DVB-I embraces multicast ABR, LL-DASH for tuner-less delivery

An early flurry of pre-IBC announcements have been teased in the last couple of weeks, none odder than the DVB saying it will demonstrate a new open approach for delivering OTT video. Leaning heavily on multicast ABR, the broadcasting standards body has released its DVB-I specifications supporting low latency video with enhanced service discovery. In a busy week for DVB, the group also announced that TV receivers can now adapt an HDR video signal to the characteristics of the display.

Our immediate bone to pick with the organization was whether DVB-I is being positioned as an eventual successor to HbbTV services, which on first glance appears to be the agenda here. It was imperative then to get this clarified and Peter Siebert, Head of Technology at DVB, was on hand to explain that DVB-I is definitely not designed to be a successor or replacement to HbbTV in any way. HbbTV is of course built on elements of DVB standards along with technologies from the Open IPTV Forum, CEA and W3C.

“We take care of the transport and distribution while HbbTV is more about specifying software APIs. We work closely with HbbTV and I apologize if this is the impression the announcement gave off,” said Siebert, a little miffed at our assertations about HbbTV’s shortcomings.

A game of spot the difference between DVB-I and HbbTV naturally reveals significant similarities in terms of features being enabled, but DVB-I stands out as being better suited for OTT delivery with developments in multicast ABR and also Low Latency DASH (LL-DASH) – an extension of the existing DVB-DASH specification.

We spotted one key differentiator however which is that DVB-I is designed to bring services to devices without DVB tuners, while HbbTV services are delivered to set tops and connected TV sets with DVB tuners. Although, this might not be 100% true as we have heard about HbbTV Association looking into use cases delivering services without broadcast channels.

Much like its US (and South Korean) counterpart ATSC 3.0, DVB-I enables broadcasters and service providers to roll out advanced features in hybrid and broadband TV services such as integrated channel lists, interactive content guides, on-demand libraries, so called “lean-back” channel selection, UHD resolution, and – crucially – targeting. In short, DVB-I aims to bring all the features of IP video, without the drawbacks.

DVB-I will take in LL-DASH alongside multicast ABR, both of which will be showcased in Amsterdam in two months’ time. LL-DASH reduces the delay of live OTT channels down to that of broadcast channels, with DVB-I claiming ease of use similar to legacy broadcast equipment. Siebert explained that for live OTT content, LL-DASH can reduce delay from as much as 40 seconds to just 3 or 4 seconds.

DVB-DASH is already deployed by many broadcasters, often in conjunction with HbbTV, making the prospect of a low latency version to better support linear TV services a promising opportunity for broadcasters, who through the forthcoming DVB specs around multicast ABR can collaborate with network operators regarding the optimization of delivery to a large number of receivers simultaneously. We tried to extract some case study examples from Siebert but he wasn’t budging, mentioning only that 2 clients have come to DVB regarding multicast ABR and citing Broadpeak as a key partner with its proprietary technology.

A major missing piece from a standards perspective, according to DVB, is the service layer, which forms the foundations for a channel list or EPG on a smartphone, tablet, PC or TV set. The issue with the internet is that you cannot simply perform a channel scan like a traditional receiver when connected to a terrestrial or satellite antenna, as it would surface thousands of services. DVB is therefore looking into technology to allow the receiver to locate services relevant to the user, based on location as well as language and genres. But rather than leaving it to the market to solve, it urges government authorities to compile and provide a service list and for receivers to be pre-provisioned with the URLs of these lists. However, involving central authorities has the potential to disrupt the project’s open nature.

“This will probably involve the most significant technical choices for the DVB in writing the DVB-I specifications. Several existing technologies are candidates to be adopted and, if necessary, extended to fulfil the requirements,” reads a DVB statement.

Naturally, DVB-I will sit alongside existing DVB-T, DVB-S and DVB-C broadcast standards (terrestrial, satellite and cable, respectively), with DVB-I deployments available as standalone or as a hybrid broadcast-IP model.

The imminent arrival of DVB-I may have been triggered by the European Union’s reallocation of the upper high-quality 700 MHz band (694 MHz to 790 MHz) from digital terrestrial to cellular that must be completed by 2022 at the latest. Originally the EBU lobbied hard to defend DTT spectrum from mobile invasion but has more recently been focusing on influencing the development of 5G in favor of broadcasting, through a variety of projects. It is noted, however, that integrating DVB-I with 5G is a possibility down the road.

“Currently 5G has no video service layer. DVB-I has a very nice complementary interface to signal video services to end users which can provide this missing mechanism. We will produce further specifications in November this year and then we will reach out to the 3GPP,” Siebert said in conversation with Faultline Online Reporter.

DVB hasn’t yet placed a specific timeframe on when the specifications will be finalized and what state DVB-I will be in once IBC rolls around, stating only that it expects to publish a first specification in the course of 2019. “The DVB-I suite of specifications is quickly taking shape and will soon be ready for deployment,” said Peter MacAvock, chairman of DVB. The commercial requirements for DVB-I were approved in August 2018 by the DVB Steering Board.

As mentioned briefly in our opening gambit, DVB also added HDR dynamic mapping this week to its audiovisual coding specifications. The revision essentially allows content creators and device makers to adapt video content to replicate the intended appearance on a screen – for use in satellite, cable, terrestrial and broadband video delivery.

DVB’s audiovisual coding specification includes two means of providing HDR video content, namely Hybrid Log Gamma (HLG10) and the 10-bit variant of Perceptual Quantizer (PQ-10). Dynamic Mapping applies only to the latter.

“There is significant potential benefit in being able to “map” the HDR, as graded using a reference monitor, to the lower-performance TV sets typical of the consumer environment. Dynamic Mapping facilitates this functionality by way of Dynamic Mapping Information (DMI) inserted into the HDR video bitstream,” noted the DVB announcement.