Overview

The ATSC 2.0 standard fully comprehends the availability of Internet connectivity in the future viewing environment. Whether via connected TVs or hand-held devices connected to the home WiFi system, the availability of Internet access is a key feature of many of the services defined by the standard. Fundamentally, this is a departure from past attempts to extend broadcast television standards since it does not assume a single delivery path for content. Thus, a hybrid delivery system is described with the best features of broadcast combined with the point-to-point nature of the Internet in whatever path it is made available.

Key Features

Key features of the ATSC 2.0 include
  • mechanisms for carrying other types of encoded video and audio such as H.264 and HE AAC within the broadcast dramatically improving compression and, thus, the amount of content that can be carried,
  • triggers which can signal events to receivers through the broadcast or ACR, 
  • interactive services including second screen APIs, and
  • object transmission including URL references and other non-real-time (NRT) data objects.
ATSC 2.0 is actually made up of a number of standards including the Interactive Services Standard (ATSC A/105) and Non-Real Time transmission standard (ATSC A/103).

To both hasten the acceptance of the new standard(s) and to verify that the services defined are viable, the ATSC has created an ATSC 2.0 Implementation Team comprised of CE representatives, broadcasters and industry equipment vendors. This team is currently operating prior to the standard's completion so that viable working implementations of the standard may be identified and promulgated when the standard is ratified.

Open MediaHub

To begin validating the ATSC 2.0 features and functions quickly, the implementation team has adopted a conceptual device known as the Open MediaHub. The Open MediaHub architecture combines the strengths of broadcast delivery with standard Internet delivery technologies. The intent of the MediaHub is to provide a central, transparent mechanism for supplying high-quality broadcast content to any device connected to the home network. A key component of the Open MediaHub is a content caching mechanism. The Open MediaHub can perform other ATSC 2.0 receiver functions that are advantageous in a central network location. Primary among these is extracting and forwarding trigger information.

Open MediaHub Design

The MediaHub design, refer to the diagram below, contains a terrestrial broadcast receiver (Data Receiver) and an Internet connection (WAN). Central to the design is the Transparent Proxy that manages how content access requests from the Local Area Network (LAN) are fulfilled. A typical transparent proxy caches data received from requests in a local network storage cache so that subsequent access would not require fetching the same content from the Internet again. Many of these transparent caching systems can access other Internet caches through an Internet Cache Protocol (ICP). In the case of the MediaHub, an additional Cache Manager is defined that manages information received from the broadcast path. If a local device requests content from the Internet that is present in the Broadcast Cache, then the system will automatically return that content instead of content from the either the Network Cache or the Internet itself. In this way, broadcasters can “pre-position” various content, such as local news video, in the broadcast cache assuring that when a user attempts to access that content on the Internet they will receive the pre-positioned content instead.


The broadcast cache content is pre-positioned by transmitting it over the broadcast channel using the standard ATSC NRT datacasting mechanisms. Once in the cache, the content can be delivered to other devices in the home via other content transmission standards such as DLNA (UPnP), Control metadata transmitted with the content determines what standards are appropriate and which URLs should be intercepted by the proxy. This metadata originates from the broadcast side where it is collected from the various ingest mechanisms, formatted and transmitted within the NRT data stream.

The Open MediaHub modules can operate on any type of hardware and can be distributed throughout the home network. A reference implementation comprised of a wireless router with attached storage, an integrated ATSC receiver device allowing off-air reception, and Open MediaHub software is being constructed as part of the ATSC 2.0 Implementation Team activities. Implementing the Open MediaHub modules on a wireless router places the functions in the optimal position within the home network. Typically, most wireless routers are connected directly to the cable modem or other ISP gateway. Every device in the home—whether wired or wireless—uses the router to gain access to other devices within the home and the Internet. Every access can be processed and perhaps redirected to one of the local caches. Any other media protocols, such as DLNA (UPnP), are also accessible from any device on the network with limited configuration.

Note, however, that there is no restriction on where these functions reside within a home network. Indeed, it might be beneficial to have multiple ICP-enabled caches in broadcast reception equipment including smart TVs with disks to allow the central proxy system to access multiple sources of media content. One can envision smart TVs enabling ICP as well as DLNA (UPnP) allowing any device conversant in these protocols to access the content based on rights supplied by the broadcaster.

Open MediaHub Advantages

By pre-positioning content on the MediaHub, broadcasters can avoid data charges from CDNs and bandwidth changes from their ISP. Any content accessed from the broadcasters' web pages can be pre-positioned with higher quality at lower cost than can be delivered via the Web. Broadcasters could also pre-position content from other providers for a fee. Unlike an Internet acceleration service, broadcasters decide what content will be placed on the MediaHub and can optimize that content to match specific business imperatives.

The impact of the Quality of Experience (QoE) realized by consumers with pre-positioned content should not be underestimated. Typical QoE metrics are derived from a combination of content delays including initial time to view and buffering delays as well as the typical video quality metrics such as resolution and transmission-induced artifacts. A recent study showed that many consumers abandoned viewing content when startup delays exceeded more than five seconds for short form content. And roughly half the time they would abandon viewing content if they perceived issues with delivery. In an environment with so many choices, broadcasters can ill afford to lose viewers based on delivery issues. By caching content directly into the home environment on the MediaHub, broadcasters can avoid many of the issues associated with delivering content over the open Internet thus improving the QoE and retaining viewers.

Also note that with an extended MediaHub implementation, DVR-like functionality can be added to the device, caching content received directly from the linear broadcast instead of using additional bandwidth for NRT. This content can then be made available to home devices through either a Web or DLNA interface—just like the content broadcast on the data channel. In fact, if segmented correctly, the broadcaster could supply alternative content for various segments. This could be used to replace advertisements or to create targeted advertisement. Access to this content via Web accesses or DLNA would appear linear but would be seamlessly selecting from a variety of disparate segments.
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