The HbbTV standard is developed by the HbbTV association. It is a global initiative with the aim to harmonize the broadcast and broadband delivery of entertainment to the end consumer through Smart TVs and other set-top boxes [28]. The broadcasters are responsible for the content. HbbTV is vendor-independent and supported by most Smart TVs.
This chapter serves as an introduction to HbbTV and is not necessary to understand the contribution of this work. We introduce the HbbTV 1.5, 2.0 and 2.0.1 standard in Section 2.1. In Section 2.2, we present the HbbTV appearance for consumers and show the typical lifecycle of an HbbTV application.
2.1 HbbTV Standard
The European Telecommunications Standards Institute (ETSI) approved the HbbTV 1.5 standard in No-vember 2012 [29]. The standard specifies the technical framework for HbbTV applications and how the HbbTV components should be implemented in Smart TVs and set-top boxes. The technical requirement for presenting and executing HbbTV applications on a Smart TV is a customized web browser (HbbTV browser) which supports HTML, CSS and JavaScript. The HbbTV browser presents its content as an overlay over the regular TV program. It remains invisible for consumers until a trigger (e.g. an URL) is received by the HbbTV browser through the DVB1 stream. A customized JavaScript interpreter in the Smart TV can perform action on the Smart TV itself, e.g. changing the visibility of the HbbTV browser.
If the content that is available under the URL includes such a JavaScript command to show the HTML content, the Smart TV will overlay the regular TV program. Two different methods of delivering the HbbTV data to the HbbTV browser are available:
1. Entire HbbTV application through DVB. Any HbbTV content is delivered over the DVB stream and no Internet access is required.
2. URL in the DVB stream to an HbbTV application. An URL to an Internet resource is provided and the HbbTV browser automatically loads the HbbTV content from the Internet. It is required that the Smart TV is connected to the Internet.
The selection of either of one of the above mentioned delivery methods limits the level of interactivity the HbbTV application can provide, i.e., HbbTV applications delivered entirely by DVB cannot be personali-zed individually for each Smart TV, since the same DVB stream is broadcast to all devices. Combinations of both methods are feasible. As soon as the HbbTV notification, which indicates that a HbbTV applicati-on is ready to be used, is shown, the capplicati-onsumer can interact with the HbbTV applicatiapplicati-on by pressing the Red Button on the TV remote control (see Figure 2.1).
The HbbTV 2.0 standard was approved in October 2015 by ETSI [22] and includes some new features and a chapter about consumers’ privacy. It now includes tracking preference expression (DNT)2, mana-ging third party cookies, blocking tracking websites, manamana-ging persistent storage (cookies, web storage) and a short section of ”Respecting Privacy in Applications”. The “Do Not Track” specification explains which technical implementation the Smart TV should provide in order to enable HbbTV applications to
1 Digital Video Broadcast - The DVB project is an Alliance of many companies worldwide. It defines specifications for digital media delivery [30]. In this context, a DVB stream is a data stream that transports radio or TV signals via satellite (DVB-S), cable (DVB-C) or terrestrial (DVB-T) to the end devices.
2 https://www.w3.org/TR/2014/WD-tracking-dnt-20140424/
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Figure 2.1.: Red button on Samsung’s remote control.
respect consumers’ preferences. Smart TVs may block all third party cookies or if possible give the consu-mer an option to enable or disable them. The Smart TV vendor is responsible for the blocking mechanism of tracking services. The section about respecting privacy in applications state that three options exists for protecting consumer’s privacy: (1) delivering application via DVB, (2) using TLS to encrypt exchan-ged data and (3) use of cookies to record consumer’s consent. They also mention that tracking before the consumer uses the HbbTV functionality may be illegal.
Further, the standard includes support for synchronization of content between different screens. In particular, it adds support for communication between other devices like smart phones or tablets. HbbTV applications can ask for an application to be launched on a mobile device and vice versa. The synchroni-zation of different devices is specified. Support for delivering files containing audio and video content to connected storages for later consumption has been added. First devices with HbbTV 2.0 support should be available since 2016.
The newest not yet ETSI approved HbbTV standard is version 2.0.1 [31] with an additional section in the privacy chapter about the unique device ID that can identify a device. The unique device ID should be provided by default. But, consumers should be able to disable it and if necessary generate a new one.
Some minor errors in HbbTV 2.0 were corrected.
2.2 HbbTV for the Consumer
The HbbTV applications differ from channel to channel. For one broadcaster it is only a replacement for teletext, for another it is a portal to deliver a variety of additional services such as media libraries or the possibility to watch previous content. The broadcasters are in all cases responsible for the content they provide via HbbTV.
Figure 2.2 outlines the typical lifecycle of an HbbTV application that is presented to consumers. First, the regular TV program is provided via DVB (1). After a short period of time the HbbTV notification is shown on the Smart TV screen (2). The HbbTV notification (called prompt in the specification) notifies the consumer that an HbbTV application is ready to be started by the consumer. Usually, it can be started by pressing the Red Button on the remote control of the Smart TV. If the Red Button is pressed, the HbbTV application can start in full screen mode (3). That is one possible way to start an HbbTV application.
Different other possibilities are mentioned in the HbbTV specification:
• A digital teletext application can be started by pressing the TEXT button on the remote control.
• A broadcast-independent application can be started through the TV platform.
DVB
Internet Wi-Fi
SmartTV
PC
DVB Program HbbTV Application
1 2 3
Wi-Fi Hotspot
HbbTV Notification
Figure 2.2.: Lifecycle of an HbbTV application presented to the consumer.
• Another device starts an HbbTV application (called companion screen in the HbbTV specification).
• Another running application links to an HbbTV application.
• Autostart applications start in full-screen mode.
The HbbTV notifications can differ depending on the channel. Examples are depicted in Figure 2.3.
Figure 2.3.: Examples of HbbTV notifications from 2016.
We focus in this work on those HbbTV applications that are broadcast-dependent and either be starting automatically or started by pressing the Red Button.
2.2. HbbTV for the Consumer 9