One of the most important advances on the new generation PERSEUS compression codec (called PERSEUS 2 and receiving its debut at NAB this month) is the ability to use HEVC and VP9 compression as a base layer upon which PERSEUS is then used to add detail and achieve greater picture quality within a given bit rate. Currently PERSEUS can be used with H.264 (AVC) as a base layer or it can be deployed in its native form, using pure PERSEUS compression. When used with standards-based compression schemes, PERSEUS can be applied within an existing standards ecosystem and does not require any changes to workflows including DRM, streaming protocols like HLS and DASH, or ad-insertion.
PERSEUS 2 is a more efficient codec than its predecessor and one of the results is even better picture quality within crucial bandwidth thresholds that make or break the business model for new services. It enables better mobile video at 100 kbps to enable comprehensive reach, including across 2G networks, and it now supports better quality at 1Mbps for monetizable full HD video on mobile. There are picture enhancements at 2Mbps for HD on DSL and at 10Mbps, a threshold that opens the door to multichannel UHD sports on satellite and cable.
According to Fabio Murra, SVP Marketing at V-Nova, (the company behind PERSEUS), the new generation provides a step-change in performance. “We have done a lot of work to improve computational efficiency.” This results in much greater density. More density equates to lower CapEx or OpEx, whether video processing is on-premise or in the cloud.
Thanks to improved codec efficiency and a lighter decode footprint, PERSEUS can also be used with a wider range of chipsets and browsers. Decoding is now supported in the HTML5 environment. Set-top box chips as old as nine years can process the codec. V-Nova is already supported on both Broadcom and ST SoCs. Murra says: “We want to be compatible with devices doing back as far as possible. We cannot wait for handset and television replacement cycles and we have to get the best that is possible from the device ecosystem.”
A key focus for PERSEUS 2 was simplified service delivery and there is growing ecosystem support generally. Amazon Web Services and Microsoft Azure are two options for cloud encoding and transcoding.
Where a media company has control of both the headend and the endpoints, like for contribution, native PERSEUS compression is a simple option. Eutelsat has been using PERSEUS in this form for video contribution. When PERSEUS is used on top of a different base layer compression scheme, the base layer is expected to deliver one-quarter of the total resolution. So an AVC set-top box (or other device) without PERSEUS software onboard could see SD video but would get HD if PERSEUS is supported. UHD could be delivered to a PERSEUS-capable device with an HD stream ‘inside’ for an AVC-only decode.
Sky Italia uses AVC as the base layer and PERSEUS as the enhancement layer to deliver its HD channels over DSL to Telecom Italia homes. FastFilmz, the Indian mobile TV provider, uses the same codec combination for mobile resolutions. Thaicom is currently trialling direct-to-home satellite delivery of UHD with an AVC base encode and PERSEUS as the enhancement layer. There is also now an option to use HEVC as the base layer (with PERSEUS as the enhancement) for operators investing in HEVC-capable set-top boxes.
V-Nova provided a pre-NAB demonstration last week where UHD video at 25 frames per second was compressed in 4Mbps using HEVC as the base and PERSEUS for the enhancement layer. The video was shown on a widescreen TV along with a 6Mbps stream using the same compression combination.
Murra says the market has not been asking for a fixed percentage improvement in bandwidth savings. The key is achieving service thresholds like 6-7 UHD channels into one transponder. Thaicom needs UHD at 10-12 Mbps in order to make the case for direct-to-home services. Sky Italia wanted HD in 4Mbps to ensure reliable delivery to non-fibre homes. The other driver is to achieve better picture quality targets within all thresholds.
V-Nova says its PERSEUS 2 launch is a response to feedback from customers and the wider market and delivers exactly what they have been asking for. Murra is proud of releasing a much improved version two years after the original codec launch. He says this velocity is a testament to the power of software.
There are a few key technology changes that underpin the greater encoding and transcoding efficiencies and subsequent quality and cost improvements. While PERSEUS has always added detail when used as the enhancement layer, PERSEUS 2 includes some temporal correlation between the different frames. “Before we said, ‘Here is some data, please compress it’. Now we can squeeze it more intelligently,” says Murra. The company detects parts of the picture that need to be compressed in different ways – the first time it has treated one part of the video frame differently to another.
Although PERSEUS 2 can be used with HEVC, it is clear that Murra views the use of AVC with PERSEUS 2 as an alternative to an early migration to HEVC. He points to a slow take-up for HEVC compression in broadcast markets, and a lack of appetite for upgrading STBs to this codec for the sake of HD services.
Like its predecessor, PERSEUS 2 is fundamentally a software-based solution and this includes the decoding. Murra says the decode software makes low demands on device chipsets. You can read more about progress for this technology here.
