Infra-Red Remotes

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Infra-Red Remotes
Introduction
Modern Linux kernels (used in LibreELEC) have built-in support for IR remotes. IR signals are decoded by the kernel and programs see button presses from IR remotes in the same way as key presses from a normal keyboard, as Linux input events. This approach is the successor to LIRC where a separate program, lircd, decodes IR signals and programs obtain button presses from a socket as LIRC events.
While this new scheme is really handy, there's a small gotcha: Kodi's remote handling is built for LIRC and it doesn't cope well with Linux input events. In general all buttons also present on a normal keyboard, like arrows and numbers, work fine but rather important buttons like OK and channel up/down don't. To solve this LibreELEC runs eventlircd in the background to translate Linux input events into LIRC events. So "under the hood" the new scheme is being used, but remote buttons still show up as LIRC events in Kodi.
Kodi translates the received LIRC events to Kodi button names via Lircmap.xml and then buttons are mapped to Kodi actions via remote.xml and keyboard.xml files. This wiki page describes the LibreELEC configuration. Information on Kodi configuration is available in the Kodi LIRC and Kodi Keyboard.xml wiki pages.
LibreELEC still ships with LIRC so IR remotes with non-standard protocols and rather special setups can be supported. In general, keep LIRC disabled (in LibreELEC Settings → Services) and only enable it for exceptional cases where you actually need it.
Configuration
Like most current Linux distros LibreELEC uses ir-keytable to configure Infra-Red Remotes. Each IR receiver kernel driver installs a default keytable which specifies the IR protocol to use, e.g. RC5, RC6, NEC, and the scancode to Linux keycode mappings.
Most universal receivers work with the rc-rc6-mce table so RC6 MCE remotes can be used without further configuration. Drivers for DVB devices sold with a remote usually install their own keytable, e.g. the Hauppauge remote that came with a Hauppauge DVB stick.
After the kernel driver is loaded ir-keytable -a is automatically run to change the kernel default configuration. First /etc/rc_maps.cfg determines which keytable to load. Then the corresponding keytable file from /usr/lib/udev/rc_keymaps is used to configure the remote control driver.
As most of the LibreELEC filesystem is read-only, we use a system of boot-time file overrides to read user-created configuration from the persistent /storage area:
/storage/.config/rc_maps.cfg overrides /etc/rc_maps.cfg.
/storage/.config/rc_maps.cfg.sample has simple examples.
/storage/.config/rc_keymaps overrides /usr/lib/udev/rc\_keymaps\.
/etc/rc_maps.cfg uses the libreelec_multi keytable instead of rc6_mce.
The default libreelec_multi keytable allows us to support Xbox 360/One remotes "out of box" in addition to MCE/RC6 remotes. This is configured via the following change:
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# use combined multi-table on MCE receivers
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#*      rc-rc6-mce               rc6_mce
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*       rc-rc6-mce               libreelec_multi
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Can I use?
While most IR receivers can be used with a large variety of remotes the answer to “Can I use remote X with IR receiver Y?” depends on many factors:
Some IR receivers cannot be configured and you can only use the remote they came with.
Some receivers only support a subset of protocols, e.g. only RC5, not RC6.
If a remote uses a protocol not supported by the IR receiver, or a protocol not supported by the Linux kernel, the last option is the RAW (lirc) protocol which allows userspace LIRC to configure it via a custom lirc.conf file.
Configuration (Easy)
LibreELEC includes 100+ remote keytable files from the Linux kernel so there is a good chance your remote has a known configuration, or a partially working keytable can provide a starting point for adding the missing buttons (see the "Hard" section).
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Look at the keytable files in /usr/lib/udev/rc_keymaps/.
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If one of the filenames suggests it could match your remote, try using it.
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If it doesn't work, keep trying..
To test a different keytable file run ir-keytable -c -w /path/to/keytable-file e.g.
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LibreELEC:~ # ir-keytable -c -w /usr/lib/udev/rc_keymaps/samsung
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Read samsung table
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Old keytable cleared
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Wrote 30 keycode(s) to driver
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Protocols changed to nec
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If the output ends with these lines the protocol is not supported by the IR receiver:
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Invalid protocols selected
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Couldn't change the IR protocols
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If the keytable loaded without errors press the up, down, left, right and OK buttons to see if navigation in Kodi works?
If you find a working keytable file the config can be made persistent by creating /storage/.config/rc_maps.cfg with the name of the keytable, e.g. if the samsung keytable works the file with the following content:
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* * samsung
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Running ir-keytable -a /storage/.config/rc_maps.cfg and the output should look like:
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LibreELEC:~ # ir-keytable -a /storage/.config/rc_maps.cfg
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Old keytable cleared
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Wrote 30 keycode(s) to driver
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Protocols changed to nec
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Test the buttons work again, and if all is okay, reboot.
Configuration (Hard)
If you cannot find a working keymap or the keymap has misssing buttons you can create your own. The keytable file is plain text with a simple format. The first line contains a header with a descriptive name (free text, but avoid special characters and spaces) and the remote protocol (important!). This is followed by lines that map remote scancode to Linux keycode. A typical keytable file looks like this:
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# table justboom, type: RC5
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0x101a KEY_UP
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0x101b KEY_DOWN
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0x1013 KEY_LEFT
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0x1014 KEY_RIGHT
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0x1015 KEY_OK
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To capture the keycodes you must stop Kodi and eventlircd first, or these services capture IR input and you will see no output from ir-keytable:
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systemctl stop kodi
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systemctl stop eventlircd
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Next we have to identify the IR protocol. If you found a partially working keytable file (with the protocol listed in the header) you can skip this step. First we run ir-keytable to find out which protocols tthe receiver driver supports. Look at the Supported protocols: line, e.g.
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LibreELEC:~ # ir-keytable
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Found /sys/class/rc/rc0/ (/dev/input/event1) with:
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        Driver gpio-rc-recv, table rc-rc6-mce
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        Supported protocols: lirc rc-5 rc-5-sz jvc sony nec sanyo mce_kbd rc-6 sharp xmp
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        Enabled protocols: lirc nec rc-6
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        Name: gpio_ir_recv
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        bus: 25, vendor/product: 0001:0001, version: 0x0100
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        Repeat delay = 500 ms, repeat period = 125 ms
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Run ir-keytable -p PROTOCOL -t and press buttons on the remote. If you discover the correct protocol you will see EV_MSC events and the scancode of the button pressed, e.g.
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LibreELEC:~ # ir-keytable -p rc-5 -t
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Protocols changed to rc-5
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Testing events. Please, press CTRL-C to abort.
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1503592437.660155: event type EV_MSC(0x04): scancode = 0x101a
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1503592437.660155: event type EV_SYN(0x00).
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1503592437.774129: event type EV_MSC(0x04): scancode = 0x101a
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1503592437.774129: event type EV_SYN(0x00).
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1503592437.921009: event type EV_MSC(0x04): scancode = 0x101a
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If you see no events stop ir-keytable with CTRL-C and try another protocol from the list. You can ignore lirc as this is not a real protocol.
Once you find the correct IR protocol create /storage/.config/rc_keymaps/custom_remote and set the header file. In the example above the protocol is rc-5 so we set:
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# table custom_remote, type: rc-5
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If you found a partially working keytable, clone it and then edit the header to say custom_remote:
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cp /usr/lib/udev/rc_keymaps/samsung /storage/.config/rc_keymaps/custom_remote
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Next we capture the scancodes and document the keycode mapping. Some users find it easiest to open two SSH connections; one to see ir-keytable scancode output in, and one so they can copy/paste scancodes directly into the custom_remote keytable file, e.g. in one open the nano editor:
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nano /storage/.config/rc_keymaps/custom_remote
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And in the second run ir-keytable -t to find out the scancode of each button. For each button do the following:
Press a button and note the scancode (the 0x… value after scancode:)
Add a new line with the scancode (including 0x).
Add the Linux keycode, separated with a blank.
You can get a list of all supported Linux keycodes via irrecord -l | grep ^KEY but it is easiest to use keycodes listed in the <remote device=“devinput”> section of /usr/share/kodi/system/Lircmap.xml else you must also create a Kodi lircmap.xml with Linux keycode to action mappings.
The table below has a selection of common keycodes:
Keycode
Keycode
Keycode
Keycode
KEY_LEFT
KEY_STOPCD
KEY_INFO
KEY_TEXT
KEY_RIGHT
KEY_FASTFORWARD
KEY_PROPS
KEY_1
KEY_UP
KEY_FORWARD
KEY_ZOOM
KEY_2
KEY_DOWN
KEY_REWIND
KEY_ANGLE
KEY_3
KEY_OK
KEY_VOLUMEUP
KEY_MUTE
KEY_4
KEY_ENTER
KEY_VOLUMEDOWN
KEY_POWER
KEY_5
KEY_SELECT
KEY_CHANNELUP
KEY_SLEEP
KEY_6
KEY_DELETE
KEY_CHANNELDOWN
KEY_WAKEUP
KEY_7
KEY_ESC
KEY_PAGEUP
KEY_EJECTCD
KEY_8
KEY_MEDIA
KEY_PAGEDOWN
KEY_EJECTCLOSECD
KEY_9
KEY_HOME
KEY_NEXT
KEY_DVD
KEY_0
KEY_EXIT
KEY_NEXTSONG
KEY_MENU
KEY_NUMERIC_STAR
KEY_BACK
KEY_PREVIOUS
KEY_VIDEO
KEY_NUMERIC_POUND
KEY_BACKSPACE
KEY_PREVIOUSSONG
KEY_AUDIO
KEY_RED
KEY_ESC
KEY_EPG
KEY_MP3
KEY_GREEN
KEY_RECORD
KEY_TITLE
KEY_CAMERA
KEY_BLUE
KEY_PLAY
KEY_TV2
KEY_IMAGES
KEY PVR
KEY_PLAYPAUSE
KEY_CONTEXT_MENU
KEY_TUNER
KEY_RADIO
KEY_PAUSE
KEY_SUBTITLE
KEY_TV
​
KEY_STOP
KEY_LANGUAGE
KEY_PVR
​
Once you are finished with the keytable, save the file, stop ir-keytable -t with + and then restart it with the keytable file:
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LibreELEC:~ # ir-keytable -c -w /storage/.config/rc_keymaps/custom_remote
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Read justboom table
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Old keytable cleared
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Wrote 12 keycode(s) to driver
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Protocols changed to rc-5
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Now run ir-keytable -t and press buttons. In addition to EV_MSC scancode events you should now see EV_KEY events, e.g.
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LibreELEC:~ # ir-keytable -t
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Testing events. Please, press CTRL-C to abort.
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1503599395.150849: event type EV_MSC(0x04): scancode = 0x1019
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1503599395.150849: event type EV_KEY(0x01) key_down: KEY_VOLUMEUP(0x0073)
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1503599395.150849: event type EV_SYN(0x00).
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1503599395.264827: event type EV_MSC(0x04): scancode = 0x1019
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1503599395.264827: event type EV_SYN(0x00).
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1503599395.413668: event type EV_MSC(0x04): scancode = 0x1019
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1503599395.413668: event type EV_SYN(0x00).
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1503599395.673626: event type EV_KEY(0x01) key_up: KEY_VOLUMEUP(0x0073)
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1503599395.673626: event type EV_SYN(0x00).
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If the test is successful, make the keytable persistent by creating /storage/.config/rc_maps.cfg with the following content:
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* * custom_remote
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Reboot and you should have a working remote in Kodi.
Troubleshooting
Check the obvious. Batteries run down and either stop the remote from working or reduce the working range. Try using the remote in-front of the receiver. You can also try pointing the IR transmitter at the sensor of a digital camera or smartphone in a dark room. If the IR transmitter works you should see it light up the camera/smartphone screen.
If the remote is sending signals, we need trace the problem and
There are several steps until a button press on your remote finally triggers an action in Kodi. Use this guide to check if each of the steps works. Check if the remote is transmitting signals
To check if the IR receiver driver is loaded run ir-keytable. If you see the error message /sys/class/rc/: No such file or directory no driver is loaded.
To check if the IR receiver is receiving any signals, see if ir-keytable shows lirc as a supported protocol. If yes, run ir-ctl -r to show raw, undecoded signals from the receiver. If IR reception works you will see lots of pulse and space lines when pressing a button. Note: On kernels before 4.3 lirc may be listed in Supported protocols but not in Enabled protocols. In this case run ir-keytable -p lirc to enable it first (remembering this will disable other decoders).
To check if lircd is running run ir-keytable. If only lirc shows up in Enabled protocols: lircd is running. When it starts it disables all other protocols). You can also run ps | grep /usr/sbin/lircd to check for /usr/sbin/lircd and /usr/sbin/lircd-uinput processes. If you see them LIRC enabled. If LIRC is enabled, disable it in LibreELEC Settings > Services and reboot.
To check if the correct keytable is loaded run ir-keytable -r to show the current keytable and protocol. Compare this to the header in /storage/.config/rc_keymaps/custom_remote and check /storage/.config/rc_maps.cfg references the correct keytable name.
To check if IR decoding works correctly stop Kodi and eventlircd:
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systemctl stop kodi
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systemctl stop eventlircd
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Then run ir-keytable -t and press buttons on the remote. You should see EV_MSC events with the scancode and EV_KEY events with the Linux keycode, e.g.
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LibreELEC:~ # ir-keytable -t
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Testing events. Please, press CTRL-C to abort.
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1503599395.150849: event type EV_MSC(0x04): scancode = 0x1019
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1503599395.150849: event type EV_KEY(0x01) key_down: KEY_VOLUMEUP(0x0073)
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If you only get EV_MSC but no EV_KEY events, verify if the correct keytable is configured.
After this test, restart eventlircd and Kodi (or reboot):
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systemctl start eventlircd
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systemctl start kodi
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To check if eventlircd translates the input events to LIRC events run irw to show the translated LIRC events Kodi sees. When pressing a button you should see messages like this:
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LibreELEC:~ # irw
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72 0 KEY_VOLUMEDOWN devinput
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72 1 KEY_VOLUMEDOWN devinput
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72 2 KEY_VOLUMEDOWN devinput
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To check if Kodi receives the translated LIRC events enable debug logging in System Settings > Logging then watch the logfile:
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tail -f /storage/.kodi/temp/kodi.log
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When you press a button you should see log entries with LIRC: Update like this:
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21:55:33.891 T:1945866240   DEBUG: LIRC: Update - NEW at 60659:6c 0 KEY_DOWN devinput (KEY_DOWN)
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21:55:33.891 T:1945866240   DEBUG: OnKey: 167 (0xa7, obc88) pressed, action is Down
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The LIRC line indicates Kodi received the LIRC event. The OnKey: line shows the action generated after applying Lircmap.xml and remote.xml. If you see LIRC lines but incorrect actions, check your Kodi Lircmap.xml and remote.xml config files are correct.
Known Issues
USB data transfers can interfere with GPIO IR recievers on Raspberry Pi 0/1/2/3 hardware, and since Ethernet is internally connected via USB playing large movies from a NAS can exhibit the problem. This is a known issue: see this forum post for details and there is nothing we can do. Common workarounds are to use a USB IR receiver like Flirc or CEC.
LIRC Support
Most remotes are now supported by the Linux kernel but "LIRC" (the userspace lircd daemon and tools) is still useful for handling unusual remotes with odd protocols and no kernel drivers. Since LibreELEC 8.2.0 LIRC is disabled by default, but can be enabled in LibreELEC Settings > Services > Lirc. Configuration is handled in (almost) the same way as most desktop Linux distros:
The /etc/lirc/lirc_options.conf file configures the default LIRC driver and /dev/lirc0.
The /etc/lirc/lircd.conf file includes remote configs for MCE, Xbox 360, Xbox One, and a few others.
The embedded files can be overriden at boot time by creating /storage/.config/lircd.conf and /storage/.config/lirc_options.conf with needed changes.
In LibreELEC lircd-uinput reads decoded LIRC events from /run/lirc/lircd.socket and translates these to Linux input events via the Linux uinput driver. The Linux input events from lircd-uinput are then picked up by eventlircd and fed to Kodi as LIRC events via the /run/lirc/lircd socket.
It might seem odd to translate between LIRC, Linux input and (again) LIRC events, but Kodi can only receive LIRC events on a single LIRC socket, and this allows eventlircd to collect all remote events and feed them to Kodi so we can support LIRC-decoded and kernel-decoded remotes without needing user input or complex scripts to change the configuration.
To use LIRC with an IR receiver that supports in-kernel decoding it's best to disable ir-keytable auto configuration with an empty rc_maps.cfg file:
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touch /storage/.config/rc_maps.cfg
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Although lircd disables all remote protocols (and thus in-kernel decoding) on startup ir-keytable auto-configuration runs in parallel, and if it happens to run after lircd starts it can re-enable in-kernel decoding. This causes duplicate decoding as both lircd and kernel will receive and proocess the IR signals. This issue is often intermittent since it depends on the timing of lircd start. Sometimes lircd will run after ir-keytable and in-kernel decoding is disabled as expected.
Note: If you stop or disable LIRC in LibreELEC Settings you will need too reboot or set ir-keytable manually from the SSH console. Disabling LIRC does not automatically re-enable in-kernel decoding.
Apple IR Remotes
Older LibreELEC relases used atvclient to support the Apple IR sensor and send LIRC events to Kodi. Since 9.2.0 we use the native Linux kernel driver for the IR sensor, which sends normal HID events. Create a custom keymap in /storage/.kodi/userdata/keymaps/keymap.xml with the following content to map a White or Silver remote:
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<keymap>
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    <global>
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        <keyboard>
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            <browser_back>Left</browser_back>
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            <browser_forward>Right</browser_forward>
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            <volume_up>Up</volume_up>
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            <volume_down>Down</volume_down>
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            <key id="61952">Back</key>
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        </keyboard>
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    </global>
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    <Visualisation>
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        <keyboard>
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            <volume_up>VolumeUp</volume_up>
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            <volume_down>VolumeDown</volume_down>
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        </keyboard>
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    </Visualisation>
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    <FullscreenVideo>
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        <keyboard>
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            <volume_up>VolumeUp</volume_up>
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            <volume_down>VolumeDown</volume_down>
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        </keyboard>
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    </FullscreenVideo>
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</keymap>
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