme. However, it
|
|
|
|
|
should not always return the same version as the kernel, if, for example,
|
|
|
|
|
an stable or distribution-modified kernel uses the V4L2 stack from a
|
|
|
|
|
newer kernel.</para>
|
|
|
|
|
<para>The version number is formatted using the
|
|
|
|
|
<constant>KERNEL_VERSION()</constant> macro:</para></entry>
|
|
|
|
|
</row>
|
|
|
|
|
<row>
|
|
|
|
|
<entry spanname="hspan"><para>
|
|
|
|
|
<programlisting>
|
|
|
|
|
#define KERNEL_VERSION(a,b,c) (((a) << 16) + ((b) << 8) + (c))
|
|
|
|
|
|
|
|
|
|
__u32 version = KERNEL_VERSION(0, 8, 1);
|
|
|
|
|
|
|
|
|
|
printf ("Version: %u.%u.%u\n",
|
|
|
|
|
(version >> 16) & 0xFF,
|
|
|
|
|
(version >> 8) & 0xFF,
|
|
|
|
|
version & 0xFF);
|
|
|
|
|
</programlisting></para></entry>
|
|
|
|
|
</row>
|
|
|
|
|
<row>
|
|
|
|
|
<entry>__u32</entry>
|
|
|
|
|
<entry><structfield>capabilities</structfield></entry>
|
|
|
|
|
<entry>Available capabilities of the physical device as a whole, see <xref
|
|
|
|
|
linkend="device-capabilities" />. The same physical device can export
|
|
|
|
|
multiple devices in /dev (e.g. /dev/videoX, /dev/vbiY and /dev/radioZ).
|
|
|
|
|
The <structfield>capabilities</structfield> field should contain a union
|
|
|
|
|
of all capabilities available around the several V4L2 devices exported
|
|
|
|
|
to userspace.
|
|
|
|
|
For all those devices the <structfield>capabilities</structfield> field
|
|
|
|
|
returns the same set of capabilities. This allows applications to open
|
|
|
|
|
just one of the devices (typically the video device) and discover whether
|
|
|
|
|
video, vbi and/or radio are also supported.
|
|
|
|
|
</entry>
|
|
|
|
|
</row>
|
|
|
|
|
<row>
|
|
|
|
|
<entry>__u32</entry>
|
|
|
|
|
<entry><structfield>device_caps</structfield></entry>
|
|
|
|
|
<entry>Device capabilities of the opened device, see <xref
|
|
|
|
|
linkend="device-capabilities" />. Should contain the available capabilities
|
|
|
|
|
of that specific device node. So, for example, <structfield>device_caps</structfield>
|
|
|
|
|
of a radio device will only contain radio related capabilities and
|
|
|
|
|
no video or vbi capabilities. This field is only set if the <structfield>capabilities</structfield>
|
|
|
|
|
field contains the <constant>V4L2_CAP_DEVICE_CAPS</constant> capability.
|
|
|
|
|
Only the <structfield>capabilities</structfield> field can have the
|
|
|
|
|
<constant>V4L2_CAP_DEVICE_CAPS</constant> capability, <structfield>device_caps</structfield>
|
|
|
|
|
will never set <constant>V4L2_CAP_DEVICE_CAPS</constant>.
|
|
|
|
|
</entry>
|
|
|
|
|
</row>
|
|
|
|
|
<row>
|
|
|
|
|
<entry>__u32</entry>
|
|
|
|
|
<entry><structfield>reserved</structfield>[3]</entry>
|
|
|
|
|
<entry>Reserved for future extensions. Drivers must set
|
|
|
|
|
this array to zero.</entry>
|
|
|
|
|
</row>
|
|
|
|
|
</tbody>
|
|
|
|
|
</tgroup>
|
|
|
|
|
</table>
|
|
|
|
|
|
|
|
|
|
<table pgwide="1" frame="none" id="device-capabilities">
|
|
|
|
|
<title>Device Capabilities Flags</title>
|
|
|
|
|
<tgroup cols="3">
|
|
|
|
|
&cs-def;
|
|
|
|
|
<tbody valign="top">
|
|
|
|
|
<row>
|
|
|
|
|
<entry><constant>V4L2_CAP_VIDEO_CAPTURE</constant></entry>
|
|
|
|
|
<entry>0x00000001</entry>
|
|
|
|
|
<entry>The device supports the single-planar API through the <link
|
|
|
|
|
linkend="capture">Video Capture</link> interface.</entry>
|
|
|
|
|
</row>
|
|
|
|
|
<row>
|
|
|
|
|
<entry><constant>V4L2_CAP_VIDEO_CAPTURE_MPLANE</constant></entry>
|
|
|
|
|
<entry>0x00001000</entry>
|
|
|
|
|
<entry>The device supports the
|
|
|
|
|
<link linkend="planar-apis">multi-planar API</link> through the
|
|
|
|
|
<link linkend="capture">Video Capture</link> interface.</entry>
|
|
|
|
|
</row>
|
|
|
|
|
<row>
|
|
|
|
|
<entry><constant>V4L2_CAP_VIDEO_OUTPUT</constant></entry>
|
|
|
|
|
<entry>0x00000002</entry>
|
|
|
|
|
<entry>The device supports the single-planar API through the <link
|
|
|
|
|
linkend="output">Video Output</link> interface.</entry>
|
|
|
|
|
</row>
|
|
|
|
|
<row>
|
|
|
|
|
<entry><constant>V4L2_CAP_VIDEO_OUTPUT_MPLANE</constant></entry>
|
|
|
|
|
<entry>0x00002000</entry>
|
|
|
|
|
<entry>The device supports the
|
|
|
|
|
<link linkend="planar-apis">multi-planar API</link> through the
|
|
|
|
|
<link linkend="output">Video Output</link> interface.</entry>
|
|
|
|
|
</row>
|
2024-09-09 08:57:42 +00:00
|
|
|
<row>
|
|
|
|
|
<entry><constant>V4L2_CAP_VIDEO_M2M</constant></entry>
|
|
|
|
|
<entry>0x00004000</entry>
|
|
|
|
|
<entry>The device supports the single-planar API through the
|
|
|
|
|
Video Memory-To-Memory interface.</entry>
|
|
|
|
|
</row>
|
|
|
|
|
<row>
|
|
|
|
|
<entry><constant>V4L2_CAP_VIDEO_M2M_MPLANE</constant></entry>
|
|
|
|
|
<entry>0x00008000</entry>
|
|
|
|
|
<entry>The device supports the
|
|
|
|
|
<link linkend="planar-apis">multi-planar API</link> through the
|
|
|
|
|
Video Memory-To-Memory interface.</entry>
|
|
|
|
|
</row>
|
2024-09-09 08:52:07 +00:00
|
|
|
<row>
|
|
|
|
|
<entry><constant>V4L2_CAP_VIDEO_OVERLAY</constant></entry>
|
|
|
|
|
<entry>0x00000004</entry>
|
|
|
|
|
<entry>The device supports the <link
|
|
|
|
|
linkend="overlay">Video Overlay</link> interface. A video overlay device
|
|
|
|
|
typically stores captured images directly in the video memory of a
|
|
|
|
|
graphics card, with hardware clipping and scaling.</entry>
|
|
|
|
|
</row>
|
|
|
|
|
<row>
|
|
|
|
|
<entry><constant>V4L2_CAP_VBI_CAPTURE</constant></entry>
|
|
|
|
|
<entry>0x00000010</entry>
|
|
|
|
|
<entry>The device supports the <link linkend="raw-vbi">Raw
|
|
|
|
|
VBI Capture</link> interface, providing Teletext and Closed Caption
|
|
|
|
|
data.</entry>
|
|
|
|
|
</row>
|
|
|
|
|
<row>
|
|
|
|
|
<entry><constant>V4L2_CAP_VBI_OUTPUT</constant></entry>
|
|
|
|
|
<entry>0x00000020</entry>
|
|
|
|
|
<entry>The device supports the <link linkend="raw-vbi">Raw VBI Output</link> interface.</entry>
|
|
|
|
|
</row>
|
|
|
|
|
<row>
|
|
|
|
|
<entry><constant>V4L2_CAP_SLICED_VBI_CAPTURE</constant></entry>
|
|
|
|
|
<entry>0x00000040</entry>
|
|
|
|
|
<entry>The device supports the <link linkend="sliced">Sliced VBI Capture</link> interface.</entry>
|
|
|
|
|
</row>
|
|
|
|
|
<row>
|
|
|
|
|
<entry><constant>V4L2_CAP_SLICED_VBI_OUTPUT</constant></entry>
|
|
|
|
|
<entry>0x00000080</entry>
|
|
|
|
|
<entry>The device supports the <link linkend="sliced">Sliced VBI Output</link> interface.</entry>
|
|
|
|
|
</row>
|
|
|
|
|
<row>
|
|
|
|
|
<entry><constant>V4L2_CAP_RDS_CAPTURE</constant></entry>
|
|
|
|
|
<entry>0x00000100</entry>
|
|
|
|
|
<entry>The device supports the <link linkend="rds">RDS</link> capture interface.</entry>
|
|
|
|
|
</row>
|
|
|
|
|
<row>
|
|
|
|
|
<entry><constant>V4L2_CAP_VIDEO_OUTPUT_OVERLAY</constant></entry>
|
|
|
|
|
<entry>0x00000200</entry>
|
|
|
|
|
<entry>The device supports the <link linkend="osd">Video
|
|
|
|
|
Output Overlay</link> (OSD) interface. Unlike the <wordasword>Video
|
|
|
|
|
Overlay</wordasword> interface, this is a secondary function of video
|
|
|
|
|
output devices and overlays an image onto an outgoing video signal.
|
|
|
|
|
When the driver sets this flag, it must clear the
|
|
|
|
|
<constant>V4L2_CAP_VIDEO_OVERLAY</constant> flag and vice
|
|
|
|
|
versa.<footnote><para>The &v4l2-framebuffer; lacks an
|
|
|
|
|
&v4l2-buf-type; field, therefore the type of overlay is implied by the
|
|
|
|
|
driver capabilities.</para></footnote></entry>
|
|
|
|
|
</row>
|
|
|
|
|
<row>
|
|
|
|
|
<entry><constant>V4L2_CAP_HW_FREQ_SEEK</constant></entry>
|
|
|
|
|
<entry>0x00000400</entry>
|
|
|
|
|
<entry>The device supports the &VIDIOC-S-HW-FREQ-SEEK; ioctl for
|
|
|
|
|
hardware frequency seeking.</entry>
|
|
|
|
|
</row>
|
|
|
|
|
<row>
|
|
|
|
|
<entry><constant>V4L2_CAP_RDS_OUTPUT</constant></entry>
|
|
|
|
|
<entry>0x00000800</entry>
|
|
|
|
|
<entry>The device supports the <link linkend="rds">RDS</link> output interface.</entry>
|
|
|
|
|
</row>
|
|
|
|
|
<row>
|
|
|
|
|
<entry><constant>V4L2_CAP_TUNER</constant></entry>
|
|
|
|
|
<entry>0x00010000</entry>
|
|
|
|
|
<entry>The device has some sort of tuner to
|
|
|
|
|
receive RF-modulated video signals. For more information about
|
|
|
|
|
tuner programming see
|
|
|
|
|
<xref linkend="tuner" />.</entry>
|
|
|
|
|
</row>
|
|
|
|
|
<row>
|
|
|
|
|
<entry><constant>V4L2_CAP_AUDIO</constant></entry>
|
|
|
|
|
<entry>0x00020000</entry>
|
|
|
|
|
<entry>The device has audio inputs or outputs. It may or
|
|
|
|
|
may not support audio recording or playback, in PCM or compressed
|
|
|
|
|
formats. PCM audio support must be implemented as ALSA or OSS
|
|
|
|
|
interface. For more information on audio inputs and outputs see <xref
|
|
|
|
|
linkend="audio" />.</entry>
|
|
|
|
|
</row>
|
|
|
|
|
<row>
|
|
|
|
|
<entry><constant>V4L2_CAP_RADIO</constant></entry>
|
|
|
|
|
<entry>0x00040000</entry>
|
|
|
|
|
<entry>This is a radio receiver.</entry>
|
|
|
|
|
</row>
|
|
|
|
|
<row>
|
|
|
|
|
<entry><constant>V4L2_CAP_MODULATOR</constant></entry>
|
|
|
|
|
<entry>0x00080000</entry>
|
|
|
|
|
<entry>The device has some sort of modulator to
|
|
|
|
|
emit RF-modulated video/audio signals. For more information about
|
|
|
|
|
modulator programming see
|
|
|
|
|
<xref linkend="tuner" />.</entry>
|
2024-09-09 08:57:42 +00:00
|
|
|
</row>
|
|
|
|
|
<row>
|
|
|
|
|
<entry><constant>V4L2_CAP_SDR_CAPTURE</constant></entry>
|
|
|
|
|
<entry>0x00100000</entry>
|
|
|
|
|
<entry>The device supports the
|
|
|
|
|
<link linkend="sdr">SDR Capture</link> interface.</entry>
|
|
|
|
|
</row>
|
|
|
|
|
<row>
|
|
|
|
|
<entry><constant>V4L2_CAP_EXT_PIX_FORMAT</constant></entry>
|
|
|
|
|
<entry>0x00200000</entry>
|
|
|
|
|
<entry>The device supports the &v4l2-pix-format; extended
|
|
|
|
|
fields.</entry>
|
2024-09-09 08:52:07 +00:00
|
|
|
</row>
|
|
|
|
|
<row>
|
|
|
|
|
<entry><constant>V4L2_CAP_READWRITE</constant></entry>
|
|
|
|
|
<entry>0x01000000</entry>
|
|
|
|
|
<entry>The device supports the <link
|
|
|
|
|
linkend="rw">read()</link> and/or <link linkend="rw">write()</link>
|
|
|
|
|
I/O methods.</entry>
|
|
|
|
|
</row>
|
|
|
|
|
<row>
|
|
|
|
|
<entry><constant>V4L2_CAP_ASYNCIO</constant></entry>
|
|
|
|
|
<entry>0x02000000</entry>
|
|
|
|
|
<entry>The device supports the <link
|
|
|
|
|
linkend="async">asynchronous</link> I/O methods.</entry>
|
|
|
|
|
</row>
|
|
|
|
|
<row>
|
|
|
|
|
<entry><constant>V4L2_CAP_STREAMING</constant></entry>
|
|
|
|
|
<entry>0x04000000</entry>
|
|
|
|
|
<entry>The device supports the <link
|
|
|
|
|
linkend="mmap">streaming</link> I/O method.</entry>
|
|
|
|
|
</row>
|
|
|
|
|
<row>
|
|
|
|
|
<entry><constant>V4L2_CAP_DEVICE_CAPS</constant></entry>
|
|
|
|
|
<entry>0x80000000</entry>
|
|
|
|
|
<entry>The driver fills the <structfield>device_caps</structfield>
|
|
|
|
|
field. This capability can only appear in the <structfield>capabilities</structfield>
|
|
|
|
|
field and never in the <structfield>device_caps</structfield> field.</entry>
|
|
|
|
|
</row>
|
|
|
|
|
</tbody>
|
|
|
|
|
</tgroup>
|
|
|
|
|
</table>
|
|
|
|
|
</refsect1>
|
|
|
|
|
|
|
|
|
|
<refsect1>
|
|
|
|
|
&return-value;
|
|
|
|
|
</refsect1>
|
|
|
|
|
</refentry>
|
