Update 2/10/04 : This project is now continuing at www.lemurvision.org
Research Concerning the Creation of a Low-Cost Reference Platform for Interactive Television
One of the primary difficulties facing an interactive television developer is obtaining the necessary hardware and software platform for content development. These problems are exacerbated by the lack of standardization between the various ITV systems. The focus of this project was to research the technical feasibility of creating an Open Source standard reference platform for ATVEF-A style interactive television.
Hardware:
Most ITV deployments happen on a set top box provided by the regional cable company. This device is basically a low powered computer with a tuner board, an NTSC output and an Ethernet or modem connection. The hardware specification for our proposed platform duplicates these functionalities, but with easily available off the shelf components. The specifications are as follows: The cheapest computer at your local computer retailer (as of this writing a GHz class Celeron or PIII, on board Ethernet, 128 Mb RAM, 40 Gig HD, approx $300) an NTSC tuner board (recommended a Hauppauge winTV card $50 as of this writing), and a monitor card that supports NTSC output (A wide variety are available which are supported under V4L2, the Linux video support mechanism, approx $100). This puts the total Hardware cost at less than $500 for a unit that has all the functionality and a great deal more power than a comparable cable system set top box.
Software:
Most cable set top boxes contain a proprietary operating system such as PowerTV or VX Works which handle various cable specific functions, and a browser such as OpenTV's Device Mosaic which handles interactivity. Because our project was to be Open Source, our choice of an operating system was Linux, specifically Red Hat 7.2 which was both easily available in a commercial distribution and which contained the necessary support for video devices. Our choice for a browser was Mozilla, essentially an open source version of the popular Netscape product.
Implementation:
While this system could potentially emulate the function of a cable company set top box, it also allowed us to rectify a number of problems with many of these systems such as weak scripting and non existent plug in support. This hypothetical platform would be an excellent place to develop truly cutting edge ITV applications. It would also be useful to use this platform to test and develop for more basic functionality provide on other platforms.
At the time of this projects initial inception, the National Institute of Standards and TechnologyDDE-1 (SMPTE 343M). Unfortunately two years and many budget cuts later, NIST has abandoned this program leaving us without a code verifier. Nonetheless, by exercising the proper care and attention to documentation a developer could still use this platform for developing an application for a real world deployment.
The above scenario presented two challenges in coding. The first was passing URLs contained in line 21 of the vertical interval into Mozilla in accordance with the ATVEF-A specification. As it happened this was easily accomplished. There has been a fair amount of work done on accessibility in the Open Source community. A review of available Open Source software turned up an open source closed caption decoder created by Mike Baker. Source code to this application is provided below under the GNU General Public License. With some minor hacks we were able to happily pass URLs to Mozilla from our tuner card.
The second software challenge of this project was getting video into Mozilla in accordance with the ATVEF-A style "TV:" object. Additionally it was desired to further integrate video into the browser, by extending the TV object functionality so that a video element could be used anywhere that any other standard HTML element, such as a GIF or JPEG, could be used. While not an insurmountable problem, implementing this capability was beyond the resources of this project. (See Reference:TV Support in Mozilla/XFree86/Linux)
Conclusions, moving forward:
While our reach exceeded our grasp in this project in some respects, with this initial research, this project could be completed in relatively short order given additional resources. However it should be noted that technology and the industry have moved substantially during the time of this project necessitating a re-evaluation of this platform.
The growing availability of cable systems Video on Demand (VOD) offerings and of personal video recorder systems, such as TiVo, enable entirely new types of interactivity that point the way towards the next generation of advanced television applications. Two examples of these type of applications can be viewed on this website. (See: TV Dinners:VOD and PVR in Interactive TV [Antiques Roadshow] and TV Dinners:Advanced Functionality [eArthur])
In moving forward on a project of this kind, it would be necessary to implement support for more advanced content scenarios by implementing both an onboard PVR system and controls for cable VOD systems. A PVR could be implemented by using an open source PVR product such as Myth TV or Freevo. VOD is a bit more problematic as it would involve not only cable companies and their VOD vendors, but the rights holders of the content. While an in depth discussion is outside the scope of this paper, it should be noted that much useful research in this area could be done with a property owned by the producing station, thus avoiding any rights issues.
Implementation of the additional functionality would require some additional coding tasks. These would include the extension of JavaScript to allow for control of external systems such as VOD and PVR from within the browser environment, implementation of an electronic program guide, integration of MPEG encode/decode for recording of content, implementation of time code referencing of MPEG recorded material, and creation of metadata structure to support these functions.
Many of the first steps of these tasks have been taken in the context of the ETV cookbook and are documented on this web site. It is our hope that it will serve as a useful starting point for those who wish to take this project and build it out to its logical conclusion.
Revised Tuesday, 10-Feb-2004 20:03:27 CST
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