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1.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later2.. c:namespace:: V4L3 4.. _VIDIOC_ENUMAUDOUT:5 6***********************7ioctl VIDIOC_ENUMAUDOUT8***********************9 10Name11====12 13VIDIOC_ENUMAUDOUT - Enumerate audio outputs14 15Synopsis16========17 18.. c:macro:: VIDIOC_ENUMAUDOUT19 20``int ioctl(int fd, VIDIOC_ENUMAUDOUT, struct v4l2_audioout *argp)``21 22Arguments23=========24 25``fd``26 File descriptor returned by :c:func:`open()`.27 28``argp``29 Pointer to struct :c:type:`v4l2_audioout`.30 31Description32===========33 34To query the attributes of an audio output applications initialize the35``index`` field and zero out the ``reserved`` array of a struct36:c:type:`v4l2_audioout` and call the ``VIDIOC_G_AUDOUT``37ioctl with a pointer to this structure. Drivers fill the rest of the38structure or return an ``EINVAL`` error code when the index is out of39bounds. To enumerate all audio outputs applications shall begin at index40zero, incrementing by one until the driver returns ``EINVAL``.41 42.. note::43 44 Connectors on a TV card to loop back the received audio signal45 to a sound card are not audio outputs in this sense.46 47See :ref:`VIDIOC_G_AUDIOout <VIDIOC_G_AUDOUT>` for a description of struct48:c:type:`v4l2_audioout`.49 50Return Value51============52 53On success 0 is returned, on error -1 and the ``errno`` variable is set54appropriately. The generic error codes are described at the55:ref:`Generic Error Codes <gen-errors>` chapter.56 57EINVAL58 The number of the audio output is out of bounds.59