T. Wahl and K. Rothermel. Representing time in multimedia systems. In Multimedia Computing and Systems, Boston, USA, May 1994.  Home/Search   Document Details and Download   Summary   Related Articles   Check

....great use in presentations where the duration of items is statically known. This particular system includes other powerful features relating to its hypermedia usage. Temporal relations: A number of authors have built systems based on the well known Allen relations [All83] or on variations of them [SHT96, WR94]. These relations are binary, but may be composed to relate arbitrary sets of items. Such temporal relations encompass the timeline approach, but in addition provide for indeterminate speci cation, as will occur with the display of a media item, or with a delay, whose duration is unpredictable ....

....and is fully deterministic since the start time and duration of every item, that is, each of the ve rings and the intervening periods of silence, are known in advance. This level can equally well be speci ed using any of the sets of temporal relations referred to above, for example those in [WR94]: line105 before(25) line106 line105 before(0) five rings five rings before(0) line106 line106 cobegin(0) pick up phone We are grateful to Bob Morris for suggesting this to us. 3 Level Two: The actor is now given a measure of artistic licence. She may pick up the phone any time after line ....

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T. Wahl and K. Rothermel. Representing time in multimedia systems. In Proc. of the Int. Conf. on Multimedia Computing and Systems, 1994. 13

....in our model are based on temporal constraints to specify the execution scenario of their component activities. Our proposition is mainly based on works axed on time specification for the management of multimedia data presentation. Such works have resulted in temporal relations definition [13][14][15] causal relations between intervals [16] and synchronous and asynchronous relations specification [9] In reference to these works and after having identified useful relations between activities we have built the six temporal operators presented in fig.1, where A and B are activities process, ....

T. Wahl & Rothermel, Representing Time in Multimedia Systems, Proc. IEEE Conference on Multimedia, Boston, 1994.

....by C components, according to a temporal specification. Different methods include interval, axes, control flow, event, and script based synchronization specifications[19] The information provided in the Event Descriptors is designed to support such specifications. Interval based methods [8, 1, 22] allows specifications such as e1 before e2 and e1 while e2 for events e1 and e2. We have based our design upon a common knowledge of global time in all components. It is well known that in a distributed system, global time can only be available down to certain levels of accuracy. The most widely ....

T. Wahl and K.Rothermel. Representing time in multimedia systems. In Proceedings of International Conference on Multimedia Computing and Systems, pages 538--543. IEEE Computer Society Press, 1994.

....components. We consider both spatial distributions of objects and objects stacking up. ii) temporal aspects, i.e. when are the components presented. The topic of relations between temporal intervals has been addressed in [1] This model has been widely used in the context of multimedia systems [9]. We propose some extensions to declarative temporal models such as [3] and [4] iii) composition aspects, i.e. how define the logical structure of the document. iv) database aspects, can express collection features or constraints. This means that query results can be used as a whole in the ....

T. Wahl, Rothermel, Representing Time in Multimedia Systems, Proceedings of IEEE Conference on Multimedia, Boston, U.S.A., 1994.

.... this paper, we present existing models (Section 2) present the proposed composition model (Section 3) give some examples (Section 4) and outline conclusions (Section 5) 2 Existing models Existing temporal models for multimedia can be divided into two classes: point based and interval based [23]. In point based models, the elementary units are points in a time space. Eachevent in the model has its associated time point. The time points arranged according to some relations suchasprecede, simultaneous or after form complex multimedia presentations. An example of the point based ....

....unstructured graph and temporal consistency must be verified. An interesting feature of the model are user interactions allowing forward and backward skips in a complex presentation. TIEMPO [24] considers integration of user interactions in a previously developed temporal composition model [23]. A fixed set of user interactions is defined and it includes either selections or Temporal Access Control functions such as for example pause, faster or backward. The model also proposes hierarchical grouping by means of macros. King proposes a different formalism based on an interval temporal ....

T. Wahl and K. Rothermel. Representing time in multimedia systems. In Proc. IEEE International Conference on Multimedia Computing and Systems., Boston, MA, May 1994.

....comprehensible. and to reduce explicit temporal constraints. We do not show the syntax here, but restrict ourselves to the presentation of a generic temporal interval model that is depicted in Fig. 7 in comparison to the well established generic models of OCPN [11] and the interval relations from [14]. On sequence diagrams, we can distinguish different dimensions of time: virtual, local) object time for each (application) object LectureDiscussion.start(x) application x:SubjectVideo application x.sound:Speech application x.subs:Subtitle application trail:Trailer ....

T. Wahl and K. Rothermel. Representing time in multimedia systems. In Proc. IEEE 1st Intl. Conf. on Multimedia Computing and Systems (ICMCS'94), pages 538--543.

....of internal or external non deterministic events. 1.1 Keywords Hypermedia documents, temporal consistency, formal verification, RT LOTOS, internal and external nondeterminism. 2. Introduction Different models have been proposed in the literature to express temporal constraints [Allen 83] Wahl 94] but relatively few works have dealt with the analysis of temporal scenarios [Buchanan 93] Kim 95] Results from the artificial intelligence area, like the temporal CSP (Constraint Satisfaction Problem) Vidal 95] have been used within the multimedia area, with the purpose of expressing and ....

Wahl, T.; Rothermel, K. Representing time in multimedia systems. IEEE Int. Conf. on Multimedia Computing and Systems, May 1994

....describe the interactions that trigger the actions in the course of an IMAP. One of the important aspects in the modeling of IMAPs is the spatio temporal composition to relate multiple media in the temporal and spatial dimension. There are several approaches to model the temporal aspects of IMAPs [3, 13,19], while the spatial aspects are rather under addressed in the literature. Some of the interesting efforts in this area are [9, 18] 2.1 Temporal aspects of IMAPs To make the media objects participating in an IMAP scenario perceptible, they must be presented for a certain period of time, i.e. ....

T. Wahl, K. Rothermel. "Representing Time in Multimedia Systems". In Proc. of the IEEE Int. Conf. on Multimedia Computing and Systems, Boston MA, pp. 538-543.

....specifications cannot model nondeterminism (objects with unknown durations) It should also be pointed out that both the scripting and timeline approaches do not scale well. The relation based specifications can be further divided into two major flavors: interval based vs. point based [17]. In interval based models, each media object is associated with a temporal interval, which is characterized as a nonzero duration of time. According to Allen, given any two temporal intervals, there are 13 mutually exclusive relationships [1] The 13 temporal relations can be represented as ....

....are inverse relations, by simply swapping the labels. For instance, after is the inverse relation of before. In point based approaches, relations are based on time instants. Given two time instants, there are 3 mutually exclusive relationships, namely before ( simultaneous to ( and after ( [17]. Few existing multimedia systems are solely based on point based specifications; Madeus [9] is purely based on Allen s interval relations; most other systems, such as CMIF [7] ISIS [11] OCPN [13] Firefly [5] and CHIMP [6] are based on a hybrid of the two approaches. Our temporal ....

T. Wahl and K. Rothermel. Representing Time in Multimedia Systems. Proceedings of IEEE ICMCS'94, pp. 538-543, May 1994.

....models, it is very hard to represent iterative document scenarios using the CMIF model, and it is unclear from the literature [9] how hyperlinks are represented, i.e. how the change of presentation course can be represented, in the CMIF model with other elements. The TIEMPO of Wahl et al. 11] [10] supports various user interactions and temporal synchronizations through interval based temporal relations and hierarchical grouping of media items. It supports various temporal relations of equalities and inequalities. However, the graphical illustrations of document scenarios become very ....

T. Wahl and K. Rothermel. Representing time in multimedia system. Technical Report TR-93-12, Universitat Stuttgart, Germany, 1993.

....Figure 1 Binary Temporal Relations [1] Advanced model of synchronization based on intervals. Based on Allen s binary temporal relations, Wahl and Rothermel defined their model of synchronization based on inter vals with 29 temporal relations identified as relevant to multimedia presentation [18]. These relations were used to define the 10 operators shown in Figure 2. A d1 before(d1) B A d1 beforeendof(d1) B A d1 cobegin(d1) B A d1 coend(d1) B A d1 d2 while(d1 , d2) B A d1 d2 delayed(d1 , d2) B A d1 d2 startin(d1 , d2) B A d1 d2 endin(d1 , d2) B A d1 d2 cross(d1 ....

.... B A d1 cobegin(d1) B A d1 coend(d1) B A d1 d2 while(d1 , d2) B A d1 d2 delayed(d1 , d2) B A d1 d2 startin(d1 , d2) B A d1 d2 endin(d1 , d2) B A d1 d2 cross(d1 , d2) B A overlaps(d1 , d2, d3) d1 d2 d3 B Figure 2 Ten operations of synchronization based on intervals [18] B B B A A A A B A equals B A starts B A overlaps B A before B B B B A A A A meets B A during B A finishes B In this figure, each arrow indicates that the starting or ending point of object A activates a delay which, when finished, determines the starting or ending of object ....

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Wahl, T.; Rothermel. K.; Representing Time in Multimedia Systems. Proceedings of International Conference on Multimedia Computing and Systems, p. 538-543, May, 1994. Annex A

....be assertions, used perhaps for consistency checking, rather than constituents of the specification of the relation. King [Kin96] refers to these specifications as display forms. By way of concluding this section, we note that the Allen taxonomy is not the only one of use. Wahl and Rothermel [WR94] develop a set of twenty nine interval relations, derived from an initial set of relationships between start and end points of media items. They then demonstrate how the twenty nine may be reduced to ten generic relationships similar to the four just given. Keramane and Duda [KD96] present a set ....

Thomas Wahl and Kurt Rothermel. Representing time in multimediasystems. In Proceedings of the IEEE International Conference on Multimedia Computing and Systems, pages 538--543, 1994.

....adaptation, and presentation neutral representation, which we expect to be demanded more and more by future multimedia applications. The requirements constitute a metric along which selected multimedia document models are analyzed in Section 4. Temporal model. A temporal model (see also [17, 24, 5, 8]) describes temporal dependencies between the media elements of a multimedia document. One can find four types of temporal models: point based temporal models, interval based temporal models, and event based temporal models. Another way to specify temporal relations between media elements is by ....

T. Wahl and K. Rothermel. Representing Time in Multimedia Systems. In Proc. IEEE International Conference on Multimedia Computing and Systems, pages 538--543, Boston, MA, May 1994.

....order. Possible approaches could be to provide policies as service configuration options or to introduce up calls to the application level to let the user decide and make event composition programmable. As many applications like CSCW need more powerful temporal relations between composite events [48], we suggest to think of composite events having a start and endpoint thus associating an interval with the composite event instead of using the timestamp of the terminating event. Then we can provide composition operators that allow for interval relations [1] Applications with demands for high ....

T. Wahl and K. Rothermel. Representing Time in Multimedia-Systems. IEEE Conf. on Multimedia Computing Systems, Boston, 1994.

....The temporal characteristics of continuous media types are one of the most important features of multimedia systems. Thus, different models have been dedicated to modeling temporal behavior and timing constraints (e.g. the timed Petri nets OCPN in [15] or the interval based modeling presented in [23]) More elaborate models also account for interactivity (e.g. the timeline tree model of [12] since typical multimedia applications are expected to be highly interactive. Some of these models are rather technical, e.g. OCPN [15] The MOAP approach presented in [24] is merely a textual ....

T. Wahl and K. Rothermel, Representing time in multimedia systems, Proc. IEEE 1st Intl. Conf. Multimedia Computing and Systems, Boston MA, May 1994, pp. 538-543.

....offers more flexibility for the management of the Quality of Service parameters. For instance, a temporal formatter can optimize a temporal layout by stretching or shrinking media components durations [BZ93] ffl modeling synchronization non determinism in inter media synchronization schemes [WR94] In particular, indeterminate synchronization schemes allow the partial and imprecise knowledge of a system to be expressed. ffl handling environmental mismatches. Due to portability concerns and to the asynchronous behavior of distributed hypermedia systems, multimedia presentation scenarios ....

T. Wahl and K. Rothermel. Representing Time in Multimedia Systems. In Proc. IEEE Int. Conf. on Multimedia Computing and Systems, pages 538--543, Boston, May 1994.

....another fixed amount of time d2 Intervals In the interval based synchronization specification, the presentation duration of an object is called an interval. 13 different types of synchronization have been defined for synchronizing two time intervals. The enhanced interval based model, defined in [11], identifies 29 interval relations identified as relevant for multimedia presentations. Constraint cWhile[sB,sA,eA,eB] d1,d2,d3,d4:time) where sA, sB, A B [d1,d2] A B [d1,d2] d3,d4] B A [d1,d2] A B [d1,d2] A B [d1,d2] A B [d1,d2] d3,d4] A B [d1,d2] d3,d4] A B [d1,d2] ....

T. Wahl and K. Rothermel. Representing Time in Multimedia Systems. In Proc. IEEE Int. Conf. on Multimedia Computing and Systems, pages 538-- 543, Boston, May 1994.

.... Some models handle a communication delay by adjusting the playout deadline schedule for the media streams; however, they do not provide the necessary actions for different communication delays [1, 5, 7] Third, existing conceptual models are either too complex for the users to understand [1, 7, 10, 11] or too simple to let users see the whole view of the presentation schedule [5] Fourth, few existing conceptual models model both temporal and spatial relations. They either develop a temporal model to capture synchronization information [1, 5, 7, 10, 11] or use image computer vision techniques ....

....too complex for the users to understand [1, 7, 10, 11] or too simple to let users see the whole view of the presentation schedule [5] Fourth, few existing conceptual models model both temporal and spatial relations. They either develop a temporal model to capture synchronization information [1, 5, 7, 10, 11] or use image computer vision techniques to get content based information in the image or video. In our previous works, we have already shown that an augmented transition network (ATN) and multimedia input string can model the temporal and spatial relations, user interaction, user loop, graphical ....

T. Wahl and K. Rothermel, "Representing Time in Multimedia Systems," Proc. Int'l Conf. on Multimedia Computing and Systems, CS Press, Los Alamitos, Calif., pp. 538-543, 1994.

....the interactions that trigger the actions in the course of an IMAP. One of the important aspects in the modeling of IMAPs is the spatio temporal composition to relate multiple media in the temporal and spatial dimension. There are several approaches to model the temporal aspects of IMAPs [LG93,WR94, BZ93, Ho92] while the spatial aspects are rather under addressed in the literature. Some of the interesting efforts in this area are [VTS96, IDG94] 2.1 Temporal aspects of IMAPs To model the temporal aspects of an IMAP we consider a suitable representation of time. A unique point in time is ....

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T. Wahl, K. Rothermel, "Representing time in multimedia systems". In Proceedings of the IEEE Int. Conference on Multimedia Computing and Systems, Boston MA, pp. 538-543.

.... this purpose, we developed a simple temporal synchronization model, the Media Relation Graph (MRG) and its SGMLconforming [16] file format, HSL (Hypermedia Synchronization Language) MRG, our synchronization model, is based on a hybrid of interval based and point based synchronization approaches [17]. The presentation of an HSL document is achieved by traversing the vertices in the corresponding MRG in the appropriate order; the authoring of an HSL document is simply a stepwise construction of the corresponding MRG. The Hypermedia Presentation and Authoring System (HPAS) is the testbed for ....

....specifications cannot model nondeterminism (objects with unknown durations) It should also be pointed out that both the scripting and timeline approaches do not scale well. The relation based specifications can be further divided into two major flavors: interval based vs. point based [17]. In interval based models, each media object is associated with a temporal interval, which is characterized as a nonzero duration of time. According to Allen, given any two temporal intervals, there are 13 mutually exclusive relationships [1] The 13 temporal relations can be represented as ....

[Article contains additional citation context not shown here]

T. Wahl and K. Rothermel. Representing Time in Multimedia Systems. Proceedings of IEEE ICMCS'94, pp. 538-543, May 1994.

.... of this paper, we present existing models (Section 2) present the proposed composition model (Section 3) give some examples (Section 4) and outline conclusions (Section 5) 2 Existing models Existing temporal models for multimedia can be divided into two classes: pointbased and interval based [23]. In point based models, the elementary units are points in a time space. Each event in the model has its associated time point. The time points arranged according to some relations such as precede, simultaneous or after form complex multimedia presentations. An example of the point based ....

....unstructured graph and temporal consistency must be verified. An interesting feature of the model are user interactions allowing forward and backward skips in a complex presentation. TIEMPO [24] considers integration of user interactions in a previously developed temporal composition model [23]. A fixed set of user interactions is defined and it includes either selections or Temporal Access Control functions such as for example pause, faster or backward. The model also proposes hierarchical grouping by means of macros. King proposes a different formalism based on an interval temporal ....

T. Wahl and K. Rothermel. Representing time in multimedia systems. In Proc. IEEE International Conference on Multimedia Computing and Systems., Boston, MA, May 1994.

....and third, adapt the presentation in a user controlled manner to the given resource situation. Of course, the third approach requires an appropriate document model as well as an adaptive scheduling mechanism. In this paper, we are going to propose extensions to the temporal model Tiempo 1 [7, 8] to support this type of adaptability. The Tiempo model is hierarchical. Temporal dependencies between media objects are defined by so called interval operators. Interaction is modeled by reaction relations. The desired adaptability is achieved by selection groups and Quality of Service ranges. ....

....by single or composite media objects. The CTS of the top composite object represents the whole document and its presentation interval the document presentation period. To define the temporal layout of a CTS, presentation intervals of contained media objects are arranged by interval operators [7] relative to each other or the CTS. The specification example in Figure 1 describes a scene where an animation is presented after a video clip. Here, the interval operator before specifies that the animation has to be started 1 second after the video has ended. The cobegin operator describes ....

Thomas Wahl and Kurt Rothermel. "Representing Time in Multimedia Systems", in Proc. of IEEE 1st Intl. Conference on Multimedia Computing and Systems, Boston, USA, pp. 538--543, 1994.

.... that occur, for instance, in the context of user interaction in multimedia presentations (e.g. Object Composition Petri Nets (OCPN) LG93] Therefore, enhanced interval based temporal models have been proposed to handle open time intervals and indefinite interval relationships [DK95, HFK95, WR94] In an event based model of time, events determine the temporal course of the presentation. An event is connected to actions and when an event occurs, e.g. a video reaches a certain point in time, the corresponding actions, typically start and stop of the presentation of other media elements, ....

T. Wahl and K. Rothermel. Representing Time in Multimedia Systems. In Proc. IEEE International Conference on Multimedia Computing and Systems, pages 538--543, Boston, MA, May 1994.

....last alternative, flexible document models are required, which allow to compile different presentations from a given document specification depending on the resource situation. In the TIEMPO 1 project which was supported by the Deutsche Forschungsgemeinsachaft (DFG) a flexible document model [12, 15, 16] was developed. In this model documents are composed of single media objects, such as video, audio or text, and composite media objects, such as pages or scenes. The desired adaptability is achieved by selection groups which allow to define alternative media objects or presentation parts ....

....samples or pictures are positioned. The arrangement of data units and the extent of a single media objects TS is fixed when its content is generated. To define the temporal layout of a composite media objects TS, presentation intervals of included media objects are arranged by interval operators [12]. In Figure 1, the left side shows a simplified composite media object specification and the right side shows how the temporal layout of the presentation is generated by projection of TSs. In this example, the interval operator before specifies that the animation should be started 1 second after ....

Thomas Wahl and Kurt Rothermel. "Representing Time in Multimedia Systems," in Proc. IEEE Intl. Conference on Multimedia Computing and Systems, Boston, USA, pp. 538--543, 1994.

....The synchronization requirements must be speci ed to the application, so that the application can invoke services, protocols and mechanisms for its provision. Known synchronization speci cations are time axis based speci cation, timed petri nets, interval based speci cation, or time ow graphs ([SN95, Lit93, LKG94, WR94, PLL96], etc. From the synchronization speci cation, the internal system derives presentation schedulers and local synchronizers. Examples of systems which include this type of schedulers are MODE [Bla93] multimedia teleorchestra [LKG94] continuous media I O server [AH91] or ACME [AH91] systems. ....

T. Wahl and K. Rothermel. Representing Time in Multimedia Systems. In Proceedings of Multimedia Computing and Systems, pages 538-543, Boston,MA, May 1994.

....(7) In the tree model, the circles represent the times that asynchronous events (corresponding to the symbols shown at the circle) become activated. Those events will be deactivated only when the presentation flow branches to another timeline. 2. 4 Example The following example, also used by [5] (but without the Logo Graphic) illustrates the use of different timelines. Figure 10 shows how an author can create a scenario with the following properties: any slide starts being rendered three seconds before its corresponding talk to allow a silence period to give viewers a first impression ....

.... End End Start Start Start Audio1 Video Audio2 Simultaneous with Simultaneous with Simultaneous with Simultaneous with Simultaneous with Simultaneous with Simultaneous with Start Start Simultaneous with No response Engine Figure 15 : Firefly temporal view of the car example Wahl and Rothermel [5] have presented a high level interval based temporal model by defining powerful operators that include both temporal equalities and inequalities between events. Each operator is represented by a certain pattern of edges that are labeled with delay values. As before, in complex interactive ....

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T.Wahl and K. Rothermel, "Representing Time in Multimedia Systems," Proc. of the International Conference on Multimedia Computing and Systems, IEEE Computer Society Press, Los Alamitos, CA , pp. 538-543, May 1994.

....objects ends with their selection by a user. Two continuous presentation objects could be simultaneously started without knowing the end of each single presentation. Therefore, enhanced temporal interval models have been proposed to handle open time intervals and indefinite interval relationships [12, 36]. When creating a multimedia composition it might be desirable to change the appearance of presentation objects during their presentation. This alteration can be requested interactively or can be specified in the multimedia composition. The modeling of the temporal course must therefore include ....

T. Wahl and K. Rothermel. Representing Time in Multimedia Systems. In Proceedings of the International Conference on Multimedia Computing and Systems, pages 538--543, Boston, MA, May 1994. IEEE Computer Society Press.

....we are investigating the relationship between active and realtime databases because we think that this can be useful to efficiently handle multimedia data. Several other works on temporal (multimedia) database has also been used to define the STORM model [Allen83, Adiba86, Adiba90, Little90] In [Wahl94] one can find an interesting study of different concepts to represent time in multimedia systems. First, point based and interval based frameworks are compared and translations between them are discussed. Then, an evaluation of multimedia time models is provided. Third, multimedia in general and ....

T. Wahl, K. Rothermel, Representing time in multimedia systems, International Conference on Multimedia Computing and Systems, Boston, Mass., May 1994

....over heterogeneous platforms. In this context, during the multimedia hypermedia authoring process, one of the main issues concerned is the specification of the temporal and logical behavior of these applications. The literature points out several models to specify these constraints [9,10,11,12]. Thus, Courtiat et al. 14] proposed a general purpose model that integrates all these models into one design process which can be used for modelling temporal and logical synchronizations of a multimedia hypermedia document. Based on the model proposed by Courtiat et al., this paper proposes an ....

.... wait(d) ev2; exit endproc process cBeforeAtLeastAndNoMore[ev1,ev2] d1:time,d2: time) exit is ev1; wait(d1) ev2 t [t = d2 d1) exit endproc Figure 3 Temporal Equalities and Inequalities Another temporal constraint model additioned in the constraint library was proposed by Wahl et al. [10], in which interval based synchronization specifications are used to produce 13 different object models. An interval is considered to be the duration of an object presentation. Some of the E LOTOS specifications of these models are depicted in Figure 4. process cWaitLatest[eA,eB,eC,end] exit is ....

[Article contains additional citation context not shown here]

Wahl, T.; Rothermel, K, "Representing Time in Multimedia Systems", In Proc. IEEE Int. Conf. on Multimedia Computing and Systems, pages 538-543, Boston, May, 1994.

....and third, adapt the presentation in a user controlled manner to the given resource situation. Of course, the third approach requires an appropriate document model as well as an adaptive scheduling mechanism. In this paper, we are going to propose extensions to the temporal model TIEMPO 1 [12, 13] to support this type of adaptability and an adaptive scheduling algorithm. In Tiempo, documents are composed of single media objects, such as video, audio or text, and composite media objects, such as pages and scenes. The temporal dependencies between media objects are defined by so called ....

....by single or composite media objects. The CTS of the top composite object represents the whole document and its presentation interval the document presentation period. To define the temporal layout of a CTS, presentation intervals of contained media objects are arranged by interval operators [12] relative to each other or the CTS. Figure 1 shows the available interval operators. In the specification example in Figure 2, the interval operator before specifies that the animation should be started 1 second after the video has ended. The cobegin operator describes that the CTS starts with ....

Thomas Wahl and Kurt Rothermel. "Representing Time in Multimedia Systems," in Proc. of IEEE 1st Intl. Conference on Multimedia Computing and Systems, Boston, USA, pp. 538--543, 1994.

.... (Section 2) analyze possible arrangements between two time intervals (Section 3) present the proposed composition model (Section 4) and outline conclusions (Section 5) 2 Existing models Existing temporal models for multimedia can be divided into two classes: point based and interval based [13]. In point based models, the elementary units are points in a time space. Each event in the model has its associated time point. The time points arranged according to some relations such as precede, simultaneous or after form complex multimedia presentations. An example of the point based approach ....

T. Wahl and K. Rothermel. Representing time in multimedia systems. In Proc. IEEE International Conference on Multimedia Computing and Systems., Boston, MA, May 1994.

....as we do not know the termination instant of our media items, we cannot align it on a time axis, which is the traditional approach of defining multimedia schedules. So for specifying interaction, traditional deterministic temporal models such as the time line approach are no longer applicable [WaRo94] Therefore, the supported temporal interaction this is interaction that affects the temporal layout of a multimedia title has a significant impact on the design of multimedia authoring systems. 2. Classification of temporal interaction forms 3 Currently, we are developing the TIEMPO ....

....event that might occur during presentation. So at authoring time, we do not know when the user will interact. Consequentially, only temporal models that include uncertainty are applicable for modeling interaction. e.g. deterministic models such as the time line model are not appropriate [MeMo94] WaRo94] Indeterministic relational models include uncertainty because only known relations are specified and the author is not forced to specify a relation if it is not predictable. Temporal models can be based on instants as their elementary unit, e.g. in [BuZe93] BuZe92] or on intervals [WaRo94] ....

[Article contains additional citation context not shown here]

Thomas Wahl and Kurt Rothermel. Representing Time in Multimedia Systems. In IEEE 1st Intl. Conference on Multimedia Computing and Systems, Boston, pages 538--543, 5 1994. 7. Summary 17

....this complexity, a second goal of TIEMPO is to offer an authoring interface for easy and rapid composition of multimedia titles. This paper presents the system design and architecture of the TIEMPO authoring and presentation environment. Further information on temporal modeling can be found in [WaRo94] and on interaction and user interface modeling in [WWR95] The paper is organized as follows. In section 2, we describe the research goals of TIEMPO. In section 3 we describe the applied notations to describe specifications for various purposes. Then, the architecture of the presentation system ....

....topics integrated in a presentation, their preparation can be neglected in case of limited system resources. The development of synchronization strategies is still not finished and the presentations are not optimized so far. 5. Authoring scenario We have defined an interval based temporal model [WaRo94] which is used by the TIEMPO language. Currently, we have just finished the first version of the graphical document editor prototype. Figure 5 shows the temporal view of the editor with a presentation specification. 5. Authoring scenario 10 As the editor is object oriented, the graphical ....

Thomas Wahl and Kurt Rothermel. Representing Time in Multimedia Systems. In IEEE 1st Intl. Conference on Multimedia Computing and Systems, Boston, pages 538--543, 5 1994.

....general document standard for multimedia would alleviate this problem. HyTime [HyTi92] defines a standardized language for specifying the essentials of multimedia documents, such as addressing documents or defining temporal constraints. When developing our multimedia presentation system TIEMPO 1 [WaRo94], we considered HyTime as a document model. The architecture of HyTime is described by [Gold91] and [NKN91] Further, Erfl94] examined how to specify synchronization constraints in HyTime but he excludes the question how to specify interaction. As multimedia application tools increasingly support ....

....compatibility was one of the intentions of the standardization process. Therefore, new interactive multimedia applications require standardized architectural forms with a predefined semantics. Further, it would be advantageous to have HyTime variables to express indeterministic temporal relations [WaRo94], which exist in interactive systems because many temporal relations are not resolved before rendition time due to interactive events. A Standard Multimedia Scripting Language (SMSL) is currently developed by the International Standards Organization [BRR94] By SMSL, embedding scripting languages ....

Thomas Wahl and Kurt Rothermel. Representing Time in Multimedia Systems. In IEEE 1st Intl. Conference on Multimedia Computing and Systems, Boston, pages 538--543, 5 1994.

....general document standard for multimedia would alleviate this problem. HyTime [HyTi92] defines a standardized language for specifying the essentials of multimedia documents, such as addressing documents or defining temporal constraints. When developing our multimedia presentation system TIEMPO 1 [WaRo94], we considered HyTime as a document model. The architecture of HyTime is described by [Gold91] and [NKN91] Further, Erfl94] 1 TIEMPO: grant of the Deutsche Forschungsgemeinschaft DFG Temporal integrated model to present multimedia objects 2 Interaction 1 examined how to specify ....

....element types with a predefined Figure 7: Projection with reverse interactions unprojected event projected events projection projection proj. time reverse reverse 7 References 18 semantics. Further, it would be advantageous to have HyTime variables to express indeterministic temporal relations [WaRo94], which exist in interactive systems because many temporal relations are not resolved before rendition time due to interactive events. A Standard Multimedia Scripting Language (SMSL) is currently developed by the International Standards Organization [BRR94] By SMSL, embedding scripting languages ....

Thomas Wahl and Kurt Rothermel. Representing Time in Multimedia Systems. In IEEE 1st Intl. Conference on Multimedia Computing and Systems, Boston, pages 538--543, 5 1994.

....the relations , and are the relevant PRs in multimedia environments. Powerful pointbased temporal models should be able to express at least this set of relations. According to Section 2.3, the PRs , and generate the 29 interval relations. An enumeration of the 29 IRs is given in [WaRo93] Since at most 187 (Table 3) out of 2 13 1 = 8191 consistent IRs have a point based conjunctive notation, we qualified only 187 29 = 158 as irrelevant for multimedia by looking at the PR notation. So, what is the relevance of the 8191 187 = 8004 indefinite IRs that cannot be represented by a ....

....including those specifying the location, the quality or associated media of a presentation are not subject of our investigation. 5.2 Enhanced interval based model Section 3 showed that the 4 multimedia relevant PRs generate 29 IRs. So, an interval based model should cover at least the 29 IRs [WaRo93] If an interval operators is defined for each IR, the 29 operators represent a complete model. However to use 29 different operators, seems to complicate a presentation specification. Therefore, it would be good to have fewer, more powerful operators which are still intuitive to multimedia ....

Thomas Wahl and Kurt Rothermel. Representing Time in Multimedia Systems. Technical Report 12, Universitaet Stuttgart, 10 1993.

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T. Wahl and K. Rothermel. Representing time in multimedia systems. In Multimedia Computing and Systems, Boston, USA, May 1994.

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. Wahl, T., Rothermel, K.: Representing time in multimedia systems. In Proc. of IEEE International Conference on Multimedia Computing and Systems, Boston, USA, May 1994

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T. Wahl and K. Rothermel, "Representing time in multimedia systems," in Proc. of Multimedia Computing and Systems, Boston, MA, pp. 538--543, May 1994.

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T. Wahl, K. Rothermel, Representing Time in Multimedia Systems , Int. Conf. On Multimedia Computing and Systems, Boston, USA, May 1994.

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T. Wahl and K. Rothermel, Representing time in multimedia systems, Proc. IEEE 1st Intl. Conf. Multimedia Computing and Systems, Boston MA, May 1994, pp. 538-543.

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Thomas Wahl and Kurt Rothermel. Representing time in multimedia systems. In Proceedings of the International Conference on Multimedia Computing and Systems, Boston, 1994. 29

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Wahl, T,; Rothermel, K. "Representing Time in Multimedia Systems". In Proceedings of the IEEE International Conference on Multimedia Computing and Systems". 1994.

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