1 .. -*- coding: utf-8; mode: rst -*-
5 **************************************
6 ioctl VIDIOC_G_AUDOUT, VIDIOC_S_AUDOUT
7 **************************************
9 *man VIDIOC_G_AUDOUT(2)*
12 Query or select the current audio output
18 .. c:function:: int ioctl( int fd, int request, struct v4l2_audioout *argp )
20 .. c:function:: int ioctl( int fd, int request, const struct v4l2_audioout *argp )
26 File descriptor returned by :ref:`open() <func-open>`.
29 VIDIOC_G_AUDOUT, VIDIOC_S_AUDOUT
37 To query the current audio output applications zero out the ``reserved``
38 array of a struct :ref:`v4l2_audioout <v4l2-audioout>` and call the
39 ``VIDIOC_G_AUDOUT`` ioctl with a pointer to this structure. Drivers fill
40 the rest of the structure or return an EINVAL error code when the device
41 has no audio inputs, or none which combine with the current video
44 Audio outputs have no writable properties. Nevertheless, to select the
45 current audio output applications can initialize the ``index`` field and
46 ``reserved`` array (which in the future may contain writable properties)
47 of a :c:type:`struct v4l2_audioout` structure and call the
48 ``VIDIOC_S_AUDOUT`` ioctl. Drivers switch to the requested output or
49 return the EINVAL error code when the index is out of bounds. This is a
50 write-only ioctl, it does not return the current audio output attributes
51 as ``VIDIOC_G_AUDOUT`` does.
53 Note connectors on a TV card to loop back the received audio signal to a
54 sound card are not audio outputs in this sense.
59 .. flat-table:: struct v4l2_audioout
71 - Identifies the audio output, set by the driver or application.
79 - Name of the audio output, a NUL-terminated ASCII string, for
80 example: "Line Out". This information is intended for the user,
81 preferably the connector label on the device itself.
89 - Audio capability flags, none defined yet. Drivers must set this
98 - Audio mode, none defined yet. Drivers and applications (on
99 ``VIDIOC_S_AUDOUT``) must set this field to zero.
107 - Reserved for future extensions. Drivers and applications must set
115 On success 0 is returned, on error -1 and the ``errno`` variable is set
116 appropriately. The generic error codes are described at the
117 :ref:`Generic Error Codes <gen-errors>` chapter.
120 No audio outputs combine with the current video output, or the
121 number of the selected audio output is out of bounds or it does not
125 .. ------------------------------------------------------------------------------
126 .. This file was automatically converted from DocBook-XML with the dbxml
127 .. library (https://github.com/return42/sphkerneldoc). The origin XML comes
128 .. from the linux kernel, refer to:
130 .. * https://github.com/torvalds/linux/tree/master/Documentation/DocBook
131 .. ------------------------------------------------------------------------------