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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 10:05:51 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 10:05:51 +0000 |
commit | 5d1646d90e1f2cceb9f0828f4b28318cd0ec7744 (patch) | |
tree | a94efe259b9009378be6d90eb30d2b019d95c194 /Documentation/userspace-api/media/v4l/vidioc-g-audioout.rst | |
parent | Initial commit. (diff) | |
download | linux-upstream/5.10.209.tar.xz linux-upstream/5.10.209.zip |
Adding upstream version 5.10.209.upstream/5.10.209upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r-- | Documentation/userspace-api/media/v4l/vidioc-g-audioout.rst | 99 |
1 files changed, 99 insertions, 0 deletions
diff --git a/Documentation/userspace-api/media/v4l/vidioc-g-audioout.rst b/Documentation/userspace-api/media/v4l/vidioc-g-audioout.rst new file mode 100644 index 000000000..194f22493 --- /dev/null +++ b/Documentation/userspace-api/media/v4l/vidioc-g-audioout.rst @@ -0,0 +1,99 @@ +.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later +.. c:namespace:: V4L + +.. _VIDIOC_G_AUDOUT: + +************************************** +ioctl VIDIOC_G_AUDOUT, VIDIOC_S_AUDOUT +************************************** + +Name +==== + +VIDIOC_G_AUDOUT - VIDIOC_S_AUDOUT - Query or select the current audio output + +Synopsis +======== + +.. c:macro:: VIDIOC_G_AUDOUT + +``int ioctl(int fd, VIDIOC_G_AUDOUT, struct v4l2_audioout *argp)`` + +.. c:macro:: VIDIOC_S_AUDOUT + +``int ioctl(int fd, VIDIOC_S_AUDOUT, const struct v4l2_audioout *argp)`` + +Arguments +========= + +``fd`` + File descriptor returned by :c:func:`open()`. + +``argp`` + Pointer to struct :c:type:`v4l2_audioout`. + +Description +=========== + +To query the current audio output applications zero out the ``reserved`` +array of a struct :c:type:`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 device +has no audio inputs, or none which combine with the current video +output. + +Audio outputs have no writable properties. Nevertheless, to select the +current audio output applications can initialize the ``index`` field and +``reserved`` array (which in the future may contain writable properties) +of a struct :c:type:`v4l2_audioout` structure and call the +``VIDIOC_S_AUDOUT`` ioctl. Drivers switch to the requested output or +return the ``EINVAL`` error code when the index is out of bounds. This is a +write-only ioctl, it does not return the current audio output attributes +as ``VIDIOC_G_AUDOUT`` does. + +.. note:: + + Connectors on a TV card to loop back the received audio signal + to a sound card are not audio outputs in this sense. + +.. c:type:: v4l2_audioout + +.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}| + +.. flat-table:: struct v4l2_audioout + :header-rows: 0 + :stub-columns: 0 + :widths: 1 1 2 + + * - __u32 + - ``index`` + - Identifies the audio output, set by the driver or application. + * - __u8 + - ``name``\ [32] + - Name of the audio output, a NUL-terminated ASCII string, for + example: "Line Out". This information is intended for the user, + preferably the connector label on the device itself. + * - __u32 + - ``capability`` + - Audio capability flags, none defined yet. Drivers must set this + field to zero. + * - __u32 + - ``mode`` + - Audio mode, none defined yet. Drivers and applications (on + ``VIDIOC_S_AUDOUT``) must set this field to zero. + * - __u32 + - ``reserved``\ [2] + - Reserved for future extensions. Drivers and applications must set + the array to zero. + +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 outputs combine with the current video output, or the + number of the selected audio output is out of bounds or it does not + combine. |