.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later .. c:namespace:: V4L .. _VIDIOC_ENUMAUDIO: ********************** ioctl VIDIOC_ENUMAUDIO ********************** Name ==== VIDIOC_ENUMAUDIO - Enumerate audio inputs Synopsis ======== .. c:macro:: VIDIOC_ENUMAUDIO ``int ioctl(int fd, VIDIOC_ENUMAUDIO, struct v4l2_audio *argp)`` Arguments ========= ``fd`` File descriptor returned by :c:func:`open()`. ``argp`` Pointer to struct :c:type:`v4l2_audio`. Description =========== To query the attributes of an audio input applications initialize the ``index`` field and zero out the ``reserved`` array of a struct :c:type:`v4l2_audio` and call the :ref:`VIDIOC_ENUMAUDIO` 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 inputs applications shall begin at index zero, incrementing by one until the driver returns ``EINVAL``. See :ref:`VIDIOC_G_AUDIO ` for a description of struct :c:type:`v4l2_audio`. 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 ` chapter. EINVAL The number of the audio input is out of bounds.