Name

VIDIOC_ENUMOUTPUT - Enumerate video outputs

Synopsis

.. c:macro:: VIDIOC_ENUMOUTPUT

int ioctl(int fd, VIDIOC_ENUMOUTPUT, struct v4l2_output *argp)

Arguments

fd File descriptor returned by :c:func:open().

argp Pointer to struct :c:type:v4l2_output.

Description

To query the attributes of a video outputs applications initialize the index field of struct :c:type:v4l2_output and call the :ref:VIDIOC_ENUMOUTPUT with a pointer to this structure. Drivers fill the rest of the structure or return an EINVAL error code when the index is out of bounds. To enumerate all outputs applications shall begin at index zero, incrementing by one until the driver returns EINVAL.

.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.5cm}|

.. c:type:: v4l2_output

.. flat-table:: struct v4l2_output :header-rows: 0 :stub-columns: 0 :widths: 1 1 2

* - __u32
  - ``index``
  - Identifies the output, set by the application.
* - __u8
  - ``name``\ [32]
  - Name of the video output, a NUL-terminated ASCII string, for
example: "Vout". This information is intended for the user,
preferably the connector label on the device itself.
* - __u32
  - ``type``
  - Type of the output, see :ref:`output-type`.
* - __u32
  - ``audioset``
  - Drivers can enumerate up to 32 video and audio outputs. This field
shows which audio outputs were selectable as the current output if
this was the currently selected video output. It is a bit mask.
The LSB corresponds to audio output 0, the MSB to output 31. Any
number of bits can be set, or none.

When the driver does not enumerate audio outputs no bits must be
set. Applications shall not interpret this as lack of audio
support. Drivers may automatically select audio outputs without
enumerating them.

For details on audio outputs and how to select the current output
see :ref:`audio`.
* - __u32
  - ``modulator``
  - Output devices can have zero or more RF modulators. When the
``type`` is ``V4L2_OUTPUT_TYPE_MODULATOR`` this is an RF connector
and this field identifies the modulator. It corresponds to struct
:c:type:`v4l2_modulator` field ``index``. For
details on modulators see :ref:`tuner`.
* - :ref:`v4l2_std_id <v4l2-std-id>`
  - ``std``
  - Every video output supports one or more different video standards.
This field is a set of all supported standards. For details on
video standards and how to switch see :ref:`standard`.
* - __u32
  - ``capabilities``
  - This field provides capabilities for the output. See
:ref:`output-capabilities` for flags.
* - __u32
  - ``reserved``\ [3]
  - Reserved for future extensions. Drivers must set the array to
zero.

.. tabularcolumns:: |p{7.5cm}|p{0.6cm}|p{9.2cm}|

.. _output-type:

.. flat-table:: Output Type :header-rows: 0 :stub-columns: 0 :widths: 3 1 4

* - ``V4L2_OUTPUT_TYPE_MODULATOR``
  - 1
  - This output is an analog TV modulator.
* - ``V4L2_OUTPUT_TYPE_ANALOG``
  - 2
  - Any non-modulator video output, for example Composite Video,
S-Video, HDMI. The naming as ``_TYPE_ANALOG`` is historical,
today we would have called it ``_TYPE_VIDEO``.
* - ``V4L2_OUTPUT_TYPE_ANALOGVGAOVERLAY``
  - 3
  - The video output will be copied to a :ref:`video overlay <overlay>`.

.. tabularcolumns:: |p{6.4cm}|p{2.4cm}|p{8.5cm}|

.. _output-capabilities:

.. flat-table:: Output capabilities :header-rows: 0 :stub-columns: 0 :widths: 3 1 4

* - ``V4L2_OUT_CAP_DV_TIMINGS``
  - 0x00000002
  - This output supports setting video timings by using
``VIDIOC_S_DV_TIMINGS``.
* - ``V4L2_OUT_CAP_STD``
  - 0x00000004
  - This output supports setting the TV standard by using
``VIDIOC_S_STD``.
* - ``V4L2_OUT_CAP_NATIVE_SIZE``
  - 0x00000008
  - This output supports setting the native size using the
``V4L2_SEL_TGT_NATIVE_SIZE`` selection target, see
:ref:`v4l2-selections-common`.

Return Value

On success 0 is returned, on error -1 and the errno variable is set appropriately. The generic error codes are described at the :ref:Generic Error Codes <gen-errors> chapter.

EINVAL The struct :c:type:v4l2_output index is out of bounds.