mirror of https://github.com/Qortal/Brooklyn
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
88 lines
3.3 KiB
88 lines
3.3 KiB
.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later |
|
|
|
.. _fm-rx-controls: |
|
|
|
***************************** |
|
FM Receiver Control Reference |
|
***************************** |
|
|
|
The FM Receiver (FM_RX) class includes controls for common features of |
|
FM Reception capable devices. |
|
|
|
|
|
.. _fm-rx-control-id: |
|
|
|
FM_RX Control IDs |
|
================= |
|
|
|
``V4L2_CID_FM_RX_CLASS (class)`` |
|
The FM_RX class descriptor. Calling |
|
:ref:`VIDIOC_QUERYCTRL` for this control will |
|
return a description of this control class. |
|
|
|
``V4L2_CID_RDS_RECEPTION (boolean)`` |
|
Enables/disables RDS reception by the radio tuner |
|
|
|
``V4L2_CID_RDS_RX_PTY (integer)`` |
|
Gets RDS Programme Type field. This encodes up to 31 pre-defined |
|
programme types. |
|
|
|
``V4L2_CID_RDS_RX_PS_NAME (string)`` |
|
Gets the Programme Service name (PS_NAME). It is intended for |
|
static display on a receiver. It is the primary aid to listeners in |
|
programme service identification and selection. In Annex E of |
|
:ref:`iec62106`, the RDS specification, there is a full |
|
description of the correct character encoding for Programme Service |
|
name strings. Also from RDS specification, PS is usually a single |
|
eight character text. However, it is also possible to find receivers |
|
which can scroll strings sized as 8 x N characters. So, this control |
|
must be configured with steps of 8 characters. The result is it must |
|
always contain a string with size multiple of 8. |
|
|
|
``V4L2_CID_RDS_RX_RADIO_TEXT (string)`` |
|
Gets the Radio Text info. It is a textual description of what is |
|
being broadcasted. RDS Radio Text can be applied when broadcaster |
|
wishes to transmit longer PS names, programme-related information or |
|
any other text. In these cases, RadioText can be used in addition to |
|
``V4L2_CID_RDS_RX_PS_NAME``. The encoding for Radio Text strings is |
|
also fully described in Annex E of :ref:`iec62106`. The length of |
|
Radio Text strings depends on which RDS Block is being used to |
|
transmit it, either 32 (2A block) or 64 (2B block). However, it is |
|
also possible to find receivers which can scroll strings sized as 32 |
|
x N or 64 x N characters. So, this control must be configured with |
|
steps of 32 or 64 characters. The result is it must always contain a |
|
string with size multiple of 32 or 64. |
|
|
|
``V4L2_CID_RDS_RX_TRAFFIC_ANNOUNCEMENT (boolean)`` |
|
If set, then a traffic announcement is in progress. |
|
|
|
``V4L2_CID_RDS_RX_TRAFFIC_PROGRAM (boolean)`` |
|
If set, then the tuned programme carries traffic announcements. |
|
|
|
``V4L2_CID_RDS_RX_MUSIC_SPEECH (boolean)`` |
|
If set, then this channel broadcasts music. If cleared, then it |
|
broadcasts speech. If the transmitter doesn't make this distinction, |
|
then it will be set. |
|
|
|
``V4L2_CID_TUNE_DEEMPHASIS`` |
|
(enum) |
|
|
|
enum v4l2_deemphasis - |
|
Configures the de-emphasis value for reception. A de-emphasis filter |
|
is applied to the broadcast to accentuate the high audio |
|
frequencies. Depending on the region, a time constant of either 50 |
|
or 75 useconds is used. The enum v4l2_deemphasis defines possible |
|
values for de-emphasis. Here they are: |
|
|
|
|
|
|
|
.. flat-table:: |
|
:header-rows: 0 |
|
:stub-columns: 0 |
|
|
|
* - ``V4L2_DEEMPHASIS_DISABLED`` |
|
- No de-emphasis is applied. |
|
* - ``V4L2_DEEMPHASIS_50_uS`` |
|
- A de-emphasis of 50 uS is used. |
|
* - ``V4L2_DEEMPHASIS_75_uS`` |
|
- A de-emphasis of 75 uS is used.
|
|
|