Today's broadcaster content contribution networks are undergoing significant changes as HD content becomes more ubiquitous and as the cost for fiber-optic connectivity becomes more affordable. This changing environment presents new challenges and opportunities for broadcasters and service providers that offer video transport solutions.
The digital video format for these broadcast-grade contribution networks is SDI. Both HD and SD-SDI formats are defined by SMPTE. They are 270Mb/s for SD-SDI (SMPTE 259M) and 1.485Gb/s for HD-SDI (SMPTE 292M).
Most providers have historically been offering a 270Mb/s service to enable transport of SD-SDI from facility to facility content, be it from a sports venue to a production studio or among various geographically dispersed pre- and post-production facilities. Forward-looking service providers are now establishing rates to address uncompressed HD-SDI content.
Challenges
There are a number of unique challenges faced by broadcasters and service providers when transporting broadcaster-grade video. The high bandwidth associated with the HD-SDI video signal poses significant challenges, requiring creative solutions for leveraging existing infrastructure.
In addition, broadcasters will continue to require transport of SD-SDI content, as well as encoded ASI content. Many times, this is a program-specific requirement that means that simplicity is important to affording viable customer premise-based solutions.
As fiber becomes more available, it is clear that the use of dedicated, dark fiber solutions will be growing, particularly among major facilities. However, spurs to venues and small studios will continue to rely on leased circuits. Providers and broadcasters will require flexibility in interfacing with a number of various infrastructures.
Most important to broadcasters is the quality of the transport associated with these valuable signals. Solutions must offer minimal delay and jitter-free performance. In addition, redundant operation is essential to ensuring the successful delivery of the content.
Solution
Cisco, in conjunction with its new subsidiary Scientific Atlanta, has developed a flexible suite of solutions for broadcasters and service providers to provide them with efficient multiplatform transport. These solutions draw on the extensive video and networking expertise of the company to offer integrated, high-quality systems that support a wide variety of applications.
The solution set consists of three key components that can be deployed individually or in combination with each other:
- Scientific Atlanta Prisma IP video adaptor;
- Cisco ONS 15454 multiservices provisioning platform (MSPP); and
- Cisco ONS 15454 multiservices transport platform (MSTP).
The IP video adaptor addresses a variety of video formats and infrastructure types to meet the varying programming requirements while minimizing investment. The adaptor offers six video ports that can be used in four configurations:
- Up to six SD-SDI and/or ASI inputs.
- One uncompressed HD-SDI and up to three SD-SDI and/or ASI inputs.
- Two losslessly compressed HD-SDI inputs.
- One losslessly compressed and up to four SD-SDI and/or ASI inputs.
The video adaptor leverages a standards-based SONET/SDH interface and uses redundant, modular optics, so it can be deployed as a standalone transport in multiple configurations:
- Configuration 1A simple point-to-point video connection over dark fiber. (See Figure 1.)
- Configuration 2A simple point-to-point video connection over a wavelength. (See Figure 2.)
- Configuration 3A simple point-to-point video connection over SONET/SDH circuit. (See Figure 3.)
- Configuration 4A simple drop-and-continue video connection over dark fiber or SONET/SDH. (See Figure 4.)
In addition to the more simple video-only configurations demonstrated previously, Cisco can offer multiservices, multiwavelength solutions that feature full connectivity from any feed to any location:
- Configuration 5Multiservices, any-to-any connectivity over SONET/SDH. (See Figure 5.)
- Configuration 6Multiservices, high-bandwidth network over multiple wavelengths. (See Figure 6.)
These approaches leverage a combination of the video adaptor and the MSPP and MSTP. Extensive interoperability testing has been completed to verify broadcast-grade performance.
The transport solutions are capable of supporting the high bandwidths associated with video contribution services. However, it is clear that bandwidth efficiency is important to successfully deliver these services.
There are three key features that offer this desired efficiency:
- SONET/SDH multiplexingUse of the standards-based OC-48c/STM-16c within the video adaptor allows multiplexing into an OC-192/STM-64 circuit by the MSPP. Additionally, the MSTP offers a 4xOC-48 to OC-192 wavelength.
- Wavelength multiplexingThe MSTP offers the ability to multiplex up to 40 10Gb/s (OC-192/STM-64) signals onto a single fiber. On a smaller scale, the coarse or dense wavelength division multiplexing (CWDM and DWDM, respectively) modular optics in the video adaptor enables efficient use of fiber assets.
- Lossless compressionThe video adapter offers a compression mode that enables two 1.485Gb/s HD-SDI feeds to be transported over a single OC-48/STM-16 (2.5Gb/s). The differential pulse code modulation (DPCM) algorithm provides transparent compression affording broadcast-grade video and full pre- and post-production processing.
As with any video transport solution, the key concern is quality, particularly when associated with the extremely valuable content contribution. Scientific Atlanta's video experience in conjunction with Cisco's networking expertise ensures jitter-free performance and the successful delivery of services.
Conclusion
HD-SDI video will continue to grow in importance and usage. Broadcasters' content contribution networks will evolve to address the required incremental bandwidth and availability of fiber-optic infrastructure.
The Prisma IP and ONS 15454 platforms offer the performance quality and deployment flexibility that broadcasters and service providers need.
Robert Collmus is director of business development for transmission network systems at Scientific Atlanta.
