This is an application I wrote that drives the Ambient Light rig I built. It captures colors from the TV using a webcam, then samples colors at the edge of the screen and updates a bunch of LEDs at the back with those colors.
The sampling region and other camera properties can be controlled by a separate client that connects up to this server. The client is a python qt application that lives in another repo: https://github.com/waldobronchart/AmbientLightPyClient
A video of the project and details on how I built it can be found on my blog:
Building the application
If you're interested in getting this to work and changing it fit your own needs, here's a long list of things you need to do to get it to build.
Preparing the SD card
You'll need at least 4GB space on the card.
Get Arch Linux from: http://www.raspberrypi.org/downloads (I used archlinux-hf-2013-07-22.img) and burn the image:
- Windows: burn it with http://sourceforge.net/projects/win32diskimager/
- OSX: using Terminal, find the target sd volume name with
diskutil listand unmount it with
unmountDisk /dev/.... Then write the image with
dd if=archlinux.... of=/dev/...(replacing /dev/... appropriately)
Resizing the partition and access setup
Boot the pi and either plug in a keyboard or connect to it via ssh.
SSH should already be enabled, so you should be able to connect up to it via the Terminal with
ssh firstname.lastname@example.org (Default password should be root too). On windows, use Putty.
From here, just follow this tutorial to repartition the card: http://jan.alphadev.net/post/53594241659/growing-the-rpi-root-partition
If you're going to be ssh'ing, I'd recommend setting up a static IP too: https://wiki.archlinux.org/index.php/Network_Configuration#Manual_connection_at_boot_using_systemd
It's probably also best to create some swap space in case we run out of memory while compiling:
cd ~ fallocate -l 512M /swapfile mkswap /swapfile swapon /swapfile
Get all updates for Arch linux and installing build tools
pacman -Syu pacman -S gcc pkg-config git make cmake
The first line updates your package databases and installs updates to packages already installed.
The second like installs the needed build tools we need to compile AmbiLightServer.
Clone this git repo or your fork to your home folder (default /root/).
cd ~ git clone https://github.com/waldobronchart/AmbientLightServer (or your own fork)
Install all prerequisites.
# Jannson: JSON library used for serialisation pacman -S jansson # Log4Cplus: logging library # have a coffee because this will take 25-30mins # it might also install to /usr/local/lib instead of /usr/lib cd ~ wget http://downloads.sourceforge.net/project/log4cplus/log4cplus-stable/1.1.2/log4cplus-1.1.2-rc2.tar.gz tar -zxvf log4cplus-1.1.2-rc2.tar.gz rm log4cplus-1.1.2-rc2.tar.gz cd log4cplus-1.1.2-rc2 ./configure make make install # Boost: used for network communication and update loop timers pacman -S boost # WiringPi: library to interface with the output pins pacman -S wiringpi # OpenCV: used for capturing frames from the webcam cd ~ wget http://downloads.sourceforge.net/project/opencvlibrary/opencv-unix/2.4.7/opencv-2.4.7.tar.gz tar -zxvf opencv-2.4.7.tar.gz rm opencv-2.4.7.tar.gz cd opencv-2.4.7 ./configure make make install
OpenCV doesn't currently allow turning off Auto Exposure on the camera, so I currently hackily do it with
uvcdynctrl. It doesn't seem to be present on arch linux by default, so you'll need to install that too (included in libwebcam).
wget http://downloads.sourceforge.net/project/libwebcam/source/libwebcam-src-0.2.4.tar.gz tar -zxvf libwebcam-src-0.2.4.tar.gz cd libwebcam-src-0.2.4 cd build cmake .. make make install
I should actually stop using OpenCV and use libwebcam directly, but I'm lazy and it works just fine :).
Compiling and running
This takes about 10mins:
cd ~/AmbiLightServer/ mkdir build make
Once built, use
sh run.sh to start the server.
At this point you may want to create a service that automatically runs it when the Pi boots.