SMPTE Looks Beyond 3 Gbps at Annual Tech Conference
Managing video services was the topic of the day at SMPTE’s annual Tech Conference on Wednesday, as contribution networks continue to evolve from static point-to-point links to dynamic any-to-any networks and transport of signals upwards of 12 Gbps via linked 3-Gbps pipes moves closer to reality.
“I don’t know when, but they are coming, and it’s exciting times,” said Ciena’s Michael Watford in a presentation.
Ciena, a specialist in high-performance optical networks, has built out a country-wide network in Switzerland for sports-production needs, with several hundred 3G-SDI pipes as well as several Gigabit Ethernet/10GbE circuits in place at sports venues and TV studios and facilities. Most impressive, latency over the network is only 10 milliseconds, thanks to the lack of compression encoding and decoding.
“The wide area network covered the entire country of Switzerland and was basically a high-capacity network to transparently carry uncompressed video signals,” says Watford. “So we didn’t need to learn about compression and formats.”
That also meant the project became one focused on providing raw capacity via a multiple-wavelength optical mesh network that offered reconfigurable light paths. The system works by moving the 3G-SDI signals across the packet-switched networks by turning the SDI bitstream into a sequence of packets. The SDI signal is chopped into fixed Internet packets, which are then reconstituted on the other end with the help of clocking information included in the header of each bit packet.
“There is no magic; you just need sufficient bandwidth,” Watford added. “And legacy SONET/SDH networks are giving way to converged packet/optical networks. And carrier Ethernet services offer flexible bandwidth grooming and switching.”
As to Watford’s final point, Nigel Seth-Smith, head of strategic technical marketing for Gennum Corp., discussed how 3G and 4K can be transported via multiple 3 Gbps-SDI to provide even more bandwidth.
For example, a move to 6 Gbps would provide enough bandwidth for two 1080p 50/60 signals, ideal for 3D demands. It can also open the door to 4:4:4 1080p 50/60 transport or 4:4:4:4 10-bit quality signals. And next-generation services like 2K 50/60 for 3D or at 4:4:4 are also possible.
And 12 Gbps opens up the opportunity for 4K transport.
“There is an ad hoc group in SMPTE, TC-32NF20, that is standardizing transport mappings and multilink rules,” he explained. Among the issues being addressed: whether moving a stereo pair of 3-Gbps signals over two links or a stereo pair of 6-Gbps signals over four 3-Gbps links is possible.
“As much as possible, they are trying to follow existing concepts so there is no need to reinvent the wheel,” Seth-Smith said. “They are also trying to stick with existing 3G single-link-compatible timing formats.”
Of course, pushing that much data requires the use of fiber optic although it is possible over coax using SDI techniques. Cable length, however, is reduced, although 12-Gbps signals have been transported over coax for upwards of 75 meters.
Leaving aside the potential for 12 Gbps is today’s reality of managing 3-Gbps infrastructures, which are evolving as baseband transport meets IP transport.
“We are seeing a huge uptick in IP technology for metro and long-haul video transport, and that means an integrated approach is required to manage the video services,” said Chin Koh, director of product management for Nevion. “And it is about more than just video and audio but provisioning to make sure circuits turn on and off at the right time and not in the middle of an event.”
Koh noted that there is a need for flexibility to meet customer needs. And, given the move to IP-based transport, it is no longer as simple as selecting a router video input and output.
“Unfortunately, the problem is, there are a lot of non-expert users and operators working on these services, so we need to provision circuits as easily as possible,” he explained. “We need to determine what problems may occur and target those areas before things go wrong.”
With a managed-services infrastructure, the goal is to fill in the gaps between the compressed or uncompressed audio and video signals and the transport pipes, whether they are Sonnet/SDH, Ethernet/IP, or fiber and coax.
“We have to tie those together to provide provisioning of the network, management, and secure the network,” said Koh. “Ultimately, it is about controlling the circuits, allowing for self-service scheduling and reporting, and offering a service that allows the client to manage their own video transport.”
End-to-end provisioning means controlling not only the devices on each end but also everything in between.
“Whenever a user requests a connection,” said Koh, “we look at network resources, availability of what is available to use, any constraints such as latency, load balancing, and apply those constraints and compute the shortest path first.”
Service analytics are a key component, allowing the user and provider to monitor the baseband layer, the video and audio signals, and more via constant “data mining” of the signals.
“Those services are key to delivering a good contribution network,” said Koh. “They determine what is going on so any faults can be connected and we can provide dynamic path monitoring and be proactive if there are packet losses with dynamic path routing.”