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- .. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
- .. c:namespace:: V4L
- .. _VIDIOC_ENUMAUDOUT:
- ***********************
- ioctl VIDIOC_ENUMAUDOUT
- ***********************
- Name
- ====
- VIDIOC_ENUMAUDOUT - Enumerate audio outputs
- Synopsis
- ========
- .. c:macro:: VIDIOC_ENUMAUDOUT
- ``int ioctl(int fd, VIDIOC_ENUMAUDOUT, struct v4l2_audioout *argp)``
- Arguments
- =========
- ``fd``
- File descriptor returned by :c:func:`open()`.
- ``argp``
- Pointer to struct :c:type:`v4l2_audioout`.
- Description
- ===========
- To query the attributes of an audio output applications initialize the
- ``index`` field and zero out the ``reserved`` array of a struct
- :c:type:`v4l2_audioout` and call the ``VIDIOC_G_AUDOUT``
- ioctl 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 audio outputs applications shall begin at index
- zero, incrementing by one until the driver returns ``EINVAL``.
- .. note::
- Connectors on a TV card to loop back the received audio signal
- to a sound card are not audio outputs in this sense.
- See :ref:`VIDIOC_G_AUDIOout <VIDIOC_G_AUDOUT>` for a description of struct
- :c:type:`v4l2_audioout`.
- 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 number of the audio output is out of bounds.
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