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58 lines
1.5 KiB
58 lines
1.5 KiB
.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later |
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.. c:namespace:: V4L |
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.. _VIDIOC_ENUMAUDOUT: |
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*********************** |
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ioctl VIDIOC_ENUMAUDOUT |
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*********************** |
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Name |
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==== |
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VIDIOC_ENUMAUDOUT - Enumerate audio outputs |
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Synopsis |
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======== |
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.. c:macro:: VIDIOC_ENUMAUDOUT |
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``int ioctl(int fd, VIDIOC_ENUMAUDOUT, struct v4l2_audioout *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_audioout`. |
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Description |
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=========== |
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To query the attributes of an audio output applications initialize the |
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``index`` field and zero out the ``reserved`` array of a struct |
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:c:type:`v4l2_audioout` and call the ``VIDIOC_G_AUDOUT`` |
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ioctl with a pointer to this structure. Drivers fill the rest of the |
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structure or return an ``EINVAL`` error code when the index is out of |
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bounds. To enumerate all audio outputs applications shall begin at index |
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zero, incrementing by one until the driver returns ``EINVAL``. |
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.. note:: |
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Connectors on a TV card to loop back the received audio signal |
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to a sound card are not audio outputs in this sense. |
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See :ref:`VIDIOC_G_AUDIOout <VIDIOC_G_AUDOUT>` for a description of struct |
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:c:type:`v4l2_audioout`. |
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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 number of the audio output is out of bounds.
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