ATSC 3.0 is the next-generation broadcast television suite of around 20 standards including transmission, audio, video, captioning, metadata, watermarking, companion devices, security, and personal- ization.
Among others, ATSC 3.0 uses MPEG DASH delivery format for broadcast and broadband delivery of media and data. In order to fulfil the use cases and requirements of ATSC 3.0 including broad- cast-only, broadband and hybrid (broadcast/ broadband) delivery, as well as a multitude of new features, DASH-IF developed a DASH in- teroperability profile specifically designed for ATSC 3.0 standard.
This profile supports broadcast and broadband delivery, codec sig- nalling (audio, video, subtitle), interactivity & events, metadata, targeted & personalized ad insertion, and advanced security & content protection schemes.
By the choice of DASH formats and HTML-5 based applications, ATSC 3.0 services are expected to be consuma- ble not only on vertically integrated devices such as TV sets, but also on other types of devices such as PCs, tablets, game consoles and mobile phones.
This paper will introduce the rationales, benefits and opportunities of such an approach and provide an overview of the ATSC 3.0 DASH profile.
ATSC 3.0 revolutionizes TV broadcast distribution. For the first time, a hybrid system is designed from day 1 in order to support broadcast and broadband distribution in an inte- grated manner and to target different receiver platforms.
In order to leverage the advances in standardized OTT video distribution, ATSC has decided in ATSC A/331 Candidate Standard (1) to distribute the TV content with DASH-based media formats, for both broad- cast and broadband distribution.
In an ongoing collaborative effort, ATSC and DASH In- dustry Forum (DASH-IF) are developing a DASH profile for ATSC 3.0 use cases, addressing the convergence between broadcast and OTT content distribution. In addition, as DASH naturally interfaces with HTML-5 browsers, ATSC 3.0 convergence with the web world is also inherently achieved.
In the remainder of this paper, the ATSC 3.0’s architec- ture around DASH as well as the technical enablers are introduced.
ATSC 3.0 ARCHITECTURE AND PROTOCOL STACK
ATSC 3.0 not only supports broadcast services, but also integrates the ability to distribute parts of the service over unicast, primarily over an HTTP CDN.
Figure 1 provides a high- level architecture that shows that both delivery paths, broadcast and broadband, terminate in a single DASH player. This is achieved by abstracting the broadcast transport to an object oriented protocol.
According to the ATSC Delivery Specification A/331 (1), the protocol stack, as presented in Figure 2 defines the major components of the ATSC delivery system. In particular, DASH formats play a central role as the encapsulation and delivery format, in the context of ATSC3.0 for broadcast, broadband and hybrid delivery.
In case of broadcast delivery, the interface between the underlying delivery system and the DASH Player is conceptually based on an HTTP proxy that is included in the receiver.
In addition to the interfaces to the transport system, the DASH Player also provides the functionality to playout media properly and to interface with native or downloadable appli- cations, typically in a browser-centric environment.
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