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+.. -*- coding: utf-8; mode: rst -*-
+
+.. _VIDIOC_G_AUDIO:
+
+************************************
+ioctl VIDIOC_G_AUDIO, VIDIOC_S_AUDIO
+************************************
+
+Name
+====
+
+VIDIOC_G_AUDIO - VIDIOC_S_AUDIO - Query or select the current audio input and its attributes
+
+
+Synopsis
+========
+
+.. cpp:function:: int ioctl( int fd, int request, struct v4l2_audio *argp )
+
+.. cpp:function:: int ioctl( int fd, int request, const struct v4l2_audio *argp )
+
+
+Arguments
+=========
+
+``fd``
+    File descriptor returned by :ref:`open() <func-open>`.
+
+``request``
+    VIDIOC_G_AUDIO, VIDIOC_S_AUDIO
+
+``argp``
+
+
+Description
+===========
+
+To query the current audio input applications zero out the ``reserved``
+array of a struct :ref:`v4l2_audio <v4l2-audio>` and call the
+:ref:`VIDIOC_G_AUDIO <VIDIOC_G_AUDIO>` ioctl with a pointer to this structure. Drivers fill
+the rest of the structure or return an ``EINVAL`` error code when the device
+has no audio inputs, or none which combine with the current video input.
+
+Audio inputs have one writable property, the audio mode. To select the
+current audio input *and* change the audio mode, applications initialize
+the ``index`` and ``mode`` fields, and the ``reserved`` array of a
+:ref:`struct v4l2_audio <v4l2-audio>` structure and call the :ref:`VIDIOC_S_AUDIO <VIDIOC_G_AUDIO>`
+ioctl. Drivers may switch to a different audio mode if the request
+cannot be satisfied. However, this is a write-only ioctl, it does not
+return the actual new audio mode.
+
+
+.. _v4l2-audio:
+
+.. flat-table:: struct v4l2_audio
+    :header-rows:  0
+    :stub-columns: 0
+    :widths:       1 1 2
+
+
+    -  .. row 1
+
+       -  __u32
+
+       -  ``index``
+
+       -  Identifies the audio input, set by the driver or application.
+
+    -  .. row 2
+
+       -  __u8
+
+       -  ``name``\ [32]
+
+       -  Name of the audio input, a NUL-terminated ASCII string, for
+	  example: "Line In". This information is intended for the user,
+	  preferably the connector label on the device itself.
+
+    -  .. row 3
+
+       -  __u32
+
+       -  ``capability``
+
+       -  Audio capability flags, see :ref:`audio-capability`.
+
+    -  .. row 4
+
+       -  __u32
+
+       -  ``mode``
+
+       -  Audio mode flags set by drivers and applications (on
+	  :ref:`VIDIOC_S_AUDIO <VIDIOC_G_AUDIO>` ioctl), see :ref:`audio-mode`.
+
+    -  .. row 5
+
+       -  __u32
+
+       -  ``reserved``\ [2]
+
+       -  Reserved for future extensions. Drivers and applications must set
+	  the array to zero.
+
+
+
+.. _audio-capability:
+
+.. flat-table:: Audio Capability Flags
+    :header-rows:  0
+    :stub-columns: 0
+    :widths:       3 1 4
+
+
+    -  .. row 1
+
+       -  ``V4L2_AUDCAP_STEREO``
+
+       -  0x00001
+
+       -  This is a stereo input. The flag is intended to automatically
+	  disable stereo recording etc. when the signal is always monaural.
+	  The API provides no means to detect if stereo is *received*,
+	  unless the audio input belongs to a tuner.
+
+    -  .. row 2
+
+       -  ``V4L2_AUDCAP_AVL``
+
+       -  0x00002
+
+       -  Automatic Volume Level mode is supported.
+
+
+
+.. _audio-mode:
+
+.. flat-table:: Audio Mode Flags
+    :header-rows:  0
+    :stub-columns: 0
+    :widths:       3 1 4
+
+
+    -  .. row 1
+
+       -  ``V4L2_AUDMODE_AVL``
+
+       -  0x00001
+
+       -  AVL mode is on.
+
+
+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
+    No audio inputs combine with the current video input, or the number
+    of the selected audio input is out of bounds or it does not combine.