Video nodes and video webs: use of video in hypermedia

Extended Abstract Digital video consists of temporally correlated audio and visual data elements. Audio elements are basically sequences of digitized audio samples , while visual elements are sequences of raster frames. In either case the sequences may not be stored explicitly, but instead stored in a compressed representation, or an alternate representation from which the sequences are produced (as when audio is synthesized from a symbolic representation , such as musical notation, or video frames are rendered from animation data). Because of the temporal nature of digital video, its production and consumption often requires specialized devices capable of the real-time handling of streams of data. Until recently this equipment was expensive and not readily available. However a number of significant advances are now taking place that are greatly increasing the use of digital video. These developments include advances in high-bandwidth networks and protocols facilitating real-time transfer of digital video; improvements in storage media such as high-capacity magnetic disks and writable CDs; faster rendering rates for graphics hardware allowing real-time animation; greater availability of special-purpose audio and video processors on workstations; and better computer interfaces to both commercial and professional video products such as camcorders, VCRs, and video mixers. Another significant development is real-time compression and decom-pression hardware for digital video. The compressed video has data rates comparable to bus and disk bandwidths and so opens the possibility of video recording and playback from conventional secondary storage devices. " In ad'dition, an anticipated future development having broad-impact on the use of video, will be the emergence of standards for HDTV. In light of these changes, new possibilities are arising for application developers-in particular those who aim to enhance hypertext, or hy-permedia, with video capabilities. Early interactive video systems relied on analog read-only videodisc technology. This " first generation)' of video-based hypermedia provided very good video quality, but suffered from limitations imposed by the videodisc. Now digital video offers a way around many of the drawbacks of the " videodisc-digital video can be edited and modified, it can be processed, and, like any other form of data, it can be stored and retrieved from conventional storage systems. This presentation will focus on implications of digital video for hypermedia. A short overview of video technology will be provided, introducing such topics as video formats, video compre~ sion, and video editing. Several low-cost platforms for running digital video applications will be described and illustrated …