154 lines
4.4 KiB
ReStructuredText
154 lines
4.4 KiB
ReStructuredText
.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
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.. c:namespace:: V4L
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.. _VIDIOC_ENUMOUTPUT:
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***********************
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ioctl VIDIOC_ENUMOUTPUT
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***********************
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Name
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====
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VIDIOC_ENUMOUTPUT - Enumerate video outputs
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Synopsis
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========
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.. c:macro:: VIDIOC_ENUMOUTPUT
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``int ioctl(int fd, VIDIOC_ENUMOUTPUT, struct v4l2_output *argp)``
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Arguments
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=========
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``fd``
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File descriptor returned by :c:func:`open()`.
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``argp``
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Pointer to struct :c:type:`v4l2_output`.
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Description
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===========
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To query the attributes of a video outputs applications initialize the
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``index`` field of struct :c:type:`v4l2_output` and call
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the :ref:`VIDIOC_ENUMOUTPUT` with a pointer to this structure.
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Drivers fill the rest of the structure or return an ``EINVAL`` error code
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when the index is out of bounds. To enumerate all outputs applications
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shall begin at index zero, incrementing by one until the driver returns
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``EINVAL``.
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.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.5cm}|
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.. c:type:: v4l2_output
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.. flat-table:: struct v4l2_output
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:header-rows: 0
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:stub-columns: 0
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:widths: 1 1 2
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* - __u32
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- ``index``
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- Identifies the output, set by the application.
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* - __u8
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- ``name``\ [32]
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- Name of the video output, a NUL-terminated ASCII string, for
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example: "Vout". This information is intended for the user,
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preferably the connector label on the device itself.
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* - __u32
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- ``type``
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- Type of the output, see :ref:`output-type`.
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* - __u32
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- ``audioset``
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- Drivers can enumerate up to 32 video and audio outputs. This field
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shows which audio outputs were selectable as the current output if
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this was the currently selected video output. It is a bit mask.
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The LSB corresponds to audio output 0, the MSB to output 31. Any
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number of bits can be set, or none.
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When the driver does not enumerate audio outputs no bits must be
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set. Applications shall not interpret this as lack of audio
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support. Drivers may automatically select audio outputs without
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enumerating them.
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For details on audio outputs and how to select the current output
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see :ref:`audio`.
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* - __u32
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- ``modulator``
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- Output devices can have zero or more RF modulators. When the
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``type`` is ``V4L2_OUTPUT_TYPE_MODULATOR`` this is an RF connector
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and this field identifies the modulator. It corresponds to struct
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:c:type:`v4l2_modulator` field ``index``. For
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details on modulators see :ref:`tuner`.
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* - :ref:`v4l2_std_id <v4l2-std-id>`
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- ``std``
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- Every video output supports one or more different video standards.
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This field is a set of all supported standards. For details on
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video standards and how to switch see :ref:`standard`.
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* - __u32
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- ``capabilities``
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- This field provides capabilities for the output. See
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:ref:`output-capabilities` for flags.
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* - __u32
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- ``reserved``\ [3]
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- Reserved for future extensions. Drivers must set the array to
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zero.
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.. tabularcolumns:: |p{7.5cm}|p{0.6cm}|p{9.2cm}|
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.. _output-type:
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.. flat-table:: Output Type
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:header-rows: 0
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:stub-columns: 0
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:widths: 3 1 4
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* - ``V4L2_OUTPUT_TYPE_MODULATOR``
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- 1
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- This output is an analog TV modulator.
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* - ``V4L2_OUTPUT_TYPE_ANALOG``
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- 2
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- Any non-modulator video output, for example Composite Video,
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S-Video, HDMI. The naming as ``_TYPE_ANALOG`` is historical,
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today we would have called it ``_TYPE_VIDEO``.
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* - ``V4L2_OUTPUT_TYPE_ANALOGVGAOVERLAY``
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- 3
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- The video output will be copied to a :ref:`video overlay <overlay>`.
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.. tabularcolumns:: |p{6.4cm}|p{2.4cm}|p{8.5cm}|
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.. _output-capabilities:
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.. flat-table:: Output capabilities
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:header-rows: 0
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:stub-columns: 0
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:widths: 3 1 4
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* - ``V4L2_OUT_CAP_DV_TIMINGS``
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- 0x00000002
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- This output supports setting video timings by using
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``VIDIOC_S_DV_TIMINGS``.
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* - ``V4L2_OUT_CAP_STD``
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- 0x00000004
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- This output supports setting the TV standard by using
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``VIDIOC_S_STD``.
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* - ``V4L2_OUT_CAP_NATIVE_SIZE``
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- 0x00000008
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- This output supports setting the native size using the
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``V4L2_SEL_TGT_NATIVE_SIZE`` selection target, see
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:ref:`v4l2-selections-common`.
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Return Value
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============
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On success 0 is returned, on error -1 and the ``errno`` variable is set
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appropriately. The generic error codes are described at the
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:ref:`Generic Error Codes <gen-errors>` chapter.
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EINVAL
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The struct :c:type:`v4l2_output` ``index`` is out of
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bounds.
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