Electrical computers and digital processing systems: multicomput – Computer-to-computer protocol implementing – Computer-to-computer data transfer regulating
Reexamination Certificate
1998-04-24
2001-06-26
Lim, Krisna (Department: 2153)
Electrical computers and digital processing systems: multicomput
Computer-to-computer protocol implementing
Computer-to-computer data transfer regulating
C709S232000, C709S233000, C709S234000, C709S235000
Reexamination Certificate
active
06253245
ABSTRACT:
The invention relates to a transmission system, including a plurality of network elements for the transmission of a plurality of data units from at least one network element, including a data source, to at least one further network element which includes a data sink and a data buffer.
Such a transmission system is known from “Avid AirPlay MP”, Avid Technology Inc., 1966, p.2.
Transmission systems of this kind are used, for example in news stations so as to form high-quality news items, for example for television news broadcasts. Available news material (for example, audio/video data, text contributions, images, . . . ) is stored in different, interconnected network elements (servers, workstations, data memories) at various locations in a network. In order to do research in the available news material and to compose the news items, which must satisfy severe quality requirements and are usually formed under pressure of time because of topicality, the transmission system must provide given functionalities. They include notably the single step mode, in which individual data units (for example, single images of a video sequence) are requested by the user, and the streaming mode, in which continuous output of a sequence of data units is requested and the user determines only start and stop but not the temporal control of the continuous data output. Moreover, data units are stored in different network elements and often additional requirements are imposed, for example the temporally simultaneous output of the same data at different network elements.
It is an object of the invention to provide an improved transmission system on the basis of the transmission system described above.
This object is achieved according to the invention in that there are provided first means for the temporal control of the data transmission from the data source to the data buffer and second means for the temporal control of the data transmission from the data buffer to the data sink.
It is thus achieved that less severe quality requirements may be imposed on the data source, on its temporal control and on the data transmission paths of the transmission system (from the data source to the data buffer). Nevertheless, real-time data output to the data sink is still possible. The data transmission from the data source to the data buffer takes place independently after the start, without it being necessary to call the data units individually. Small temporal disturbances of this data transmission do not affect the data transmission from the data buffer to the data sink, since this data transmission is performed under own, separate temporal control. Because this data transmission path is only very short, hardly any disturbances can occur, so that the real-time data output by the data sink is ensured. If only the data transmission from the data buffer to the data sink were temporally controlled, but not the data transmission from the data source to the data buffer, there would be a problem in that in the event of simultaneous access to the same data of the same data source by several users, the data source would be overloaded by the plurality of data requests. In a transmission system in which the data transmission were temporally controlled directly from the data source to the data sink, very severe quality requirements would have to be imposed on the data source and its temporal control. Moreover, in such a transmission system the critical data path from the data source, via the network, to the data sink would be comparatively long, so that delays and disturbances could readily occur during the data transmission.
The first means in an embodiment of the invention includes a data source control module for controlling the data source, the data source control module supplying a respective control instruction to the data source for the transmission of data units from the data source to the data buffer, the second means including a data sink control module for controlling the data sink and the data buffer, the data sink control module supplying a respective control instruction to the data buffer for the transmission of data units from the data buffer to the data sink. The control modules independently control the associated elements in conformity with a data stream control protocol. Each network element provided with a data source or a data sink includes such a control module for each data source or data sink.
A further embodiment which is based thereon is provided with a control unit for outputting a start instruction to the control module in order to start the data transmission from a network element to a further network element. The control modules are connected to the control unit via control leads and receive the instructions for starting and stopping the data transmission therefrom. In this further embodiment, therefore, the control unit need apply only a single start instruction to each control module involved, which control modules then independently take over the temporal control of the associated data source or data sink of the associated data buffer. Analogously, for the stopping of the data transmission the control unit applies merely a single stop instruction to each control module. This offers the advantage that the construction of the control unit, which may be configured as a separate network element or be implemented in one of the other network elements, may be simpler and that the data sources or data sinks and data buffers can always be controlled independently of one another.
In a preferred embodiment of the invention, in order to control the data buffer the data sink control module is constructed in such a manner that for data output the data is transmitted from the data buffer to the data sink at equal distances in time. Temporally exact output of data in conformity with a predetermined temporal order is thus achieved, for example in real time.
The control unit in a preferred embodiment of the invention is arranged to output start instructions to the data sink control module in order to synchronize the data output at a plurality of data sinks, each of which includes an associated data buffer, in such a manner that the data transmission from the data buffers to the data sinks is started simultaneously. The data sinks with the associated data buffers can then be arranged in the same or in different network elements. In this embodiment the data transmission from the data source to the data buffer can take place simultaneously or temporally offset relative to an arbitrary instant prior to the synchronized data transmission from the data buffers to the data sinks. The control unit initially applies a start instruction to the data sink control module, requesting it to start the data transmission from the data buffers to the data sinks simultaneously. The control unit then applies various parameters to the data sink control module, said parameters providing timing of the control module and enabling the synchronized data output.
In a further embodiment which is based thereon the control unit for controlling the data source control module is constructed in such a manner that the data units are transmitted from the data source to the data buffer in a temporally offset manner. This enables a reduction of the size of the data buffer and also a mitigation of the temporal requirements imposed on the transmission lines from the data source to the data buffer.
The invention also relates to a network element which includes a data source or a data sink and a data buffer for a transmission system of the kind set forth, the network element including means for temporal control of the data transmission from the data source to the data buffer or from the data buffer to the data sink. These means can be implemented in hardware as well as in software.
The invention also relates to a control unit for a transmission system of the kind set forth which is constructed in such a manner that the data transmission from the data source to the data buffer and the data transmission from the data buffer to the data sink can both tak
Lim Krisna
U.S. Philips Corporation
Verdonk Peter L.
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