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Compression holds key to 4K production

The advent of ultraHD (UHD), or 4K, will actually simplify coverage of life events for broadcasters, but only if it can be compressed down to 1Gb/s so that production video can be transported via readily available 1-GE (Gigabit-Ethernet) networks. This was a takeaway message from Swedish media transport system vendor Net Insight at IBC 2013, which also highlighted a growing need for reliable Internet transmission, for contributing content from events and also as low-cost backup for satellite and terrestrial networks. These two trends will combine to enable 4K transport at the production, contribution and primary distribution levels over the next few years.

Net Insight has addressed the first of these trends with its Nimbra 600 MSR series, enabling lossless transport of 4K streams at 1Gb/s using the JPEG2000 compression algorithm widely deployed for video production and contribution. Uncompressed 4K video requires 12Gb/s, which means it cannot be transported even over 10-GE networks, making it incompatible with today’s production infrastructures. “But now we can compress it down to 1Gb/s, it is not that expensive to transport between two sites,” said Per Lindgren, Net Insight founder and CTO.

As Lindgren pointed out, most movies are now shot in 4K and the ability to compress it to 1Gb/s would help build momentum behind migration to the format in the broadcast production environment. He argued that 4K would make coverage of outside events easier for broadcasters because the higher resolution enables footage shot from single cameras to cover a wider area and be reused during production through zooming in and out. “4K will lead to simpler workflows,” says Lindgren. “From the event perspective, broadcasters will be able to make do with fewer cameras because they can zoom in and use different parts of the picture in production.”

At the same time as migrating to 4K production, broadcasters will be looking increasingly to the Internet for contribution and primary distribution because of its much lower cost, Lindgren added. “We see this happening in sports coverage, where it is too costly to have managed fiber connections for contribution. The same Internet connection can also be for live streaming with sub-second delays,” said Lindgren. “Then, when it comes to back-up systems, both for satellite and terrestrial, Internet can provide extremely efficient and low-cost back-up.”

Net Insight has announced its Nimbra VA 210 for transport over the Internet, bringing the ability to maintain high-quality video with up to 30percent packet loss. This is achieved by intelligent Forward Error Correction (FEC) combined with selective retransmission within latency targets. “We look into the MPEG stream so that we can apply forward error correction just to the important bits and combine that with selective retransmission,” said Lindgren. A key step is use of buffering to hold up the video long enough so that packets sent within about three times the round-trip transmission delay will still arrive in time at the destination. “This means we can send key dropped packets two or three times,” said Lindgren.