Activating your multimedia keys with ReMoot

Playback

By Federico Kereki

www.sxc.hu

From this article, you will learn how to make Linux (with KDE) recognize special-function keys and how to make them function with all your favorite multimedia applications.

Many contemporary desktop and laptop keyboards include multimedia keys (for "Play," "Mute," "Volume Up," and so on), but often these special keys don't work well with Linux. Recently, I decided it was high time to get the multimedia keys on my laptop to work.

The Key Problem

I needed to solve two problems. The first was getting Linux to recognize the (potentially non-standard) keys; the second was getting each key to perform the necessary multimedia function. Fortunately, KDE lets you easily associate keyboard actions with commands, and a tool called ReMoot provides the necessary command set for accessing multimedia applications. In this article, I describe how to activate keyboard and laptop multimedia keys with ReMoot.

The Solution

The first step is getting the keys to work. If you want to go to the effort, you can define your own keyboard map and use a tool such as Lineak [1] to configure special keys, but the xmodmap program offers a simpler approach.

For each key you want to use, first identify its scancode (what the key produces when you press it). To identify the scancode, open a command window and key in xev.

You'll see lots (I mean lots!) of messages in the command window. Press any of the multimedia keys and watch the output. In my case, when I press the "Volume Up" key I get:

KeyRelease event, serial 31, synthetic NO, window 0x2a00001,
    root 0x4c, subw 0x0, time 1349394, (173,-13), root:(922,5),
    state 0x0, keycode 176 (keysym 0x0, NoSymbol), same_screen YES,
    XLookupString gives 0 bytes:
    XFilterEvent returns: False

The important feature of this output is the number after "keycode," which is the desired scancode value; in this case, the "Volume Up" key generates a 176. For each multimedia key on your laptop, you will have to go through this process, and don't forget to use modifiers (Shift, Control, Alt); you will discover that you have many more possibilities available than you imagined.

Other behaviors might be noted. For example, I found out that the "Brightness Up" and "Brightness Down" keys weren't recognized by xev, so I couldn't configure them with this technique.

Now you know your keys, but Linux still doesn't, so you must assign a specific keycode to each key. To get the possible keycodes, examine the /usr/X11R6/lib/X11/XKeysymDB file near the bottom: you want the lines starting with XF86 that match your keys. (By the way, the path for this file can vary among distributions; if you cannot find it, use the find / -name XkeysymDB command to locate it.)

After getting all scancodes and deciding the corresponding keycodes, I created in my home path a file named .Xmodmap (note the initial period; the period makes the file hidden) with the following contents; of course, you will have to modify this file to suit your own machine:

keycode 144 = XF86AudioPrev
keycode 153 = XF86AudioNext
keycode 164 = XF86AudioStop
keycode 174 = XF86AudioLowerVolume
keycode 176 = XF86AudioRaiseVolume

The format of the file is quite simple: Each scancode has a line (those I found with xev) relating it to a keycode. Finally, I added a short script, keys.sh (the name doesn't matter), under my home directory at .kde/Autostart/ with two lines:

#!/bin/sh
xmodmap .Xmodmap

It runs automatically whenever you start a session; don't forget to make this script executable with chmod +x keys.sh.

Installing ReMoot

Now that Linux recognizes the multimedia keys, you have to specify what you want the keys to do. For starters, go to the ReMoot website [2] and click on Source Download to get the latest version of ReMoot (v0.9).

ReMoot is a Perl script. After the download (which should be over quickly for the 12KB file), go to the directory from which you downloaded it, su to root, and enter:

$ tar zxf remoot-0.9.tar.gz
$ cd remoot-0.9/
$ chmod +x *moo*
$ cp *moo* /usr/bin

ReMoot comprises three related packages: The ReMoot application itself; daemoot, which is used by ReMoot; and remoot-remote, a graphical front-end. (A separate package, Rewww00t, lets you use a Palm Pilot or Nokia N800 as a remote for ReMoot.) In this case, ReMoot is enough, but feel free to experiment with the other tools; you'll find more information at the ReMoot wiki [3]. If you don't have Perl, use your favorite package manager to install it.

To see whether ReMoot is working, open any music program and start playing something (Amarok and some jazz works for me!), then try raising or lowering the volume with the commands shown in Table 1. remoot mute should immediately mute the sound; key in the same command again, and you will get the sound back.

What's great about ReMoot is that it supports many programs: If you are running Amarok, then remoot playpause will pause the playback, and if you are running Kaffeine, the result is the same. As long as you are running a program known to ReMoot (see the box "Programs Supported by ReMoot"), you will get consistent results; the multimedia keys will work no matter what program you are using to listen or view media.

Once you install ReMoot, all that's left is to associate ReMoot commands with the multimedia keys. If you use KDE, open the Control Center, and in the Regional & Accessibility tab, pick the Input Actions option. Then, add a group with the New Group command and name it something like Multimedia Keys (see Figure 1). Then, for each key:

• add a new action to the group (see Figure 2);

• go to the General tab and fill the Action name field;

• set the Action type to Keyboard Shortcut -> Command/URL (simple);

• go to the Keyboard Shortcut tab, click on the button, and press the special key you want to link to this action - remember, you can also use the Shift, Control, and Alt modifiers if they work with the key (see Figure 3); then

• go to the Command/URL Settings tab and type a ReMoot command you want to execute whenever you press the key (e.g., for the "Volume Up" key, I specified the remoot volup command) (see Figure 4).

If all goes well, these steps will map the multimedia keys to the necessary ReMoot commands.

Figure 1: Defining a new group for the multimedia keys.

Figure 2: Creating a new action for the "Next Song" key.

Figure 3: Assigning a keyboard shortcut to "Next Song."

Figure 4: Specifying the remoot command for "Next Song."

Success

Getting the multimedia keys to work wasn't as complicated as I first imagined. KDE lets you associate commands with keyboard actions, and ReMoot makes it easy to control multimedia applications from the command line.