Digital Equipment Corporation

Ascom Timeplex Trading Ag

Jeffrey B Mendelson

Matthew S Goldman

David E Morris

Zigmunds Andis Putnins

David Solomon

David W Gish

In a video server a transport stream is generated. The transport stream is to be transported over a circuit of a network signalling at a constant bit rate. During generation, timed program content is encoded as a variable bit rate stream. The variable bit rate stream is transported over a constant bit rate circuit of a network. While transporting the variable bit rate stream, an accumulated difference between the number of bits transported in the variable bit rate stream and the number of bits required for the constant bit rate circuit is measured periodically. In response to the measured difference, a secondary untimed content is supplied to the constant bit rate circuit at a rate which minimizes the accumulated difference, and where the secondary content is evenly distributed over the transport stream.

Apparatus and method for interleaving timed program data with secondary

In an interactive video-on-demand system, real-time programs are encoded as a transport stream including a plurality of transport stream packets. Some of the transport stream packets include timing signals indicating the real time of the program. The transport stream packets are formatted into transport cells for transport over an asynchronous transfer mode network from a source to a destination. The cells are transported at a transport rate which is determined by a network clock. The transport rate is chosen to deliver the transport stream faster than the real time of the program. While transporting the transport stream, it is determined if the transport stream is being transported ahead of the real time of the program. In this case, idle cells are injected into the transport stream to have the program arrive at the destination in the real time of the program.

Transport controller for timed program data

Method and apparatus for conditioning timed program independent of

A communications controller coupled to a synchronous network generates local clock reference signals from network clock signals. The network clock signals are used to transport data over the network at a constant rate. The controller receiving a bit stream while generating the local clock reference signals. The bit stream including program clock reference signals, the program clock reference signals being independent of the network clock signals. The program clock reference signals are extracted from the bit stream and compared, after normalization, with the local clock reference signals. If the program clock reference signals are, time-wise, in advance of the local clock reference signals, transport of the bit stream is suspended, otherwise the bit steam is transported over the network. While transport of the bit stream is suspended, data from an alternative bit stream can be transported.

Multiplexed gapped constant bit rate data transmission

The bandwidth of a packet data transmission node is switched asynchronously without interruption of data transmission and with a minimum of circuit complexity. In particular, a packet channel is permitted to 'breathe', gaining bandwidth when additional bandwidth becomes available from other temporarily unused digital channels and losing such additional bandwidth when such unused digital channels revert to other use. To permit such uninterrupted asynchronous operation, a 'pad' or 'throw away' character is defined which is ignored or discarded when it is received by another packet network node. Such a 'pad' or 'throwaway' character is unique only in the sense that it is distinct from and may not be confused with characters or bytes which may occur in normal data transmission sequences.

Growing community of inventors

Shrewsbury, MA, United States of America

Jeffrey B Mendelson