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.. -*- coding: utf-8; mode: rst -*-
.. _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() <func-open>`.
``argp``
Description
===========
To query the attributes of an audio input applications initialize the
``index`` field and zero out the ``reserved`` array of a struct
:ref:`v4l2_audio <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 <VIDIOC_G_AUDIO>` for a description of struct
:ref:`v4l2_audio <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 <gen-errors>` chapter.
EINVAL
The number of the audio input is out of bounds.
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