Abstract: A service gateway provides a proxy between a client protocol and a plurality of standard communication protocols. The service gateway provides asymmetrical routing, data compression and encryption to optimize client processing power and communication link bandwidth. The service gateway enables content translation between clients and service providers. The service gateway keeps track of client available memory and sequence numbers in messages to generate error codes when applicable. A store and forward message capability is provided along with abstract session identifiers. The service gateway supports user datagram protocol.

Abstract: A distributed computer system, as for transmitting and receiving executable multimedia applications, includes a source of a continuous data stream repetitively transfering data representing a distributed computing application and a client computer, receiving the data stream, for extracting the distributed computing application representative data from the data stream, and executing the extracted distributed computing application.

Abstract: A distributed computer system is disclosed which comprises a source of a continuous data stream repetitively including data representing a distributed computing application and a client computer, receiving the data stream, for extracting the distributed computing application representative data from the data stream, and executing the extracted distributed computing application.

Abstract: A distributed computer system, as for transmitting and receiving executable multimedia applications, includes a source of a continuous data stream repetitively transfering data representing a distributed computing application and a client computer, receiving the data stream, for extracting the distributed computing application representative data from the data stream, and executing the extracted distributed computing application.

Abstract: A method for asynchronously maintaining an image on a display device comprises the following steps. First, a drawing request is received from the application program. Then a drawing area of the image is determined in response to the received drawing request and an entry representing the drawing area is inserted into a list of entries representing respective drawing areas. A screen update request is then received from the application program. In response to this received screen update request, an entry representing a drawing area is retrieved from the list, and graphic objects are redrawn if any portion of the graphic object lies within the drawing area represented by the retrieved entry.

Abstract: In an audio video interactive (AVI) receiver receiving a packet stream including a directory and an AVI program having an associated identifier in the directory, a method is disclosed for controlling the execution of the AVI program comprises the following steps. First, loading the AVI program into a memory in response to the presence of the AVI program in the packet stream. Then beginning execution of the loaded AVI program. And then minimizing the executing AVI program when a directory identifying a different AVI program is detected in the packet stream.

Abstract: A method is disclosed for processing modules in an audio video interactive (AVI) receiver receiving a packet service including a plurality of modules, each module having a name and including time multiplexed transmission units, each transmission unit including a header packet containing the name of the module. First a request to perform a process on a module identified by a name is received and an entry containing the received name and requested process is inserted into a list of entries. A header packet in the packet service is then detected. If the name in the detected header packet matches a name in an entry in the list, packet processing circuitry performs the process in the matching entry and a message is sent indicating that the process has been performed.

Abstract: Apparatus and a method for formatting executable codes and data, defining interactive applications, with video and audio program material, for reliable and convenient access includes compressing (18, 21) audio and video programs according to a protocol such as MPEG. The compressed audio and video (A/V) programs are formed (19, 22) into transport packets. Interactive application programs associated with A/V programs are compiled (10) into functional modules, condensed and formed into transport packets. A module may be executable software or data. Further modules designated "Signal modules", are generated to condition respective receivers to suspend or resume execution of an interactive application. Video packets, audio packets and application packets are time division multiplexed (16) for transmission. Signal modules are multiplexed in the packet stream to appropriately reprogram respective receivers on the occurrence of such changes in received signal components.

Abstract: In a video signal coder blocks of pixels are generated, scanned in a pseudo-random order and transformed blocks of coefficients which are stored in a buffer. The resulting blocks of coefficients are quantized individually by the use of a quantization level and the coefficients of each block are individually quantized by the use of a quantization matrix. The quantization level is determined by the fullness of the buffer.