Abstract: The present invention is for multi-screen session mobility between terminal groups. The invention uses a set of screen groups and a set of terminal groups to perform a mapping of the screen groups onto the terminal groups. Both the screen groups and the terminal groups have a geometry, which in one embodiment is defined by columns and rows. In cases where the number of columns in the screen group is less then or equal to the number of columns in the terminal group and where the number of rows in the screen group is also less then or equal to the number of rows in the terminal group, a first mapping scheme is employed. In cases where the number of columns in the screen group exceeds the number of columns in the terminal group or the number of rows in the screen group exceeds the number of rows in the terminal group, a second mapping scheme is employed. In one embodiment, the first mapping scheme maps the screen group directly onto the terminal group.

Abstract: The present invention comprises a method and apparatus for detection motion in video in which frames from an incoming video stream are digitized. The pixels of each incoming digitized frame are compared to the corresponding pixels of a reference frame, and differences between incoming pixels and reference pixels are determined. If the pixel difference for a pixel exceeds an applicable pixel difference threshold, the pixel is considered to be “different”. If the number of “different” pixels for a frame exceeds an applicable frame difference threshold, motion is considered to have occurred, and a motion detection signal is emitted. In one or more other embodiments, the applicable frame difference threshold is adjusted depending upon the current average motion being exhibited by the most recent frames, thereby taking into account “ambient” motion and minimizing the effects of phase lag.

Abstract: Authentication and session management can be used with a system architecture that partitions functionality between a human interface device (HID) and a computational service provider such as a server. An authentication manager executing on a server interacts with the HID to validate the user when the user connects to the system via the HID. A session manager executing on a server manages services running on computers providing computational services on behalf of the user. The session manager notifies each service in a session that the user is attached to the system using a given HID. A service can direct display output to the HID while the user is attached to the system. When a user detaches from the system, each of the service's executing for the user is notified via the authentication manager and the session manager. Upon notification that the user is detached from the system, a service can continue to execute while stopping its display to the HID.

Abstract: A method of updating a remote display device associated with a remote system to fill at least a portion of a display area on the display device with a tiled pattern including repetitions of a tile image data stored at a host system interconnected to the remote system via a communication link. The host system determines the number of replications of the tile image data to fill the display area and transmits display information to the remote system via the communication link, including: the tile image data; a number of repetitions of said tile image data to fill said portion of said display area; and coordinate data representing the position of the display area on the display device.

Abstract: A mechanism for the migration of open network connections is described herein. According to one or more embodiments of the present invention, an active computing environment called compute capsule is provided. Each capsule has a unique locator. Packets are used to send information between capsules using the locators. When a capsule migrates, any open network connections that existed before the migration may continue when the capsule finishes the migration.

Abstract: The present invention provides a mechanism for grouping several standard computers and making them act as one to generate a multi-head display. In one embodiment, the computers are designated as either “primary” or “secondary” terminals. In one embodiment, a set of policy modules decides whether and what type of computational service should be provided to the terminal. For a secondary terminal, the module determines whether the primary terminal of the group has an active session connected to any of the servers. If the primary terminal is being controlled by the server to which the secondary terminal is connected, then session connection information for the primary is augmented to indicate that the secondary is attached to the same session. If not, then the secondary is commanded to attach to the server hosting the primary terminal. A special session is presented where the primary is not attached to any server.

Abstract: The invention is directed to an error correction scheme used in a computer system where data is provided from a service to a terminal. The data is dynamically changing, and the user is interested more in a final or current state of the data than in intermediate states. Data is provided in a stream of blocks with sequential “sequence” numbers associated with each block. The invention assumes that the data provider transmits data blocks in order of sequence. The terminal tracks the sequence numbers of incoming blocks. When the terminal finds that one or more blocks have been skipped or are missing, the terminal sends a request to the central source for update data. Unlike prior art systems, which request that the missing block or blocks be re-sent, the present invention requests that the information contained in the missing command be provided, for example the current data at the display area associated with the missing block.

Abstract: Authentication and session management can be used with a system architecture that partitions functionality between a human interface device (HID) and a computational service provider such as a server. An authentication manager executing on a server interacts with the HID to validate the user when the user connects to the system via the HID. A session manager executing on a server manages services running on computers providing computational services on behalf of the user. The session manager notifies each service in a session that the user is attached to the system using a given HID. A service can direct display output to the HID while the user is attached to the system. When a user detaches from the system, each of the service's executing for the user is notified via the authentication manager and the session manager. Upon notification that the user is detached from the system, a service can continue to execute while stopping its display to the HID.

Abstract: The present invention is a media interface unit that couples media input (e.g. cameras, microphones) to a network and can receive media input from a network and provide it to playback devices (e.g. monitors, speakers). The interface unit eliminates the need for a computer system when transmitting and receiving media data to and from the internet and other networks. The unit comprises analog audio and video inputs and outputs on one side, and a computer communications network interface on the other side. By coupling sources/sinks of audio/video to one side and by coupling the other side to a network, it is possible to send and receive audio and video data as though the digital communications network were the same as the cables typically used to transport analog audio and video. The invention functions as a multi-media network appliance.

Abstract: In a video server hard disk storage unit, video layout ensures average case bandwidth and case seek time during bounded-time information transfers, to maximize access of users S. The storage unit includes D hard disks whose platters are divided into Z zones. Each movie is divided into i blocks and is striped across all D disks such that movie block i is stored on disk (i mod D). In one embodiment, movie block i is placed in zone (i/D) mod Z of disk (i mod D). User streams are organized into slots containing N=S/D streams and the number of streams in each slot accessing a zone is .ltoreq.(N/Z). Seeking is to the nearest end of a set of accesses, where total seek time for a set of N accesses is .ltoreq.N*seek (1.5/N). Preferably two storage buffers/stream are used. Admission policy permits stream assignment to any slot, but streams do not transfer until the needed data block is on the disk needed by the other streams in the slot, and until the block is in the proper disk zone.

Abstract: A pipelined process execution control system for multiprocessors is disclosed that enables multiple processors to cooperatively execute one or many software processes so that cache locality is not violated and extensive state, or context, information need not be saved and restored for each small piece of work performed on multiple data items. The present pipelined process execution control system incorporates (1) a software procedure defined as a pipelined sequence of normal or parallel steps, (2) multiple threads running on the multiprocessor, each of which executes the entire sequence of steps on one datum or data item from a received data stream, and (3) a process control structure to control the threads executing the sequence of steps, so that the normal steps are executed by only one thread at a time and the threads begin executing (or "enter") subsequent normal steps in the sequence in the same order as the threads entered the first step of the sequence.

Abstract: A software-based encoder is provided for an end-to-end scalable video delivery system that operates over heterogeneous networks. The encoder utilizes a scalable video compression algorithm based on a Laplacian pyramid decomposition to generate an embedded information stream. The decoder decimates a highest resolution original image, e.g., 640.times.480 pixels, to produce an intermediate 320.times.240 pixel image that is decimated to produce an intermediate 160.times.120 pixel image that is compressed to form an encodable base layer 160.times.120 pixel image. This base layer image is decompressed to form an image that is up-sampled by interpolation to produce an up-sampled 320.times.240 pixel image. This up-sampled image is subtracted from the intermediate 320.times.240 pixel image to form an error image that is compressed and encoded as a first enhancement 640.times.480 pixel layer. The decompressed base layer image is also up-sampled at step to produce an up-sampled 640.times.

Abstract: The present invention provides a mass storage system suitable for incorporation in a video-on-demand server that is capable of detecting and correct errors without a substantial increase in processor capacity or memory buffer size, and without any increase in disk input/output (I/O) bandwidth. The mass storage system includes a server controller, a cluster of data disk drives and a parity drive associated with the cluster of data disk drives. The controller provides video data streams to a number of viewers. Data is stored as contiguous data strips in the cluster of data drives. Each data strip includes a plurality of contiguous data slices logically distributed across the cluster of data drives. A plurality of parity slices, each parity slice corresponding to each data strip, is stored in the parity drive. When the failure of one of the data drives is detected, the parity drive is read in place of the failed drive.

Abstract: A method for simulating multiple instruction launch in a single-scalar computer system is disclosed. A video data signal having a plurality of data components arranged contiguously is reformatted by inserting overflow buffers between the data components such that they are no longer contiguous. The reformatted video data signal may then be operated on by a single instruction because there will be no propagation of a carryover value between contiguous data components. Upon completion of the instruction, the overflow buffers are checked to determine if overflow has occurred. If there has been overflow, overflow compensation is performed. After overflow compensation, or if there was none, the result of the instruction may be placed in an appropriate format for use in a display device.

Abstract: A software-based encoder is provided for an end-to-end scalable video delivery system that operates over heterogeneous networks. The encoder utilizes a scalable video compression algorithm based on a Laplacian pyramid decomposition to generate an embedded information stream. The decoder decimates a highest resolution original image, e.g., 640.times.480 pixels, to produce an intermediate 320.times.240 pixel image that is decimated to produce an intermediate 160.times.120 pixel image that is compressed to form an encodable base layer 160.times.120 pixel image. A decompressed base layer image is also up-sampled at step to produce an up-sampled 640.times.480 pixel image that is subtracted from the original 640.times.480 pixel image 200 to yield an error image. At the receiving end, the decoder extracts from the embedded stream different streams at different spatial and temporal resolutions. Because decoding requires only additions and look-ups from a small stored table, decoding occurs in real-time.

Abstract: A computer system includes bus bandwidth management for operation of a high-speed bus. The high-speed bus is coupled to a plurality of modules. A plurality of client applications operate on the computer system, and request services from the high-speed bus to transfer data from a source module to at least one destination module. The bus bandwidth management system contains a bus manager, a dispatcher, a global controller, and a local controller contained on each module. Transfer requests for data transfer on the high-speed bus are made from the client applications to the bus manager. The bus manager takes the requested information and, based on a bus management policy management in effect, schedules a transfer order for the transfer requests. The bus manager then transfers the ordered transfer requests to the dispatcher. The dispatcher decomposes the ordered transfer requests into individual bus transfer operations.