Sunday, April 19, 2015

Problembehebung Unity-Engine und Linuxspiele

English version

Problem: Maus zieht nach oben / Spiel friert nach ein paar Sekunden ein

In manchen Spielen, die die Unity-4-Engine nutzen, gibt es Probleme mit der Maus: typisch sind ein ständig nach oben flüchtender Mauszeiger und ein nach wenigen Sekunden einfrierendes Bild. Wenn man mit Alt + Tab aus dem Spiel heraus- und wieder hineinwechselt (in machen Umgebungen genügt es auch schon, im Spiel eine Maustaste zu drücken), dann funktionieren Bild / Maus wieder für wenige Sekunden. Betroffen sind davon besonders Spiele, die aus der Egoperspektive gespielt werden.

Bekannte Workarounds

Workaround Option 1
Spiele das Spiel im Fenstermodus und setze eine Auflösung, die der Auflösung des Desktops minus der Breite der Fensterdekoration entspricht (z.B. 1912×1072 statt 1920×1080) - weniger geht natürlich auch. Die Konfigurationdatei des Spiels, in der diese Einstellungen angepasst werden können, findet sich in einer Datei namens ~/.config/unity3d/<Entwicklername>/<Spielename>/prefs.

Workaround Option 2
Verwende einen anderen Fenstermanger (z.B. openbox, fluxbox, blackbox, wmaker, fvwm2, twm).

Weitere Workarounds
KDE-Nutzer können auch folgendes versuchen: http://steamcommunit … #c846965882766096888

Betroffene Spiele

Folgende noch betroffene Spiele sind mir derzeit bekannt, die Liste ist aber ziemlich sicher nicht vollständig. Ob das Problem tatsächlich auftritt hängt wohl auch von der Abtastrate der Maus und dem verwendeten Fenstermanager ab - nur weil ein Spiel in dieser Liste auftaucht heißt nicht unbedingt, dass das Problem auch überall auftritt.

  • Doorways
  • Surgeon Simulator 2013
  • Gone Home
  • Ravensword
  • MirrorMoon EP
  • Jazzpunk
  • Galak-Z
  • Nimble Quest

Problem: Im Spiel passieren seltsame Dinge

Manche Unity-4-Spiele kommen nicht mit nicht-englischen Spracheinstellungen zurecht. Typische Symptome sind Ereignisse, die nicht oder erst nach sehr langer Verzögerung ausgelöst werden, sich überlagernde Grafiken in der Benutzeroberfläche oder ein schwarzer Bildschirm nach dem Laden.

Oder in anderen Worten: Wenn ein Unity-Spiel nicht wie erwartet funktioniert, dann versuch’s einfach mal mit diesem Workaround :-)


Starte das Spiel z.B. von der Kommandozeile mit den Variablen LC_ALL=C LANG=C, für Ravensword beispielsweise mit

LC_ALL=C LANG=C ./rs2.x86

Troubleshooting Unity engine games on Linux

Deutsche Version

Problem: Mouse constantly moving to the top / game freezes after a few seconds

Some games using the Unity 4 engine seem to be affected by a problem using the mouse: Typically the mouse is constantly moving up to the top of the screen and the picture is freezing after a few seconds. If you change to another application via Alt + Tab and change back to the game again (in some environments clicking a mouse button in the game is also sufficient), picture and mouse will move for a few seconds again. Especially games played from a first person perspective are affected.

Known workarounds

Workaround option 1
Play the game in window mode and set the resolution to your native resolution minus the width of your window decoration (e.g. 1912×1072 instead of 1920×1080) or lower. The game’s configuration file where you can adjust those settings can be found in ~/.config/unity3d/<Developer name>/<Game name>/prefs

Workaround option 2
Use another window manager (e.g. openbox, fluxbox, blackbox, wmaker, fvwm2, twm are known to work).

Other workarounds
KDE users may also try the following: http://steamcommunit … #c846965882766096888

Affected games

I’m currently aware of the following games still affected, which is almost certainly not a complete list. Whether the problem occurs or not seems to be dependent on the mouse polling rate and window manager, so just because those games are listed here doesn’t necessarily mean you will also get this problem.

  • Doorways
  • Surgeon Simulator 2013
  • Gone Home
  • Ravensword
  • MirrorMoon EP
  • Jazzpunk
  • Galak-Z
  • Nimble Quest

Problem: Strange things are happening in the game

Some Unity 4 games don’t like non english locales. Typical symptoms when this happens are events that won’t be triggered or will be triggered only after a long delay, overlapping graphical elements in the user interface or a black screen after loading the main game.

Or in other words: If a Unity based game doesn’t work as expected just try this workaround :-)


Start the game e.g. on the command line with the variables LC_ALL=C LANG=C; for example Ravensword would be started with

LC_ALL=C LANG=C ./rs2.x86

Wednesday, February 20, 2013

Setting the default wallpaper and theme in KDE4

Google didn’t know the answer, so here’s the solution:



and set the appropriate entries.

You can also put this file into your Kiosk profile, the location would be

<path to your Kiosk profile>/share/apps/desktoptheme/default/metadata.desktop


Thursday, November 17, 2011

Backing up your physical media (like CDs / DVDs) including copy protection

When my first floppy discs slowly went unreadable I finally decided to create images of all of my physical media. However this is not as trivial as one would think: A lot of discs (especially games) have copy protections included, so you have to plan what you want to do. My goal is always to create 1:1 copies of the original discs. Please also note that the following information is to the best of my knowledge and / or future hardware may be able to circumvent some of today’s limits (though I doubt that’s too likely).

Without copy protection

ISO / disc dumps

Both terms are equivalent - a file used for optical media (CD, DVD, BlueRay) is usually called an ISO image, while images of other media (floppies, hard discs) often have the ending .img.

These images can be easily created with the UNIX command ‘dd’:

dd if=/dev/<device_you_want_to_make_the_image_from> of=<filename_of_the_image>

Note: While various forum entries praise these commands as the panacea of all copying needs, dd is in fact quite limited or even useless when dealing with copy protections. As dd operates on the UNIX file system, it can only copy the data section of any media - additional information like subchannel data is not visible on this layer and thus cannot be saved. Additionally dd will abort at any read error (or alternatively it will write zeros or skip those sectors completely) - even the most simple protections will check if the error is still there, which wouldn’t be the case any more. And dd will only save the first track of a disc, making it worthless to create copies of Mixed Mode or Audio CDs.


This format has a lot of similarities to the ISO format - in fact, if the media has only a single session the resulting .bin file is exactly the same as the ISO file from above. The difference is that it is possible to store several tracks at once: The .bin file contains the binary data, the .cue file tells where and how to split the file for the individual tracks.

While the format is not an official standard it is easy to understand and has broad support among programs (e.g. almost every burning software and DOSBox, which will also play the audio tracks; notable exceptions are Virtual Machines (VMWare, VirtualBox) which are usually limited to ISO images / disc dumps).

The following commands will create the files:

cdrdao read-cd --datafile <filename>.bin --driver generic-mmc:0x00020000 --device /dev/<CD_DEV> <filename>.toc
toc2cue <filename>.toc <filename>.cue

This first command will create this .bin file and a .toc file (instead of expected .cue file). cdrdao is using the toc files internally, but it offers the converter toc2cue to generate the more common CUE file from that. Another thing to note is the option “–driver generic-mmc:0×00020000”: Most modern CD drives will return audio data in little endian order, however most programs expect the data in big endian order. You can also switch the order later, you can find a handly little program on

Note: I couldn’t get cdrdao to create usable images of copy protected discs, though the options “–read-raw” and “–read-subchan=rw_raw” sounded like they could do so (though the later option will create BIN/CUE files which are not compatible with other programs).

Copy protected discs

Old protection systems (- ~2002)

Old protection systems are based on defect sectors and / or subchannel data. Both of them can be stored with cdrecord:

readcd dev="/dev/<CD_DEV>" -clone -nocorr retries=0 f="<filename>.raw"

New protection systems

… will not work. The reason is simple: The current hardware is not able to create images that are exactly like the original - some programs check for physical properties of the disc, others will create unreachable sectors etc.

While workarounds DO exist it, they require emulation, modified binaries or additional data on the discs. The manufacturers of copy protection mechanisms finally seem to have found a way to really prevent to be able to copy a CD…

Even if the hardware should support all those techniques one day, you still have to invent a new image format to be able to store that information in Linux and extend the burning software to use it.

Wednesday, September 7, 2011

Videos on Squeezebox Radio / Touch / Controller

Note: This blog post is the long version of the article. For a short HOWTO better visit the Squeezebox forum post.


Welcome to another chapter of the series “Making devices do things they weren’t designed for” ;-)

Before you get too excited because of the title I should probably warn you: This solution is a hack. When following this guide you will be bypassing SqueezePlay (meaning no integration into the devices’ GUI) and the solution is not really straightforward either (i.e. more complicated than you may be willing to accept). Also a decent amount of Linux knowledge is required.

Looking on the bright side: You will be able to watch videos after this tutorial - you may even want to experiment yourself and find more effective ways to do some things or work on the integration into SqueezePlay and Logitech Media Server :-)

This article was written using a Squeezebox Radio, however I don’t see any reason why it shouldn’t also work for the Squeezbox Touch or Squeezebox Controller. If you try it with any of those please drop me a note if it worked!

The goal

Watching videos on the Squeezebox!


The hardware

Newer Squeezebox devices (i.e. all devices with a LCD display) have an ARM processor and are running an embedded Linux. The devices aren’t really powerful - Radio has a 400 MHz CPU with integrated audio acceleration, but no floating point or video acceleration unit. In fact it is way too slow to play most of today’s video contents from the web, as most newer codecs (like MPEG4/H.264 or OGG Theora) require a lot of computing power.
The embedded Linux system is very minimal and mainly exists to run SqueezePlay (called jive in the process list), using a framebuffer driver for graphics and an ALSA driver for audio output. The system itself, using kernel, is stored on 128MB of flash memory, which is formatted with UBIFS.
To access the device we will be using SSH (if you are on Windows you may use Putty or similar programs for this).

Choosing a video player

We want to play videos, so we have to find some video playback program that can be used on the Squeezebox. There are several good video players for Linux, and most of them will run on Squeezebox’ ARM architecture. The only additional requirement is framebuffer output, as that is everything the Squeezebox has. Several candidates match these requirements, among them are

In this tutorial we will be using MPlayer because it has a few advantages which make it perfect for a quick hack:

  • The package is self contained, i.e. it already contains all required libraries, making it much easier to compile
  • Most of the libraries can be statically linked into the binary, so only a few additional files are needed on the Squeezebox.

Compiling MPlayer

Note: This step can be quite a lengthy process, so you may just skip it and download the binaries I have built from here instead: http://digitalimagec … s/mplayer_arm.tar.gz
(You may also try to use a mplayer binary from another Linux distribution for ARM, however those usually have a lot of dependencies…)

First you have to set up a cross compile environment to build MPlayer for the Squeezebox. Please follow the instructions from SqueezeOS Build Instructions Wiki page to do so.

When you have set up your environment download the MPlayer source and extract it. Change to the directory containing the MPlayer source and enter the following commands:

SQUEEZEOS="<enter path containing the poky directory from your SqueezeOS checkout>"
./configure --enable-cross-compile --host-cc=gcc --cc="${SQUEEZEOS}/poky/build/tmp-jive/cross/armv5te/bin/arm-none-linux-gnueabi-gcc" --target=arm-linux --enable-alsa --extra-cflags=-I"${SQUEEZEOS}/poky/build/tmp-jive/staging/armv5te-none-linux-gnueabi/usr/include" --extra-ldflags=-L"${SQUEEZEOS}/poky/build/tmp-jive/staging/armv5te-none-linux-gnueabi/usr/lib"

Your will find the resulting binary in the root directory of the MPlayer source. You will also need three libraries from your SqueezeOS build:, and

MPLAYERFILES="<enter a path where you want to store the files for your Squeezebox>"
cp mplayer "$MPLAYERFILES"
cp "${SQUEEZEOS}/poky/build/tmp-jive/work/armv5te-none-linux-gnueabi/ncurses-5.4-r11/image/usr/lib/"
cp "${SQUEEZEOS}/poky/build/tmp-jive/work/armv5te-none-linux-gnueabi/lzo-2.02-r1/image/usr/lib/"
cp "${SQUEEZEOS}/poky/build/tmp-jive/work/armv5te-none-linux-gnueabi/jpeg-6b-r6/image/usr/lib/"

(The version numbers of the libraries are from SqueezeOS 7.7, change them if you use another version.)

Finding a /home

Now that we finally got our binaries we just have to copy them to our Squeezebox and use them. But - surprise - there’s trouble ahead: The root file system doesn’t have enough space to store our files. And even worse: We can’t change that: The (old) kernel doesn’t support mounting more than one UBIFS file system, so even if we add another UBIFS volume using unallocated space we will not be able to mount it - see http://lists.infrade … 009-July/026422.html for details.
However ‘df’ reveals another possible location for our files: /dev. When looking at the ‘mount’ output we see can see that it’s mounted with tmpfs, so we will loose all files from there after a reboot - but hey, we don’t have any other chance, do we?

So for now, copy the mplayer binary and the library files to your Squeezebox:

scp "$MPLAYERFILES"/* root@<IP of your Squeezebox>:/dev

Trying to play a video

If you want you can try to play a video now. First of all make sure that your device is turned on (i.e. you can see the menu). Now log into your Squeezebox and enter the following commands:

cd /dev

Not very successful, is it? Press Ctrl+C to cancel the video. It seems that the video won’t start because the audio device cannot be opened. Looking around which process is blocking the device we see that it’s Jive. Rings a bell? This is the Squeezebox GUI…

Let’s try to turn it off:

/etc/init.d/squeezeplay stopwdog     # Important: Always use the option "stopwdog" (instead of "stop"), otherwise your Squeezebox will reboot after a few seconds.

Well… At least we are seeing something. You may have noted a few things:

  1. The picture is rotated
  2. Even if it would have the correct orientation it would be too big
  3. The movie is way too slow
  4. The sound is way too loud (if there was any)

Let’s try to optimize things a bit:

./mplayer -volume 50 -vf rotate=2,scale=240:320 -vfm ffmpeg -vo fbdev -framedrop

Still too slow, but we’re coming closer otherwise.

Let’s try the same command, but this time with a MPEG-1 video instead of MPEG-4:

./mplayer -volume 50 -vf rotate=2,scale=240:320 -vfm ffmpeg -vo fbdev -framedrop

Finally! Not perfect, but something we can start with.

Recoding the video

As we can see the Squeezebox isn’t fast enough for any real world video playback, so we have to recode the videos (similar to watching videos on Sony’s PSP ;-)).

There are dozens of video transcoding programs for all platforms - it doesn’t matter what program or operating system you use for this step. You do, however, have to put the transcoded video on a webserver or provide a live stream (i.e. some remote protocol mplayer can handle like HTTP, FTP or RTP) if you are using a Squeezebox Radio; Touch and Controller users should also be able to use the external storage. Personally I’m using an Excito B3, a small Linux based NAS, to convert and serve the videos via HTTP.

I’m using ffmpeg for video conversion. Another popular program (also available for Windows users) would be VLC which also offers a graphical interface. Both programs also support video streaming, so if your PC is fast enough you may try to recode your video in realtime.

Example: My daily script to recode the stream at 8:00 PM

#!/bin/bash -x

# Get the filename of the stream and periodically check if has been uploaded yet
cd /tmp
filepattern="`date +http://media\\\.tagesschau\\\.de/video/%Y/%m%d/TV-%Y%m%d-.*\\\.h264\\\.mp4`"
while [ ! "$filename" ]; do
        filename=`grep -o "$filepattern" index.html`
        rm index.html
        if [ ! "$filename" ]; then
                let retries++
                if [ $retries -gt 60 ]; then
                        rm "$VIDEOFILE"
                        exit 1;
                sleep 180;

# Convert the stream
ffmpeg -y -i "$filename" -vcodec mpeg1video "$VIDEOFILE"

Btw: If anyone finds an all-purpose call for ffmpeg converting from any format to something suitable for the Squeezebox please post a comment :-)

Mission accomplished: Now just play your converted file, using the playback command from the last chapter :-)

Bonus: Automatic video playback

If you want to initiate playback remotely there are a few other things to consider: First of all the speaker is turned off when the Squeezebox is not active, so it has to be turned on first. I’m using the CLI interface of the Logitech Media Server to do so. To automate the calls you should also log in to your Squeezebox with a certificate (instead of username and password) to avoid being asked to enter them manually.

The following script is run on my server hosting the Logitech Media Server:


DEVICENAME="<Name of your Squeezebox device (from Logitech Media Center)>"
SQUEEZEBOX="<IP or DNS name of your Squeezebox device>"
VIDEO_URL="<URI of the file to be played (e.g.>"
USERNAME="" # Only required if your Logitech Media Server is password protected
PASSWORD="" # Only required if your Logitech Media Server is password protected

# Turn on Squeezebox
cat << EOF | expect
        spawn nc -q 3 localhost 9090
        sleep 2
        if { "$USERNAME" != "" } {
                send "login $USERNAME $PASSWORD\r"
        send "$DEVICENAME power 1\r"
        send "$DEVICENAME display Video%20playback%20will%20begin shortly... 60\r"
        expect "shortly"

# Copy required programs to the Squeezebox
cd /opt/squeezebox
scp mplayer root@${SQUEEZEBOX}:/dev

# Remotely prepare the Squeezebox and play the video
ssh root@${SQUEEZEBOX} " \
  /etc/init.d/squeezeplay stopwdog; \
  cd /dev; \
  export LD_LIBRARY_PATH=.; \
  ./mplayer -volume 50 -vf rotate=2,scale=240:320 -vfm ffmpeg -vo fbdev -framedrop "$VIDEO_URL"; \
  /etc/init.d/squeezeplay restart; \