Ubuntu on Ouya

I was testing Markus Tavenrath’s EGL branch of the XBMC on my Ouya and noticed that OMX_UseEGLImage segfaults on Debian but doesn’t on Ubuntu. The segfault happens inside the NVIDIA’s OMX binary, so there is not much to debug. And with Ubuntu 13.10 I had rendering issues. Then I tried Debian Jessie just to discover it is already using X.Org Video ABI 15.

So here is the summary of my discoveries:

  • Debian Wheezy: Segfault in OMX_UseEGLImage with XBMC.
  • Debian Jessie: X.Org Video ABI 15, no driver.
  • Ubuntu 12.04: Old.
  • Ubuntu 12.10: Old.
  • Ubuntu 13.04: No obvious issues.
  • Ubuntu 13.10: X.Org Video ABI 14, rendering problems.
  • Ubuntu 14.04: X.Org Video ABI 15, no driver.
HW accelerated video and GLES2.

HW accelerated video and GLES2.

I noticed that Totem has moved to GStreamer 1.0 so it does not use NVIDIA’s GStreamer plugins. I changed Parole to use nvxvimagesink instead of the de-facto xvimagesink and it works well. I’ve uploaded the binary to my tmp.

Pulseaudio seemed to cause slow playback and extra CPU consumption so I just removed it.

My instructions for creating Ubuntu Raring rootfs for Ouya can be found from github. Do leave a comment if there is anything broken with the instructions!

Steam on Debian Stable

I like the idea of being able to play games on Linux, so the announcement of Steam for Linux was a big thing. Too bad Debian Stable has too old C-library for it. During the past year I’ve occasionally tried to get Steam running on Debian Stable (Wheezy) with usually little success. Currently I think installing Debian Testing (Jessie) to a chroot is the most easiest way. It is not as complicated as it may first sound.

One catch is that you need to be running the same version of NVIDIA’s drivers inside the chroot and outside of it. Luckily at least at this precise moment the backports for Wheezy has the same version as the Jessie has.

On my gaming PC I use self-compiled kernel and the latest drivers from NVIDIA. On my media box in the living room I have some old integrated NVIDIA chip. Trine 2 runs nicely on my Gaming PC (GTX 760) and awfully on the integrated chip. I assume it’s about the chip and not about the different driver version (319.72 vs 331.20) and I doubt I’ll install the latest drivers just to verify that.

Update NVIDIA drivers from backports:
NOTE: The versions doesn’t match anymore, so this approach doesn’t work. Reviced instructions coming later.

$ sudo vi /etc/apt/sources.list.d/backports.list
# Edit to look like this: deb http://ftp.[your country domain here].debian.org/debian/ wheezy-backports main non-free contrib
$ sudo apt-get update
$ sudo apt-get install -t wheezy-backports glx-alternative-nvidia libgl1-nvidia-glx:amd64 libgl1-nvidia- glx:i386 libgl1-nvidia-glx-i386 libnvidia-ml1:amd64 nvidia-alternative nvidia-driver nvidia-installer-cleanup nvidia-kernel-common nvidia-kernel-dkms nvidia-settings nvidia-support nvidia-vdpau-driver:amd64 xserver-xorg-video-nvidia

It’s not mandatory to use Debian packaged NVIDIA drivers. Just be sure to install the same NVIDIA driver package inside the chroot that you are running outside with the 32bit OpenGL libraries. You should skip installing the kernel module inside the chroot:

$ sudo sh NVIDIA-Linux-x86_64-331.20.run --no-precompiled-interface --no-runlevel-check --no-kernel-module --no-x-check --no-kernel-module-source --no-distro-scripts --no-nvidia-modprobe --accept-license

If you see “ERROR: Unable to create ‘(null)’ for copying (Bad address)” just hit OK several times. Also you may need to add /etc/ld.so.conf.d/nvidia.conf with “/emul/ia32-linux/usr/lib/” in it and run “sudo ldconfig” after adding it.

Create Jessie schroot

These instructions are adapted from https://wiki.debian.org/Schroot and assumes 64bit host Debian.

WARNING: removing schroot with “rm -rf” while it is active will delete your home directory as well! You should reboot and make sure there is nothing mounted inside the chroot before removing it.

Install schroot for chrooting and debootstrap for creating the Jessie root filesystem:

$ sudo apt-get install schroot debootstrap
$ sudo mkdir -p /srv/chroot/jessie

Create the Jessie rootfs (the last parameter is optional for faster downloads):

$ sudo debootstrap --include sudo jessie /srv/chroot/jessie http://ftp.[your country domain here].debian.org/debian/
$ sudo mkdir /srv/chroot/jessie/run/shm
$ sudo chmod 1777 /srv/chroot/jessie/run/shm

Configure Jessie schroot (note that you need to add your user account’s group name in there):

$ sudo vi /etc/schroot/schroot.conf

description=Debian Jessie (testing) 64-bit
groups=[your group name]

$ sudo vi /etc/schroot/default/fstab
# Uncomment /run/shm

The /etc/group is shared between the chroot and the host Debian. Rest of the instructions assume your account belongs to the sudo group:

$ sudo adduser [your user name] sudo

Finishing the schroot

Schroot into Jessie and verify sudo:

$ schroot
$ cat /etc/debian_version
# Should say Jessie
$ sudo -l
# Should show that you can run ALL

Configure APT to use non-free packages and multiarch with i386:

$ sudo vi /etc/apt/sources.list
# Append "non-free contrib"
$ sudo dpkg --add-architecture i386
$ sudo apt-get update

Install Steam from Jessie and some dependencies:

$ export LC_ALL=C
$ sudo apt-get install python xdg-utils less libvdpau-dev libalut0 pciutils lsb-release libopenal1:i386 libvorbisfile3:i386 libglu1-mesa:i386 build-essential libgl1-nvidia-glx:i386 libgl1-nvidia-glx:amd64 steam
$ exit

The schroot is now ready and you can launch Steam directly from the host Debian:

schroot steam

If you spot a mistake in the instructions do leave a comment below so I know to fix it.

My first 3D print

Mechanics has always been a problem in my robotic projects but now that the 3D printing is such a hot topic I decided to test it out.

It seems that the 3D printing services use STL format and many of the popular 3D modeling applications can export it, so there are plenty of applications to choose from. I wanted to use Blender for the modeling as I have used it briefly in the past and I would like to know it better. It was easy to use boolean operators to shape my model but it turned out that even though the model looks nice on the screen, it is not enough for real world printing. I had some broken surfaces, holes, etc. in there. As I am a Blender rookie I ended up creating the simplest cylinder and modifying its subdivided surfaces to shape my model. Easy and quite fun :)

Now that I had the model, the next step was to print it. The nearby public libraries provide 3D printing services for free or nearly free with printers from MakerBot and MiniFactory. After a couple of visits I realized that it is not that easy to jump into the 3D printing world with them. You need to know how to tune the parameters of the software, how to clean up and prepare the printer, how to preheat it, etc. You also need to model your creation in such a way that the printer can print it. The plastic is hot during the printing and not very strong so you may need to add some supporting structures during modeling. At least some of the 3D printer applications can add the supporting structures automatically but I was told they might not be very good at it.

Below is a photo showing the first three layers of an automatically created supporting structure. That looked OK but the actual model started to go wrong already on the first layer so the printing was canceled.

First layers of a 3D printed supporting structure.

First layers of a 3D printed supporting structure.

After a couple of miserable failures somebody hinted that Shapeways is a much easier way to get 3D prints and the price is low enough. They seem to be using selective laser sintering and I didn’t need to worry about supporting structures or fine tuning parameters. They also have a bunch of different materials and colors to choose from. I chose “Coral Red Strong & Flexible Polished”:

3D printed Camera Housing

Original part and the 3D printed version with my additions.

3D Printed Camera Housing Fits

The 3D printed part fits perfectly.

I have used cable ties and Meccano parts earlier but I needed something more lightweight (and better looking) and the Shapeways might very well be the solution for me.

Debian on Ouya: All Systems Go

I finally got all the major subsystems working and Debian is now usable on Ouya. I prefer Debian but Ubuntu should work similarly.

Working video and 3D

In the above screenshot I’m playing 1080p H264 while running glmark2-es, an OpenGL ES benchmark. And the CPUFreq ondemand governor doesn’t even raise the CPU frequency from the minimum as everything is properly accelerated. I do have to admit that the 1080p video isn’t running smoothly with the benchmark running at the same time.

A disclaimer before telling more: Trying this out might void the warranty and flashing anything to Ouya may easily brick it forever. So don’t try it, unless you are willing to buy a new one.

That said, the idea is not to touch Ouya’s Android at all. Kernel is booted from RAM and Debian from an SD card or USB stick.

The instructions for debootstrapping your own Debian Wheezy rootfs are described in the github repository and the needed binaries are in a temporary location that will probably change at some point.

WiFi is working as well but I’m not sure if the firmware binaries are redistributable, so you need to copy them from the Android rootfs after booting to Debian.

One of my main goals for this whole exercise is video encoding and I’m happy to say that H264 encoding from an USB webcam works nicely with hardware acceleration as well.

I’ve also noticed some issues:

  • Hciconfig doesn’t show BT devices, I didn’t debug much further.
  • Mpg123 seems to play but nothing is heard. Maybe it tries to pass MP3 onwards instead of PCM? GStreamer provides acceleration for MP3 and AAC though.
  • Video acceleration works only with GStreamer and nvxvimagesink. Mplayer can’t even use XV video output correctly.
  • Tegra3 supports only OpenGL ES 2.0 with EGL, so no full OpenGL with GLX.
  • Xrandr seems to be able to switch the resolution but after the switch there was window decoration corruption.

Despite the deficiencies I think Tegra3 is quite well supported in the X.Org world and many things work well with this 99$ device.

If you test my instructions, let me know how it goes and what you think about it! :)

Pleco Phase02 completed

It’s been two years already since I posted about Phase01 being completed. It was a simple track based vehicle using cheap DC motors and the hull was built from Meccano parts:

Pleco Phase01

For Phase02 I decided to go with a ready made car and bought an RC Rock Crawler. It’s about four times the size of the Phase01:

Pleco Phase02 open

Pleco Phase02

The software is roughly the same as it was for Phase01. I’ve fixed a lot of bugs, simplified some things and added a bunch of new features. The slave has a sonar next to webcam and it measures the distance to what ever the camera is pointing at. The slave also measures the current consumption and battery voltage level. All details are shown on the GUI.

The hardware on the other hand has changed a lot. Instead of handling the servos directly from Linux there’s now a separate self-designed Cortex-M4 based microcontroller board for driving the PWM signals. In the future the microcontroller can update the PWM signals real-time based on other sensors without having to worry about latency issues in Linux.

The Linux is now running on a Tegra3 based Ouya gaming device. Ouya is not as convenient for robotics as Gumstix was but personally I think Tegra has better Linux support than OMAPs. And since there is now a separate control board for motors and sensors, it’s enough for the Ouya to only have a USB connection to the control board.

Ouya needs 12 volts while the motors need 5 volts and I’m expecting to need 3.3 volts as well. So I now have three switching regulators connected to the battery for the needed voltage levels. And a USB hub because of the USB based control board and webcam. There are also lots of cables. So I’m not actually able to get everything nicely inside the car, but almost.

Controlling an RC car with a keyboard is inconvenient, so I’ve added support for gamepads. I’m currently using a Bluetooth based gamepad from Logitech:

Logitech F710 gamepad

When driving in a local WiFi network, there’s no noticeable latency at all. It’s still not possible to really drive based on the camera only, the viewing angle is too narrow, turning the camera is cumbersome and the video quality needs some tweaking.

Now that I’ve made some nice progress with the project, I have clear goals for the Phase03:

  1. Disassemble the webcam to get the size and the weight down and to be able to attach fish eye lenses to it.
  2. 3D print a frame for the electronics and the webcam.
  3. Tweak the video quality and camera controls so that it would finally be possible to drive based on the video stream.
  4. Control the webcam based on driver’s head orientation?

So there are plenty of interesting things to learn :)

Oh, and I’ve moved the code to github.

Debian on Ouya


Ouya is a 99$ Tegra3 based gaming console without a display.

My goal is to use Ouya in my robotics project for video encoding but first I want to have Debian running there with hardware accelerated X.Org, OpenGL ES and video.

I now have the Debian running but with a few bigger issues that I’ll describe shortly. If you want to try it out, you can find my instructions for creating the rootfs in github. That might void the warranty even though the kernel is booted from RAM and the rootfs mounted from USB stick so the Ouya software should remain intact.

Ouya is easily brickable permanently, so you need to be careful not to flash anything there and you’ll be doing it at your own risk.

About the Issues.


2013-09-05: HDMI works now with multiple resolutions and is not so picky about having the cable connected already on boot.

Ouya display kernel driver is hardcoded to use HDMI as the primary display with 1920×1080 resolution. That works relatively well as long as you keep your monitor/TV always on. I couldn’t get anything but black if I e.g. switched my monitor to another input and back.

I tried to enable the normal behaviour in the display driver and by disabling the LVDS in xorg.conf but the TV remains black and doesn’t seem to change the resolution. Maybe there is still something hardcoded in the display driver or maybe the driver is trying to enable the non-existent internal panel and gets confused.


2013-09-11: Got audio working with a simple asound.conf. I also run /etc/init.d/alsa-utils stop but unsure if that affected anything.

aplay -l lists HDMI as the first device and tegrawm8903 as the second. If I make the tegrawm8903 the default the audio plays but only from the left speaker and half the speed.

I don’t know if this is related to the HDMI problems above or if I should just have the correct ALSA mixer configuration.


2013-09-05: Totem has configurable video sink: gconftool-2 -s /system/gstreamer/0.10/default/videosink nvxvimagesink –type=string

Hardware accelerated video decoding and rendering is supported through GStreamer. Currently videos play well with playbin2 as long as the audio is disabled with audio-sink=fakesink and the correct video sink is selected with video-sink=nvximagesink.

Maybe the GStreamer’s autovideosink should be patched to use nvxvimagesink instead of xvimagesink to make nvxvimagesink the default in applications using playbin2


2013-09-05: CPUfreq with ondemand governor is working and enabled in the kernel nby default now.

CPU core hot-plugging works but switching to the low power core seems to lead to a kernel bug (arch/arm/mach-tegra/pm.c:509). Same bug seems to happen with ondemand CPUFreq governor. I haven’t really tried to get those working yet but both of them are working with Nexus7 so maybe it’s possible to get them working on Ouya as well.

If you want to test Debian on Ouya, you can find the needed blobs from my /tmp but I might set up something more appropriate later.

Command-line sharing for Harmattan

I use IRC and I want to be able to share photos there easily. For n900 I had implemented a sharing plugin and that worked nicely. When I got the n950 I of course wanted to do the same with that but it turned out to be a difficult task.

I started to implement webupload and SSO plugins but I never got them to work. The biggest show stopper was lacking documentation for the SSO part. Finally Mika Suonpää pointed me to Share UI plugins and now, only a few days later, I have the first version of it working for n950 :)

For some reason I don’t get my icons visible, they are always shown as a red square. All hints about that are most welcome. As is testing and feedback of the plugin. The plugin settings are in Settings -> Applications -> Command-line Share, and from there you need to enable the plugin and set the command to be run. After that the sharing plugin is visible in the Gallery -> share.

The source code can be found here and the corresponding forum thread here.

Ogg-support 1.1.1: Performance

After almost two years there’s a new version of the Ogg Support in the Fremantle Extras.

The decoder code has changed completely. Where the old one used libvorbis and vorbisdec from the GStreamer base plugins, the new one uses libav (formerly FFmpeg) and gst-av from Felipe Contreras. The impact on performance should be significant because the vorbis decoder in libav is more efficient on the n900 than the libvorbis and Felipe’s gst-av also outperforms the vorbisdec.

Thanks to Felipe for doing all the hard work. I’ve just been updating the version numbers of the dependencies and tracking the bugzilla for the known issues and fixes :)

MeeGo 1.2 ARMv7 chroot (beta)

I’ve always liked the Scratchbox approach to cross-compiling. Run ./configure && make and you have an ARM binary, no need to explicitly tell the configure we are cross-compiling nor fix the bad behaving build scripts.

MeeGo doesn’t provide an SDK for the (ARM) platform. There’s an SDK for building Qt applications and there’s an QEMU for emulating the ARM device environment. For building the lower level components (Qt itself, GStreamer, etc) you are expected to use OBS. OBS is a very good build infrastructure tool, especially as you can link your own OBS to upstream OBS instances like MeeGo or OpenSUSE and have your OBS build only your own components or modified upstream components.

But OBS is a bit overkill when you are developing your own component that you don’t want to be a part of anything bigger yet. The OBS client side tool, osc, allows you to build components locally in a chroot but still you need an OBS account and those aren’t automatically available for everyone, not even in the community OBS.

I took the chroot created by osc build and modified it a bit with the help from stskeeps @ #meego-arm. The produced chroot is capable of building ARMv7 hard-float binaries without OBS or OBS account. It includes a minimal set of dependencies to make it smaller for easy download (it’s still 162MB), and the project specific dependencies can be installed normally with zypper from the standard MeeGo repositories.

The benefit from using a chroot over a QEMU image is the installed speed tools; many of the components taking time during a build are actually x86 binaries. These include e.g. bash, compilers and bzip2. Running these as emulated ARM binaries (or natively on an ARM hardware) would be much much slower.

I’ve used this approach with my own Qt + GStreamer project and it has been working well but that’s only a small use case so there can be all kinds of issues still. I use the same account inside the chroot and outside and bind mount my $HOME to the chroot so I can build project under my $HOME.

Current known issues:

  • Zypper doesn’t find noarch packages (this is an upstream bug, not related to my chroot).
  • Tested only on Debian Squeeze. At some point there was a linker issue on Ubuntu and I don’t know if that still exists.
  • My instructions mention libqt4-devel although the package name is libqt-devel.

If you want to try it out, it’s available via BitTorrent at http://tuomas.kulve.fi/tmp/torrent/ (temporary location). After extracting the tarball, see the readme file in the root directory.