Audio description and automatic user identification: a promising marriage in Digital Terrestrial Television (DTT)

Transcription

1 Audio description and automatic user identification: a promising marriage in Digital Terrestrial Television (DTT) Rita Oliveira,Telmo Silva, Jorge Ferraz de Abreu, Ana Margarida Almeida, Osvaldo Pacheco University of Aveiro Aveiro, Portugal Curriculum Vitae Rita Oliveira Activity: FCT ( Fundação para a Ciência e a Tecnologia ) PhD Researcher PhD Student in ICPD ( Informação e Comunicação em Plataformas Digitais ) Doctoral Program Research interests: - Web 2.0 Accessibility; - Design and development of web-based assistive tools for visually impaired users; - Universal Design applied to Digital Terrestrial Television; - Design and development of assistive interactive television services for visually impaired users. Telmo Silva Activity: Assistant Professor at Department of Communication and Arts in University of Aveiro PhD Student in ICPD ( Informação e Comunicação em Plataformas Digitais ) Doctoral Program Research interests: - Design and development of Interactive TV services, mostly based on IPTV platforms; - Computer networks; - Design and development of applications to mobile devices; - Web applications based on Content Management Systems. 1 ABSTRACT (n.b.: En el idioma original de la Comunicación, Español, Inglés, Portugués o Francés, 250 palabras máximo) The DTT (Digital Terrestrial Television) switchover will enable the development of a television infrastructure with more resources and technological capabilities. In fact, DTT can encompass a variety of features and services where users can take on an interactive and participatory role. Nevertheless, the interactive services reveal interaction problems for visually impaired users (VIU). For this reason, it is important to apply accessibility, usability and design-oriented principles to the development of accessible interactive television systems. The present paper introduces a research project related to universal design issues on the Interactive Television scope, having as main objective the development of an audio description service offered by DTT that comprises an automatic identification system and an easy and simple interaction. Therefore, it will be prototyped an interactive and enhanced audio description system that includes new features and functionalities, is based on universal design principles and is supported by a users' identification system that is sustained through RFID tags and readers.

2 KEY WORDS Audio Description, User identification, Universal Design, DTT, Interactive TV Grupo temático 1: Televisión 3.0, nuevos modelos de negocio en la red. 1. Introduction The interactive services currently supported by digital TV providers enclose a high visual component, bringing added interaction difficulties for visually impaired users (VIU). In this framework, Digital Terrestrial Television (DTT) can play an important role. The emergence of DTT switchover will contribute for an increasing number of digital TV providers benefiting of a more promising infrastructure that extends beyond TV transmission improvements. Despite higher noise immunity, a better image quality and spectral efficiency, the expected incremental access to the Internet made available on DTT Set-Top Boxes 1 (STB) can provide a promising framework for the implementation of interactive TV services. As currently happens with analogue transmission and according to the Portuguese Television Law, DTT should also ensure the delivery of a part of television programming along with communication aids (e.g.: audio description). It is in this particular scenario that an interactive application developed to a DTT STB (with internet connection) can support these type of aids in a more interactive and personalised way, e.g. with pitch control, volume, language, narrator s voice, etc. However, a true service personalisation relies not on the identification of STB users but on the user itself, since commonly the same STB is used by multiple viewers with different profiles. It is worth to mention that the benefits of an automatic and non intrusive user identification system extends beyond the support to an enhanced audio description service, since the TV provider can offer other valuable interactive and personalised services if he knows who actually is in front of the screen. In this context and based on the universal design principles, this work aims to conceptualise an interactive and personalised enhanced audio description system to DTT. Starting from an identification of the VIU s needs as consumers of TV content, the research aims to determine the user identification techniques more promised for an enhanced audio description service and also propose new features to build an audio description service based on a set of universal design principles Considering these objectives at the end of this research, we expect to contribute to the VIU interaction support in DTT context, developing an interactive audio description service based on user automatic identification, which allows users access in an easy and intelligible way Digital Terrestrial Television (DTT) 1 An external device that is connected to the TV set and in conjunction with it allows the decoding of digital television signal, to ensure that its content (TV programming, interactive services, etc.) can be viewed by the enduser.

3 2.1. Definition Libro Nuevos Medios, Nueva Comunicación The analogue television is the oldest TV broadcasting type and for this reason all TV sets are ready to receive this signal without any additional device or technology. During decades the analogue television was the only way to view TV. In Portugal, even with the introduction of cable and satellite television, the analogue is the main television access system (Cardoso, 2008). However, analogue television has two major problems: i) one is the lack of bandwidth and consequently the capability to use channels in a profitable way; ii) the other is related to the image quality, because it is very dependent on the conditions of signal reception. In contrast, DTT deals with these problems in an effective way by performing its specific signal modulation (Lundström 2006). The DTT transmission is performed via hertzian waves, using part of radio frequency spectrum, which is currently occupied by the analogue television transmission. Therefore, the TV contents are digitalised, encoded and spread over the air by broadcast stations, and then are received by the antennas placed in each building (Figure1). Finally, the TV signal is again converted by a TV integrated digital decoder or when it does not exist, via digital STB (PT, 2009). 3 Figure 1 DTT Broadcasting System (PT, 2009) The European Commission established that all European Union countries should gradually introduce DTT with the objective of reducing radio spectrum usage and also achieving lower operating costs in television broadcasting. All member countries necessarily have to make the analogue transmission switch-off until The DVB-T Standard The DVB-T standard 2 (Digital Video Broadcasting for the Terrestrial Television Transmissions) was developed by the European DVB Project and supports the broadcasting performed by DTT. The DVB-T uses advanced MPEG-2 compression and also OFDM modulation (orthogonal frequency-division multiplexing), which enable the digital processing of analogue signal. The main feature of this standard is the high-quality signal replication, even under adverse conditions. Following are identified some advantages of DVB-T compared to analogue transmission (ANACOM, 2002): Higher quality image and sound: a reception with no ghosts. 2

4 Flexibility: it allows simultaneous transmission of multiple services and programmes (while conventional system can only use one programme per channel in each geographic area). Portable reception: provides coverage for mobile and portable TV reception with high quality standards. Additionally, the DVB-T system is based on a global solution based on a common core of standard specifications (MPEG-2), providing a complete framework for digital television broadcasting and data. Due to the DVB-T features, DTT implies a more advanced technology comparatively with analogue television and provides users a set of advantages, such as audio and video reception without noise and offers up to forty channels (about five to eight times more than analogue television). Besides these advantages, DTT also enables the television experience enhancement. Below are described some of them: The possibility of television transmission to be carry out in HD (High- Definition), which provides a higher resolution than conventional systems; The use of functionalities and advanced services such as Electronic Programme Guides (EPG) and Personal Video Recorder (PVR); The sound quality is much better than analogue television; due to signal digitalisation it is possible to make use of Dolby Digital Sound, which allows storing audio on multiple independent channels. In this context, the DVB-T standard offers a great flexibility for the deliver of new types of services then it is a great way to add audio description on the DTT transmission system Audio Description on Television 3.1. Definition Generally, the audio description on TV is based on an audio track that is added to the television broadcast and verbally describes what happens on the screen (Godinho, 2007). The main objective of this assistive communication media is to support blind and partially sighted users in television programmes viewing. In audio description scenes and images on the screen are described by a narrator alternately with the characters statements, allowing the entire understanding of audiovisual narrative. The audio description is made between the statements and in sync with other narrative information: facial expressions, clothing, and environment. Thus, this technical support does not overlap to sound content, but operates with it in order to provide a better understanding of a scene (Figure 2).

5 Figure 2 Illustration of the audio description of Elmo s World (ADA, 2008) In this context, the audio description production follows several specific sequential steps (Audiodescrição.com, n.d.): Learning and Script: An expert audio descriptor studies the piece to be described and produces a script with the text to be narrated, which follows specific rules. Tests and adjustments: After the script ready, audio descriptor should test the descriptions positions in the previously chosen locations. In addition, are also made time adjustments and/or vocabulary exchange. Recording: At this stage, audio descriptor comes into a studio with the recording director and a technician to perform the recording of the script descriptions. Sync: The recorded audio file is edited and associated to the original soundtrack of the movie or programme in a new audio file, or in a specific audio channel Interactive Services ZON Multimédia On December 3, 2004, it was launched the audio description service of ZON (formerly TV Cabo), in partnership with Lusomundo movie channels (now TVCine) (Quico, 2005). This release date was chosen in order to celebrate the International Day of People with Disabilities. The first movie that used audio description was the Portuguese classic movie O Pátio das Cantigas. The ZON audio description was the first service (and so far the only) oriented for people with special needs broadcasted by a Portuguese digital TV provider. The process of this service consists in an additional description to the audiovisual narrative soundtrack. To access it, ZON customers should press the green button of STB remote control and press OK in Áudio descrição option (ZON, 2010). In order to return to the TV programme without audio description, the user must select Sem áudio descrição option present on the screen and press OK Sky

6 The British satellite broadcasting company Sky has recently increased the amount of programmes with audio description to 20% on their channels, with the exception of Sky Sports and Sky News which is not required to provide audio description due the amount of spoken words used in news reading (Sky, 2009a). Sky customers can access the listings of all relevant audio described programmes for the next seven days at its website or alternatively they can directly contact Sky via post or to require the listings. Another way to know which programmes are audio described in Sky is through an Audio Narrative Beep feature, which allows visually impaired customers to identify when an audio description track is present on the TV programme (Sky, 2009b). Sky customers can set up audio description permanently or temporarily, the steps they have to follow to do this are described bellow (Sky, 2009b). To set up audio description permanently in a Sky Digibox and Sky+ box, users should: Press the Services Button on the remote control Then number 4 for System Set Up Press number 3 for Language and Subtitles Highlight Narrative, using the right/left arrow key change to On Highlight save New Settings and press Select To set up audio description permanently in a Sky+ HD box, users should: Select Options on the top menu (single screen navigation) Then select Subtitles from the middle menu This will then bring up the following menu Choose Audio Description On/Off change to On 6 To switch on the audio description temporarily without accessing the Language (Sky Digibox and Sky+ box) and Subtitles (Sky+ HD) menu, users should: Press the Help button on the remote control Use the up/down arrow button, highlight Narrative Press the left/right arrow button and change to ON with Narrative highlighted Press Select to continue If Narrative is not available on a particular programme, the message Unavailable will be displayed Smart Talks The Smart Talks is a TV set-top box that announces all on-screen information, including programme guides and menus, using synthetic speech. It was designed and developed in conjunction with RNIB to provide full access to Freeview (a British company that provides free-to-air digital TV channels) and radio services for blind and partially sighted people (RNIB, 2010a). As is well known audio description is not always available on every programme, so with Smart Talks users can identify if it is available on programme information window, where the word 'AD' is displayed. Users can access to information about the programme they are currently watching pressing the Info button on the remote

7 control. They can also view programme information whilst they are in any of the channel menus by pressing the Info button on the selected channel. The audio description function isn t on by default, to set up this option on or off users have to press the AD button on the remote control. Besides this simple option, users can access advanced features related with audio description. Following are explained how users can do it (RNIB, 2010b): Press the Menu button, Preferences is the first option and will be highlighted, press Ok. Select Audio description preferences and use the up and down buttons to select Turn AD on/off and Turn AD alert on/off By selecting Turn AD on/off use the up and down buttons to select either 'Turn AD' on or 'Turn AD off' By selecting Turn AD alert on/off use the up and down buttons to select whether you would like to be alerted that the programme you are watching has audio description (this will appear in the programme information bar). This option will be in the form of a double beep. 4. User Identification User identification is a sensitive research area because adding to technical details it also has many social aspects that should be considered in services development (e.g.: to ensure data privacy). Watching TV is commonly a social activity which makes difficult the exact identification of who is watching. Television broadcasters use commonly the identifier associated with STBs to distinguish viewers, but this is an imprecise way (it is impossible to know who is actually in front of the TV). Despite this, it allows some customisation as, for example, allowing the deliver personalised advertisement to a group of users. To television operators, viewer's identification is extremely important because it allow knowing customers profiles and adjusting services to the profiles User identification in television There are already some work done on the detection and identification of TV viewers, both within academic and commercial scope. There are some examples using identification based on user data insertion through user name and password, like, for example, TiVo service (Inc 2010) that asks user s data (it can be inserted via a virtual keyboard) and then allows access to personalised services. Telekom Austria (Austria 2010) provides a remote control for TV sets that allows user s identification through fingerprints. This type of systems has special characteristics like the high percentage of correct identification when compared with others that are based, for example, in sensors networks. So, due to its safety and reliability, they can also be used to identify users in sensitive systems such as banks and shopping. Besides the use of fingerprints there are other approaches to user s identification like image processing to perform detection and face recognition. An example is proposed in (Hwang, Ha et al. 2007). This type of solution does not require the user to enter data maximising the ease of interaction. However, such systems can induce to users

8 a feeling of loss of privacy because cameras capture what goes on in living rooms, bedrooms and other places of a house. Further the works already mentioned, Chang et al. in (Chang, Hightower et al. 2009) described a platform for viewer identification that uses accelerometers in remote controls to see who is ahead of the TV set. This system analyses the handling of remote control and, based on data collected, infers who is watching. There are other types of technologies used to identify users such as using sensors RFID (Radio Frequency Identification) (LLC 2010). For example, Taikyeong Jabbar et al. presents in (Jabbar, Taikyeong et al. 2008) one application of RFID sensors to identify and authenticate the spectators, allowing them to access to an interactive and personalised IPTV (Internet Protocol TV) infrastructure. There are other works in this research area like the one described in (Philipose, Fishkin et al. 2004) where RFID bracelets are used to perceive (and collect data about) what objects are used by participants and then, using search algorithms, identify daily living events. In addition to these works there are others that, using data about user interaction activities (choice of TV contests, favourite channels and shows) draws a user profile. These profiles are then used to deliver content adjusted to viewer preferences. Two examples of such systems are documented in (Zimmerman, Kurapati et al. 2005) and (Thawani, Gopalan et al. 2004). The identification of users can also be done using Bluetooth devices. This identification scheme is already patented (Bluetooth SIG 2010) and can be used to identify the audience of interactive TV systems. Park et al. described in (Youn-Kyoung, Sun-Hee et al. 2008) a system that uses the mobile communications network and a smart card reader (Alliance 2010), to identify users of a platform for IPTV. Such systems can store the user's preferences (on a card (smart card) that has storage capabilities) like volume, pitch control, brightness, etc. The systems discussed earlier have limitations, both at i) technological level because most of them were only tested in laboratories; ii) and at sociological level, because most of them uses biometric or other sensitive data or requires identification through any piece of hardware or software. In addition, few systems presented allow identification of more than one viewer which derails their use, for example, in characterisation of audiences. Almost all works presented are at an early stage of development and are, mostly, academic prototypes. Concerning DTT, there are also some works related with content personalisation. In DTT is possible to transmit data together with video signal and Amaral in (Amaral, Goncalves et al. 2009) showed the concept of Personalcasting applied to these data and how it is possible to distribute contents to specific users An user identification system to an audio description service of DTT As explained by Amaral in (Amaral, Goncalves et al. 2009), DTT allows data transmission along with video and as a result it is also possible to transmit all data associated to an audio description service. Thus, the STB used to decode free-to-air (FTA) signal can also be used to detect the user that is in front of TV set. This can be done using multiple ways as explained in previous section. In this work we propose the use of RFID tags and readers due to its flexibility, reliability and ease of development. The Figure 3 depicts the system proposed.

9 Elmo: Say hello Dorothy! A.D.: An orange goldfish. STB RFID reader RFID Tag 9 Figure 3 User identification system to an audio description service of DTT 5. Enhanced audio description service Currently, there are several interactive audio description systems supported by Digital Terrestrial Television, most of which are developed in the UK, as mentioned earlier. However, beyond the activation of audio description, and alerts about audio description support, these services are somewhat limited in additional features. In addition to these conventional features, the proposed system wants to add advanced and customized features allowing user to have some system configuration options available without a great configuration effort. These new features are mostly related with adaptation of user preferences, and will be explained below User Preferences Volume The volume control feature may be used for three types of content: audio description, set-up box and assistive navigation (explained below). The developed interface will allow user to customize each of these volumes and associate them to his profile. When the user is identified, theirs customizations will be loaded automatically. Beyond the specific customization (parameter by parameter) user can choose his profile from a default set Image and text zoom

10 As is the case of the volume parameterisation interface, it will be allowed to user to associate to his profile the zoom value of image and text for each of the following content types: i) text related to audio description, ii) set-top box menus; and iii) television content Narrator s voice and language The parameterisation interface will also allow user to associate to his profile the narrator s voice (female or male voice for example) of audio description, the language (among those available in the TV program) and the speech speed control. When the user is identified, the system will automatically adjust to their preferences User experience Assistive navigation The assistive navigation feature encompasses two main components: i) the menu options narration; and ii) the help option always available. The options narration will be triggered when the user selects any menu item. On the other hand, the help option will always be present through a shortcut key. The user, on his profile, can parameterize this feature (enable, disable, set volume, etc.) Favorite TV channels with audio description The system will allow user the possibility to choose what he wants to see at the moment from a list that includes all their favourite channels with audio description. For this, the system has to record all channels with audio description and record the channels user s choices Target advertising Due to the specificity of the system target audience, it is appropriate to adjust the advertising to their characteristics. Broadcasters can include advertising focussed specifically at VIU on the channels with audio description Advantages There are two advantages types related with systems that have the characteristics explained previously, one is concerned to broadcasters and the other is allied to users. Some of them are following described. Broadcasters Users Know audience of programmes with audio description; Widening the spectrum of potential viewers; Potential increase in advertising returns. High level of customisation; Access to a wider spectrum of contents; Ease and simple use.

11 5.4. Universal Design Libro Nuevos Medios, Nueva Comunicación The features described previously, which incorporate the enhanced audio description service, will be implemented considering universal design principles, developing an intuitive and usable system. Thus, the system interaction design will follow the guidelines explained below (CUD, 1997). Equitable Use: the system can be used by people with diverse abilities. Flexibility in Use: the system accommodates a wide range of individual preferences and abilities. Simple and Intuitive Use: the system is easy to understand, regardless user's experience, knowledge, language skills, or current concentration level. Perceptible Information: the system communicates necessary information effectively to the user, regardless of ambient conditions or the sensory abilities. Tolerance for Error: the system minimizes risks and the consequences of accidental or unintended actions. Low Physical Effort: the system can be used efficiently and comfortably and with a minimum of fatigue. Size and Space for Approach and Use: size and space should be appropriated for approach, reach, manipulation, and use regardless of user's body size, posture, or mobility Final Notes The presented research project has as assumptions the study of new strategies for the integration of persons with visual impairment on the Interactive Television scope, as well as the development of an audio description service interaction model that meets the specificities and needs of this type of users. In this sense, the development of this research aims mainly to contribute to facilitate VIU s interaction in the DTT context and develop an interaction model that allows easy and understandable access and use of an enhanced audio description service for VIU. On a more practical level, these results will be achieved through the addition of new features and functionalities that are in compliance with universal design principles, and consequently act in response to problems experienced by VIU. Accordingly, the prototype interaction model will include: an user identification system based on RFID tags and readers; adding features to the audio description system (volume control, image and text zoom, narrator s voice and language) an user experience improvement through the adaptation of an audio assistive navigation (providing feedback to VIU for menu options and select items), the provision of a personal list of favourite channels that include audio description in

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