Abstract: A personal recorder/playback system (10) includes a recording agent (32) configured to transparently receive multiple audio/visual streams from analog and/or digital sources. The streams are temporarily stored in queues (52,54) for subsequent analysis. The streams, after analysis, are either discarded, stored permanently in an audio/visual collection (48,50), or used to improve the quality of previously stored streams in the collection. The recording agent (32) provides features such as virtual channels (42) and a “top-ten” list (38) of most popular stored audio/visual streams.

Abstract: A method for breathing of scheduling algorithms for a storage device (110). The method including: (a) computing a worst-case duration of a breathing cycle (P) for the storage device (110); (b) starting a breathing cycle; (c) determining if one of the following becomes true before the end of P: (i) a number of real-time requests is at least a predetermined threshold based on a number of data streams and performance parameters of the storage device; and (ii) a number of pending requests for any single stream becomes more than one; (d) if at least one of (i) and (ii) remain true during the duration of P, starting a subsequent breathing cycle after completion of the breathing cycle; and (e) if both of (i) and (ii) are not true during the duration of P, waiting P time units from the start of the breathing cycle before starting the subsequent breathing cycle.

Abstract: A multimedia server retrieves blocks of data from a storage medium and supplies the blocks in the form of data streams to users. The streams include a group of high bit rate streams and a group of low bit rate streams. The system has a reader for in a sweep reading data blocks from the storage medium for a selected group of streams and for storing the data blocks in respective buffers. The system further has a scheduler for determining which of the streams is to be serviced, i.e. for which of the streams a block is to be read, in the next sweep of the reader. The scheduler according to the invention is operative to determine to service a low bit rate stream less often than a high bit rate stream.

Abstract: The invention relates to a storage system (100) such as a video on demand system, comprising a plurality of storage units (110-120) such as disk drives. Each one of the storage units (110-120) has a number of storage zones (121-126) with mutually different expected data retrieval times. Data is stored in data units, with each data unit comprising N blocks, wherein N≧2. The blocks of a data unit are distributed over the storage units (110-120). The blocks comprise redundant information such that any one of a plurality of selections comprising N−K of the N blocks suffices for retrieving the data unit, wherein K≧1. For retrieving a data unit from the storage units (110-120), a reader determines which N−K of the N blocks to retrieve on the basis of a selection procedure. In accordance with the invention, the selection procedure takes into account the expected data retrieval times in order to optimize bandwidth utilization.

Abstract: In an audio/video server blocks of data are read from a storage medium by a reader and supplied to users in the form of data streams. The storage medium includes a plurality of storage units. The blocks are stored in at least two different and randomly selected storage units. A scheduler controls reading of blocks from the storage medium. For each block to be read, the scheduler selects one storage unit from the storage units in which the block is stored such that the playback load on the storage units is balanced. The scheduler issues a read request to the reader for reading the block from the selected storage unit.

Abstract: A system, like a video on demand server, retrieves blocks of data from a storage medium 100 and supplies the data to users in the form of at maximum nmax data streams. Upon creation, a data stream is in a new state in which no sufficient data is present for consumption by a user, whereas a user may consume data for a data stream in an active state. A scheduler 170 repeatedly selects a group of data streams for which a data block of a predetermined size needs to be read and causes a reader 180 to read the data in one sweep and to store the read data in buffers 125. The group is formed by active data streams whose associated buffers 125 have room for storing the data block. The scheduler 170 variably determines the size of the data block for each next sweeping operation through an expression that, with respect to a number of data streams, is substantially based on an actual number nact of active data streams instead of nmax.

Abstract: 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.

Abstract: In an audio/video server blocks of data are read from a storage medium by a reader and supplied to users in the form of data streams. The storage medium comprises a plurality of record-carrier based storage units. A reader reads a batch of data units from a storage unit in a single relative movement of a reading head of the storage unit with respect to the record-carrier of the storage unit. A scheduler controls reading of blocks from the storage medium by determining from which storage unit(s) data unit(s) need to be read for the block and placing a corresponding carrier access request in a read queue. The scheduler extracts for each of the storage units a batch of carrier access requests from the queue and issues the batch to the reader in an asynchronous manner, in response to the reader having substantially completed reading data units for a previous batch for the storage unit.

Abstract: A system, such as for example, a video server in a multimedia system, delivers data to a number of users, each of which may have a variable consumption rate. The system reads data blocks from the storage medium in successive sweeps and places the data in user buffers. The system in accordance with the invention reads, for a given user, one block of data from the storage medium no more than every other sweep, so that the duration of a sweep is shorter. Thus, whether a user needs data is checked more frequently and fewer data need be stored in the buffer of the user. As a result, the size of the buffer may be smaller.

Abstract: A method and a system for the interleaving of real-time files so as to form an interleaved combination for storage or transmission. They can be used for a multimedia application in which real-time files containing audio and/or video information are combined so as to form a real-time file for use by the application. The invention utilizes a structure in which the real-time files are stored in dependence on their period in conformity with a given space-saving criterion. Subsequently, on the basis of the structure, an interleaved combination is formed in which the number of empty positions in the combination is limited.