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Compression Conversation: Evaluating the State of the HEVC Standard

Encoder manufacturers put a lot of time and study into deciding how to employ HEVC in their products.

Though the majority of video work is not yet completed in ultra-high definition, there are many solutions for acquiring and posting in 4K. More problematic, however, is delivering such material. If one uses the same compression codec for 4K that’s being used for HD video, it takes more or less four times the bit rate. When viewed by the accounts payable department, that’s four times the money to deliver UHD video.

Fortunately, forward-lookers started work years ago on a solution: High Efficiency Video Coding (HEVC). The HEVC standard is also known as H.265 by the ITU-T VCEG (ITU Telecommunication Standardization Sector Video Coding Experts Group) and as MPEG-H Part 2 by the ISO/IEC MPEG (International Organization for Standardization/International Electrotechnical Commission Moving Picture Experts Group). Those organizations were co-developers of HEVC, the first version of which was completed and published in 2013.

Telestream added HEVC encoding capabilities to Vantage way back in 2014.

“Customers have been interested in HEVC, evaluating HEVC as a possible replacement for current encoders that are doing either MPEG-2 or H.264,” says Abdulla Merei, director of compression systems for Evertz. (MPEG-2 and H.264, aka MPEG-4, are long-established encoding standards that provide a lower compression ratio than HEVC.)

Encoder manufacturers put a lot of time and study into deciding how to employ HEVC in their products. “We’ve implemented and selected the codec that had the best compromise of throughput and quality, and we’ve integrated this codec so that we can support HEVC-transcoded output,” says Matthieu Fasani, senior product manager of France-based Dalet Digital Media Systems.

Dalet licensed Vanguard Video’s HEVC codec SDK for its AmberFin media processing platform in 2016.

Imagine Communications chief product officer Brick Eksten says his company shops for best of breed for targeted requirements. “Our philosophy on codecs, especially in the early days of any new codec, is that there are going to be multiple vendors of technology that have specialized in different areas,” he says.

Telestream has offered H.265 in its products for quite some time now, according to Paul Turner, Telestream’s vice president of enterprise products. “It’s been through customer demand. For the end user, it’s really the only viable method of getting UHD content distributed out to customers. H.264’s perfectly capable of dealing with 4K—it’s just nowhere near as efficient as H.265.”

Harmonic’s EyeQ software codec reduces the bit rate of H.264 by 50 percent.

However, there’s not a big rush away from H.264, according to Thierry Fautier, vice president of video strategy at Harmonic. While Harmonic does offer several HEVC-capable products, the company recently introduced EyeQ, a software codec that brings down the bit rate of H.264 by 50 percent. “That kind of makes HEVC obsolete at this stage,” Fautier says.

When encoders first hit the market, they were enigmatic black boxes that contained each vendor’s proprietary mix of hardware and software. Over the years, the paradigm has shifted so that the heavy lifting of encoding is performed in software, while the associated hardware is a commodity tool, or what the high-tech world calls COTS (commercial off-the-shelf) products.

Chuck Meyer, chief technical officer of production at Grass Valley, points to the divergent paths of software-based encoders and dedicated hardware in the form of an application-specific integrated circuit (ASIC). “These things present certain tradeoffs in terms of power consumption or what kind of product can be built in terms of cost, in terms of upgradability,” he says. Upgradeability is important, Meyer adds, because the H.265 codec is going to evolve. “Even MPEG-2 has had constant tweaks and improvements in the profiles,” he says. “It’s the same for H.264.”

Evertz’ 3482TXE-HEVC provides high-density HEVC encoding for the distribution of UHD with HDR signals.

Customers rightly want to know how they get from H.264 solutions to H.265-capable equipment without sending their existing equipment off to the landfill. The upgrade path is complicated by the fact that codecs are written to function in the hardware of the day. For instance, RAM was very expensive when MPEG-2 was being developed, so MPEG-2 can be encoded and decoded with relatively little RAM. By the time H.264 was being written, RAM was much cheaper and could be delivered in a much denser form. H.264 requires more RAM to function, which makes it difficult to use the AVC codec in hardware developed for MPEG-2.

The modular nature of an encoding system, however, permits users to upgrade pieces without junking the whole system. Besides cost savings, this means users can retain a familiar user interface and workflow throughout the upgrade. In the near future, this same story will be written about the successor to HEVC. But that’s then, and HEVC is now.