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February 2014 www.tvbeurope.com


IP is not only low cost and widely available, but it has also reduced the cost of technology development due to the fact that it shields developers from designing for the physical layer


TVBEurope 15 The Workflow


Weigner: “4K is the defining point in time where SDI failed to deliver and IP did”


interference between these flows, and low (predictable) latency and jitter, adds Vermaele. However, “most IP/Ethernet


networks fall short of these requirements” offering only best-effort QoS. “The benefits of IP are well documented, including the fact that it is everywhere. But it does have limitations, which make its


Scott-South: “We don’t need to shoehorn IP into every point-to- point link”


“IP can be completely reliable


and predictable in a controlled environment,” says Shen. “However, when IP is in a public environment such as the internet, there will always be some kind of unpredictability. In a video-over- IP environment, compression, packet loss, and packet jitter can magnify its impact on picture. As a result, a number of technologies


Heinzer: “IP has limitations that “ make its use for high-quality live-content a challenge”


very unreliable 3G/4G links or the public internet. “The key to success when using IP networks is to plan ahead and test out your connections, especially when you plan to load the system with heavy data traffic and you’re routing through multiple switches,” says Scott-South. “For good quality video links, it’s not


“It is a myth that IP means higher latency or lower reliability”


use for high-quality live-content a challenge,” agrees Heinzer. “IP networks can be much


more reliable than SDI networks especially when it comes to seamless failover. You just need the right stuff - the right switches, proper cabling and of course the right architecture to start with. The new SDN products help,” says Weigner.


such as error correction are often used to minimise the impact of the interference.” To combat interference, TVU


uses variable bitrate encoding, so that the transmission continues when network throughput fluctuates, together with forward error correction allowing live HD to be transmitted reliably, even over


Jan Weigner, Cinegy


just a case of turning up and plugging into the nearest Ethernet port, at least not yet. As part of its first RevolutionQ


project, Quantel is now working with video over IP, taking delivery of signals that arrive as RTP streams. Although the signal will typically be transmitted over IP compressed (at 10, 15 or 20Mbps), the first thing the central server


Shen: “IP can be completely reliable and predictable in a controlled environment”


will do is to convert it to 100Mbps AVC-Intra, which considerably increases the data storage needed. If we can store the files as transmitted over IP and then only convert the finished result to a more traditional broadcast file format, it is much more efficient. Particularly as news, for example, only uses 1% or less of the original media,” says Francis.


Standard deviation “Audio/Video Bridging (AVB) is currently the best (only) way to reliably transport realtime, uncompressed audio and video across Ethernet networks with very low latency (2ms network latency),” claims Eveleens. “It provides synchronisation, bandwidth management/ protection and traffic shaping (and some more) and has been standardised by the IEEE so is open for everybody to use.” SMPTE’s 2022 range of


standards can map video and


Francis: “SDI is incredibly reliable, but it suffers with a lot of issues”


other broadcast signals over IP, and 2022 “scales nicely for both compressed and uncompressed broadcast signals and makes use of generic IP infrastructure in the core networks,” responds Heinzer. “SMPTE 2022-based equipment has proven its reliability for live broadcast signals over wide area networks, thus enabling improved workflow and cost efficiency for live productions. SMPTE 2022- encapsulated video, audio and data can be used in the broadcast facility and for any type of live content exchange network. “In comparison, AVB is designed for the local area or facility only, does not support any options for compression and demands specialised Ethernet infrastructure,” argues Heinzer. “In order to transport AVB mapped content over IP networks, converters from AVB to IP are necessary, which represents a huge disadvantage


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