Documentation/media/v4l-drivers/v4l-with-ir.rst - arm/linux - Git at Google

 Infrared remote control support in video4linux drivers
 ======================================================

 Authors: Gerd Hoffmann, Mauro Carvalho Chehab

 Basics
 ------

 Most analog and digital TV boards support remote controllers. Several of
 them have a microprocessor that receives the IR carriers, convert into
 pulse/space sequences and then to scan codes, returning such codes to
 userspace ("scancode mode"). Other boards return just the pulse/space
 sequences ("raw mode").

 The support for remote controller in scancode mode is provided by the
 standard Linux input layer. The support for raw mode is provided via LIRC.

 In order to check the support and test it, it is suggested to download
 the `v4l-utils <https://git.linuxtv.org/v4l-utils.git/>`_. It provides
 two tools to handle remote controllers:

 - ir-keytable: provides a way to query the remote controller, list the
   protocols it supports, enable in-kernel support for IR decoder or
   switch the protocol and to test the reception of scan codes;

 - ir-ctl: provide tools to handle remote controllers that support raw mode
   via LIRC interface.

 Usually, the remote controller module is auto-loaded when the TV card is
 detected. However, for a few devices, you need to manually load the
 ir-kbd-i2c module.

 How it works
 ------------

 The modules register the remote as keyboard within the linux input
 layer, i.e. you'll see the keys of the remote as normal key strokes
 (if CONFIG_INPUT_KEYBOARD is enabled).

 Using the event devices (CONFIG_INPUT_EVDEV) it is possible for
 applications to access the remote via /dev/input/event<n> devices.
 The udev/systemd will automatically create the devices. If you install
 the `v4l-utils <https://git.linuxtv.org/v4l-utils.git/>`_, it may also
 automatically load a different keytable than the default one. Please see
 `v4l-utils <https://git.linuxtv.org/v4l-utils.git/>`_ ir-keytable.1
 man page for details.

 The ir-keytable tool is nice for trouble shooting, i.e. to check
 whenever the input device is really present, which of the devices it
 is, check whenever pressing keys on the remote actually generates
 events and the like.  You can also use any other input utility that changes
 the keymaps, like the input kbd utility.


 Using with lircd
 ================

 The latest versions of the lircd daemon supports reading events from the
 linux input layer (via event device). It also supports receiving IR codes
 in lirc mode.


 Using without lircd
 ===================

 Xorg recognizes several IR keycodes that have its numerical value lower
 than 247. With the advent of Wayland, the input driver got updated too,
 and should now accept all keycodes. Yet, you may want to just reasign
 the keycodes to something that your favorite media application likes.

 This can be done by setting
 `v4l-utils <https://git.linuxtv.org/v4l-utils.git/>`_ to load your own
 keytable in runtime. Please read  ir-keytable.1 man page for details.
	Infrared remote control support in video4linux drivers
	======================================================

	Authors: Gerd Hoffmann, Mauro Carvalho Chehab

	Basics
	------

	Most analog and digital TV boards support remote controllers. Several of
	them have a microprocessor that receives the IR carriers, convert into
	pulse/space sequences and then to scan codes, returning such codes to
	userspace ("scancode mode"). Other boards return just the pulse/space
	sequences ("raw mode").

	The support for remote controller in scancode mode is provided by the
	standard Linux input layer. The support for raw mode is provided via LIRC.

	In order to check the support and test it, it is suggested to download
	the `v4l-utils <https://git.linuxtv.org/v4l-utils.git/>`_. It provides
	two tools to handle remote controllers:

	- ir-keytable: provides a way to query the remote controller, list the
	protocols it supports, enable in-kernel support for IR decoder or
	switch the protocol and to test the reception of scan codes;

	- ir-ctl: provide tools to handle remote controllers that support raw mode
	via LIRC interface.

	Usually, the remote controller module is auto-loaded when the TV card is
	detected. However, for a few devices, you need to manually load the
	ir-kbd-i2c module.

	How it works
	------------

	The modules register the remote as keyboard within the linux input
	layer, i.e. you'll see the keys of the remote as normal key strokes
	(if CONFIG_INPUT_KEYBOARD is enabled).

	Using the event devices (CONFIG_INPUT_EVDEV) it is possible for
	applications to access the remote via /dev/input/event<n> devices.
	The udev/systemd will automatically create the devices. If you install
	the `v4l-utils <https://git.linuxtv.org/v4l-utils.git/>`_, it may also
	automatically load a different keytable than the default one. Please see
	`v4l-utils <https://git.linuxtv.org/v4l-utils.git/>`_ ir-keytable.1
	man page for details.

	The ir-keytable tool is nice for trouble shooting, i.e. to check
	whenever the input device is really present, which of the devices it
	is, check whenever pressing keys on the remote actually generates
	events and the like. You can also use any other input utility that changes
	the keymaps, like the input kbd utility.


	Using with lircd
	================

	The latest versions of the lircd daemon supports reading events from the
	linux input layer (via event device). It also supports receiving IR codes
	in lirc mode.


	Using without lircd
	===================

	Xorg recognizes several IR keycodes that have its numerical value lower
	than 247. With the advent of Wayland, the input driver got updated too,
	and should now accept all keycodes. Yet, you may want to just reasign
	the keycodes to something that your favorite media application likes.

	This can be done by setting
	`v4l-utils <https://git.linuxtv.org/v4l-utils.git/>`_ to load your own
	keytable in runtime. Please read ir-keytable.1 man page for details.