4.3.1.1 Functionality Innovation

The DVB-VCR demonstrator is a prototype digital video recorder for digital video broadcasts. It uses the SMASH Combo as a storage device in a client-server concept. The DVB-VCR differs from existing VCR's in many ways, including:

• New technology: the DVB-VCR stores and reproduces broadcast signals in the digital domain (DVB).
• Mass storage: the storage capacity of the tape used in the demonstrator is 10-14 hours of video. Next generations of the tape unit will increase the capacity to several tens of hours on a single tape volume.
• Fast access storage: the presence of a hard disk gives many possibilities. Not only does it allow fast retrieval of all kinds of data (table of contents, electronic program guide, images), but by smart buffering it allows simultaneous recording and playback on a single tape volume.

The application translates all these technological differences to new functionality, such as:

• The ability to record and play back simultaneously. This can be recording a movie while watching another previous recording, or watching a movie with delay, while it is still being recorded.
• Easy programming and retrieval. The user can always get an overview of what is on his tape (TOC: table of contents) and what is on TV (EPG: electronic program guide). Operations like programming for recording and selecting for playback are all done in simple point & click style.
• Content management. The systems keeps track of ‘what is where’ on the tape, the consumer is not aware of the details. In fact, a program can be scattered over a tape in order to use space efficiently. The user only creates (by recording) and deletes programs, much like in a file system on a PC.
• Graphical navigation. The use of key-frames enables easy navigation through a program. It also gives the consumer a quick visual impression of a recording.

4.3.1.2 User interface

After studies on the possible user interaction with the DVB-VCR application, a interaction design was chosen. All screens are displayed on a TV set, and can be controlled via the buttons of a remote control. Below, the main screens of the application are described.

The combined TOC - EPG screen

The screen in figure 15 gives an overview of programs which are available now or in the near future. Hence, it combines an electronic program guide (EPG) with the table of contents (TOC) of the tape. The blue columns on the right show the TV schedule for today, or several days ahead. Using the cursor, the consumer can easily navigate through the channels and programs. Once the user selected a program, he can mark it for recording, notification, or additional information supplied by web sites and teletext. The green columns on the left contain the recorded programs. A recorded program automatically appears in the column labelled 'Recent', from which the user can decide to drag it to the 'Keep' column, or to delete it. Recording a program for viewing is a simple matter of pointing to it and hitting the button, regardless of the column.

Figure 15: User interface screen displaying a combined table of contents and electronic  program guide.

The information and key-frame screen

The information and key-frame screen shows the collected textual information on a particular program, at present limited to title, time and date, and a short description. In addition, a series of key-frames, acquired during recording, are available to the user. The user can choose to animate them, which gives him a quick impression of the program. The user may also browse through them, and choose to start playback from a particular key-frame.

Figure 16: User interface screen displaying information on a selected recorded program, including a textual description from the EPG, and key-frames for quick browsing or navigation.

The pause button function

An interesting feature that is enabled by the ability to record and playback simultaneously, is the pause button function. When watching a live broadcast, the user can 'pause' the program, e.g. to answer the phone. Later he may resume the program, i.e. resume watching it with a time delay with respect to the live transmission. What actually happens is that upon activation the function starts recording. Resuming simply means to start playing back from the beginning of the recording, while the recording still continues. The user may catch up the live broadcast by playing fast forward, or by skipping parts.
If the tape and hard disk are both used for this buffering, the buffer will practically never be full. In case of a hard disk only system, or when the tape is full, the buffer capacity of a 1 GByte disk enables roughly a 30 minute buffer.

Figure 17: User interface screen displaying the pause button function. The video is frozen during a pause, and the buffer state is displayed.

4.3.1.3 User responses

The system described above is fully operational, and works perfectly well with live DVB transmissions. Large-scale user test could not be performed within the framework of this project. However, the system has frequently been demonstrated, in total to several hundreds of people.
The reactions of the people who have seen and tested the demonstration so far are almost unanimously positive. The main conclusions are:

• Everyone recognises the need for content management on a VCR. The what-is-where problem is universally acknowledged, and our approach is welcomed as the long-sought solution.
• The point & click operation is seen a major step forward with respect to the customary showview functionality in programming for recording.
• The key-frames are generally seen as a big advantage, both for getting a quick impression and for selective viewing.
• Simultaneous recording and playback is not generally seen as a great feature, until we explain that it enables you to come home half an hour late for a movie, and watch it anyway (instead of waiting for the recording to finish and watch it the next day).
• The pause button function is very attractive, but some people find the link with a VCR illogical, the function would be more at home in a TV.
• Quite some people wonder why a tape is still used when optical discs (DVD)is available. (the answer being that it is a matter of storage capacity, tape is a factor of 10 ahead and much cheaper).

In summary, the reactions are very positive and encourage us to continue this work.

4.3.2.1 Features and functionality innovation

The WEB-VCR demonstrator is an application prototype for remote accessing and locally storing video streams from the Internet. It exploits the SMASH Combo System as a storage device in a client server architecture. The application presents the following features and functionality:

• an integrated and easy to use environment for accessing WEB pages with related video streams from the Internet and for storing and thereafter accessing them from the local Combo System
• a familiar VCR like Interface during the interaction of the user both with the Internet and the Combo System
• a dynamically downloadable application into an appropriate WEB Browser such as the Netscape one, enhancing the Browser with VCR-like capabilities
• to play MPEG-1 video streams coming from either the network or the Combo System
• to record them and to record full WEB pages along with their user selected first level video links in the Combo System
• to play and record video streams in parallel
• the capability to deal equally well with a large number of small pieces of information such as the Internet pages and the huge sized MPEG-1 video streams

The system architecture:

The application runs in a Windows PC with an MPEG-1 decoder board allowing to decompress MPEG-1 files and play them in video overlay on the PC screen. The "Real Magic" MPEG-1 decoder from SIGMA Design has been chosen as it matches more strictly the application requirements such as the possibility to handle a buffered flow of data from the digital video file to the decoder board and the availability of a low-level API to interface the playback functionality of the board from a Windows (either 16 or 32 bit) application environment.

The application has been designed with a layered architecture using the JAVA paradigm as shown in the following figure:

Figure 18: The WEB-VCR software architecture

The graphical User Interface of the application is implemented through a JAVA applet while the software functionality has been implemented in a JAVA "Package" called StreamVideo.
The Stream Video package holds the class hierarchy of the objects that map the data model of the WEB-VCR application (see Deliverable #9 for Stream Video package description).
The interaction of the application with the decoder board has been realized through the methods of the StreamVideo package that deal with video files as "JAVA native methods", i.e. as methods whose code is written in a different language from JAVA (such as C or C++).
Moreover, in order to improve the performance of the application, the native methods have been implemented as "Netscape Plug-in" using the Netscape LiveConnect technology providing high performance improvement and allowing to interface Java applets with local plug-ins.
The LiveConnect JAVA RunTime extends the standard JAVA RunTime adding a new Package to the JAVA Class hierarchy. This new package contains the "Plugin" class whose methods are implemented as Native Netscape Plugin.

4.3.2.2 User interface

The WEB-VCR application has been designed to allow the following types of interaction with the user:

• Internet Interaction: when the user refers a video stream stored on a remote Internet site
• Combo Interaction: when the user refers a video stream stored on the Combo System.

Internet Interaction

The user interacts with the application trough a VCR-like interface which provides the following buttons with the following commands:

During the so called ‘Internet Interaction’ the user can select a video link thus enabling the activation of the JAVA applet which features a VCR user-interface.
When a video link is selected the command PLAY, RECORD and PAGE RECORD are enabled and the user can push one of them to start the selected functionality.

Figure 19: The User Interface of WEB-VCR ‘remote side’

The play functionality starts a connection between the local PC and the remote server where the video stream is stored. The MPEG frames coming from the server are passed to the MPEG decoder board, which decodes them and play them in a video-overlay window on the PC screen.
The record functionality acts in a similar way as the play function except for the buffer data that are played and simultaneously stored in a file in the COMBO System. The user assigns a name to the recording video stream using the text box located near to the buttons of the VCR interface. When the recording phase comes to an end, an HTML page referring to the recorded MPEG-1 video stream and to the VCR applet is automatically generated. Moreover, an index, the local ComboIndex HTML page, is updated with the reference to the new-recorded stream. The ComboIndex HTML page contains the entry points to all the video streams and the Internet HTML pages recorded in the Combo Tape.

The PAGE record functionality allows to store an HTML page and acts like the RECORD functionality for the selected video streams linked by the page.

Combo Interaction

The user interacts with the video streams stored in the COMBO system from a WEB browser trough a VCR-like Interface providing the following commands:

play pause stop delete

The play functionality, in particular, starts a connection between the local PC and the Combo device to enable the buffered data flow from the Combo towards the MPEG-1 decoder board.

Figure 21: The User Interface of the WEB-VCR side Combo

The delete function allows cancelling a video stream from the COMBO together with all the references to it. As regards to the "Internet Interaction", the record function is not available because it is not meaningful in a Combo context.

4.3.3.3 User responses

The WEB-VCR application prototype has been tested internally on an Intranet Subsystem using a 100 Mbit connection which simulates a broadband network of a digital city. The interface has been perceived familiar and easy to use. A critical aspect of the application could be the response time of the network which has to allow a continuous data flow to enable a video stream playing. However the internally performed tests based on the Intranet Subsystem have presented acceptable results.

4.3.3.1 Functionality Innovation

The remote-education application (REA) is a multimedia-supported WWW educational tool, which uses the SMASH Combo as a mass storage device. The REA differs from existing educational tools in many ways, including new technology and new functionality:

• Usage of a mass storage device to locally store a large collection of lecturing material (in the form of interactive experiments, high quality pictures, and movies) on the tape. In particular, high quality pictures and movies are stored in large data files which are not suitable for repeated downloads to local personal computers at home.
• Interoperability between the mass storage device and the Internet in an automated way. The user doesn’t need to care where the lecturing material is. He / she can study a course from the tape and at the same time browse over the Internet for similar material or send an e-mail to the teacher. He / she can also retrieve homework from the remote computer at the school.
• Elimination of the low-speed-transmission restricting factor for the on-line multimedia-supported remote education. Using the mass storage device, the low speed transmission caused by narrow-bandwidth lines and modems doesn’t restrict usage of remote education because only a small amount of data is transferred on-line over the Internet.
• Optimization of the sequence of files in which they are stored on the tape to minimize the average access time for files on the tape. Using the knowledge about the course structure and the size of files, the optimized sequence of files on the tape is established. Additional reduction of access time is obtained by using the hard disk in the mass storage device for caching.
• Graphical navigation based on mind maps. The graphic user interface is built using Java applets and supports browsing of lessons in a graphic way using mind maps as well as browsing through a usual Windows tree structure.

4.3.3.2 Remote-education application

The remote-education application (REA) is based on the WWW and it is implemented in the Java programming language. It consists of different programs (a Web browser, a simple WWW server, and a tape controller) combined together into one program application. A graphic user interface is built under the WWW browser like Netscape or Microsoft Internet Explorer. The idea is to keep the application as general as possible. This means that the same concept of the educational tool can be used with or without a local mass storage device [22]. To achieve such a goal, an interface between the application level and the storage device is used to hide the storage from the application. As the interface is used a simple WWW server. It accepts an HTTP request for a file on the local storage device from the WWW browser and it sends back the required files as an HTTP response. If the required file is not on a hard disk, it sends an API command to the tape-device controller running on the server to copy the file from the tape to the hard disk [19].

The remote-education application is based on the client – server architecture. The client is a PC with Windows 95 or Windows NT operating system, which has installed the WWW browser (Netscape or Microsoft Explorer) with multimedia and Java 1.1 support. A PC with a tape drive for 13 GB linear tapes under the Linux operating system is used as a server called Combo. The Combo and the client PC are connected with the Ethernet. Usage of the REA in a computer classroom is shown in Figure 23.

In general, the teacher’s system is the same as the student’s system but this is really a minimum requirement. Usually, the teacher should have a more powerful computer with additional software for editing different types of multimedia files. An additional program is required for copying the prepared courses on the tape.

Figure 23: The Remote-Education Application (REA) used by students in a computer classroom.

The REA uses a large number of mostly small files, while other SMASH applications deal with only a few very large files (movies). The problem is how to write all these small files on the tape to avoid long delays when the selected file should be copied from the tape to the disk. Because the structure of the course is known in advance, an optimization of the sequence of files on the tape is performed using a genetic algorithm.

4.3.3.3 User interface

The remote-education application itself is written in Java and JavaScript programming languages and runs in both popular WWW browsers (Netscape and Microsoft Internet Explorer). The user interface is developed on the idea of mind maps to give a better insight into the course materials and the relations between the topics [25]. A view of the user interface can be seen in Figure 24. The interface is divided into three sections:

Figure 24: Application’s user interface

1. The upper smaller part of the window contains the toolbar with various buttons for additional interaction with the application. Besides navigation buttons (arrows), the toolbar also contains three network-related buttons ("new browser window", "send e-mail", and "get homework"), an option button (to mark chapters as learned / not learned, or to close all of the expanded chapters in the course) and a help button for online help.
2. The main part of the window (main view) contains a mind map of the selected chapter or the courseware document describing the chapter. A mind map is a visual representation of a concept and its related sub-concepts. The presented concept is displayed as the central item of the mind map, with its related sub-concepts arranged around it.
3. On the left side of the window the students see the chapter-based linear structure of the course they are studying (course view). A structure similar to the well-known Windows 95 tree structure (representing files and directories) is used for this purpose.

Students have several possibilities for navigation within REA:

• Display the contents of individual chapters by clicking on the chapter titles in the course view,
• Browse the courseware materials by clicking on the three arrow buttons on the toolbar,
• Move through the courseware by clicking on mind maps in the main view, and
• Navigate by clicking on hypertext links within the materials (As when exploring non-required topics through mind maps, a new window opens up with the contents of hyperlink. When students finish with browsing, they close the window and return to the topic, they last studied.)

The first two possibilities were designed to follow the lecture material defined by the lecturer. The third one was added to browse the material in an arbitrary way and to explore the material which is not included in the lecture. The results of the questionnaire show that despite the different purposes of the ways the material can be reached, usually, a particular user prefers only one way, but different users have chosen different possibilities as preferable.

4.3.3.4 Evaluation of the system

The remote education application has been tested on demo lessons of computer graphics, virtual reality and digital signal processing. User trails have been performed to evaluate the concept of the application. The system was tested by 15 users who were mainly researchers and students that are involved in various aspects of the SMASH project in Ljubljana. The results of the evaluation of the user trials are summarized in the following table:

Users' impressions about using this learning system were positive. The users like the design of graphical interface, the concept of the mind patterns and the possible interactions. The only concern goes to system response time in the cases when the system has to reach the material stored on the tape. For this purpose it should be added special warnings to inform the user about the expected time in which the required services can be completed and allow the user to cancel the required service.

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