U.S. Philips Corporation

Edzer Lawerman

Johannes H Korst

Serverius P Pronk

Giel Van Doren

In a system 100, such as a video-on-demand-server, a reader 180 reads data from a storage medium 110 and stores the read data in buffers 125. The data is supplied from the buffers 125 to users 130 for consumption in the form of a plurality of data streams. The data streams may be fixed rate or variable rate with an identical maximum consumption rate of R.sub.max data elements per second. The reader 180 is controlled by a scheduler 170. The scheduler 170 divides a predetermined period of t.sub.cycle seconds, wherein for each active data stream at least R.sub.max *t.sub.cycle data elements can be read from the storage medium, into n successive time intervals, each of t.sub.interval seconds. For each data stream a corresponding buffer 125 is reserved for storing at least R.sub.max *(n+1)*t.sub.interval data elements. The data is read from the storage medium 110 by repeatedly sweeping the storage medium 110 for a group of data streams. Immediately before causing the reader 180 to perform a next sweep, the scheduler 170 determines the composition of the next group of data streams to be supplied with data. At least data streams whose corresponding buffer 125 comprise less then R.sub.max *2*t.sub.interval data elements are assigned to this group.

Method and system for supplying streams of data having identical maximum

In a multimedia system, such as a video-on-demand server, a file with data is stored in a series of successive clusters which may be distributed across the disc. A cluster consists of physically successive sectors which can be read in blocks by a user application. By repeating a part of the data at the end of a cluster at the beginning of the next cluster, the system enables reading of a block of sectors from an arbitrary sector, said block and the subsequent blocks nevertheless being accessible by way of one seek operation. The interactive response time is thus substantially improved in situations in which the user requests an arbitrary data fragment.

Growing community of inventors

Eindhoven, Netherlands

Edzer Lawerman