KOBI POVOLOZKY /
04.01.2005
Originally featured on BroadcastEngineering.com
The Optibase/ADI streaming platform


The MGW 1100 TV streaming platform from Optibase is designed for broadcasters looking for carrier-grade stability and redundancy.


Transporting video content from one location to another has become a daily reality for broadcasters and networks as they seek to deliver live or non-live video to major news distribution points, provide ready-to-use material to affiliates, exchange footage from studio to studio or stadium to production center and distribute programming to several television channels.

The problem

The process, known as video contribution, or, in broadcast vernacular, video backhauling or video trunking, involves moving massive quantities as quickly and reliably as possible. Once at its destination, the content can go straight to air with no further post-production, or it can be edited, spliced for commercials and branded with logos or other overlays.

A typical transmission infrastructure for video contribution requires broadcasters to transfer their content using either satellite links or dedicated analog lines leased on an hourly basis. Because these links can be expensive, few broadcasters can afford to maintain them full time.

The solution

An end-to-end solution that uses broadband IP instead of a satellite or dedicated leased lines is one alternative that allows broadcasters to reduce video contribution expenses while gaining valuable new flexibility. A good example of such a solution that meets the needs and requirements of broadcasters and at the same time adheres to transmission and quality standards is the TV-over-IP streaming platform from Optibase and ADI.

In this scenario, digital or analog video footage at the broadcasting headquarters is fed into an Optibase encoding and streaming platform. This platform encodes the streams and then transmits them over an IP network to the receiving station. Each encoding and streaming platform is equipped with a network interface card that connects directly to the IP network.

At the receiving end, an ADI MX decoder converts the signal back to its original form.

Key requirements

Optibase offers two TV streaming platforms; the MGW 2000e and the MGW 1100. The MGW 2000e can encode and transmit up to six analog or SDI signals, encode them in real time to MPEG-1 or MPEG-2, and then stream them over an IP network in multicast or unicast mode. The MGW 1100 can stream up to 30 channels with hot-swap support for all boards except the switch and host.

What should broadcasters look for in an IP-based link? Key to the encoding and decoding process is the ability to maintain broadcast standards throughout the IP video contribution chain. SDI is the most common video format. This standard provides lossless digital encoding of NTSC and PAL formats for use in broadcast-quality environments. The front end, therefore, necessitates 4:2:2 encoding in order to ensure high-color resolution for further editing, or MPEG-2 I-frame-only GOP structure for content that is re-edited and encoded more than once.

Also important for delivering video point-to-point via IP is minimal delay. Encoding and decoding delay is determined by the equipment used and has a strong impact on the overall quality of the transmission.

Jitter is another consideration. Broadcasters should look for an IP solution with an acceptable level of timing distortion. Too much intersymbol interference can introduce data and synchronization errors. Similarly, users will want optimum A/V synchronization between the transmitter and receiver. A suitable amount is typically less than five milliseconds difference between audio/video lip sync.

The benefits

Finally, broadcasters should protect themselves against error and loss of information. This means choosing a system that ensures enough bandwidth during transmission to allow a continuous flow of data.

Streaming delivery with Optibase and ADI provides several tangible advantages without compromising on quality or delivery. First, IP networks can help broadcasters save significantly on expensive satellite links and dedicated lines. When using an IP network, the cost of sending 1Mb/s upwards of $60 when using a satellite line — can be reduced to a little as $3. IP is also more cost- effective and efficient when compared to other delivery methods, such as FTP or hand-delivery via courier.

Video contribution via IP streaming also allows broadcasters to manage bandwidth in a far more efficient way. Bandwidth capacity with IP corresponds to the bit rate of the streams being transmitted. In contrast, satellite links have a fixed capacity of 27Mb/s or 38Mb/s per transponder. A related benefit is that IP networks are accessible around the clock, whereas satellite links are usually leased on an hourly basis.

In terms of video fidelity, the Optibase/ADI streaming platform uses MPEG-2 encoding to maintain top broadcast quality. A patent-pending eversync mechanism keeps audio and video in sync 24/7, while its traffic-shaping technology lets operators smooth bit-rate fluctuations and keep bit rates constant.

Finally, broadcasters should choose an IP network system that employs QoS technology so their video signal quality is preserved end-to-end. Using a broadcast-quality IP delivery system provides all the quality benefits of satellite at a lower cost plus 24/7 availability.




Kobi Povolozky is Manager, International Marketing & Business development, for Optibase.



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