Documentation/linux_tv/media/v4l/vidioc-enumaudioout.rst

.. -*- coding: utf-8; mode: rst -*-

.. _VIDIOC_ENUMAUDIOOUT:

***********************
ioctl VIDIOC_ENUMAUDOUT
***********************

*man VIDIOC_ENUMAUDOUT(2)*

Enumerate audio outputs


Synopsis
========

.. c:function:: int ioctl( int fd, int request, struct v4l2_audioout *argp )

Arguments
=========

``fd``
    File descriptor returned by :ref:`open() <func-open>`.

``request``
    VIDIOC_ENUMAUDOUT

``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` 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.


.. ------------------------------------------------------------------------------
.. This file was automatically converted from DocBook-XML with the dbxml
.. library (https://github.com/return42/sphkerneldoc). The origin XML comes
.. from the linux kernel, refer to:
..
.. * https://github.com/torvalds/linux/tree/master/Documentation/DocBook
.. ------------------------------------------------------------------------------