vidioc-enumoutput.rst

  1.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
  2.. c:namespace:: V4L
  3
  4.. _VIDIOC_ENUMOUTPUT:
  5
  6***********************
  7ioctl VIDIOC_ENUMOUTPUT
  8***********************
  9
 10Name
 11====
 12
 13VIDIOC_ENUMOUTPUT - Enumerate video outputs
 14
 15Synopsis
 16========
 17
 18.. c:macro:: VIDIOC_ENUMOUTPUT
 19
 20``int ioctl(int fd, VIDIOC_ENUMOUTPUT, struct v4l2_output *argp)``
 21
 22Arguments
 23=========
 24
 25``fd``
 26    File descriptor returned by :c:func:`open()`.
 27
 28``argp``
 29    Pointer to struct :c:type:`v4l2_output`.
 30
 31Description
 32===========
 33
 34To query the attributes of a video outputs applications initialize the
 35``index`` field of struct :c:type:`v4l2_output` and call
 36the :ref:`VIDIOC_ENUMOUTPUT` with a pointer to this structure.
 37Drivers fill the rest of the structure or return an ``EINVAL`` error code
 38when the index is out of bounds. To enumerate all outputs applications
 39shall begin at index zero, incrementing by one until the driver returns
 40``EINVAL``.
 41
 42.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.5cm}|
 43
 44.. c:type:: v4l2_output
 45
 46.. flat-table:: struct v4l2_output
 47    :header-rows:  0
 48    :stub-columns: 0
 49    :widths:       1 1 2
 50
 51    * - __u32
 52      - ``index``
 53      - Identifies the output, set by the application.
 54    * - __u8
 55      - ``name``\ [32]
 56      - Name of the video output, a NUL-terminated ASCII string, for
 57	example: "Vout". This information is intended for the user,
 58	preferably the connector label on the device itself.
 59    * - __u32
 60      - ``type``
 61      - Type of the output, see :ref:`output-type`.
 62    * - __u32
 63      - ``audioset``
 64      - Drivers can enumerate up to 32 video and audio outputs. This field
 65	shows which audio outputs were selectable as the current output if
 66	this was the currently selected video output. It is a bit mask.
 67	The LSB corresponds to audio output 0, the MSB to output 31. Any
 68	number of bits can be set, or none.
 69
 70	When the driver does not enumerate audio outputs no bits must be
 71	set. Applications shall not interpret this as lack of audio
 72	support. Drivers may automatically select audio outputs without
 73	enumerating them.
 74
 75	For details on audio outputs and how to select the current output
 76	see :ref:`audio`.
 77    * - __u32
 78      - ``modulator``
 79      - Output devices can have zero or more RF modulators. When the
 80	``type`` is ``V4L2_OUTPUT_TYPE_MODULATOR`` this is an RF connector
 81	and this field identifies the modulator. It corresponds to struct
 82	:c:type:`v4l2_modulator` field ``index``. For
 83	details on modulators see :ref:`tuner`.
 84    * - :ref:`v4l2_std_id <v4l2-std-id>`
 85      - ``std``
 86      - Every video output supports one or more different video standards.
 87	This field is a set of all supported standards. For details on
 88	video standards and how to switch see :ref:`standard`.
 89    * - __u32
 90      - ``capabilities``
 91      - This field provides capabilities for the output. See
 92	:ref:`output-capabilities` for flags.
 93    * - __u32
 94      - ``reserved``\ [3]
 95      - Reserved for future extensions. Drivers must set the array to
 96	zero.
 97
 98
 99.. tabularcolumns:: |p{7.5cm}|p{0.6cm}|p{9.2cm}|
100
101.. _output-type:
102
103.. flat-table:: Output Type
104    :header-rows:  0
105    :stub-columns: 0
106    :widths:       3 1 4
107
108    * - ``V4L2_OUTPUT_TYPE_MODULATOR``
109      - 1
110      - This output is an analog TV modulator.
111    * - ``V4L2_OUTPUT_TYPE_ANALOG``
112      - 2
113      - Any non-modulator video output, for example Composite Video,
114	S-Video, HDMI. The naming as ``_TYPE_ANALOG`` is historical,
115	today we would have called it ``_TYPE_VIDEO``.
116    * - ``V4L2_OUTPUT_TYPE_ANALOGVGAOVERLAY``
117      - 3
118      - The video output will be copied to a :ref:`video overlay <overlay>`.
119
120
121.. tabularcolumns:: |p{6.4cm}|p{2.4cm}|p{8.5cm}|
122
123.. _output-capabilities:
124
125.. flat-table:: Output capabilities
126    :header-rows:  0
127    :stub-columns: 0
128    :widths:       3 1 4
129
130    * - ``V4L2_OUT_CAP_DV_TIMINGS``
131      - 0x00000002
132      - This output supports setting video timings by using
133	``VIDIOC_S_DV_TIMINGS``.
134    * - ``V4L2_OUT_CAP_STD``
135      - 0x00000004
136      - This output supports setting the TV standard by using
137	``VIDIOC_S_STD``.
138    * - ``V4L2_OUT_CAP_NATIVE_SIZE``
139      - 0x00000008
140      - This output supports setting the native size using the
141	``V4L2_SEL_TGT_NATIVE_SIZE`` selection target, see
142	:ref:`v4l2-selections-common`.
143
144Return Value
145============
146
147On success 0 is returned, on error -1 and the ``errno`` variable is set
148appropriately. The generic error codes are described at the
149:ref:`Generic Error Codes <gen-errors>` chapter.
150
151EINVAL
152    The struct :c:type:`v4l2_output` ``index`` is out of
153    bounds.