GB2428329A - Interactive switching between different versions of the same audiovisual event or production - Google Patents

Abstract

Various embodiments of the present invention relate to a media product, such as a DVD product, storing different versions of the same event (e.g. POP VIDEO, LIVE 1, LIVE 2) and to an interactive on-screen menu operable during playback of one of the different versions (e.g. POP VIDEO) to switch to an equivalent playback position in one of the other versions (e.g. LIVE 2). The menu can be arranged to appear overlaid on the first version, and can be controlled by a user, without otherwise interrupting playback of that version, and the different versions do not need to have the same duration to facilitate switching between equivalent playback positions. The arrows in fig. 4 show potential transitions between the POP VIDEO, LIVE 1, LIVE 2. Each clip has the same number of transition points and are contextually synchronized but may not be temporally synchronized.

Description

Media products and methods of authoring media products Ref 0039GB) The

present invention relates to media products and methods of authoring media products In particular, embodiments of the present invention relate to media products and methods of authoring media products having interactive menus that may be used for controlling playback of audiovisual content, for example stored on a DVD product.

In general terms, audiovisual content such as a movie or other presentation comprises multiple sections or clips of raw audio and visual content, which are typically referred to generically as assets". The process of generating audiovisual content in this way is usually termed an "authoring" process wherein the raw sound clip and video clip assets are progressively assembled and edited together for use in the finished audiovisual product. The audiovisual product is then recorded on a recording medium Previously, this would be an analogue medium such as celluloid film or analogue videotape (e.g. VHS format video tape), which typically plays back the product in a sequential manner from beginning to end. More recently, it has become common to record audiovisual content onto random access media including in particular optical disk media, such as a DVD-ROM, or other forms of random storage such as magnetic hard drives or electrically re-wntable solid state memory, for example flash memory. These random access media have many advantages in terms of size, data capacity, playback speed, image quality and so on.

An optical disc is a convenient and relatively cheap storage medium for many different purposes. One kind of optical disc, a DVD-ROM disc, has been developed with a capacity of up to 4.7Gb on a single-sided single-layer disc, and up to 17Gb on a double- sided, double-layer disc. There are presently several different DVD-ROM application formats, including DVD-Video and DVD- Audio, amongst others. Of these formats, DVD-Video is particularly intended for use with pre- recorded audiovisual content, such as a motion picture, or movie'. As a result of the large storage capacity and ease of use, DVD-Video discs have become popular and commercially important.

Conveniently, a DVD-Video disc is played using a dedicated playback device with relatively simple viewer controls, and DVD players for playing DVD-Video discs are widely available and becoming relatively cheap to buy. More detailed background information concerning the DVD- Video format specification is available from the DVD Forum at www. dvdforum.org, and elsewhere.

Much of the following description herein uses examples based on the DVDVideo specification and DVD-Video discs in particular. For the sake of brevity of description, unless otherwise indicated or where context dictates otherwise, the term "DVD" alone will be used hereafter to mean a DVD-Video disc. Of course, broadly speaking and unless specifically stated, aspects and embodiments of the preset invention are not limited only to DVD, since the principles taught can be far more widely applied, for example, to hard disc or solid state memory device storage. Indeed, the principles are likely to apply also to next generation optical disc technology, for example HD-DVD or Blu-ray, and, as such, aspects and embodiments of the present invention also apply thereto.

As well as providing significantly higher video and audio quality, the DVD-Video specification provides many additional features compared with the features that are associated with, for example, VHS format videotape. Specifically, among many features, a DVD permits. up to eight soundtracks, to support multiple languages and supplemental audio, with each soundtrack being able to include surround sound channels; up to 32 subpicture tracks, which are, in effect, pre-authored graphical overlays, for providing subtitles, captions and the like; up to nine different camera angles, which enables a viewer to switch between different viewpoints; and menus, which will be described in more detail below, which enable a viewer to select for playback particular combinations of the foregoing. These features are facilitated by the random access nature of a DVD Data is stored on a DVD as a multiplexed and interleaved data channel, which is read from the DVD as a data stream (or simply a stream') . This stream contains a video stream, an audio stream, a subpicture stream and a presentation control stream. The video stream typically comprises plural interleaved individual video streams, one for each camera angle (where plural angles arc present). Likewise, the audio stream typically comprises plural interleaved individual audio track streams and the subpicture stream typically comprises interleaved individual subpicture streams. The program control information is provided in order to tell the DVD player (typically in response to viewer selection in advance) which individual video, audio and subpicture streams to extract and replay and where physically on the DVD the respective data is stored.

In principle, DVD authoring is generally a linear procedure, which requires an author to gather together all of the assets required to generate a DVD presentation and encode the assets into a form suitable for DVD formatting and replication. For example, video content is typically encoded into an MPEG video stream, audio content may be encoded into a DolbyTM Digital audio stream and menus, subtitles and the like may be generated using a graphics design software package and then encoded into subpicture streams. Next, the various assets are generally linked together either by assigning timing information to the assets or by associating the assets with program control commands. For example, video streams may be linked to their respective audio streams using timing information and menus and audiovisual content may be linked by various link or jump instructions.

Thereafter, a software compiler program is generally used to gather the assets together in accord with the linking information and convert them into a DVD-compliant, multiplexed and interleaved data channel. In commercial scale production at least, the data may be written to a storage medium, for example a linear tape, in a formatting or pre- mastering step, which is then used in a mastering process to generate a DVD master. The DVD master is typically then used in a manufacturing process to stamp final reproduction DVD discs.

Due to the relatively large number of assets that may need to be gathered together and linked for a single DVD product, DVD authoring may be extremely time consuming, complex and error- prone. Typically, creating and gathenng the assets and then linking them together is a labourintensive exercise, which, for more complex titles containing many menus, can take of the order of several man months. One commercial authoring system, which can be used in this kind of authoring process, is Scenaristi'M, which is available from Sonic SolutionslM of Novato, California (www.sonic.com). A more recent authoring system is DVDEXTRATM STUDIO, available from ZOOtechTM Limited (www.zoo-tech.com). Many other, mainstream, systems are available to home users, who wish to author home movies, photo albums or the like. Such systems include Power DirectorTM3 by CyberlinkTM, Pinnacle StudioTM 9 by PinnacleTM and WinDVD CreatorlM by InterVideoTM One advantage of using any of the available authonng systems is that a user does not need to learn or understand in any depth the DVDVideo specification, which is extremely complex.

This is because the systems typically provide an abstraction of the specification, which enables users to enter information in a higher-level syntax or language. The systems then, in effect, compile the userinputted, higher-level information into a lower-level byte code form, which is the level understood by DVD players. The compilation process is similar to typical software generation, wherein a software programmer writes high level code in, for example, C, C++ or Java, and then uses a commercially available software compiler that converts the high level code into machine executable code, or machine code: a software programmer never needs to understand and write machine code as such. The detailed description herein is written in terms that will be readily understood by the normally skilled person, who does not need an in depth understanding of the DVD-Video specification but who is familiar with DVD authoring and related authoring systems. If a reader is minded to learn about more specific features of the DVD-Video specification, he is referred to the extensive information available free of charge on the Internet, for example see http://dvd.sourceforge.netJdvdinfo/indexhtrnl or one of the various text books on the subject, for example "DVD Demystified" by Jim Taylor, published by McGraw-Hill-Education, ISBN 0071350268.

It is known that a DVD typically has at least one menu, sometimes called the title menu' or top menu', from which a viewer usually has the option to at least play the main DVD content The DVD-Video specification permits a DVD to have as many menus as is desired by the author of the DVD. Conversely, there may be no other menus. There is no facility in the specification to define a hierarchy of menus, as such. However, a de facto hierarchy can be generated by providing plural menus and defining the menus to have options to select other menus in any manner an author requires For example, many commercially available films arc produced on a DVD that has a top menu, including common options to play the film', select a language', select a chapter of the film' and set other playback options'. Each option of the top menu is typically associated with a respective sub- menu, and sub-menus may provide access to further sub-menus, and so on. DVD menus are populated by one or more menu buttons, or hot spots', which are defined as rectangular regions on screen that can be selected and activated. Menu buttons arc visualised on screen using appropriate graphics, for example using subpictures or background content. Up to 36 buttons can be defined for a single menu using one subpicture stream. A menu button may be selected under program control or by navigating, or Jumping, to the button under viewer control from within a current menu or from another menu Typically, navigation from one button to another is achieved using the arrow keys (left, right, up.

down) of a typical DVD player remote controller. Each menu button includes four directional links that determine which next button is selected when respective remote controller arrow keys are pressed The links between buttons may or may not correspond to the physical arrangement of menu buttons on screen. In practice, directional links are typically not displayed and menu navigation between menu buttons is intended to be intuitive: for example, moving from one button to a button located, physically on screen, directly below is achieved by pressing the down arrow key of a respective remote controller. Each menu button can also have an associated command, which is executed by activating the menu button using the Select' (or Enter' or OK') key on the remote controller. Commonly, when a menu button is selected, or highlighted, its appearance changes according to a corresponding defined select state' of the button. For example, highlighting may be achieved by varying the respective subpicture pixel colour or intensity. Similarly, the button may be defined to change appearance momentarily after it is activated and before the respective command takes over.

Most commonly, menus are displayed independently of, for example before or after, normal audiovisual content playback. For example, a menu may present a viewer with playback options and selecting an option typically causes the menu to disappear and playback of specified audiovisual content, for example a film, to start or resume. It is, however, also possible, using subpictures, to superimpose a menu onto otherwise normal content during its playback. One approach to providing a relatively more interactive viewer expenence is employed in the British Broadcasting Corporation's DVD production of "Walking With Beasts", 200 1. In this documentary production, the main feature plays in a window, which forms an upper region of the overall viewable area of the screen. A permanent menu at the bottom of the screen provides options to switch playback between the "Main Feature", "Facts" supporting the main feature, "Evidence" supporting the Facts and "Making Of", providing-behind-the- scenes insights into the creation of the main presentation. During playback a viewer can move seamlessly between these options using the menu and respective arrow key presses.

The content for each playback option is authored to include both the audiovisual content and the menu option graphics. In other words, the basic menu graphics do not rely on subpictures. However, the menu options are highlighted during playback, as a result of viewer selection, using a subpicture. The content for each option is defined on the DVD as an alternative camera angle and, as such, all streams are synchronised. in effect, when a viewer switches between the streams, he is simply selecting a different camera angle, as fur as the DVD player is concerned Another example of using multiple synchronised camera angles for providing an interactive user experience is described in US patent application no. 2004/0126085. The system described provides plural camera angles, or zooms, of a single recorded live event, and a user menu for switching between the camera angles or zooms during playback. In that way, the viewer can switch between, for example, close-ups of musicians or an entire music stage.

Use of interactive menus is also well-known in the field of computer software, which executes on a standard, programmable computer, for example running the WindowsTM XP operating system. In such an environment, the computer typically has a relatively powerful processing capability and can generate new, complex graphics and menus on-the-fly, in response to appropriate software code instructions and environment context. In contrast, a DVD player has extremely limited means for generatrng new graphics at the time that the audiovisual product is played Consequently, all possible menu images must typically be prepared in advance and recorded as images as part of the authoring of the audiovisual product. Unfortunately, this leads to a relatively lengthy and complex authoring process, which can provide a significant technical and commercial barrier to the mainstream production of highly interactive DVD content.

In addition to using a dedicated DVD player to play a DVD, a DVD may be played using a DVD-ROM player apparatus, which forms part of a personal computer system, and appropriate DVD- Video player emulation software, such as PowCrDVDTM Version 3.0, by CyberlinkTM Corporation.

Emulation software of this kind is well known. The software typically decodes the DVD content and replays it in a window of a computer screen. The physical controls (keys, buttons, etc.) that are typically associated with a dedicated D\TD player are provided via a graphical user interface control panel, which may be accessed using a mouse or the keyboard of the personal computer The arrow keys of a remote controller, which would be used to navigate menus and the like during DVD replay, may be replaced, in a software emulator, by arrow keys on the keyboard. The OK or Select key of a remote controller may be replaced by the Enter key on the keyboard. In addition, for example using PowerDVD, control options may be accessed at any time by pressing a right mouse button, when the respective on-screen pointer is positioned over the video playback window The software responds by causing a pop-up menu to appear, options of which can be selected, again, using the mouse. The pop- up menu may be superimposed over video content, without interfering with playback, and provide options to Play, Stop, Pause, move to Next scene, move to Previous scene, change camera angle, change language, and configure the emulator software's playback options, among other options.

Different emulation software may offer different options. These menus are not stored on the DVD as DVD content. Rather, such menus are generated onthe-fly by the emulation software, which is executing on the computer. As already described, the ability to generate menus on-the-fly in this way is a characteristic of a computer, which has powerful graphical processing capabilities.

An object of the present invention is to provide a viewer with an improved or at least alternative playback menu system, and an associated authoring method and system, which is available, for example, dunng playback of a DVD by a dedicated DVD player.

According to a first aspect, the present invention provides a media product comprising plural audiovisual clips that relate to different versions of the same event or production and a user interface for facilitating during playback of a first clip switching from the first clip to a corresponding point of a second clip.

According to a second aspect, the present invention provides a media product comprising plural audiovisual clips, at least one clip provided with one or more transition points and a user interface for facilitating dunng playback of a first clip switching from the first clip to a transition point of a second clip.

In embodiments of either of the forgoing aspects of the present invention, the clips might be, for example, different versions of a musical rendition, an opera, a ballet, a film (e.g. original version and remake) or a play. The different versions or renditions may have been recorded at different times.

Indeed, the different versions or renditions might involve different people or different locations relating the same underlying plot or performance. Alternatively, for example, the clips might be alternative versions of an exercise video, an educational product or a documentary, wherein the different versions might be directed towards different levels of fitness, difficulty or depth respectively.

The aforementioned alternatives are by no means an exhaustive list.

According to embodiments of the second aspect, transitions points might be chapter points, according to the DVD-Video specification, or other points, partitions or logical or physical constructs from where decoding of an encoded data stream may start. For example, a transition point might be a cell boundary, if the cell boundary is arranged to be at the desired location and as long as switching can be arranged to be from one cell boundary to another cell boundary in the same program (again, in DVDVideo terminology).

According to embodiments of the first aspect, in the case of a DVD product, the clips may reside within the same multi-angle block or at different locations or in different streams of the media product. Thus, in the latter case, embodiments can emulate the behaviour of multi-angle switching but without the restriction of the former case of being limited to no more than eight angle streams. This principle can even be applied in a case where, for example, more than nine camera angles are required for a recorded live event, such as a football match, where having even more than nine camera angles could be desirable. According to pnor art techniques, playback would have been limited to a maximum of nine camera angles.

A media product according to the second aspect might comprise plural clips, each having one or more predefined transition points The media product might comprise at least one clip having plural transition points. In this case. more than one clip may have plural transition points.

Two or more clips might have analogous transition points. The transition points may be analogous in time or context, or both time and context.

Two or more clips may have the same number of transition points. At least some transition points of one clip might have a temporal arrangement, which is substantially the same as a temporal arrangement of analogous transition points in another clip. The transition points of one clip might have a temporal arrangement, which is substantially different from the temporal arrangement of analogous transition points in another clip.

Two neighbouring transition points in one clip may have a temporal spacing that is different from the temporal spacing of two analogous neighbouring transition points in another clip. In other words, the portion of a clip between the two transition points may be different in one clip than in another A contextual arrangement of transitions points in one clip may be substantially the same as a contextual arrangement of analogous transition points in another clip. By "contextual" we mean each clip has substantially the same sequence of events, but that the duration of an event in one clip may not be the same as the duration of the same event in another clip.

The user interface may facilitate switching from the first clip to a temporally equivalent position in the second clip.

In addition, or alternatively, the user interface may facilitate switching from the first clip to a contextually equivalent position in the second clip.

The user interface may provide a menu comprising at least one menu option, the menu being displayable during playback of a clip and comprising a menu option to cause display of another clip.

The menu may be displayed automatically or as a result of a user event, for example a user pressing a key of a remote controller (or an equivalent operation).

The user mtcrface may provide at least a first menu and a second menu, each menu compnsing at least one menu option, the first menu being displayable dunng playback of the clip and comprising a menu option to cause display of the second menu dunng playback of the clip. Then the second menu might comprise a menu option or options for switching between the clips. Further, the menu(s) is/are arranged to be displayed at least partially transparently. Each menu might comprise a sequence of individual menu instances or definitions, which are arranged to coincide, temporally at least, with a playback sequence of the clip or clips. The menu instances or definitions may vary over time during playback. For example, the definitions may vary in terms of the behaviour of a menu button but not in on screen appearance of the button In other instances, menu button appearance may also change over time during playback.

The individual instances or definitions of the first menu may be arranged into an addressable data stream or streams and the individual instances or definitions of the second menu may be arranged into a different addressable data stream or streams. Then, individual instances or definitions of the first menu may include a menu option that switches to a display of the addressable data stream of the second menu.

According to a third aspect, the present invention provides a media product comprising an optical disc product. For example, the product might be a CD-ROM, a DVD-ROM or a future product, such as a Blu-ray or HD- DVD product In the ease of DVD-ROM, the product may also conform to the DVD-Video format.

In any event, the switching operation may be substantially seamless.

According to a fourth aspect, the present invention provides a method of authoring a media product comprising the steps of: selecting plural media clips; identifying for each clip plural corresponding transition points, at which playback may switch between the clips; and providing a user interface to enable a user to switch between corresponding transition pomts5, wherein the temporal spacmg between transition points within one clip is different from the temporal spacing of the corresponding transition points within another clip.

Embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings, of which: Fig. I is a diagram of a typical audiovisual system; Fig. 2 is a diagrammatic representation of three clips of the same musical rendition, wherein each clip has the same temporal characteristics; Fig. 3 is a diagrammatic representation of the same three clips of Fig. 2 including transition points; Fig. 4 is a diagrammatic representation of three clips of the same musical rendition, wherein each clip has different temporal arrangement, Fig. 5 is a diagrammatic representation of possible transitions between a first clip and a second clip; Fig 6 is a diagrammatic representation of three clips representing alternative versions of a workout or fitness video, wherein the versions have the same temporal characteristics, Fig 7A is a diagrammatic representation of three clips representing alternative versions of a workout or fitness video, wherein the versions have the different temporal characteristics; Fig 7B is a diagrammatic representation of three clips representing alternative versions of a workout or fitness video, wherein the versions share warm-up and wind-down sections with one version; Fig. 8A is a diagram of a screen produced during playback of a clip, including a displayed menu button; Fig. 8B is a diagram of a screen produced during playback of a clip, including a menu, which is produced by activating the menu button of Fig. 8A; Figs 9A-9C are tables showing the breakdown into various streams, for example of Fig. 3; Figs. 1 OA- I OC are tables showing in more detail alternative ways of switching between the clips of Fig. 3; Fig. 11 is a diagram that illustrates the makeup of a PGC; Fig. 12 is a table illustrating menu button assignments according to one exemplary embodiment; Fig. 13 is a table illustrating menu button assignments according to another exemplary embodiment; Fig. 14 is a diagram of apparatus suitable for authoring audiovisual content, Fig. 15 is a diagram illustrating authored content, as stored on an optical disc; Fig. 16 is a flow diagram of a process of authoring audiovisual content compnsing a menu structure according to embodiments of the present invention; and Fig. 17 is an example of a text document, which describes menu button set definitions and is automatically generated according to an embodiment of the present invention.

The diagram in Fig. 1 illustrates a typical home audiovisual system, which is suitable for playing a DVD. The system comprises components including a television 100, a stereo music player with speakers 115, a videocassette player/recorder 120 and a DVD player 130 for playing the DVD. Each component is standard in the art and has an infrared detector 105 for receiving infrared signals from a respective remote controller 140, only one of which is shown.

The diagram in Fig. 2 illustrates three horizontal bars, which represent a logical arrangement of three different renditions of an audiovisual production, which are in preparation for an audiovisual product, such as a D\TD. By logical arrangement', as opposed to physical arrangement', we mean the bars merely represent the three individual renditions in a format independent manner.

In this example, each rendition of the production comprises musicians in a pop band performing a musical composition, or record. The first rendition, or first clip, is a recording of a POP VIDEO', for example, which is released to promote record sales. The second clip LIVE 1' is, for example, a recording of an early live performance of the same composition; and the third clip LIVE 2', for example, is a more recent live performance of the same composition. As shown, each rendition of the composition has a start point, an end point, three verses - VERSE I, VERSE 2 and VERSE 3 - and two repetitions of the CHORUS between verses The clips are shown as being synchronised That is, the verses and choruses occur (or each start) in time, or temporally-speaking, at exactly the same points, which are indicated by the vertical, broken lines intersecting each of the bars. In addition, it will be appreciated that the verses and choruses occur in the same order, or context. In other words, the points relate to the same portions of content and occur in the same order in each clip.

The start point, end point, and starting points of the verses and chorusesin the renditions are also labelled in Fig. 2 as points A-F.

The diagram in Fig. 3 illustrates using similar horizontal bars the same three renditions of the composition that are illustrated in Fig 2. In this instance, the verses and choruses are labelled differently for each composition. Specifically, the verses and choruses arc marked as follows: for the POP VIDEO they are labelled as Al-Fl for LIVE I they are labelled as A2-F2 video; and for LIVE 2 they are labelled as A3-F3. As shown, thc three clips in Fig. 3 remain synchronised in time and context.

According to a first exemplary embodiment of the present invention, each bar in Fig. 3 is shown logically divided into five sequential, subdivisions - one for each verse and chorus - as denoted by four equispaced, short vertical lines within each bar. Of course, in a practical scenario, the lines need not, and probably would not, be equi-spaced within any one rendition More particularly, the vertical lines herein represent transition points' according to embodiments of the present invention. As used herein, a transition point is a point in an audiovisual clip from which playback can be initiated, without having to read from the beginning of the clip to reach the point. For example, audiovisual content intended for a DVD can be arranged during an audiovisual content authoring procedure to have none, one, a few or many such transition points. One kind of transition point in DVD audiovisual content is a Part of Title construct, which is commonly referred to as a Chapter Point. However, there are a number of other known ways that audiovisual content can be arranged to have transition points, which can be addressed, or accessed, for playback purposes.

According to the diagram in Fig. 3, there are double-headed arrows between clips, illustrating the potential transitions between clips, according to the first embodiment. As illustrated, it is possible to switch between any two of the clips at any of the corresponding transition points Bn-En For example, it is possible to switch from the LIVE 2 clip at transition pomt D3 to the corresponding POP VIDEO clip at transition point Dl. In other words, a viewer can switch after the second verse of the LIVE 2 clip to replay the rendition of the chorus as presented on the POP VIDEO clip.

According to a second exemplary embodiment of the present invention, the diagram in Fig. 4 illustrates an alternative scenario comprising three renditions of another musical performance.

In this example, the POP VIDEO clip is the similar in form to the two previous examples in Figs. 2 and 3. However, in this example, a LIVE 1 clip is included, which has extended first and final verses. The extended verses may, for example, result from an extended musical introduction and an extended musical conclusion. There may, of course, be many other reasons for the different timings of the verses in the LIVE I clip. Live performances can be, after all, unpredictable In addition, as shown in Fig. 4, a LIVE 2 clip is included, which includes the same number of verses and choruses as both the POP VIDEO and LIVE I clips. However, the LIVE 2 clip rendition of the production has a reduced tempo, and, thus, the clip is longer in every respect than the POP VIDEO rendition.

As before, the clips in Fig. 4 include transition points between the verses and choruses. In this case, it is clear that the renditions are not synchronised. In other words, the transition points are not, temporally-speaking, at exactly the same points. However, the transition points are still contextually synchroniscd, inasmuch as each clip has the same number of transition points, representing the same portions of the clip in the same order Again, in Fig. 4, the double-headed arrows represent potential transitions between clips, from a transition point in one clip to a corresponding transition point in another clip. For example, it is possible to switch from transition point E3 of the LIVE 2 clip to the transition point El of the POP VIDEO clip, even though, temporally, the POP VIDEO transition point E3 occurs later in its respective rendition than the equivalent transition point El occurs in its respective rendition.

As will be described hereinafter, a media player can be arranged to provide a facility for transition point switching as illustrated by Figs. 3 and 4.

The diagram in Fig. 5 illustrates three possible transition point switching operations, illustrated with respect to two exemplary clips. In Fig. 5, the bold arrows labelled X and Y represent different potential user events occurring at two possible times. The events may comprise, for example, a user initiating an operation in a media player for switching between clips by pressing a remote controller button. If a user presses the button at point X in the playback of the first clip, which is between transition points B I and CI, one option is to initiate an immediate switch to either transition point B2 or transition point C2 of the second clip. It can be appreciated that the preference of switching to B2 or C2 might depend on whether the event occurs close, in terms of time, to point B 1 or point Ci and how long the gap is between the two points. For example, if the gap is one second, it might not matter which point the media player switches to If, however, the gap is large, for example ten seconds, it might be preferable to switch to point C2, jumping forward by two seconds, rather than to point B2, jumping back eight seconds. Alternatively, it may be decided that jumps should only ever be backwards in context, that is to the previous corresponding transition point of the desired clip, or forwards in context, that is to the next corresponding transition point of the desired clip.

Alternatively, if a user event occurs at point Y in the playback of the first clip, which is between transition points Dl and El, another option is to delay the transition operation until the next transition point El is reached. An advantage of this operation is that no content, in terms of context, is repeated or missed. That is, for example, a whole verse and the whole following chorus are reproduced, since the transition occurs at the end of the verse of one clip and the beginning of the chorus of the next clip. However, a potential disadvantage is that the delay between the user event and the actual switching operation might be perceived to be undesirable, with a viewer not knowing whether their operation has been accepted. This potential disadvantage could be overcome by displaying an indicator, which informs the viewer that a switch will soon occur. Such an indicator could be part of a menu display, for example.

A decision as to whether a switch operation occurs immediately or after a delay depends on the particular scenario being considered and may be influenced by how close transition points are to one another. For example, in the scenarios represented in Figs. 2 to 4, there is only one transition point depicted at the beginning of each verse and chorus. A practical scenario would typically have far more transition points, for example every few seconds, within each rendition.

While embodiments of the present invention relate to pop music, it will be appreciated that the principle of providing different renditions of the same performance can be applied far more generally For example, the principles may be applied to different renditions respectively of an opera, a ballet, a film (e.g. original version and remake) or a play. Indeed, embodiments of the present invention may be applied to any production that follows a specified flow, sequence, screenplay or script of some kind. Embodiments of the present invention are intended to encompass these and any other similar or equivalent kinds of presentation.

Other embodiments of the present invention relate to productions having plural different alternative playback options.

In one example, a fitness video production has three levels of difficulty, where each level comprises at least one clip. In a first example, as illustrated in Fig. 6, a fitness video comprises three versions; NOVICE, INTERMEDIATE and EXPERT. In Fig. 6, each version of the fitness video comprises five sections of generally equal length: a warm-up Un-Vn; three exercise sections Vn-Yn; and a warm-down Yn-Zn. That is, each section is temporally equivalent in terms of where sections start and end. Each section is charactensed by a video of a fitness tutor providing instructions and demonstrating exercises for a viewer to emulate. The same music track or tracks may be played throughout each workout, in order to provide an overall consistent look and feel between exercise levels. However, the exercises presented in each level arc different. For example, the EXPERT level provides highly energetic exercises whereas the NOVICE level provides more basic exercises. At any point during one level, a viewer can switch to another level according to the present embodiment. For example, if a viewer feels they are coping too easily with a certain level, they may be minded to increase the level of difficulty by switching to the next higher level. Or, if the viewer finds they are attempting a level that is too advanced, they can reduce the level In a second example of a fitness video, as illustrated in the diagram in Fig. 7A, there are provided again three levels of difficulty. However, in this example, the levels are each characterised by having different durations, with more difficult levels taking longer. At any time, the viewer can swatch to a higher or lower level according to their standard of fitness and the time they have available.

For example, a viewer may be comfortable exercising at the EXPERT level but have limited time In this case, they may opt to use the short warm-up and warm-down sections of the NOVICE level and the relatively longer three exercise sections Un-Vn of the EXPERT level.

In the two foregoing fitness video examples, the switching operation may occur at the start or end of a section or at any time in between, depending on where switching points occur. As with previous examples, the switching points can be placed practically anywhere, although only those at the boundaries of section are shown.

In addition, the levels may comprise different amounts of content from one another. For example, there may only be one standard warm-up section and one standard warm-down section, which are both associated with an INTERMEDIATE level, as illustrated in Fig. 7B. After the warm- up section is completed, playback of the INTERMEDiATE section continues unless the viewer intervenes and selects either one of the NOVICE or EXPERT levels; where all three levels include all three exercise sections Vn-Yn. When the third section of either the NOVICE or EXPERT sections is completed, playback reverts automatically to the INTEMEDLATE level in order to play back the sole warm-down section.

More generally, one or more of the clips, or levels, may have more or fewer sections than one or more other ones of the clips. For instance, there may be optional clips for switching between at some times and not others. Preferably, whether or not there is an option to switch between clips can be made obvious to a viewer by using an on screen indicator or the like.

The means for providing on-screen user menus for switching between clips will now be described.

Fig. 8A illustrates a video presentation of a band playing music, shown on a television screen. The video presentation, in this example, is recorded on a DVD storage medium and played back on a DVD media player The video playback appears normal apart from a MENU button being visible in the bottom left hand corner of the screen. In use, according to an embodiment of the present invention, the menu button indicates to the viewer that playback options for the video presentation are available. In this example, the playback options enable the viewer to switch between three different versions of the musical rendition.

Fig. 8B illustrates the playback image obtained by the viewer if the OK button (or any other button) of the media player remote controller is pressed Pressing the OK button activates the MENU button of Fig. 8A, which switches to the menu shown in Fig. 8B. Specifically, as shown in Fig. 8B, the MENU button has disappeared and been replaced by a menu comprising four new buttons; STUDIO, LIVE 1, LIVE 2 and MENU OFF As the button names suggest, the STUDIO, LIVE I and LIVE 2 buttons cause the video presentation to switch between a studio recording, a first live event recording and a second live event recording of the musical rendition. In this example, the buttons remain visible even as the playback is switched between the renditions. The fourth button, MENU OFF, causes the display to revert to that shown in Fig. 8A, in which only the MENU button is visible The double-headed arrows shown between menu buttons illustrate the movement by a button highlight as the viewer navigates between buttons using the arrow keys of the remote controller The tables in Figs. 9A to 9C illustrate an arrangement of data streams required to produce the presentation and menu structures of Figs. 8A and 8B As shown, there are three sets of data streams: one set for the STUDIO clip (Fig. 9A), one set for the VIDEO I clip (Fig. 9b) and one set for the VIDEO 2 clip (Fig. 9C). Each set of data streams comprises a video stream (Video n), a respective audio stream (Audio n), two subpicture streams (Subpicture I and Subpicture 2) and a menu button highlight stream (Highlight).

In each data stream set, the subpicture and highlight streams appear the same: the Subpicture 0 stream representing the menu for turning the switching menu on, as shown in Fig. 8A, and the Subpicture 1 stream representing the menu for switching between renditions, as shown in Fig 8B. As also shown, each of the subpicturc and menu highlight streams comprise plural instances, which occur, or repeat, each second during playback of the respective clip. This is required in DVD embodiments of the present invention in which the menu remains visible each time the viewer switches from one rendition to another, since a feature of DVD media players is that when an on-screen menu button is activated the associated menu disappears. In other words, without subpicture and highlight stream definition replication, when a viewer activates a button to switch to another rendition, the menu would disappear. The choice of a one second replication rate for subpicture and highlight stream definitions is relatively arbitrary and shorter or longer periods could instead be selected.

According to the prior art, switching between different views of a single performance is achieved simply by causing a media player to switch between different DVD camera angles, either by pressing a dedicated angle button of a remote controller or by pressing other buttons assigned to the same task. According to embodiments of the present invention, it is not possible to use the aforementioned prior art multi-angle switching techniques if different performances are not substantially temporally synchronised Instead, according to one embodiment of the present invention in which the playback medium and media player is DVD-based, switching between views, or clips, is achieved using so- called transition points that are associated with various points along each view. According to a preferred embodiment, the transition points are realised using DVD-Video chapter points, although other kinds of transition point arc envisaged, as will be described hereinafter.

A video clip can be arranged to accommodate chapter points at specified positions in the clip. Up to 99 chapter points can be associated with one clip. More than 99 chapter points can be associated with a clip if the clip is split into multiple clips, or sub-clips.

Chapter points can be added to a clip during a DVD authoring procedure of known kind. For example, chapter points are commonly inserted into movies, and a viewer can start playback at (or jump to) any chapter of the movie from any particular position, typically using a movie chapter menu.

According to embodiments of the present invention, chapter points can be added to a clip in a number of different ways.

If renditions are of similar length, say two minutes each, chapter points could be added at regular intervals throughout each rendition For example, if a DVD author wishes to add thirty chapter points to each rendition, the chapter points could be added at four-second intervals throughout each rendition. In this way, the beginnings and ends of verses and choruses would be a maximum of two seconds away from the nearest chapter point. As such, it would not be necessary to identif' points manually in each clip and chapter point placement could be automated, for example using a simple automated software script.

Alternatively, it may be desirable to place chapter points more precisely, for example if respective renditions are different lengths and there need to be corresponding chapter points at temporally different but contextually corresponding times throughout the clips, as illustrated in Fig. 4.

In such cases, an author could replay each clip individually and note playback time codes at points where there is a desire for a chapter point. Then, using commercially available DVD authoring software, the chapter points could be added at the selected time code positions in each clip Of course, chapter points can be added in any other known way, for example, using commercially available DVD authoring software Once each clip has been authored to include associated chapter points, the menu buttons used for switching between renditions need to be arranged to cause a switch from one position in a first clip to a corresponding position (chapter point) in a second clip.

The diagrams in Figs. 1 OA to I OC illustrate three different ways in which menu buttons may be assigned or defined according to embodiments of the present invention. Each figure illustrates an alternative way of arranging menu button assignments for the Subpicture I stream of the data stream set in Fig. 9A. As shown in Figs. 10A to bC, three chapter points (CPn) are arranged to occur at three-second intervals in the data streams.

In Fig 1 OA, the menu buttons associated with the Subpicture I stream are assigned so that, if at any time a menu button is activated, the respective button causes playback to jump to the nearest preceding chapter point of the selected switched-to rendition. Specifically, in this example, for the first three seconds after the first chapter point CP 1, before reaching the second chapter point CP2.

usmg a menu button to switch to an alternative rendition causes switching to the nearest preceding chapter point CP I of the other rendition, in this way, no equivalent material of the switched-to rendition is skipped and missed, but a certain amount of the equivalent footage is repeated.

The diagram in Fig. lOB illustrates an alternative button arrangement. In this example, if at any time a menu button is activated, the button causes playback to jump to the nearest following chapter point of the selected switched-to rendition. Specifically, in this example, for the second three seconds after the second chapter point CP2, before reaching the third chapter point CP3, using a menu button to switch to an alternative rendition causes switching to the nearest following chapter point CP3 of the other rendition. In this way, no equivalent material of the switched-to rendition is repeated and a certain amount of the equivalent material may be missed.

The diagram in Fig. 1OC illustrates another alternative button arrangement. In this example, if at any time a menu button is activated, in dependence upon the particular time when the menu button is activated, the button causes playback to jump to either the nearest preceding or the nearest following chapter point of the selected switched-to rendition. Specifically, for the two second period after a chapter point, for example CP 1, using a menu button to switch to an alternative rendition causes switching to the nearest preceding chapter point CP I of the other rendition, so that no equivalent matenal is missed. However, after the first two second period, and before the second chapter point CP2 is reached, using a menu button to switch to an alternative rendition causes switching to the nearest following chapter point CP2 of the other rendition, so that a final second of equivalent material is skipped. This third example of menu button arrangement might be appropriate if, for example, chapter points are spaced relatively far apart and an author wishes to strike a balance between repeating too much equivalent material and skipping too much equivalent material of a switched-too rendition The ability to change menu button behaviour as playback progresses is made possible by having a sequence of individual menu button instances, for example every second or so, as shown in the Figs. 9A-9C and 1 OA- 1 OC. Each individual menu button instance can be arranged to cause a different action even though, during playback, the image on screen of the menu button may not change at all. Thus, according to embodiments of the present invention, thcrc are two benefits of having individual menu button instances; firstly, so that the menu does not disappear after a button is activated and, secondly, so that the behaviour of a menu button can change as playback progresses.

The repetition rate of the menu button instances is selected to accommodate both requirements while attempting to present a viewer with an optimum viewing experience.

The method by which switching between renditions of a performance will now be described with reference to the diagram of a Program Chain (PGC) in Fig. II. The diagram in Fig. 11 illustrates a PGC 1100 according to the DVD-Video format. A PGC 1100 typically contains a program control block (PCB) 1105, which contains an ordered list of pointers P1, P2, ... Pn, which dictates the replay order of cells AV1,..AVm, into which audiovisual content of, for example, a clip according to an embodiment of the present invention is encoded. The replay order of the cells is dictated by the order of the pointers in the PCB 1105. In addition to the pointers, a PGC may contain navigation commands including pre-commands, PreCMD, which precede the cell pointers, post commands, PostCMD, which follow the cell pointers, and cell commands C I, C2,. . . Cu, which execute after each respective cell has been played The navigation commands, which are similar to CPU instructions that execute on a typical personal computer, can be used to vary the playback behaviour of a DVD player, according to embodiments of the present invention.

The various renditions of a performance or the like can be arranged into PGCs in various ways, and the selected arrangement dictates how switching between renditions is achievable. For example, each rendition may have its own PGC or be spread across plural PGCs. Alternatively, more than one, or all, renditions may be addressed by the same PGC. A choice on how to arrange renditions in terms of PGC can be influenced by how long the renditions are, how many renditions there are and by how many transition points per rendition are required, since one PGC can only support a limited number of transition points.

In a first example, it will be assumed that each rendition is associated with its own PGC within a common Video Title Set (VTS). According to the DVD-Video format, it is possible to switch between PUCs (and chapter points within PGCs) using a single command as long as the PGCs are in the same VTS. En this case, the menu buttons associated with one rendition can each be defined as illustrated in the table in Fig. 12, which shows menu button assignments for the exemplary menu in Fig. 8B. The table comprises five columns. a first column identifying the rendition STUDIO, LIVE 1 and LEVE2 with which respective menu buttons arc associated; a second column showing, for each rendition, a playback position, in terms of chapter points 1 to n (CP I -CPn); and third fourth and fifth columns identifying for each playback position, a menu button assignment respectively for the STUDIO, LIVE I and LI\TE 2 menus buttons. Each row of the table is representative of all menu buttons instances that fall within a respectively specified period. For example, if the current rendition is LIVE 2, each chapter point is separated by five seconds and menu button instances repeat each second, then the menu button assignment for the row Before CP2' would apply to five consecutive menu button instances that lie in the timeframe between CP I and CP2 According to the table in Fig. 12, activating a menu button executes a single command that causes directly a switch to the nearest next corresponding chapter point in the selected rendition (although selecting a menu button associated with the rendition that is currently playing-back has no effect or no action') By way of an example, if the STUDIO rendition is currently playing back and the playback position is Before CP4', then activating the LIVE I menu button causes playback to switch to chapter point 4 (CP4) of the LIVE 1 rendition. In DVD-Video terminology, the button assignment causes a jump or link to (LNK) the PGC associated with LIVE I and, within that PGC. to chapter point 4.

In a second example, it will be assumed that each rendition is associated with its own PGC and each PGC is in a different VTS. In this case, a single menu button cannot directly' achieve the required switching operation. Therefore, the technique summarised by the table in Fig. 13 can be implemented.

The table in Fig 13 has the same rows and columns as the table in Fig. 12. However, the button assignments arc slightly different, as will now be described. In particular, each button assignment has two parts. a first part MOV REG n', which loads an internal, general purpose DVD register (GPRM), in this case labelled REG', with a variable n, which corresponds to the desired chapter point; and a second part LNK pgc' (where pgc can be STUDIO, LIVE 1 or LIVE 2), which switches playback to the beginning of the respective PGC (in another VTS). As illustrated in Fig. 11, each PGC has a PreCMD. When playback from a PGC in one VTS is switched to a selected PGC in another VTS, the PreCMDs (if present) are executed. In this case, the PreCMDs are arranged to use the value of the register REG to jump to the appropriate chapter point. The PreCMDs have the following structure: LNKCPI IFREG== I LNKCP2IFREG==2 LNK CP3 IF REG == 3 LNKCP4IFREG=4 LNK CP5 IF REG 5 LNK CPn IF REG == n In effect, the PreCMDs behave as a series of IF... .TFIEN statements, and cause playback to jump (or LNK), by virtue of a menu button assignment from the table in Fig. 13, to a particular chapter point, the number of which corresponds to the value stored in the register REG. In this way, a switching operation can be achieved using a single menu button, even though it is not possible, according to the DVD-Video format, to switch directly from one PGC to a specified chapter point in another PGC, if the two PGCs are m different VTSs.

According to third and fourth examples, switching between renditions using transition points can be achieved without using chapter points as such. In particular, a transition point can be realised by splitting a rendition into plural DVD-Video cells'. According to the present example, a rendition is arranged into plural cells, wherein the start of each cell is arranged to coincide with a desired transition point.

In the third example, it is assumed that each rendition is associated with the same PGC; that is, pointers within a single PGC address all the cells of each rendition. In this case, menu button assignments can resemble those illustrated m the table in Fig. 12, the difference being that the LNK commands jump directly to a particular cell number rather than to a particular PGC and chapter number. For example, each of the menu button assignments could have the form: LNKCELLn In effect, this button assigmnent causes a direct jump to the specified cell in the respective

PGC In the fourth example, it is assumed once more that each rendition is

associated with its own PGC. In this case, the menu button assignments resemble those in the table in Fig. 13, the difference being that a desired cell number, rather than a chapter point number, is loaded into the register REG, and the associated PreCMDs of the switched-to PGC link to a cell number of the rendition that corresponds to the value in the register REG, rather than to a chapter point number. For example, the menu button assignments could have the form: MOV REG n LNK LIVE I In effect, the two-part button assignment loads a cell number n into a GPRM, called REG, and then jumps to the PGC associated with the rendition LIVE 1. The PreCMDs of the PGC can then have the following form: LNK CELL 1IFREG== I LNK CELL 2 IF REG == 2 LNKCELL3IFREG==3 LNKCELL4IFREG==4 LNKCELL5IFREG==5 LNK CELL n IF REG == n From the foregoing it is clear that switching from the playback of one rendition to the playback of another selected rendition, at a corresponding point, can be achieved using the principle of transition points realised as either chapter points or cell boundaries, subject to restrictions in the DVD- Video format. The D\TDVicjeo restrictions can be summarised as: If renditions are in the same PGC: it is allowable to switch directly between one rendition and another using single.

direct menu button assignments associated with either chapter point or cell-based transition points If renditions are in different PGCs in the same VTS it is allowable to switch directly between one rendition and another using single direct menu button assignments associated with chapter points, or it is allowable to switch indirectly between one rendition and another, using a combination of menu button assignments and PGC PreCMDs associated with cell- based (or chapter point) transition points.

If renditions are in different PGCs and different VTSs: it is allowable to switch indirectly between one rendition and another, using a combination of menu button assignments and PGC PreCMDs associated with chapter points.

The foregoing examples generally show how switching between renditions can be implemented if, for example, switching occurs at point X in Fig. 5, wherein switching occurs at the time - or as near as possible after the time - when a viewer presses a remote controller key to activate a menu button of an on-screen user interface. However, with reference to a viewer pressing a remote controller at point Y in Fig. 5, whereafter the switching occurs at point El only after a delay, a slightly modified approach to switching needs to be taken, as will now be described with reference to the diagramin Fig. II.

In a first example of delayed switching, each section of a clip, for example of the NOVICE fitness video of Fig 7A, is associated with a separate, single PGC 1100. During normal playback, each section of the NOVICE level plays back in sequence, by virtue of the PostCMDs of a current PGC pointing to the next PGC. However, according to this example, rather than being arranged to enact a switching operation, when activated, the menu buttons are arranged to do nothing more than update a general purpose register, which will be identified as SWITCH, with one of two values, inter' and expert', respectively representing either the INTERMEDIATE level or the EXPERT level. The register has a default value, novice', which indicates that no switching operation has been selected.

During playback of the fitness video, for example, if a viewer activates a menu button associated with switching to the EXPERT level, the menu button causes SWITCH to be loaded with a value, expert, associated with the EXPERT level. The associated menu button assignment can have the form: MOV SWITCH expert Then, when the current section of the fitness video has completed, the associated PostCMDs of the POC are arranged to execute a conditional branch operation The operation contains logic that tests whether SWITCH has been modified (due to a menu button press) and, if it has, jumps to an appropriate PGC associated with the respective EXPERT clip. For example, assuming that section Ul-Vi of the NOVICE level has just completed, the PostCMDs of the respective PGC could have the following form: LNK PGC_V1 IF SWITCH = novice LNK PGC_V2 IF SWITCH = inter LNK PGC_V3 IF SWiTCH = expert In other words, these PostCMDs cause a jump to the appropriate next PGC, PGC_Vn, on the basis of the value stored in SWITCH if the default value, novice, remains then the PGC, PGC_V I, associated with the next section VI of NOVICE plays if the value of SWITCH has been updated to inter then the next section V2 of the PGC, PGC_V2, associated with INTERMEDIATE plays, or, if the value of SWITCH has been updated to expert then the next section V3 of the PGC, PGC_V3, associated with EXPERT plays.

In the foregoing example, a transition point according to embodiments of the present invention is realised by the start of a PGC. Obviously, in this example, each clip would have five associated PGCs, one for each section, and the associated PostCMDs of each PGC would cause a switch to a respective next PGC of either the same, or a selected different, level.

In a second example of delayed switching, each clip is associated with a single PGC (NovicePGC, IntcrPGC and ExpertPGC) and the start of each section of the clip is associated with a chapter point, CPn. In addition, each section is arranged as one cell, so that a cell command can execute after each section has completed.

The menu buttons are assigned to update the SWITCH register with a respective value associated with either the INTERMEDIATE or EXPERT level An exemplary menu button assignment in this example can have the form: MOV SWITCH bc Then, at the end of a section, the respective cell command executes a conditional jump instruction, which determines whether the SWITCH register value has been updated and, if it has, causes a jump to a so-called dummy PGC. According to the DVD-Vidco specification, a dummy PGC (dPGC) contains only instructions and no pointers to audiovisual content In this example, the value of bc depends on two factors. A first factor is whether the desire is to switch from, for example, NOVICE to INTERMEDIATE or EXPERT. A second factor is which section within the desired level to start from. As already described, menu button instances are repeated every second or so, and the assignment changes in each new section; the assignment S repeating but remaining the same within each section. Since a cell command can only have a single operation, both factors can be accommodated by the value of bc. In the present case, the value of bc can be any number in the range 100-299, where numbers in the range 100-199 relate to the INTERMEDIATE level and numbers in the range 200-299 relate to the EXPERT level Then, within each range, the numbers x00 to x99 indicate which chapter point to start from For example, if the value of bc is 103, this value is interpreted as a desired switch to the third chapter point, or section X2-Y2, of the INTERMEDIATE level.

A cell command, which executes the conditional jump instruction, can have the form: LNK dPGC IF SWiTCH < > novice In effect, the instruction tests to see if the value of SWITCH has been updated from the de1ult value of novice and, if it has, causes ajump to the dummy PGC called dPGC.

The dummy PGC, dPGC, has is arranged to have a sequence of conditional jump instructions, for example having the form: LNK lnterPGC, CPI IF SWITCH == 101 LNK lnterPGC, CP2 IF SWITCH 102 LNK lnterPGC, CP3 IF SWITCH == 103 LNK InterPGC, CP4 IF SWITCH == 104 LNK ExpertPGC, CPI IF SWITCH == 201 LNK ExpertPGC, CP2 IF SWITCH 202 LNK ExpertPGC, CP3 IF SWITCH 203 LNK ExpertPGC, CP4 IF SWITCH == 204 Thus, dPGC causes playback to branch to a particular chapter point CPn within a particular PGC (InterPGC or ExpertPGC; assuming that current playback is of the NOVICE level, or NovicePOC) on the basis of a single value, bc, in the register SWITCH. In this example. the transition points are, once again, chapter points.

It will be clear from the foregoing that there are many ways to implement a switching operation by using transition points. For example, switching may be direct, using menu button assignments to switch from playback of one rendition to anther, or indirect, using menu button assignments that update a register and then cause a jump to a new PGC, which includes PreCMD logic that jumps to the start location within the respective PGC. In addition, menu button assignments may do no more than update a register, and respective cell command, PostCMDs or even dummy PGC commands can be used to cause the required switching operation. Furthennore, switching may be instantaneous or delayed. Furthermore, a transition point can be realised in several different ways, including by using carefully positioned chapter points, carefully arranged cell boundaries or various PGC arrangements. Other ways of realising transition points are envisaged.

Fig. 14 shows an exemplary authoring apparatus as may be employed in preferred embodiments of the present invention. The authoring apparatus includes a computing platform such as a client-server computer system, or a stand-alone personal computer, 1430. Optionally, raw audio and video data are received, such as through a camera 1410 and a microphone 1420, or are provided from other sources such as a file storage device 1425, or are created within the authoring apparatus such as by image and sound capture and creation software. The raw content data may include video clips, audio clips, still picture images, icons, button images and other visual content to be presented onscreen. The content is suitably in the form of MPEG, JPEG or bitmap encoded files, but may take

any suitable format.

Original audiovisual data can take any form such as a movie, or a company presentation, or a quiz game, amongst many other possibilities. The computer 1430 acting as the authoring apparatus creates the desired audiovisual product using the procedures that have been described herein. The computer 1430 writes the audiovisual product 1445 onto a storage medium such as a hard disk drive within the computer 1430 or onto an optical disk 1440.

Fig. 15 shows the general structure of the audiovisual product 1540 in more detail. The audiovisual product 1540 includes a plurality of cells 1510, in this case represented by cells AV1, AV2. AVm. Each cell 1510 contains a short section of audiovisual data. The cells are played in sequence, typically one after the other, in order to deliver the intended audiovisual representation.

under control of a playback sequence instruction 1520. The sequence instructions 1520 as shown in Fig. 15 are separate from the cells 1510. Suitably, the cells 1520 and the sequence instructions 1510 are each allocated to structure locations within the audiovisual product 1540, so as to enable navigation between instructions 1520 and from instructions 1520 to cells 1510 In the preferred example of DVD-Video specification data, the cells 1510 are played in sequence through their inclusion by reference in programs (PGs), which are in turn organised into PGCs. In Fig. IS, the sequence instructions 1520 are represented by program chains PGCI, PGC2...PGCn. Preferably, each cell 1510 contains at least one video stream, at least one audio stream, and/or at least one sub-picture stream. Menu information is included in subpicture streams, which are interleaved with the video and audio streams in the usual known way.

A method of authoring a menu structure, of the kind described above, for use in association with plural clips or renditions will now be described with reference to the flow chart in Fig. 16. In step 1600, an author generates, acquires and collates all the assets needed for the intended DVD and stores the assets, for example, on a hard disc storage device 1425 The assets include at least a video presentation, the accompanying audio streams and the images for the menu and subtitle subpictures.

The subpicture images are typically generated using a software design package and stored as JPEG or bitmap graphics files The graphics files represent the menus shown in Figs. 8A and 8B. In step 1610, the author defines the menu button sets for the respective menus. The button sets may be defined generally in accord with the tables in Figs. 9, 10, 12 or 13. In step 1620, timIngs are assigned to the menus Timings relate to when the menus are available, for example for the entire video presentation or for one part or plural parts of the presentation. In the present examples, the menus are available, either by default or on demand, all of the time In a next step, 1630, the menu structure is expanded into plural instances according both to the aforementioned timings and to a selected menu instance repetition rate, for example one instance per second or so as described above. The expanding step may be enacted manually, for example by creating a definition of each of the menu instances for each one-second block of time. For a ten second timeframe, for example, this requires I 0x2=20 menu instance definitions for the menus of Figs. 8A and 8B. Of course, where there are plural clips or renditions, which may have a duration of several minutes or even longer, and each clip or rendition requires a menu button set definition every second, defining such a high number of menu instance definitions would be error-prone and laborious.

Accordingly, an authoring method according to preferred embodiments of the present invention automates the expanding step, as will now be described.

According to a first expanding step 1631, the author generates a software script, program or routine for automatically expanding the menu subpictures into plural menu instances. The routine is preferably written in a high-level, human-oriented programming language. In the preferred embodiment, this routine is created using JavaScript (JavaScript is a trade mark of Sun Microsystems mc). JavaScript is a relatively simple and user-friendly' programming language, which has been developed primarily for use in creating HTML-based web pages. However, the inventors have found that JavaScript can also be used in other applications, and has benefits in environments other than HTML documents. One advantage of JavaScript is that it is relatively simple to learn, and has become relatively widespread. Also, by contrast with languages such as Java, C, C++ and others, JavaScript is a text-based scripting language that produces a textual output. However, other languages are suitable for use in the present invention, including VBScript or JScript, amongst others.

The routine includes at least one iterative loop, or similar functional looping structure. That is, the program will repeat one or more times any instructions contained within the loop, as appropnate. As a simple example, the ioop is controlled by a variable such as the value "n", with the variable increasing in each iteration of the loop, such as for n equals from 1 to 10'.

In a second expanding step 1632, the author compiles the high-level routine for execution as machine code on an associated computing platform. That is, depending on the implementation of the high-level language and the execution environment employed, it is usually necessary to compile the program in order that the program can be executed on the computing platform. In the event the routine is interpreted at runtime, rather than being pre-compiled, then this step may be omitted In a final expanding step, 1633, the author executes the high-level routine on the computing platform 1430. Executing the routine includes running the iterative loop. For each iteration of the loop, a textual representation of a new menu instance is automatically created, as illustrated in the text file in Fig. 17.

As shown in Fig. 17, the iterative loop generates entries for each subpicture stream. Each entry specifies the instance number, the start time in frames (where the frame rate is thirty per second) and a display image of the menu. For subpicture 0, describing the menu shown in Fig. 8A, an illustrative bitmap image file, Menu_sub.bmp, is the graphics file containing the single menu button MENU. For subpicture 1, describing the menu shown in Fig. 8B, an illustrative bitmap image file, SwitchMenu_sub. bmp, is the graphic file containing the four menu buttons STUDIO, LIVE 1, LIVE 2 and MENU OFF Each menu instance in the text file is defined according to the variable (in this case "n") as adjusted for each iteration of the iterative loop. That is, in the first iteration, say n=0, the first menu instance in subpicture stream 0 is defined with appropriate parameters instance n' (that is instance 0') and frame [n*30] ' (that is frame 0'). In a second iteration, wherein n=1, the second menu instance is defined as instance 2' and frame 60'. The interactive loop continues to for each second (30 frames) for the duration of the respective clip. In this simple example, the loop control variable "n" is used to define a command operand. However, in most practical cases, other variables within the loop may be defined and adjusted.

The menu instances are added to an overall definition of the menu structure, for example, as represented by a table in Fig. 9 or Fig. 10. In the preferred embodiment of the present invention, the menu structure is suitably defined as a textual document, or a text-based database, and held within a memory or disk storage of the personal computer 1430. The document preferably identifies, or makes reference to, menu subpicture images, which arc typically pre-defined and stored in another storage location of personal computer 1430. A similar text-based representation is produced for associated highlight streams of the menus.

In a next step 1640 of the main process, an authoring software procedure automatically reads and interprets the textual documents and multiplexes and then interleaves respective menu definitions with the other assets, for example video and audio assets, of the DVD content. The result is a multiplexed and interleaved sequence of bytecodes, which conforms to the DVD-Video specification.

This step typically includes a step of importing into each menu instance the respective menu subpicture images, which are themselves then converted into bytecodes and placed as appropriate within the final multiplexed and interleaved sequence.

It will be appreciated that the aforementioned procedures may be adapted to produce menu button assignments for any of the examples described herein.

A similar set of procedures is used to generate highlight streams for use with the subpicture streams The foregoing automated authoring process is described in more detail in the present applicant's co-pending patent application GB0408599.9, the entire contents of which are hereby incorporated herein by reference.

The menus illustrated in Figs 8A and 8B define a two-level hierarchy That is a first menu (Fig. 8A) at a first level in the hierarchy is used to reveal a second menu (Fig 8B) at a second level in the hierarchy. In other embodiments of the present invention, the menu hierarchy may comprise further menus and further levels. Indeed, the menus may be arranged into a, so-called, drop- down' menu hierarchy in which, for example, when a menu button of one level is used to reveal a next-level menu of the hierarchy, while the first menu button remains visible. Drop down menu hierarchies are described in detail in the applicant's co-pending patent application GB0427535.0, the entire contents of which are hereby incorporated herein by reference That patent application also contains particular details relating to automating an authoring process to generate a drop down menu hierarchy.

Claims (1)

1 A media product compnsing plural audiovisual clips that relate to different versions of the same event or production and a user interface for facilitating dunng playback of a first clip switching from the first clip to a corresponding point of a second clip.

2. A media product comprising plural audiovisual clips, at least one clip provided with one or more transition points and a user interface for facilitating during playback of a first clip switching from the first clip to a transition point of a second clip 3. A media product according to claim 2 comprising plural clips, each having one or more predefined transition points 4. A media product according to claim 2 or claim 3, comprising at least one clip having plural transition points.

A media product according to any one of claims 2 to 4, wherein two or more clips have analogous transition points.

6. A media product according to any one of claims 2 to 5, wherein two or more clips have the same number of transition points.

7. A media product according to any one of claims 3 to 6, wherein at least some transition points of one clip have a temporal arrangement, which is substantially the same as a temporal arrangement of analogous transition points in another clip.

8 A media product according to any one of claims 3 to 7, wherein the transition points of one clip have a temporal arrangement, which is substantially different from the temporal arrangement of analogous transition points in another clip 9. A media product according to any one of claims 2 to 8, wherein two neighbouring transition points in one clip have a temporal spacing that is different from the temporal spacing of two analogous neighbouring transition points in another clip.

A media product according to any one of claims 2 to 9, wherein a contextual arrangement of transitions points in one clip is substantially the same as a contextual arrangement of analogous transition points in another clip 11. A media product according to any one of the preceding claims, wherein the user interface facilitates switching from the first clip to a temporally equivalent position in the second clip. (

12 A media product according to any one of the preceding claims, wherein the user interface facilitates switching from the first clip to a contextually equivalent position in the second clip.

13. A media product according to any one of the preceding claims, wherein the user interface provides a menu comprising at least one menu option, the menu being displayable during playback of a clip and comprising a menu option to cause display of another clip 14. A media product according to any one of the preceding claims, wherein the user interface provides at least a first menu and a second menu, each menu compnsing at least one menu option, the first menu being displayable during playback of the clip and comprising a menu option to cause display of the second menu during playback of the clip.

15. A media product according to claim 14, wherein the second menu comprises a menu option or options for switching between the clips.

16. A media product according to any one of claims 13 to 15, wherein the menu(s) is/are arranged to be displayed at least partially transparently.

17. A media product according to any one of claims 13 to 16, wherein each menu comprises a sequence of individual menu instances or definitions, which are arranged to coincide, temporally at least, with a playback sequence of the clip or clips.

18. A media product according to claim 17, wherein the individual instances or definitions of the first menu are arranged into an addressable data stream or streams and the individual instances or definitions of the second menu arc arranged into a different addressable data stream or streams.

19 A media product according to claim 18, wherein individual instances or definitions of the first menu include a menu option that switches to a display of the addressable data stream of the second menu.

20. A media product according to any one of the preceding claims, comprising an optical disc product 21 A media product according to any one of the preceding claims, wherein the switching operation is substantially seamless.

22. A method of authoring a media product comprising the steps of: a. selecting plural media clips; b. identifying for each clip plural corresponding transition points, at which playback may switch between the clips, and c. providing a user interface to enable a user to switch between corresponding transition points5, wherein the temporal spacing between transition points within one clip is different from the temporal spacing of the corresponding transition points within another clip