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Compression systems

Time was that “compression” was a dirty word around broadcast video. Now bring in DTV, where a 1.4Gb HDTV signal is compressed down to 19.4Mb or lower. Compression is in everyone's vocabulary like it or not.

Now compression is opening some new doors to the broadcast engineer, doors that will make the distribution of video content inside or outside the facility potentially more convenient, easier and faster to accomplish. Compressed video is now being distributed across new pipes in broadcast facilities. These pipes include various Ethernet infrastructures, fiber and even telephone lines deployed inside a building or across a campus.

These compressed images can be broadcast in 30fps MPEG-1 or -2, with video qualities from approval to uncompressed serial digital component video. Images can be live, such as delivering satellite news feeds to the desktop. Images can even be cached or received for browsing by client software from various network drives, including SANs.

Applications for compressed video delivery across these new pipes used to be thought of as only the low-frame rate, low-resolution, little boxes of video on computer screens. Now, new technologies allow for full-screen, 30fps images with variable resolutions from HDTV to approval quality. Compressed images are currently viewed on computers, and set-top boxes in homes, offices and broadcast facilities around the world.

Video is different than traditional data. If it is interrupted, the video's frame rate can be changed, causing the familiar stuttered frame rates. This is sometimes solved with buffering, but buffering and the inherent delays it causes are not acceptable in broadcast. The solution to this traffic congestion problem using IP is to guarantee quality of service (QoS).

Path1 showed a technology platform that enables stable video and audio in an IP environment, TrueCircuit. It provides QoS technology platforms that allow real-time broadcast applications to occur with IP. They license this technology to carrier-class providers, system integration companies and manufacturers.

TrueCircuit technology conditions the real-time traffic before it is sent, setting up and tearing down virtual channels inside the network. These virtual channels can be thought of as temporary dedicated paths on which the video traffic can travel. The path is conditioned for real time-transmission of content, then when the content has been transmitted the virtual channel is torn down, creating additional bandwidth for other real- or non-real-time data traffic.

Leitch uses TrueCircuit in its PG1 Gigabit Ethernet Gateway. The PG1 interfaces with 1000Base-SX fiber optic circuits or to 1000Base-T Cat-5 Ethernet ports. The PG1 enables the shift from traditional wire based infrastructures to Gigabit and fiber optic network LANs and WANs.

VNCI showed technology that can utilize existing Cat 3 or Cat 5 wiring systems. VNCI uses frequency modulation technologies allowing two-way audio and video communications, operating simultaneously with telephone or data traffic without having any impact on its speed or quality.

2NetFX displayed full-motion, full-color, full screen images at resolutions from VHS, DVD and HDTV over networks from 10/100, Gigabit to ATM. The system, which uses ThunderCastIP Server software allows users to multicast or unicast video to computer desktops or set top boxes. The company also showed its Streamrider, media player software that resides in a Windows of Linux computer or set top box. It allows scheduling of programs to playback on your computer live, or record them to the local hard drive for playback at your convenience.

Motorola showed its Digicipher II, an ATSC-compliant encoding system that is format flexible, and fully supports 5.1 audio.

Telestream offered its FlipFactory, a software application that eliminates streaming's traditional process of encoding and delivery by automatically flipping source files into user specified formats and then forwarding these files to appropriate servers.

Terayon showed its CherryPicker 7000 media delivery platform. The 7000 optimizes bandwith with its statistical re-multiplexing technology, which allows operators to unbundled and combine compressed streams from a variety of input sources in order to create an output multiplex for delivery.

Astro Systems offered several new products, including the CX-565 MPEG-2 TS PCI multiplex card for contents packetizing for data broadcasting.

This year, numerous vendors at NAB either showed demonstrations of working systems or concepts that would transmit and receive compressed audio and video over various network links, from 10/100 Ethernet to fiber. As these technologies mature, we may find our traditional routing switchers, patchbays, and even our wire change to data models like our computer networks. For some applications, we can make use of our existing data and telephone wire and infrastructure, with no penalty to the uses we currently have for them now.

Compression used to be a dirty word. Now it is going to change the entire business of broadcasting, from the consumer, to our facility operations and infra-structures. It is going to offer new, revenue-generating possibilities, new creative possibilities and certainly new challenges to our infrastructure models.

Dan Stark is president of Stark Consulting.