Multiplex communications – Pathfinding or routing – Switching a message which includes an address header
Patent
1996-05-07
1998-12-01
Patel, Ajit
Multiplex communications
Pathfinding or routing
Switching a message which includes an address header
370476, 371 30, H04L 1288, H04L 1256
Patent
active
058448977
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a data transmission apparatus and data transmission method which are suitable for use in, for example, a video-on-demand apparatus etc. which can deliver video data in accordance with a request made at any time.
BACKGROUND ART
Realization of a practical video-on-demand (VOD) system which can instantly provide program data in response to a request from a receiver has been desired. A VOD system able to individually responding to requests made at all times, however, requires an extremely large data transmission apparatus for performing complex processing.
Accordingly, a near-video-on-demand (NVOD) system which can simplify the configuration of the data transmission apparatus while realizing a function similar to that of a VOD system has been proposed. An NVOD system is a system that transmits program data to a plurality of channels at predetermined time intervals and selects the channel for the programs starting from the next time zone in response to requests made in a certain time zone to provide those programs.
The data transmission apparatus used for such an NVOD system also must process a large amount of AV data (audio data and video data) at a high speed. For example, at first the video data to be supplied is transferred from a large capacity recording apparatus in which a lot of data are recorded to a high speed accessible recording apparatus. Next, the data recorded in that recording apparatus is accessed at a high speed in a fraction of the reproduction time of the video data and data recorded at a plurality of locations predetermined times apart are simultaneously reproduced. Further error correction codes are added to the series of reproduced data which are then converted to a predetermined transmission format and transmitted to the transmission lines.
Accordingly, there is a demand for a data transmission apparatus able to perform this processing using a simplified hardware configuration and a data transmission method able to perform it more efficiently.
DISCLOSURE OF THE INVENTION
An object of the present invention is to provide a data transmission apparatus which can, by a simpler hardware configuration, transmit desired data, process it at a high speed for simplified processing, and thereby raise the speed of transmission and which can easily handle multiple channels.
Further, taking note of the fact that the reason why the means for converting the format of data for transmission becomes large in scale and high speed processing is required is the generation of the error correction codes, the present invention has as its object the simplification of the configuration of the means for converting the format and the simplification of the processing. Accordingly, the data transmission apparatus and data transmission method of the present invention preferably are configured so as to record data adding an error correction code when recording data in a recording apparatus as transmission data and so as not to have to generate an error correction code for transmission at the time of transmitting the data.
Further, the recording means for inputting and outputting data to and from the recording apparatus is complicated and requires high speed access, so often has a processor for controlling the recording apparatus. In such a case, that processor is used to add an error correction code in advance and record it together with the data in the recording apparatus in the transmission format.
Accordingly, the data transmission apparatus of the present invention comprises an error correction code adding means for preliminarily adding to video data an error correction code for correcting transmission error at the time of transmitting said video data by a predetermined transmission method and thereby generating error correction code added data, a storing means for storing said error correction code added data and operative to output the same in parallel to a plurality of channels, a plurality of format converting means each provided for the respecitive channels
REFERENCES:
patent: 4977554 (1990-12-01), Iguchi et al.
patent: 5260936 (1993-11-01), Bardet et al.
patent: 5550825 (1996-08-01), McMullan et al.
patent: 5583574 (1996-12-01), Tanaka et al.
patent: 5588003 (1996-12-01), Ohba et al.
Frommer William S.
Patel Ajit
Sony Corporation
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