This project intends to demonstrate the delivery of broadcast quality video streams over a high performance IP network. The source of those streams will be cameras at Kennedy Space Center; the receivers of the streams will be computer displays at one or more NASA centers. The viewers will be presented a collection of channels that can individually be switched to and viewed on demand, with low latency between the change. Use of commercial technologies, and merging of digitized video with data network distribution, will permit a more cost-effective service to a broader community.

The primary goals of this demonstration are to show

• Greater flexibility for scene selection & viewing – a user interface permits intuitive selection of a broader set of cameras than the current mechanisms
• Decreased cost/complexity over dedicated or leased video circuits
• A network that permits improved image quality without complex re-engineering

The existing mechanisms for video distribution have some significant limitations. Currently, video distribution requires allocation of limited resources (satellite transponder capacity) or establishment of leased lines that are dedicated for the purpose. These feeds are then redistributed at a given center over an analog broadband system. This broadband system must be carefully tuned and supported to provide consistently high quality service. Futhermore, the viewer of a particular stream uses an external manual selector device to select a different camera view. This selector must have it’s own dedicated link back to the KSC video switching equipment. The separate analog video display also consumes precious workspace.

By digitizing the video near the origin, carrying the digital video stream over high performance data network facilities, and delivering of the stream to commercial off-the-shelf desktop computer platforms, economies of scale and greater workspace flexibility can be achieved.

This demonstration will make use of both proven and recently developed technology.

The existing NREN network is built using IP routers that are interconnected via ATM switches. The ATM interfaces support OC-3 (155 Mbps). This wide area network has been used extensively over the last few years for NASA technology demonstrations. The video source (NTSC) comes from Tektronix Grass Valley video switching equipment that has been in long-term production use at KSC.

The new technology revolves around MPEG-2 encoding equipment and native IP multicast distribution. There has been significant development of MPEG-2 encoding devices in the last two years, and they are beginning to be deployed in commercial settings in preparation for fully digital video services. For NTSC input, the MPEG-2 encoders can provide resolutions of 720x480 at 30 frames per second. Reasonably modern PC platforms (200 Mhz+, Pentium-II) can display such a stream with the addition of an inexpensive MPEG-2 hardware decoder. Similarly, native multicasting has been in initial deployment for many months, and has become stable enough for commercial offerings. Multicasting makes more efficient use of the network resources by enabling the delivery of a single stream to many receivers without needing to create redundant copies of the stream. Finally, a number of high speed (100Mbps) ethernet switches have capabilities that allow them to interoperate effectively with multicasting routers to optimally deliver high bandwidth streams such as digitized video.

Architecture/Configuration

Many pieces for this demonstration are already in place, but a few more will be needed. As diagrammed in Figure 1., NREN has high performance connections to most NASA centers (connections to MSFC, JSC, and KSC are in development). We will deploy a small number of MPEG-2 encoders at KSC, connected to one of the KSC video switches, and to an NREN router located at KSC. The network will be provisioned to accommodate approximately 6 video streams (6-8 Mbps per stream). On the receiving end of the stream (indicated as "NASA LAN"), a 10/100 Mbps Ethernet switch that has IGMP (multicast aware) switching capabilities will be deployed, and a Pentium-based workstation will be configured to select and display the video streams. The workstation will be connected directly to one of the ports on the ethernet switch. The switch will either be connected directly to an NREN router at the site, or via a high speed (100Mbps+) infrastructure that can accommodate several tens of Mbps of multicast traffic without impact from/to other data communications.

KSC is in the midst of a complete upgrade of their analog video camera, switching, and distribution system to an all-digital system, capable of much higher performance and resolution (i.e., SDTV, HDTV). The network configuration of our demonstration project would be amenable to supporting such future capabilities, with incremental upgrades to the ATM fabric, routers, and display systems. Digital distribution of these higher quality streams would also readily support storage, replay, and offline analysis of image sequences.