Documentation/linux_tv/media/v4l/dev-radio.rst - arm/linux - Git at Google

 .. -*- coding: utf-8; mode: rst -*-

 .. _radio:

 ***************
 Radio Interface
 ***************

 This interface is intended for AM and FM (analog) radio receivers and
 transmitters.

 Conventionally V4L2 radio devices are accessed through character device
 special files named ``/dev/radio`` and ``/dev/radio0`` to
 ``/dev/radio63`` with major number 81 and minor numbers 64 to 127.


 Querying Capabilities
 =====================

 Devices supporting the radio interface set the ``V4L2_CAP_RADIO`` and
 ``V4L2_CAP_TUNER`` or ``V4L2_CAP_MODULATOR`` flag in the
 ``capabilities`` field of struct
 :ref:`v4l2_capability <v4l2-capability>` returned by the
 :ref:`VIDIOC_QUERYCAP <vidioc-querycap>` ioctl. Other combinations of
 capability flags are reserved for future extensions.


 Supplemental Functions
 ======================

 Radio devices can support :ref:`controls <control>`, and must support
 the :ref:`tuner or modulator <tuner>` ioctls.

 They do not support the video input or output, audio input or output,
 video standard, cropping and scaling, compression and streaming
 parameter, or overlay ioctls. All other ioctls and I/O methods are
 reserved for future extensions.


 Programming
 ===========

 Radio devices may have a couple audio controls (as discussed in
 :ref:`control`) such as a volume control, possibly custom controls.
 Further all radio devices have one tuner or modulator (these are
 discussed in :ref:`tuner`) with index number zero to select the radio
 frequency and to determine if a monaural or FM stereo program is
 received/emitted. Drivers switch automatically between AM and FM
 depending on the selected frequency. The
 :ref:`VIDIOC_G_TUNER <vidioc-g-tuner>` or
 :ref:`VIDIOC_G_MODULATOR <vidioc-g-modulator>` ioctl reports the
 supported frequency range.


 .. ------------------------------------------------------------------------------
 .. This file was automatically converted from DocBook-XML with the dbxml
 .. library (https://github.com/return42/sphkerneldoc). The origin XML comes
 .. from the linux kernel, refer to:
 ..
 .. * https://github.com/torvalds/linux/tree/master/Documentation/DocBook
 .. ------------------------------------------------------------------------------
	.. -- coding: utf-8; mode: rst --

	.. _radio:

	***************
	Radio Interface
	***************

	This interface is intended for AM and FM (analog) radio receivers and
	transmitters.

	Conventionally V4L2 radio devices are accessed through character device
	special files named ``/dev/radio`` and ``/dev/radio0`` to
	``/dev/radio63`` with major number 81 and minor numbers 64 to 127.


	Querying Capabilities
	=====================

	Devices supporting the radio interface set the ``V4L2_CAP_RADIO`` and
	``V4L2_CAP_TUNER`` or ``V4L2_CAP_MODULATOR`` flag in the
	``capabilities`` field of struct
	:ref:`v4l2_capability <v4l2-capability>` returned by the
	:ref:`VIDIOC_QUERYCAP <vidioc-querycap>` ioctl. Other combinations of
	capability flags are reserved for future extensions.


	Supplemental Functions
	======================

	Radio devices can support :ref:`controls <control>`, and must support
	the :ref:`tuner or modulator <tuner>` ioctls.

	They do not support the video input or output, audio input or output,
	video standard, cropping and scaling, compression and streaming
	parameter, or overlay ioctls. All other ioctls and I/O methods are
	reserved for future extensions.


	Programming
	===========

	Radio devices may have a couple audio controls (as discussed in
	:ref:`control`) such as a volume control, possibly custom controls.
	Further all radio devices have one tuner or modulator (these are
	discussed in :ref:`tuner`) with index number zero to select the radio
	frequency and to determine if a monaural or FM stereo program is
	received/emitted. Drivers switch automatically between AM and FM
	depending on the selected frequency. The
	:ref:`VIDIOC_G_TUNER <vidioc-g-tuner>` or
	:ref:`VIDIOC_G_MODULATOR <vidioc-g-modulator>` ioctl reports the
	supported frequency range.


	.. ------------------------------------------------------------------------------
	.. This file was automatically converted from DocBook-XML with the dbxml
	.. library (https://github.com/return42/sphkerneldoc). The origin XML comes
	.. from the linux kernel, refer to:
	..
	.. * https://github.com/torvalds/linux/tree/master/Documentation/DocBook
	.. ------------------------------------------------------------------------------