The main goal of the demonstration is to document NPAC current technical ability to handle VOD technologies. To this end, we have gathered and installed the digital video equipment from few different vendors, including Sun, Parallax, and SGI. Using the software libraries provided by the vendors, we have implemented digital video browsing tools with double functionality: random access to the digital video material controlled by external GUI based on hyperlink access to the textual information, and fully interactive access (VCR+ like) to the video material. Usefulness of the implemented tools has been demonstrated on the example of the CNN Newssource access.
Infrastructure and industrial partners
Two different hardware setups have been installed: Sun-based Parallax video cards and SGI Indy workstations. These two setups have very different architectures. The Parallax cards support JPEG hardware compression for both capture and display. The APIs are provided at few toolkit levels, including Xlib, Motif, and Xview. The audio delivery is based entirely on original Sun solutions. For storage, Parallax relies on either standard UNIX file system structures or on the real-time toolkit supporting streamlined disk access. SGI solution is entirely software-based. The advanced video tools are not yet available for distribution. We have received from SGI an early version of the audio, video, compression, and movie libraries for the purpose of the demo. SGI supports several compression standards, including JPEG, MPEG (decompression only), and few proprietary SGI compression standards as MVC1 and MVC2 for video and AIFF for audio, as well as QuickTime framework for isochronous delivery.
NPAC has been chosen by Silicon Graphics as a partner for beta testing of the SGI hardware compression products. We expect to receive first specimens of the SGI Cosmo compression engine within 6 weeks. It should significantly enhance performance of the SGI digital video equipment installed in NPAC and will give us early expertise in the new line of SGI products.
The cluster of workstations used for the VOD demonstrations is linked via ATM LAN supported by the FORE ASX-100 switch. ATM links are used either to support compressed video data delivery to the browsers via NFS protocol or to deliver video imagery to a remote display from the workstation running the browser. In both cases, standard TCP/IP basic protocol layer is used on top of the ATM TAXI protocol. The real-time streamlined disk devices has not been used in the current setup, although such capability is supported and will be evaluated in near future. The FORE switch is also used to route the entire cluster network traffic to the core of NPAC facility via switch Ethernet port. This configuration, explicitly discouraged by FORE, has been installed, tested, and found stable by NPAC researchers by gaining access to the switch system-level software.
Software architecture
The basic functionality of the VOD demonstration is provided by two independent software modules: digital video browsers, implemented in NPAC, and Mosaic-based user interface from NCSA, installed in NPAC as both server and client software. Digital video browsers offer full random access to the video material, including all VCR-like functions plus extensions, like immediate access to a chosen frame, not usually supported by analog equipment. For Parallax setup, the viewer, implemented using Xview toolkit, offers full GUI. For SGI the viewer has been implemented using SGI Movie Library and supports browsing capability only via keyboard interface. More advanced interface will be implemented as soon as at least rudimentary documentation of the SGI movie API is made available.
The Mosaic interface to VOD has been chosen for compatibility with other InfoVision projects, as Simulation on Demand, and InfoSchool. In the context of the CNN demo, we have converted CNN Newsource scripts to HTML documents, providing links from this textual database to the video material. Hence, the search and browsing capabilities supported by the demo are those of the HTTP server. After the appropriate segment of the digital video has been localized, the user is given capability to either watch the selected clip, or browse the material within or beyond the clip using interactive browser. The basic capability demonstrated here is supported by both hardware architectures, and can be extended to an industrial strength system, using NPAC's other HPCC resources and capable of maintaining a huge digital video database and delivering similarly structured information to remote users.
Lessons learned
Future extensions