By Helge Stephansen CTO and Janne T. MorstÝl, COO, T-VIPS.
Itís increasingly important that content owners and network operators can ensure the flawless delivery of high quality content to TVís and other video devices. In this article, rather than look at one way in which this has become easier, we will take a top-level view of how the move to IP has made possible important new techniques in intelligent switching, remultiplexing, monitoring and video compression that have all combined to make content delivery so much more efficient and easy to manage.
Even though the bandwidth advantages of moving to IP are great, many are now finding that itís the changes in workflows enabled by IP that produces the greatest benefits. Almost all of the solutions that we now design utilize two-way IP communications for control and management. The combination of move to digital and the two-way nature of IP networks have made it possible to hardwire intelligence into the video network. At T-VIPS we have already made the first steps, with solutions such as our seamless redundancy switching, which is already deployed at major operators.
A fundamental requirement for IP contribution networks is to flawlessly handle single point of failure both in the network and in the video processing devices. IP networks are typically designed with automatic and fast re-routing in the case of a node failure. The re-routing delays are highly dependent on the network design, but can be as low as 50ms in a well-designed MPLS network.
There are several mechanisms that can be employed to increase robustness in the IP network as seen from the video edge-devices. One mechanism is to use external redundancy technology e.g. have the video edge-devices controlling external switches and thereby control which content is sent through the network. Another mechanism is to have the video edge-devices more closely integrated with the IP network. A typical scenario uses cost based routing mechanisms to select the best video signal where multiple video sources are available.
In some cases, IP networks still suffer from packet loss and the video edge-devices have to cope with these loses and still deliver uninterrupted video signals. Forward Error Correction (FEC) mechanisms are built into the video edge-devices to reconstruct loss packets.
The market is moving towards building intelligence into the edge-devices thereby enhancing the robustness of the entire system: Cost-based routing mechanisms are already being integrated in the video devices but there is much more to come. Resource Reservation Protocol (RSVP) is a transport layer protocol designed to reserve resources across a network and is capable of improving both flexibility and robustness in contribution networks. Session Initiation Protocol (SIP) is widely used for controlling communication sessions such as voice and video calls over Internet Protocol (IP) and it is possible that this protocol will also find its way into our professional video networks.
T-VIPS has been a pioneer in IP networks through our ASI to IP Video Gateways deployed in a large variety of systems including feeding of terrestrial transmitters for digital switch-over and our JPEG2000 Gateways for high quality video contribution, but our commitment to reliability doesnít end with our Video Gateways.
The following solutions from the T-VIPS range of products all support automated switching: the Transport Stream (TS) Monitoring Switch, for the intelligent switch-over between two input signals; the Seamless TS Monitoring Switch, includes flexible configuration of switching modes, the alignment of two identical TS inputs to provide seamless switching and it also enables SFN and DVB -T2 frame-aligned seamless switching. In addition T-VIPS provides a TS Monitor to handle multiple Transport Stream monitoring and error detection both over ASI and IP.
T-VIPS solutions deliver:
|Automatic input-stream redundancy|
|Improved error resilience in IP networks, with advanced FEC|
|Important QoS improvements for satellite network operators through automated traffic shaping designed to protect bit rate overflow in one service affecting other services in the multiplex.|
JPEG2000 compression, redundancy mechanisms and FEC, transport stream monitoring and intelligent switching all combine to make IP-based video-centric networks more flexible, powerful and easier to manage. IP-based transport provides high-quality content delivery and is robust, efficient, ubiquitous and flexible.
Itís becoming increasingly clear that content distribution networks need to cater for more than just broadcasting content to the TV. As operators need to reach multiple device types as well as merging broadcast services with broadband content distribution, the flexibility of IP contribution networks will become even more important, with intelligent edge-devices becoming a necessity as complexity increases.