Abstract: A video encoding method and apparatus is shown wherein image information is represented as a plurality of pixels, the pixels are organized into blocks, pixels transposition is performed on image information at the boundaries of the blocks, the blocks are transform coded and quantized. Pixel transposition involves transposition of alternate pixels at the boundaries of blocks with pixels of neighboring blocks found in a pre-determined direction. The pre-determined direction may be fixed by a system or may be applied on an image by image basis. In the event that the pre-determined direction is not established by a system, a pixel transposition circuit includes a transposition keyword in the output bit stream which is used by a decoded to determine the direction of pixel transposition.

Abstract: A method and apparatus for generating region frames from video frames are disclosed which employs an industry standard encoder to lessen the negative impact on the quality of the transmitted video sequence while consuming fewer bits. The invention utilizes image segmentation and color replacement techniques to create the region frames. Each region frame includes a subject region, zero or more previously segmented regions and zero or more non-subject regions. The subject region is defined by the pixels of the original video frame. The previously segmented regions and non-subject regions are assigned replacement pixels P.sub.n,y and C.sub.n, respectively. The replacement pixel C.sub.n is chosen to indicate a color that is not likely to be confused with any color in the subject region R.sub.n. The replacement pixels P.sub.n,y are chosen such that the compression ratio of the region frame data is maximized.

Abstract: A predictive video coder performs gradient prediction based on previous blocks of image data. For a new block of image data, the prediction determines a horizontal gradient and a vertical gradient from a block diagonally above the new block (vertically above a previous horizontally adjacent block). Based on these gradients, the encoder predicts image information based on image information of either the horizontally adjacent block or a block vertically adjacent to the new block. The encoder determines a residual that is transmitted in an output bitstream. The decoder performs the identical gradient prediction and predicts image information without need for overhead information. The decoder computes the actual information based on the predicted information and the residual from the bitstream.

Abstract: Method and apparatus for generating variable length coded for video encoding. A plurality of memory tables contain variable length codes tailored to patterns of input video information that is likely to be input to the variable length encoder. The patterns are determined in large part by a value of a quantizer used in video encoding. A separate memory table containing separate variable length codes is established for each of a plurality of quantization parameter values. The quantization parameter is input to the encoder to enable one of the memory tables and the video information is input to the enabled table to generate the variable length code.

Abstract: A client-server network enables interconnection to both the Internet and switched network. In response to a received client service request, a connection is established over the Internet between a client and a server. Client information transmitted from the client to the server over the Internet connection is used to enable the server to provide the requested service by establishing a switched network connection to the client using a client's communication number determined from the client information.

Abstract: Real time delivery of multimedia information accessed either through the Internet, or otherwise, simultaneously, or sequentially time delayed to one more users, is enabled by delivering the multimedia information over a switched network via a multipoint control unit. A client establishes a connection with a server, or other remote location where desired multimedia information is resident, identifies the desired multimedia information and provides client information identifying the locations of the users. The client information may include the telephone numbers or other access numbers of each of the multiple users. The multimedia information is then delivered by a multimedia server to a bridging apparatus through a switched network guaranteeing high quality of service, secure connection and billing control. Connecting one or more users to a live agent is also made possible by providing the telephone numbers of the users and the live agent directly to the multipoint control unit.

Abstract: A synthesized signing image is generated which includes an original image of a subject and a sign image superimposed on the original subject image. The sign image is selected from a sign language database based on the speech (i.e., a letter or word) spoken by the subject. Based on the size and tone (intensity) of the subject's face in the original image, the database sign image is modified to match the intensity and have a proportional size to the subject's face. The modified database sign image is then superimposed on the original image of the subject to create a synthesized image in which the subject appears to be signing.

Abstract: A system and method for enhancing interactive communication between video conferencing devices of the type in which a delay is inserted into the audio transmission path to provide lip synchronization of the image and speech of the respective users thereof. Each video conferencing device includes a display device for displaying images of at least one communicating party and a speech communicating system for communicating with the communicating party. In accordance with one embodiment of the invention, a speech detecting circuit detects an utterance by a first user of a first video conferencing apparatus. An audible or visual indication is provided to at least a second user of a second video conferencing apparatus before the utterance is reproduced. As a result, the potential for simultaneous speaking by two or more users is substantially reduced.

Abstract: A method and apparatus for generating region frames from video frames are disclosed which employs an industry standard encoder to lessen the negative impact on the quality of the transmitted video sequence while consuming fewer bits. The method and apparatus utilizes image segmentation and color replacement techniques to create the region frames. Each region frame includes a subject region, zero or more previously segmented regions and zero or more non-subject regions. The subject region is defined by the pixels of the original video frame. The previously segmented regions and non-subject regions are assigned replacement pixels P.sub.n,y and C.sub.n, respectively. The replacement pixel C.sub.n is chosen to indicate a color that is not likely to be confused with any color in the subject region R.sub.n. The replacement pixels P.sub.n,y are chosen such that the compression ratio of the region frame data is maximized.

Abstract: High-resolution, progressive format video signals having high frame rates may be encoded by a base layer encoder and an enhancement layer encoder to provide two kinds of encoded video signals which share a common output channel. These encoded video signals are received at an input of a video receiver which may use one or both of the two kinds of encoded video signal. Relatively lower performance high-definition televisions may thus receive video signals from higher performance transmitters and produce satisfactory pictures. Higher performance HDTVs will be able to utilize the full performance capabilities of these video signals.

Abstract: A method and apparatus for controlling quantization and buffering for video digital signal compression wherein a processor determines a bit budget value based on a number of frames to be skipped and a target buffer fullness. The bit budget value is used to retrieve a default Q-step value from a table of default quantization step size values and corresponding bit budget values. A default Q-step value is used to quantize the input digital signal only if it is less than a maximum. If, however, the default quantization step size value exceeds the maximum, then the number of frames to be skipped and the target buffer fullness may be increased to achieve a lower default quantization step size.

Abstract: Digital video transmission rate matching techniques are disclosed. A bit stream rate matching apparatus includes a bit rate increasing device and a bit rate reducing device. The bit rate increasing device converts a video bit stream having a first transmission rate to a video bit stream having a second transmission rate wherein the first transmission rate is less than the second transmission rate. The bit rate reducing device converts a video bit stream having the second transmission rate to a video bit stream having the first transmission rate. The bit stream rate matching apparatus is useful in the context of a multimedia conference where a first endpoint device employs the first transmission rate and a second endpoint device employs the second transmission rate.

Abstract: The problems associated with slow timing recovery in an ATM receiver are overcome by detecting the transmission rate of a received bit stream and periodically detecting the transmitted Enc.sub.-- CR values, which are used to calculate additional estimated clock reference (Est.sub.-- CR) values between the actual transmitted Enc.sub.-- CR values. The Est.sub.-- CR values are then used along with the actually received Enc.sub.-- CR values to generate a phase locked loop (PLL) error signal (TC.sub.-- ERROR), wherein the PLL is caused to converge more rapidly. In one embodiment, the TC.sub.-- ERROR values are generated for each received cell or packet instead of only for each received Enc.sub.-- CR value and, consequently, timing recovery is significantly speeded up. Additionally, the Est.sub.-- CR values can be adjusted to minimize the effects of lost cells, as well as, drift in the transmission rate.

Abstract: A video sample is selected for transmission only if it differs significantly in amplitude from the sample corresponding to the same spatial point in a previous video frame. An address word which indicates by its value the position of a sample within a video line is transmitted prior to the amplitude of a sample only if the previous sample was not selected for transmission. The amplitudes for selected samples are transmitted in groups preceded by an address word and terminated by a flag word. Frame synchronization is maintained by transmitting a first sync word during the vertical blanking interval. Ordinarily, the first sample in a video line selected for transmission has an address which is lower in value than the address word of the previous sample selected for transmission and, therefore, no line synchronization is necessary.