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+.. 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.