Streaming Media
Perseus technology is in use for contribution feeds for Sky Italia; company says it accommodates greater color depth and higher dynamic range in addition to offering efficiency gains.
Compression specialist V-Nova says it will publish performance tests for its codec working on Ultra HD streams at IBC next month and says it has 8K compression tests in the works.
The London-headquartered developer, which came to prominence in April after five years of R&D, has generated considerable buzz with its claims of a technology that more than halves the bitrates necessary to deliver Netflix-style Ultra HD content to the home.
The company says it is working with a number of operators to trial and evaluate Ultra HD using its Perseus codec.
"The technology has incredible range from 8K to sub-SD and everything in between," said Fabio Murra, SVP Product & Marketing. "8K 120 fps is what will make the technology really stand out."
Streaming Media has requested twice to review Perseus, but the company hasn't agreed yet, so we asked V-Nova for baseline numbers claimed for the latency and bitrate of its compression scheme.
"Those numbers are difficult to give without the context," replied Murra, who spent seven years in product marketing at Ericsson before joining V-Nova last September.
"The headline is that our technology is capable of delivering UHD at HD rates and HD at SD rates and SD at sub-audio bitrates," he added. "This is correct, but it's a combination of factors, partly compression performance and partly the ability of our codec to behave fundamentally differently compared to existing standards."
He added, "We have re-written our codec from the ground-up."
At NAB and several demonstrations since, V-Nova has shown streaming of UHD 25p video at bitrates of 4-6Mbps for IP streaming applications.
"For a truly immersive experience, we have demonstrated the ability to do UHD 50p or 60p at 11-13Mbps," said Murra. This is about 50% the current benchmark set by HEVC live encoders, he claims, in reference to channels that are available and on air now.
"However, we are not saying that Perseus is 2-3x times better than HEVC in pure compression performance or under all conditions," said Murra.
Key to claims made for Perseus is what Murra calls its "continuous hierarchical adaptability." The "V" in the company's name is symbolic, he said, of an inverted pyramid representative of the core technology.
"Perseus' hierarchy means that it contains all levels of quality (LOQ) within a single stream and it can move between LOQs seamlessly, on a frame-by-frame basis," he explained. "This effect, which we call 'continuous hierarchical adaptability,' effectively eliminates the typical MPEG 'knee' and its nasty blocking artifacts for a more gentle, softer, pleasant picture degradation as bitrates are reduced. Operators can therefore move from extremely cautious operating points to lower ones, while maintaining a great user experience. It means, subjectively, the picture degrades a lot more gracefully, the picture doesn't break or block, so we can push the bitrate a lot lower."
In theory, what such a 'hierarchical architecture' means is that an operator can avoid simulcasting by carrying UHD, HD and SD at the same time and all at different frame rates if required, in the same stream.
"Every operator has to deliver SD, and HD and, in the future, Ultra HD," he continued. "They must simulcast these streams to different screens which becomes very inefficient. Having scrapped the single stream paradigm we are able to build a hierarchical structure which allows us to push the encoding envelope a lot harder. A Perseus UHD stream effectively carries the HD and SD feed, and HD streams include the SD equivalent. This effectively eliminates the need for simulcasting and its another important benefit beyond raw compression performance."
Sky Italia is the company's first deployment of Perseus in contribution, where feeds are brought back from stadiums from live productions to the broadcast centre at a latency measured at 3 frames, according to Murra, "and at a level of performance which is visually lossless and 30-50% better than an equivalent technology like AVC Intra or JPEG2000.
Middleware vendor Wyplay has also integrated Perseus into a STB for an unnamed European pay-TV operator.
"Things get better as data gets bigger—so there's a lot better performance with 4K," stated Murra.
V-Nova is currently testing its codec on 4K Ultra HD content ahead of publishing the results at IBC next month. "We are testing the delivery of 4K UHD content in visually lossless mode at 300Mbps," Murra said. "There is no benchmark out there, but if we can achieve this it means that all of a sudden we can route three UHD 4K feeds down a 1Gbps pipe to the home. It means delivery of Ultra HD content from a live event over IP becomes possible."
SD video could be delivered at 300Kbps, making it possible to provide mobile television over 2G networks.
Murra emphasises that Perseus fits within existing transport systems. "What comes out of our system is still wrapped around an MPEG2 transport stream. None of the infrastructure is really changing. It's just a software update at the encode and decode end."
If Perseus' qualities really do get better as things get bigger, the logical next step is surely 8K.
"Perseus is designed to support native 16-bit so it will already accommodate higher dynamic ranges and greater color depth," confirmed Murra. "Looking forward, 8K 120fps is what will make the technology really stand out. If we can get a 2x performance in HD, a 3-4x performance in 4K then one can only imagine the gains we can make for 8K. Again, there is no benchmark, but we are doing some experiments. The most difficult thing is getting hold of 8K content to work from."
An obvious tie-up might be with Japanese broadcaster NHK, which is experimenting using HEVC/H.265 for contribution and distribution.
One of NHK's partners in creating optical gear for Super Hi-Vision is Hitachi Data Systems, a partner shared by V-Nova. It provides V-Nova with server and storage systems.
"While we are experimenting with technology we are still very focused on solving real world problems for operators today," stressed Murra.
V-Nova's licensing adds to the potentially costly mix of proprietary codecs already competing in the market for HD and Ultra HD (including in the live video over IP domain the IntoPix' Tico Alliance; J2K; Sony Low Latency Video Codec; and the open source VC2).
"HEVC is a standard only because the industry decided to give a number and a name to it, but it includes single ideas from many different companies, many of whom are trying to monetise their piece," says Murra. "There are open source codecs which have no licensing but operators are nervous about adopting those because of intellectual property exposure. We offer the chance to licence one technology from one company, and we are trying to be as accommodating as possible. But we do have IP (intellectual property) and the codec is our business."
V-Nova was founded in 2011 by Guido Meardi (CEO), Luca Rossato (chief scientist), Eric Achtmann (executive chairman) and Pierdavide Marcolongo (angel investor).
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