theibcdaily Thor extenders extended Telecast By Monica Heck
Norse code: The Thor fibre optic extender family
Belden’s Telecast Fiber Systems brand is introducing several new members of its Thor family of fibre optic extenders for broadcasting, government and professional A/V applications.
The Thor DE is an optical DVI extender consisting of transmitter and receiver modules that use CWDM
Reliable transport using the unreliable internet
Kevin Ancelin, Digital SVP sales and co-founder Adtec, evaluates the fundamental pros and cons of using the low-cost internet for video transport
For years the internet has grown both in throughput and accessibility. Now, with the global reach of the internet, why not use it for video transport in lieu of the incumbent and well understood satellite and ASI methods? The pros of using the internet
are in essence: low cost and global reach. The cons are its non-deterministic nature and variable throughput. The internet,
practically speaking, behaves like a rapidly opening and closing circuit – it’s bursty by nature and bursty is very bad for transport. Balance the requirements: If
you require five nines of reliability, use of the public internet for your transport application won’t suffice. The premise that low delay yields poor picture quality is no longer true. The intent of increasing delay is to increase
reliability in the presence of congestion and even zero throughput states, not to improve picture quality. Internet transport is neither expensive nor deterministic, it is accessible and at a very low cost therefor making it very compelling. IP transport methods:
Transport over IP using UDP, RTP, and applying SMPTE 2022 FEC (COP3) are well known and
optical multiplexing to transmit four channels of WUXGA (1920x1200) graphic signals with a 60Hz refresh rate over a single fibre. The companion Thor DE
Throwdown DVI and Audio Extender drives uncompressed WUXGA (1920x1200) 60Hz DVI signals up to 2km (single- mode) or 500m (multi-mode) over a duplex LC fiber. The Thor DA Throwdown HDMI Distribution Amplifier
widely deployed methods. UDP does not provide recovery of lost or out of order packets. Unlike UDP, RTP will re-order packets when they get routed, or delayed. RTP is better, but not good enough, for transport via the internet because eventually packets will just disappear. Does SMPTE 2022 FEC solve the problem? No, because the maximum recovery for packets using a 5Mbs service is only 200ms (5-6 frames). The other transport method: TCP is widely deployed but typically for use with consumer devices employing HLS or other streaming methods. Adtec’s solution was to employ TCP for P2P broadcast transport contribution. Some would say overhead for TCP is too high, when in fact it turns out that TCP overhead is similar to that of SMPTE 2022, with the added
allows one HDMI (TMDS) single-link digital video signal to be split into multiple digital displays, with a built-in amplification function that enables HDMI signal distribution without signal loss. Finally, the Thor MR 8X8 HDMI and DVI Matrix Routers are new additions to the Thor-S KVM switcher product line, enabling customers to make cross-switches between up to eight DVI or HDMI sources and eight displays located away from the main sources. 10.B39
Opinion
Kevin Ancelin: ‘Internet transport is accessible and low cost’
benefit of higher reliability and robustness. The solution: Adtec TCP-
Transport is a newly developed transport method that balances both the transmit and receive buffers, offering low or high latencies based on your applications requirements. Higher latencies offer increased public internet transport reliability but are not required. Adtec only offers excellent picture quality solutions, and TCP-Transport adds reliability that goes well beyond unicast with SMPTE 2022 FEC. One last thing: Encoder Rate Adaptation requires an encoder that can change the bit rate on the fly without audio or video interruption. The amount of adaptability should be limited as much as possible to maintain a consistent high quality picture. Adtec’s modern AVC compression solutions are high performance and deliver high quality HD video. By managing the receive buffer transmitting an 8Mbs HD AVC service, Adtec’s TCP-Transport solution can sustain fluid low delay HD video with robustness five times greater than SMPTE 2022. 1D01