Difference between revisions of "LIRC"

Revision as of 17:44, 9 August 2018

This page is up-to-date as of MythTV version 0.27.6, the current release is 34.0

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LIRC

Introduction

LIRC stands for Linux Infrared Remote Control. It is required to use certain Remote Controls with MythTV.

LIRC is not easy to set up. Remote controls that work by keyboard control, either using a keyboard emulator or built in drivers using evdev are preferable. For details of the available options see User Manual:Setting Up#Remote_controls.

Before you start down the LIRC path validate whether your remote will work in some way as a keyboard emulator. Remote_Control#Check if your remote emulates a keyboard.

If you need to use an IR blaster to change channels on a set top box you may have to use LIRC, since there is no built in support in Linux for those.

LIRC is a software package that gives your computer the ability to send and receive infra-red remote control signals when combined with appropriate hardware. Most distributions include LIRC packages, but you may have to compile it yourself if you wish to use certain features that the distribution packagers did not include.

Hardware

There are several different hardware pieces for receiving and sending LIRC commands. A few are:

• The receiver that comes with your TV card. For example, the HD-PVR series from Hauppauge sometimes have a receiver.
• A Serial Port transmitter you can make yourself or buy for a small fee (called a homebrew transmitter)
• A commercially available USB receiver (e.g. Microsoft MCE remote control). Note that some of these may emulate a keyboard, which eliminates the need for LIRC and may make your life much easier. Some which previously required LIRC have now been added to the kernel and are supported using evdev.
• A USB receiver you can make yourself.
• A Parallel Port transmitter and/or receiver you can make yourself.
• http://www.irblaster.info/ Sells both blasters and receivers that work with lirc at a reasonable price
• http://www.iguanaworks.net/ sell combination blaster / receivers that can drive multiple devices
• http://dangerousprototypes.com/docs/USB_Infrared_Toy Works with LIRC 0.9.3a. Receives and sends IR signals.
• Refer to http://www.lirc.org/ where there is a list of available devices that work with LIRC.

Installing LIRC

Check whether your distribution includes LIRC and the version:

On an Ubuntu or Debian derivative system:

sudo apt-get update
apt-cache showpkg lirc

If your distribution includes an outdated version of LIRC, you may need to build it yourself. Please refer to http://www.lirc.org/. The LIRC Documentation page has a complete description of how to build, install and configure LIRC.

If your distribution has an outdated version of LIRC or one that has the wrong options built in you may need to download the source from lirc.org and compile it yourself.

You may also need to install specific device drivers for the device itself. Those need to be found on the device vendor's web page.

To help with installing you can use the checkinstall program, which allows you to install the package and also include it in the package management system for your distribution.

Example of build commands is below. I use the package name lirc_mod instead of lirc so that the automatic update features of the operating system do not spring into action and try to update my package with a "new version" from the repository.

apt-get install libusb-dev libusb-1.0-0-dev python3-yaml xsltproc checkinstall
./configure
make
sudo checkinstall -D --pkgname=lirc_mod --pkgversion=0.9.3 --install=no

This creates a deb package you can install and remove.

Configuring LIRC for Frontend

LIRC needs to be installed on your frontend if you are using it with a remote control device (the most common use).

/etc/lirc/lircd.conf

This file contains a section for each remote control device you are using. It maps the code generated by each key on the remote to a function name, number or letter (for example PLAY, VOLUP, 1). You can have a pile of remote control devices from different manufacturers and use any or all of them to control mythtv at the same time. This file will contain entries for each device type. The file format is described in the man page or at http://www.lirc.org/html/lircd.conf.html. On the LIRC home page there is a link to the LIRC Remotes database where you can find an lircd.conf file for almost any remote. Avoid any that use RAW codes, I have found that very unreliable. If you have more than one remote you will be using, simply concatenate the files together for your lircd.conf.

Obviously you should not use a remote that goes with another appliance in the same room as your MythTV setup, because the remote button presses will be picked up by both MythTV and your other device.

Creating your own lircd.conf

If there is no file for your remote in the database, or the one in the database uses RAW codes or does not work, you can create your own using irrecord. irrecord can also update an existing lircd.conf with additional keys. Some of the downloaded lircd.conf files only contain a few of the keys that are available on the remote. Follow the instructions to record each button of the remote you want to use.

Recording works best if you hold the remote really close to the receiver. In normal operation the idea of the remote is to operate across the living room. However for recording keys I found that holding it a few inches from the receiver worked better. If you find your configuration file contains RAW codes then you should try again. In my experience recording from across the room created raw codes that were useless, but holding the remote close to the receiver created proper codes.

/home/userid/.mythtv/lircrc

The lircrc file defines the mapping between the buttons on your own remote (as defined in the lircd.conf) and the functions you actually want it to perform.

The format of the file is documented at http://www.lirc.org/html/configure.html#lircrc_format. To find the exact syntax for a key (config parameter), run the MythTV Frontend and go to Edit Keys. Select the function you want to invoke and look at the up to 4 key assignments at the bottom of the screen. The text displayed there will be what you need to use (for example PgDown). You are actually mapping the LIRC key codes to keyboard key codes.

For example, Setting the (Gray Hauppauge's) Power button to be CTRL-Escape:

  begin
  prog = mythtv
  remote = Hauppauge_Gray
  button = KEY_POWER
  config = CTRL+Escape
  end

"remote" is optional, but if you have multiple remotes configured in your lircd.conf e.g. for IR Blasting, you can use this line to make sure that only commands from the correct remote are used.

To configure the TV button to jump to Live TV by using the key sequence ALT L, Add or modify your lircrc to contain

  begin
  prog = mythtv
  remote = Hauppauge_Gray
  button = KEY_TV
  repeat = 3
  config = ALT+L
  end

Configuring LIRC for Backend (IR Blasting)

LIRC can be used by your backend if you are using a cable Company receiver box or satellite receiver with HD PVR, firewire, etc. to receiver the signal from the converter box. You may neeed to control your converter box with an IR blaster that can emulate the command send by the cable box remote.

If your frontend and backend are the same machine then the same LIRC instance can be used for both IR blasting and receiving at the same time. The product from http://www.iguanaworks.net/ can be used this way, or you may have separate receiver and blaster.

The same lircd.conf is used as for receiving (see above). Normally there will be a different remote type for receiver and blaster functions. Using the same one for both will only cause frustration, since your commands to MythTV will be received also by the cable box and the commands from the backend will be seen by the frontend.

Add the lircd.conf file for your blaster remote to the /etc/lirc/lircd.conf, in addition to any other remote you have there. You can also create your own lircd.conf as suggested above for receiving.

This process starts by configuring the video source in the Mythtv-setup program to use an an external channel changing program. More specifically, the channel changing script is a per capture card property that is specified in the Input Connections section of mythtv-setup. If you are using LIRC, this program will be a channel changing script that invokes LIRC's irsend command, passing it appropriate arguments to send the channel changing IR codes.

Let's say MythTV wishes to tune to channel 2 (either to record a scheduled show or because it was instructed by the user viewing live TV), it invokes the external channel changing program passing it '2' as an argument. The channel changing script turns that into an invocation of irsend, and LIRC transmits the appropriate codes via your infra-red transmitter.

In practice it is more complicated. Most channel numbers are more than one digit, and you may have to pause between digits. You may have to send a Select key press after the channel number. Also you may have to power on the cable box. The cable box may be in some incorrect mode such as On Demand and will not respond correctly to a channel number.

There is an extensive script at LircChannelChanger which you can download and use.

The transmitter and receiver mentioned above are two separate devices (sometimes packaged into a single box). You cannot transmit through a receiver or receive through a transmitter.

• Using an IR Blaster with MythTV
• IguanaIR USB-based IR Transceiver

LIRC with Multiple External Tuners

If you are using a system with multiple external tuners, you can use LIRC to control each one independently. The proper irsend command for each tuner can be placed in a separate channel changing script, and then specified as an external channel changing program for the appropriate video source in the Mythtv-setup program.

Normally, only a single LIRC transmitter is required as long as each of the tuners have mutually exclusive remote codes, and the LIRC transmitter can placed in the line of sight of all tuners' IR receivers. In this configuration, each tuner will need a "Remote Block" setting in the lircd.conf file and irsend simply needs the correct REMOTE argument. This is probably the simplest solution to most multiple tuner systems.

However, there are some instances where unique control codes aren't possible (for example, you have two Comcast Cable boxes so you can record two shows at once. These would both respond to the same commands.), or simultaneous line of sight to the two receivers is not possible. In these cases, there are some options available:

• IguanaIR includes up to four output sockets for transmitters. These can be placed in positions where they are only seen by the desired tuner box.

• Load multiple LIRC drivers using irsend's --device option. For some drivers, including lirc_serial (IR Blaster, etc.), this method won't work with multiple transmitters of the same type.

• Modify the source tree to support multiple instances of the LIRC driver and use 2 separate copies of irsend compiled.

• Multiple LIRC Drivers with multiple IR emitters of the same type without having to recompile lirc_serial.

Links

There are additional pages in this wiki here:

• Category:LIRC Configuration Files
• Category:Remote Controls
• Using an IR Blaster with MythTV
• Homebrew lirc reciever parts
• Ubuntu Serial Lirc Install

Troubleshooting

irw

Use the irw program to see whether LIRC and your remote are working before going any further. It shows what events are generated by your remote. This is very helpful!

The irw tool connects to the lircd socket and displays any recognized IR signals detected by the driver. If this works, then your hardware, driver and lirc.conf is working; all that remains is your application setup. If irw does not generate the expected output though, not all is lost -- see the mode2 command below.

Logging

You can enable logging for lircd with the -L option. Use this to see the results of clients connecting to lircd daemon. Compiling lircd with debugging enabled (-D option) allows you to see much more including parsing of the remote definitions.

# /usr/local/sbin/lircd --device=/dev/lirc/0 /etc/lirc/lircd.conf -L ~/lircd.log -D7

• The log file showing "accepted new client" immediately followed by "removed client" can indicate a a ~/.lircrc or ~/.mythtv/lircrc parsing error. Check the formatting.

Make the LIRC device static

If you have more than one input device on your system, the numbering may change from one reboot to the next. You can [use udev] to ensure the input device corresponding to your remote has a name that does not change across reboots.

You may notice that it only works if you have only one card with the same vendor ID. If you have more than one card from the same vendor, but with a different name, you can use the following line to create the /dev/input symlink:

ln -fs /dev/input/`cat /proc/bus/input/devices|grep -A 3 "Hauppauge Nova-S-Plus"|grep event|cut -d ' ' -f3` /dev/input/irremote

You should run this line before running lirc, for example add it to /etc/init.d/lirc here:

echo -n "Starting lirc daemon:"
ln -fs /dev/input/`cat /proc/bus/input/devices|grep -A 3 "Hauppauge Nova-S-Plus"|grep event|cut -d ' ' -f3` /dev/input/irremote
if $START_LIRCD; then

Using an udev rule may be more elegant, but I found this one liner to be more reliable.

The above failed for me for two reasons - one, my device is not an S-plus, and two, I have more than one of the same card. My small modification of the above one-liner should work for everyone:

ln -fs /dev/input/`cat /proc/bus/input/devices | grep -A 3 "Hauppauge" | grep event | cut -d ' ' -f3 | head -n1` /dev/input/irremote

The above fails on Ubuntu 10.04. A solution to this is: (Not tested on dual card setups)

ln -fs /dev/input/event$(cat /proc/bus/input/devices | grep -A 3 "Hauppauge" | grep Sysfs | sed -e "s/^.*\(.\)$/\1/") /dev/input/irremote

This makes a symbolic link in /dev/input called "irremote" this will always point to the Hauppauge event.

mode2

The command mode2 will give each separate pulse for button pushes. Some buttons have different pulses for pushing the button than for releasing the button. Using mode2 will show all pulses and is a lower-level lirc testing tool than irw.

Devices

Depending on your setup, lirc may be looking for either /dev/lirc0 or /dev/lirc, and the wrong one will obviously break things. You can use ln -s /dev/lirc0 /dev/lirc or ln -s /dev/lirc /dev/lirc0 to fix this.

LircSocket

If you know LIRC is working, and mapped correctly in the lircrc file, but is not doing anything in MythTV, you may want to check your LircSocket (frontend settings). This was a problem for me with MythTV 0.22 installed via atrpms on Centos 5.4. The frontend log should contain clues that it was not able to connect to the lircd socket. /var/run/lirc/lircd is the default location for the lircd socket for lirc 0.8.6 and higher.

Double presses for certain buttons

You may find that you are getting double hits for some of your buttons (example: arrows) but not all of your buttons. The kernel may be listening to your remote as well as lircd. Check and see if it is:

cat /sys/class/rc/rc0/protocols

You should see something like: rc-5 nec rc-6 jvc sony mce_kbd [lirc]

If anything other than lirc has the brackets, then you need to do the following:

Create a file in /etc/udev/rules.d called remote-control-lirc.rules and put this line in it:

SUBSYSTEM=="rc", ATTRS{protocols}=="*lirc*" RUN+="/bin/sh -c 'echo lirc > /sys$env{DEVPATH}/protocols'"

After creating that file, test the rule by running:

$ udevadm test /devices/pci0000:00/0000:00:06.0/usb4/4-5/4-5:1.0/rc/rc2

(replacing that path with whatever the link in /sys/class/rc points to currently). You should see a line at the end of the output saying it's going to run the echo lirc command.

Later, when you reboot or disconnect/reconnect the receiver, the udev rule should detect the new location of the receiver and echo lirc to the appropriate file.

Reboot for changes to take effect.

Source: http://www.gossamer-threads.com/lists/mythtv/users/504746#504746

180806 - Here is an alternate udev rule for disabling kernel remote decoding.

cat /etc/udev/rules.d/99-zremote-control-lirc.rules

SUBSYSTEMS=="rc", ATTRS{protocols}=="*mce_kbd*", RUN="/bin/sh -c 'echo lirc > /sys/class/rc/%k/protocols'"

NOTES: Make sure /bin/sh exists on your system.

The ATTRS key can be removed (not recommended) if only one rc SUBSYSTEMS device is on the computer (ls -al /sys/class/rc). See below on selecting the protocol to use. %k is the kernel name for this device.

If there are multiple "rc" devices, omitting the ATTRS key will disable kernel decoding on ALL these devices. If this is not an issue, document system changes according to local policy.

To apply this rule only to the desired device, select a protocol unique to the device to have kernel based decoding disabled. In the example below, several protocols are unique to device rc1, and 'mce_kbd' was used in the rule above. To apply the rule to the rc0 device, note there is no unique protocol compared to the rc1 device. Assuming the protocol order does not change, isolating the rc0 device with ATTRS{protocols}=="*rc-6 rc-5-sz*" would work.

cat /sys/class/rc/rc0/protocols
[rc-5] rc-6 rc-5-sz [lirc]

cat /sys/class/rc/rc1/protocols
rc-5 nec rc-6 jvc sony rc-5-sz sanyo sharp mce_kbd xmp imon [lirc]

The rule will activate with the next reboot.

Other Notes

• Don't try to use a lircrc file written for irxevent if you are trying to use MythTV native LIRC support, see Lirc on Ubuntu Dapper as the basis for your own file. Or search for mythtv/configfiles/hauppauge-lircrc-nativelirc to use it as a template.
• If you're using a PVR-350, at least, it won't work with stock LIRC. You need 0.7.0 (as mentioned in Jarod's Guide)
• If you're using a PVR-500MCE, please read this page: MCE_Remote

Distribution-specific notes

Ubuntu/Mythbuntu lircrc generation

Mythbuntu provides a package that will intelligently parse your lircd.conf file and attempt to create valid button mappings for use in MythTV and other media player applications. Note that the use of this package is contingent on your remote being properly installed and working. You can install and invoke this package as follows:

sudo apt-get install lirc mythbuntu-lirc-generator
mythbuntu-lirc-generator

Restart mythfrontend. Your remote should now work with MythTV!

Please note that there is a bug which causes duplicate mappings to be generated. This can cause remote input to be processed twice. For instance if you press "down" and the menu selection moves down two items or if you press "pause" and the recording immediately pauses and then starts playing again. For more information please see the the Ubuntu Launchpad bug 779835.