IR remote and longpress

offbeat · February 17, 2022 at 6:00 PM

In most cases LibreELEC uses eventlircd as a shim to pass IR button presses from kernel to Kodi. This approach is stable and reliable, but has one rather major drawback: it’s impossible to use longpress events, which in fact halves the amount of actions you can bind to your IR remote buttons.

Alternative approach is to disable eventlircd altogether and use IR remote as a Linux keyboard device, so this is a way I went.

LibreELEC documentation says “Kodi ... doesn't cope well with Linux input events”, I’d say this is the understatement of the century, to put it mildly. Kodi keyboard handling system is archaic, weaving layer upon layer of abstractions, throwing away more and more of your keypresses, the deeper it goes.

To my understanding, the way IR keypress travels towards Kodi in is:

1) Linux kernel decodes IR signal and translates keypress to evdev scancode, based on IR remote .toml definition, loaded by ir-keytable.

2) Xkbcommon library assumes we got a standard pc105 keyboard and translates evdev code to something resembling xfree86 keycode, according to /usr/share/X11/xkb/keycodes/evdev

3) Xkbcommon library futher translates xfree86 keycode to xkb key name, mapping non-printable keys according to /usr/share/X11/xkb/symbols/inet

4) Kodi accepts a very limited subset of xkb key names, filtering them and mapping to Kodi internal keysyms, according to code in xbmc/platform/linux/input/LibInputKeyboard.cpp

5) Kodi goes through another layer of translations, from Kodi internal keysyms to Kodi internal vkeys and Kodi keynames, relevant code in xbmc/input/XBMC_keytable.cpp

6) Kodi once again translates, keynames are mapped to actions, based on default rules in /usr/share/kodi/system/keymaps/keyboard.xml and user customizations in ~/.kodi/userdata/keymaps/keyboard.xml

Every layer of this onion has some random historical subset or superset of non-printable keycodes hardcoded in, throwing away everything else, sometimes in completely illogical way. There is no way for user to bind directly to kernel evdev scancode, is all buried and hidden away. I’m afraid to look at the Windows or Android keyboard abstractions, probably not much saner.

But in the end I managed to dig through this spaghetti and made a .toml keymap for my IR remote, scraping together some 50 evdev keys Kodi actually lets through the cracks. Longpress events work for me now, yey. Hope my keymap can help someone with the same problem.

Code

[[protocols]]
name = "myoldremote"
protocol = "nec"
variant = "necx"
[protocols.scancodes]
# IR      EVDEV name           EVDEV  xkbcommon name                Kodi internal keysym       Kodi name             Notes
#-------------------------------------------------------------------------------------------------------------------------------------------
0xbf10 = "KEY_MAIL"          # 155    XKB_KEY_XF86Mail              XBMCK_LAUNCH_MAIL          launch_mail           actual button is EJECT
0xbf46 = "KEY_MUTE"          # 113    XKB_KEY_XF86AudioMute         XBMCK_VOLUME_MUTE          volume_mute
0xbf45 = "KEY_FAVORITES"     # 364    XKB_KEY_XF86Favorites         XBMCK_FAVORITES            favorites             actual button is MODE
0xbf43 = "KEY_POWER"         # 116    XKB_KEY_XF86PowerOff          XBMCK_POWER                power
0xbf40 = "KEY_F1"            # 59     XKB_KEY_F1                    XBMCK_F1                   f1                    actual button is RED
0xbf1f = "KEY_F2"            # 60     XKB_KEY_F2                    XBMCK_F2                   f2                    actual button is GREEN
0xbf00 = "KEY_F3"            # 61     XKB_KEY_F3                    XBMCK_F3                   f3                    actual button is YELLOW
0xbf41 = "KEY_F4"            # 62     XKB_KEY_F4                    XBMCK_F4                   f4                    actual button is BLUE
0xbf0b = "KEY_1"             # 2      XKB_KEY_1                     XBMCK_1                    one
0xbf0c = "KEY_2"             # 3      XKB_KEY_2                     XBMCK_2                    two
0xbf0d = "KEY_3"             # 4      XKB_KEY_3                     XBMCK_3                    three
0xbf0e = "KEY_4"             # 5      XKB_KEY_4                     XBMCK_4                    four
0xbf0f = "KEY_5"             # 6      XKB_KEY_5                     XBMCK_5                    five
0xbf01 = "KEY_6"             # 7      XKB_KEY_6                     XBMCK_6                    six
0xbf11 = "KEY_7"             # 8      XKB_KEY_7                     XBMCK_7                    seven
0xbf12 = "KEY_8"             # 9      XKB_KEY_8                     XBMCK_8                    eight
0xbf13 = "KEY_9"             # 10     XKB_KEY_9                     XBMCK_9                    nine
0xbf05 = "KEY_DELETE"        # 111    XKB_KEY_Delete                XBMCK_DELETE               delete
0xbf0a = "KEY_0"             # 11     XKB_KEY_0                     XBMCK_0                    zero
0xbf42 = "KEY_CAPSLOCK"      # 58     XKB_KEY_Caps_Lock             XBMCK_CAPSLOCK             capslock              actual button is SELECT/CAP/NUM
0xbf52 = "KEY_VOLUMEUP"      # 115    XKB_KEY_XF86AudioRaiseVolume  XBMCK_VOLUME_UP            volume_up
0xbf53 = "KEY_VOLUMEDOWN"    # 114    XKB_KEY_XF86AudioLowerVolume  XBMCK_VOLUME_DOWN          volume_down
0xbf06 = "KEY_SEARCH"        # 217    XKB_KEY_XF86Search            XBMCK_BROWSER_SEARCH       browser_search
0xbf02 = "KEY_MEDIA"         # 226    XKB_KEY_XF86AudioMedia        XBMCK_LAUNCH_MEDIA_CENTER  launch_media_select   actual button is ZOOM
0xbf4e = "KEY_F12"           # 88     XKB_KEY_F12                   XBMCK_F12                  f12                   actual button is SETUP                                        actual button is SETUP
0xbf4b = "KEY_PAGEUP"        # 104    XKB_KEY_Page_Up               XBMCK_PAGEUP               pageup                actual button is CHANNELUP
0xbf4c = "KEY_PAGEDOWN"      # 109    XKB_KEY_Page_Down             XBMCK_PAGEDOWN             pagedown              actual button is CHANNELUP
0xbf50 = "KEY_F10"           # 68     XKB_KEY_F10                   XBMCK_F10                  f10                   actual button is INFO
0xbf07 = "KEY_F11"           # 87     XKB_KEY_F11                   XBMCK_F11                  f11                   actual button is POPUP MENU
0xbf15 = "KEY_UP"            # 103    XKB_KEY_Up                    XBMCK_UP                   up
0xbf16 = "KEY_DOWN"          # 108    XKB_KEY_Down                  XBMCK_DOWN                 down
0xbf17 = "KEY_LEFT"          # 105    XKB_KEY_Left                  XBMCK_LEFT                 left
0xbf18 = "KEY_RIGHT"         # 106    XKB_KEY_Right                 XBMCK_RIGHT                right
0xbf14 = "KEY_ENTER"         # 28     XKB_KEY_Return                XBMCK_RETURN               return                actual button is OK
0xbf04 = "KEY_BACK"          # 158    XKB_KEY_XF86Back              XBMCK_BROWSER_BACK         browser_back          actual button is RETURN
0xbf51 = "KEY_HOMEPAGE"      # 172    XKB_KEY_XF86HomePage          XBMCK_HOMEPAGE             homepage              actual button is TOP MENU
0xbf48 = "KEY_PLAY"          # 207    XKB_KEY_XF86AudioPlay         XBMCK_PLAY                 play_pause
0xbf1e = "KEY_PAUSECD"       # 201    XKB_KEY_XF86AudioPause        XBMCK_MEDIA_PLAY_PAUSE     play_pause
0xbf49 = "KEY_PREVIOUSSONG"  # 165    XKB_KEY_XF86AudioPrev         XBMCK_MEDIA_PREV_TRACK     prev_track
0xbf1d = "KEY_NEXTSONG"      # 163    XKB_KEY_XF86AudioNext         XBMCK_MEDIA_NEXT_TRACK     next_track
0xbf19 = "KEY_STOPCD"        # 166    XKB_KEY_XF86AudioStop         XBMCK_MEDIA_STOP           stop
0xbf1a = "KEY_PROG1"         # 148    XKB_KEY_XF86Launch1           XBMCK_LAUNCH_APP2          launch_app2_pc_icon   actual button is SLOW
0xbf1c = "KEY_REWIND"        # 168    XKB_KEY_XF86AudioRewind       XBMCK_MEDIA_REWIND         rewind
0xbf1b = "KEY_FASTFORWARD"   # 208    XKB_KEY_XF86AudioForward      XBMCK_MEDIA_FASTFORWARD    fastforward
0xbf54 = "KEY_F5"            # 63     XKB_KEY_F5                    XBMCK_F5                   f5                    actual button is SUBTITLE
0xbf4d = "KEY_F6"            # 64     XKB_KEY_F6                    XBMCK_F6                   f6                    actual button is ANGLE
0xbf44 = "KEY_F7"            # 65     XKB_KEY_F7                    XBMCK_F7                   f7                    actual button is AUDIO
0xbf4f = "KEY_F8"            # 66     XKB_KEY_F8                    XBMCK_F8                   f8                    actual button is REPEAT
0xbf47 = "KEY_F9"            # 67     XKB_KEY_F9                    XBMCK_F9                   f9                    actual button is SHUFFLE
0xbf03 = "KEY_WWW"           # 150    XKB_KEY_XF86WWW               XBMCK_LAUNCH_FILE_BROWSER  launch_file_browser

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-=guybrush=- · April 18, 2022 at 4:18 PM

First of all, hello! I've come across your thread because I'm using one of those very cheap remotes:

to control my RPi Zero. It has indeed a very few keys (only 17) and I've barely managed to add just back and mute apart from the navigation keys, the enter one and finally the numeric ones which are relevant to me as I use LE as a TV among other things.

I was then wondering about a SHIFT function like it happens on some remotes to almost double the available keys but I don't know if LIRC handles such a scenario (I don't think so nor I've found anything about it) then I've found your thread.

Honestly speaking, looking at the toml I haven't understood well what you've done. Let's consider CHANNELUP: according to your comments, you've mapped it to both KEY_PAGEUP and KEY_PAGEDOWN by the long press workaround but at the beginning of the line I see two different keycodes which means we're talking about two different keys, not the same one. I don't know...

Another doubt has arisen inside me: your toml file uses the old syntax

Code

keycode = "action"

while now LE uses the syntax

Code

keycode "action"

and, even more, no longer accepts the let's say 'header'

Code

[[protocols]]
name = "myoldremote"
protocol = "nec"
variant = "necx"
[protocols.scancodes]

indeed, if you include it, it throws an error and doesn't use the so defined toml file. The one I've defined is indeed quite different than yours, not only because it doesn't handle longpresses and obviously is perfectly working (I'm under LE 9.2.6) like yours does too for sure. Probably, we're under different LE versions or, given that in the preface you say you've gone over eventlircd, maybe doing this reverts back to the old syntax, I don't know.

Have a nice day!

IR remote and longpress

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