WWW & TV Working Closer

M. Reha Civanlar

AT&T Labs - Research

The number of web pages that contain some form of video and the number of times a URL is mentioned in broadcast TV programs are continuously increasing. This suggests a need for an interaction between the TV and the WWW that is more than just using the TV set as a monitor for a home computer. This short note presents two examples for such interactions between the TV and the WWW. The first one is based on transmission of TV quality video over the Internet to be displayed on a TV set. The second one involves processing the pictorial information on the broadcast TV channels for automatic access to the web content.

The Internet Engineering Task Force (IETF) has defined specific payload types for the Real-time Transport Protocol (RTP) that can be used to deliver MPEG-2 encoded, TV quality video over IP networks [1, 2]. In AT&T Labs-Research, we developed a prototype system that transmits stored or live video using these payload types and it works successfully over our Intranet [3, 4]. The video outputs of such systems can be displayed directly on regular TV sets. As the Internet backbone and the residential access bandwidths increase, similar systems can be used to transmit high quality video over the Internet to residential users. Since this approach requires layer three functionality at the receivers, it may not be optimal for the transmission of regular TV broadcast channels, a task that requires multi gigabit per second data processing. On the other hand, it opens significant new avenues for video-on-demand as a part of information-on-demand and narrowcasting applications to justify its existence along with other means to carry broadcast TV channels.

One problem with the broadcast video is the sequential access. For example, we have to listen to an entire news program although we may not be interested in every news item that it includes. A much better way of viewing news programs can be made possible through a descriptive index to the news provided as a web page with links for video-on-demand transmission of the news segments. A system developed in AT&T Labs-Research, "Pictorial Transcripts," generates a digital multimedia library of TV programs automatically using scene change detection and closed captioning information [5]. Pictorial Transcripts=92 web interface used together with MPEG-2 over IP provides on-demand, non-sequential playback on a regular TV set with a video quality not distinguishable from a regular TV broadcast. Hence, the additional functionality can be provided with no compromises on the quality.

Another set of applications that benefit from MPEG-2 over IP is based on narrowcasting specialized programs using IP multicast. This way, practically everyone can run a private TV studio and programs that may be of high interest to a small group of people can be made available to them. For such applications the WWW can provide sophisticated directory and search services.

Both IP based high quality video-on-demand and narrowcasting applications can be developed based on the existing set of the Internet protocols. In particular, RTP/RTCP can be used for the transport, Session Description Protocol (SDP) can be used for transmitting the session information to the receivers and Real-time Streaming Protocol (RTSP) can be used for session control including VCR type control functionality. A guideline document describing the use of these protocols to implement a complete system may be needed to help the implementers.

The second application targets automatic extraction and use of the URL information embedded in broadcast TV pictures. Currently, URL references are used in many TV programs, e.g. providing additional information on the subject matter of the program, etc. Accessing the web pages pointed by these requires manual transfer of the displayed URLs from the TV to the web-accessing device, typically a computer. Considering the state of the frame capture and character recognition technologies of today, this task can easily be accomplished automatically. In such a system, upon a user's request, indicated by, e.g., pushing a button on a remote control device, the current picture on the active TV channel gets captured. The URL imbedded in the picture is then extracted through image analysis and character recognition and transmitted to the web-accessing device, which downloads the indicated page automatically. The need for such a system may diminish with the deployment of the digital TV that includes additional channels carrying digital information; however, until that time, it makes the integrated usage much easier with no burden on the transmitter side. This application does not need any new standardization work.

References

  1. D.Hoffman, G. Fernando, V. Goyal, M. R. Civanlar, "RTP Payload Format for MPEG1/MPEG2 Video," RFC 2250, January 1998.
  2. M. R. Civanlar, G. L. Cash, B. G. Haskell, "RTP Payload Format for Bundled MPEG," work in progress, IETF Internet Draft, draft-civanlar-bmpeg-03, April 1998.
  3. M. R. Civanlar, G. L. Cash, "A practical system for MPEG-2 based video-on-demand over ATM packet networks and the WWW," Signal Processing: Image Communication, no. 8, pp. 221-227, Elsevier, 1996.
  4. A. Basso, G. L. Cash, M. R. Civanlar, "Transmission of MPEG-2 Streams over non-guaranteed quality of service networks," Picture Coding Symposium (PCS-97), Sept. 1997.
  5. B. Shahraray, D. C. Gibbon, "Automatic generation of pictorial transcripts of video programs," Proc. SPIE 2417: Multimedia Computing and Networking, Feb. 1995, pp. 512-518.