.. Permission is granted to copy, distribute and/or modify this .. document under the terms of the GNU Free Documentation License, .. Version 1.1 or any later version published by the Free Software .. Foundation, with no Invariant Sections, no Front-Cover Texts .. and no Back-Cover Texts. A copy of the license is included at .. Documentation/userspace-api/media/fdl-appendix.rst. .. .. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections .. _VIDIOC_ENUMAUDIO: ********************** ioctl VIDIOC_ENUMAUDIO ********************** Name ==== VIDIOC_ENUMAUDIO - Enumerate audio inputs Synopsis ======== .. c:function:: int ioctl( int fd, VIDIOC_ENUMAUDIO, struct v4l2_audio *argp ) :name: VIDIOC_ENUMAUDIO Arguments ========= ``fd`` File descriptor returned by :ref:`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.