Although Internet-TV functionality as a Web service has been implemented in various TVs by several manufacturers — often under the moniker of “Smart TV” — there has not been a unified protocol for handling the TV-receiver integration of Internet-provided content and broadcast content, nor has there been a way to provide uniform features across TV manufacturers. But various initiatives are starting to define a common set of protocols that broadcasters and consumer electronics manufacturers can use to provide consistent user experiences across devices, programs and channels. These include IPTV, NRT, DASH, HbbTV and that of the Smart TV Alliance.
Internet TV is a catch-all phrase that typically describes a service that provides content — audio/video, apps, media streaming, Web browsing and games — to PCs and television sets, either by means of built-in functionality, or through a set-top box or game console connected to a TV. Internet TV can take the form of a dedicated service, like Internet Protocol TV (IPTV), which provides constant multichannel video programming distribution to users over a permanent connection, or a shared Web service, such as over an Internet connection provided by an ISP.
IP formats live video into a packetized delivery medium. When streaming video to an Internet terminal (i.e., sending a continuous “live” feed, meant to be presented in real time to a display) IP is used, which provides a method for encapsulating data into packets called datagrams and sending them to a unique terminal over a shared network. Because IP is a connectionless protocol (i.e., the transmitter does not wait for the receiver to be available), some packets may be lost in the transmission. This requires a mechanism to ensure reliability and circumvent lost or out-of-sequence packets. For this reason, IPTV that provides VOD services uses Real-time Transport Protocol (RTP), which provides jitter compensation and detection of out-of-sequence datagrams, and Real-time Streaming Protocol (RTSP), which uses DVR-like commands (e.g., play, pause, etc.) to control the stream.
Non-real-time content
NRT content is an ATSC component that can, in the near future, integrate live TV with file-based content via broadcast and Internet. The standard provides for triggers that can be used to control the presentation, behavior and synchronization between the live and stored content.
MPEG-DASH (Dynamic Adaptive Streaming over HTTP) uses adaptive-bit-rate (ABR) streaming that can accommodate channels with varying bandwidth and/or reliability. To solve the quality-of-service issue, ABR allows each device to determine the quality of its connection, and use different levels of compression as different “program chunks” that can be selected dynamically during the stream transmission. DASH as a technology is related to various proprietary schemes used by different software providers. (For more on NRT and MPEG-DASH, see the May 2013 “Transition to Digital.”)
Figure 1. HbbTV architecture provides a link between OTA and Internet content.
The Hybrid Broadcast Broadband TV specification (HbbTV) provides a way to integrate live and broadband content and apps, as shown in Figure 1. HbbTV provides a framework for the download and execution of applications on an Internet TV. Formally standardized as ETSI TS 102 796, the specification defines a Web-based terminal (Internet-TV receiver) that receives applications in the form of documents (written in HTML, JavaScript, CSS and XML) and multimedia files that together make up a complete interactive service package.
The HbbTV system architecture comprises a browser, application signaling and transport via broadcast and broadband, and synchronization of applications and broadcast services.
The HbbTV specification addresses two types of applications: broadcast-related and broadcast-independent.
A broadcast-related application is an app associated with one or more broadcast services (or events therein) that may be launched automatically or explicitly upon user request. This type of application may be downloaded via broadband or broadcast and may access its data via either method.
A broadcast-independent application, which is not associated with any broadcast service, is downloaded out-of-band (e.g., via a broadband Internet connection), and accesses all of its associated data via broadband. Over the broadband connection, HbbTV supports carriage of both live and on-demand content, and provides a means for the exchange of information between applications and application servers. HbbTV-compliant applications are presented by an HTML/JavaScript browser.
The HbbTV platform has a number of characteristics that make it attractive to both broadcasters and CE manufacturers. The specification is open and is not based on a single controlling authority or aggregator, and it makes services and content from many different and independent providers accessible by the same terminal. Applications or services provided by a device manufacturer are not specified by HbbTV, nor are video, audio and system formats for the broadcast channel, and applications can run on different types of terminals such as TVs, set-top boxes and DVRs.
HbbTV also provides a measure of security, so that applications will not have deleterious effects on the TV hardware or software. Although standard functions of the TV are available to all applications, sensitive functions like firmware upgrade or access to user information are available only to trusted applications. Services and content may be protected, too, providing a path to numerous business models. Although HbbTV was developed in Europe with DVB services in mind, its structure and signaling elements could be applied to other systems, such as ATSC. Such harmonization is currently under discussion for a future standard.
Smart TV Alliance
The Smart TV Alliance is driving common functionality from the CE side. Last year, LG and Philips (now TP Vision) agreed to work together to define common technical requirements for their Smart TVs, based on open standards such as HTML5, CE-HTML and HbbTV. Officially branded as the “Smart TV Alliance,” the group’s objective is to help define technical specifications that will enable application developers to create their applications once (with reduced application development time and costs) and run them on multiple TVs, regardless of the platform. The alliance now includes Toshiba, Panasonic and several other technology companies.
The Smart TV Alliance has made its software development kit (SDK) widely available for developers to download at no cost and use to develop their applications. The SDK is based on open Web technologies such as HTML5 and allows for Web applications to run on certified Smart TVs from participating members regardless of the underlying platform.
The alliance built on this first version and announced specifications of SDK 2.0, followed by the actual SDK 2.0 software release. With SDK 2.0, developers should be able to create applications for 2013 TV sets from participating alliance members. Typical applications are expected to provide a “lean-back experience,” meant to be viewed at a 10ft distance, with low involvement (“passive-entertainment-centric”) and operable using common remote control navigation keys (up/down, etc).
A new SDK supports richer applications, including 3-D video, using upgraded HTML5, CSS3 and JavaScript specifications. MPEG-DASH is supported, providing more reliable audio and video quality with less stuttering and freezing, and there can be more and better content choices with updated digital rights management (DRM) features that support the diverse DRM requirements from content owners.
For application developers, the newest SDK provides advanced debug tools and a common emulator that allows developers to solve application problems and test an application once to ensure it will work with all Smart TV Alliance member televisions. An application compliance-checking tool is also provided, which enables developers to test compliance automatically with cross-platform requirements.
Of course, with various solutions vying for space in TV products, Internet TV still has a way to go to become truly universal. Interested parties are encouraged to participate in the Future of Broadcast Television (FOBTV) initiative that is hoping to pave the way to a global convergence of broadcast technologies.
—Aldo Cugnini is a consultant in the digital television industry.
