Media Follow You
A Ubiquitous Computing Project
Jan Kolkmeier, Pieter Pelt and Reinout Epke
February 7, 2010
Ubiquitous computing (ubicomp) is a post-desktop model of human-computer interaction in which information processing has been thoroughly integrated into everyday objects and activities. In the course of ordinary activities, someone “using” ubiquitous computing engages many computational devices and systems simultaneously, and may not necessarily even be aware that they are doing so. This model is usually considered an advancement from the desktop paradigm.
The Media Follow You (MFY) system is a system that is aware of the positions of its users in terms of nearby Screens or Speakers. Further it is able to switch audio/video sources to output devices.
Assuming a user is watching a movie in his/her living room and suddenly starts moving around the house. The system recognizes certain positions and switches the video to the screens along these positions, resulting the movie to “follow” the user.
We identified several problems that needed to be discussed in order to meet the ubiquitous computing requirements and to technically realize a demonstration:
- How to connect and switch all those devices?
- How to detect presence of nearby users?
- How to keep administration and interaction low for the user?
- How to make it easily extensible?
- What happens if two users stand in front of one screen?
Demo setup in SmartXP-Lab
For the demo we used SunSpots. Sunspots are small devices with sensors, buttons and LED’s. They also have wireless capabilities. The last feature allowed us to detect if some SunSpots are near others, by evaluating the signal quality.
For the audio and video switching we used the Magenta Mondo III Audio/Video Switcher which is already set up in the SmartXP-Lab. This system allows to transform every UTP port into a audio/video source with the use of special transmitters and receivers. Thanks to its serial interface we were able to automate the switching.
We distinguished two types of SunSpots. The key sunspot and the TV-spot. The first are carried by the user, the latter are mounted near the screens included to the system.
The TV-spots basically build a multi-hop network, covering the whole Lab. Further, they constantly send a package with its ID into the aether.
If now a key comes closer to a TV-spot, it evaluates the signal-quality of packages recieved by TV-spots, sending an own package to the network containing its own ID and the ID of the TV-spot sending the “best” packages, which usually is the TV-spot which is nearest.
Thanks to the existing network of TV-spots, it doesn’t need a very strong signal-quality itself, because its package can be forwarded by the TV-spots to reach the endpoint of our demo-setup: The basestation.
The basestation is a PC with another SunSpot, running an Java application responsible for collecting and evaluating the data. It further is connected to the audio/video switcher and thus also responsible for the actual effect of the whole system.
- Key finds that TV1 is closest.
- Key transmits its ID and closest TV via the network to the base station.
- Basestation maps ID’s and issues the mondo to switch the video accordingly.
- Desired picture is shown on the closest screen.
Two users, same screen?
In our current demo the user that is detected the latest gets the screen. This is best for demonstration purposes. We’ve also made sure the screens won’t flicker between two sources constantly.
Our MFY consumer product concept does not use the Mondo A/V switcher because its to bulky and expensive for home use. Instead the video streaming will be done wireless over IEEE802.11 N, the base station will also switch the different streams and the receivers will also be the sensors for the nearest TV. It will be sold as an upgrade kit consisting of one base station and transmitter and two receivers and keys.
- Key detects he is near a reciever0
- Key sets a package on the network with the id of that reciever0 and the channel selected on the key (say “0”)
- Basestation orders the Transmitter with channel “0” from the key to stream to reciever0.
- Transmitter streams to the Reciever.
The base station is the heart of the network. It handles all the diferent videostreams and has an build in wireless-N router. Every device is at least indirectly connected to the base station.
The transmitters have common video and audio inputs and an ID-selector. This is the ID you can select on your key if you want to watch the stream from that particular transmitter.
The receiver is the device attached to your TV or Audio system. It has common video and audio outputs. And a wireless sensor to interact with the closest key and other receivers to hop messages to the base station.
The key is carried by the user and is configurable. The key has a screen and a button so the user can select one of the transmitters. It has a wireless sensor that interfaces with the receivers. The sensor of the key has a weak signal strength so only the TV’s nearby can detect it. With this the system knows what screens to turn on and off.
This setup, at least in theory, keeps maintenance and overall interaction with the system for the user very low.
To add a new source in the network the user would have to purchase a new transmitter. The source is connected tot he transmitter and the transmitter ID is set with the buttons.
To add a new Screen/Speakers the user has to purchase an additional receiver and connect it to the screen/speakers, no buttons needed.
A new key also just needs a channel to be selected, and its ready to go.
Since the basestation would anyway be a wireless device, further configuration could done through a webinterface running on the basestation.