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1.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later2.. c:namespace:: V4L3 4.. _VIDIOC_G_AUDOUT:5 6**************************************7ioctl VIDIOC_G_AUDOUT, VIDIOC_S_AUDOUT8**************************************9 10Name11====12 13VIDIOC_G_AUDOUT - VIDIOC_S_AUDOUT - Query or select the current audio output14 15Synopsis16========17 18.. c:macro:: VIDIOC_G_AUDOUT19 20``int ioctl(int fd, VIDIOC_G_AUDOUT, struct v4l2_audioout *argp)``21 22.. c:macro:: VIDIOC_S_AUDOUT23 24``int ioctl(int fd, VIDIOC_S_AUDOUT, const struct v4l2_audioout *argp)``25 26Arguments27=========28 29``fd``30 File descriptor returned by :c:func:`open()`.31 32``argp``33 Pointer to struct :c:type:`v4l2_audioout`.34 35Description36===========37 38To query the current audio output applications zero out the ``reserved``39array of a struct :c:type:`v4l2_audioout` and call the40``VIDIOC_G_AUDOUT`` ioctl with a pointer to this structure. Drivers fill41the rest of the structure or return an ``EINVAL`` error code when the device42has no audio inputs, or none which combine with the current video43output.44 45Audio outputs have no writable properties. Nevertheless, to select the46current audio output applications can initialize the ``index`` field and47``reserved`` array (which in the future may contain writable properties)48of a struct :c:type:`v4l2_audioout` structure and call the49``VIDIOC_S_AUDOUT`` ioctl. Drivers switch to the requested output or50return the ``EINVAL`` error code when the index is out of bounds. This is a51write-only ioctl, it does not return the current audio output attributes52as ``VIDIOC_G_AUDOUT`` does.53 54.. note::55 56 Connectors on a TV card to loop back the received audio signal57 to a sound card are not audio outputs in this sense.58 59.. c:type:: v4l2_audioout60 61.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.5cm}|62 63.. flat-table:: struct v4l2_audioout64 :header-rows: 065 :stub-columns: 066 :widths: 1 1 267 68 * - __u3269 - ``index``70 - Identifies the audio output, set by the driver or application.71 * - __u872 - ``name``\ [32]73 - Name of the audio output, a NUL-terminated ASCII string, for74 example: "Line Out". This information is intended for the user,75 preferably the connector label on the device itself.76 * - __u3277 - ``capability``78 - Audio capability flags, none defined yet. Drivers must set this79 field to zero.80 * - __u3281 - ``mode``82 - Audio mode, none defined yet. Drivers and applications (on83 ``VIDIOC_S_AUDOUT``) must set this field to zero.84 * - __u3285 - ``reserved``\ [2]86 - Reserved for future extensions. Drivers and applications must set87 the array to zero.88 89Return Value90============91 92On success 0 is returned, on error -1 and the ``errno`` variable is set93appropriately. The generic error codes are described at the94:ref:`Generic Error Codes <gen-errors>` chapter.95 96EINVAL97 No audio outputs combine with the current video output, or the98 number of the selected audio output is out of bounds or it does not99 combine.100