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.

....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] ....

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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

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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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