linux_dsm_epyc7002/Documentation/media/uapi/v4l/vidioc-enumaudioout.rst
Mauro Carvalho Chehab 41d804653e [media] docs-rst: Convert V4L2 uAPI to use C function references
Name all ioctl references and make them match the ioctls that
are documented. That will improve the cross-reference index,
as it will have all ioctls and syscalls there.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
2016-08-22 21:23:27 -03:00

60 lines
1.4 KiB
ReStructuredText

.. -*- coding: utf-8; mode: rst -*-
.. _VIDIOC_ENUMAUDOUT:
***********************
ioctl VIDIOC_ENUMAUDOUT
***********************
Name
====
VIDIOC_ENUMAUDOUT - Enumerate audio outputs
Synopsis
========
.. c:function:: int ioctl( int fd, VIDIOC_ENUMAUDOUT, struct v4l2_audioout *argp )
:name: VIDIOC_ENUMAUDOUT
Arguments
=========
``fd``
File descriptor returned by :ref:`open() <func-open>`.
``argp``
Description
===========
To query the attributes of an audio output applications initialize the
``index`` field and zero out the ``reserved`` array of a struct
:ref:`v4l2_audioout <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
:ref:`v4l2_audioout <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.