Utah State University

Scientific-atlanta, Inc.

Sorenson Communications, Inc.

Paul D Israelsen

Keith Lucas

Richard W Harris

Chien-Min Huang

Scott Ezra Budge

Kylee Devro Sealy

Hunter H Wu

Aaron Gilchrist

Chien M Huang

Douglas L Jewell

David Perkes

Kyminh Liang

A testing system for wireless power transfer systems, including a stationary plate, a rotating plate, and a driver to rotate the rotating plate with respect to the stationary plate.

Wireless power transfer test system

A video conferencing circuit () is configured to receive an input () from one of a plurality of video input devices. The video signal is then stored, compressed and transmitted by an interface circuit such as a modem (). Video signals from a remote location are received from the modem (), decompressed, stored and then transferred for display on one of a plurality of video output devices.

Video conferencing interface

The invention relates to a method and system for allocating bits for representing blocks that are transmitted in an image compression system. In a preferred embodiment, a video telephone communications system includes a video transmitting/receiving (transceiving) system including local and remote processing systems separated by a communications link. The local processing system determines indices to be sent to a remote processing system to represent the image. Under one aspect of the invention, the local processing system determines an optimal bit allocation in which the following relationship may be minimized DR=D+.lambda.R, where D is the total distortion .SIGMA.d.sub.i for a frame; .lambda. is a value determined as described below; R=.SIGMA.r.sub.i .apprxeq.R.sub.d which is the desired total number of bits for the frame. The optimal bit allocation may determine .lambda. for an entire frame. Under other aspects of the invention a lambda feedback technique, with or without predecision, may be used. The lambda feedback techniques may determine .lambda. block by block. Conditional update preselection and mode preselection are other reduced complexity procedures.

Bit allocation for sequence image compression

A video telephone system includes a camera that produces video images. Processing circuitry performs vector quantization on the video images to represent the video images with a relatively small amount of data for transmission to a remote location or memory. The video images are represented by frames which may be further divided into a blocks. A current block is the block that is being considered at a given time. A conditional previous block occupies the position in a previous frame that the current block occupies in the current frame. A motion previous block is a block of the previous frame containing data like that of the current block. To further reduce the amount of data needed to represent the video images, the processing circuitry determines what if any quantization is needed with respect to the current block. The processing circuitry may (1) perform vector quantization on the current block, (2) perform vector quantization on a residual between the current block and motion previous block, or (3) pass bits indicating that the vector quantization of the conditional previous block is adequate. The decision of which occurs depends on various distances related to the current block, the motion previous block, and the conditional previous block. The invention has application for images other than those used in video telephone systems.

Motion vector quantizing selection system

An N-stage vector quantizer in which increasingly smaller portions of a vector are compared to a threshold until the quantization error is less than the threshold. The threshold may be adaptive to insure a constant bit rate. The first stage performs VQ and inverse VQ on an input vector. The difference between the inverse VQ and the input vector is determined to create a first stage residual error. If the first stage residual error is less than a threshold, no further stages of the multistage vector quantizer are used and the input vector or first stage residual is passed on to the output stage. However, if the first stage residual error is not less than the threshold, the residual error is passed to stage two of the multistage vector quantizer where VQ and inverse VQ are performed on the first stage residual error. The process is continued until the residual is less than the threshold. If the Nth stage is reached without the residual being less than the threshold, the process is repeated on a smaller portion of the original input vector. For example, if the original input vector were a 16.times.16 vector, the smaller section could be a 16.times.8 vector.

Hierarchical adaptive multistage vector quantization

A fixed quality source coder receives and performs VQ on an input signal I.sub.D. The signal I.sub.D may be characterized by the number of samples/frame and bits per sample, and may be provided by a traditional source coder. The traditional source coder may include a sample-and-hold (S/H) circuit producing rxs samples/frame and an ADC providing n bits per pixel. In a first embodiment, the number of bits/sample is increased. In the second embodiment, the number of samples/frame is increased. In a third embodiment, both the number of bits/sample and the number of samples/frame are increased. Measurements made in simulations involving the first and second embodiments show that the fixed quality source coder has a smaller data rate, mean absolute error (MAE) and root mean square error (RMSE) than that of the traditional source coder, while maintaining the same or less maximum error. The fixed quality source coder includes an encoder and may also include a decoder. The encoder may include a lossy codec that receives and encodes the signal I.sub.D to provide encoded information to a multiplexer regarding the signal I.sub.D. The lossy codec also decodes the encoded signal to produce a decoded signal I.sub.VQ.sup.-1. A summer receives I.sub.D and I.sub.VQ.sup.-1 and determines an error signal E.sub.R, where E.sub.R may equal I.sub.D -I.sub.VQ.sup.-1. A threshold circuit receives the signal E.sub.R and passes a threshold signal E.sub.T, where a threshold level T may be set to ensure that the maximum error allowed in the encoder is equal to a particular desired maximum error.

Fixed quality source coder with fixed threshold

Apparatus for compressing data is disclosed in which input data is compressed by a vector quantization process and decoded by the vector quantization process. The input data and the decoded input data are compared and a difference signal as produced. A portion of the difference signal is preferably losslessly compressed and transmitted with the vector quantized input signal to a decoder over a communication channel. The decoder decodes the vector quantized portion of the signal and the compressed difference signal for reconstructing the input signal with an error which is less than that which would result from uncompensated vector quantization.

Method and apparatus for data compression with reduced distortion

Vector quantization of a data vector proceeds through successive stages of a multi-stage vector quantization encoder until either (i) a measure of distortion between the vector input to a given stage and the codevector selected at that stage satisfies a threshold value or (ii) the last stage of the encoder is reached. The threshold value varies according to the fullness of a buffer which stores vector quantized data to be transmitted. Consequently, the last stage reached may differ from data vector to data vector. Compression efficiency therefore improves. Preferably, the mean value of each data vector is removed prior to vector quantization.

Adaptive multi-stage vector quantization

A distortion adaptive vector quantization method is employed to select, for each input vector, several codevectors from a tree structured codebook. The first codevector defines a basis signal, and each subsequent codevector defines an enchancement signal. The basic signal is indicative of the full codebook address from which the first codevector was selected. Each enhancement signal is indicative of only so much of the additional address bits that are required, in combination with the basic signal, to identify the address of the codebook from which the subsequent codevectors were selected. The basic signal and each enhancement signal are transmitted to a decoder which may employ only the basic signal, or the basic signal and one or more of the enhancement signals to reproduce the input vector. The reproduction quality of the input vector increases with the number of enhancement signals chosen.

Progressive transmission of vector quantized data

A variable rate vector quantization apparatus and method employs a tree structured codebook. Code vectors are selected from different levels of the codebook according to the value of a threshold. The value of the threshold is periodically adjusted according to the fullness of a buffer that stores vector quantized data to be transmitted. According to the invention, vector quantized data for redundant, or similar, vectors is not transmitted. Rather, a 'copy last vector' instruction is transmitted for these vectors to achieve further data compression. A method of mean removal from vectors to be vector quantized is also disclosed.

Image compression method and apparatus employing distortion adaptive

A method of communicating data from a first location to a second location employing a vector quantization data compression technique that allows users to select the reproduction quality of the transmitted vector quantized data. According to the method, data is encoded (compressed) from the last level of a first tree search vector quantization codebook at the first location. A second tree search vector quantization codebook is provided at the second location having a number of levels equal to or less than the number of levels in the first codebook. The reproduction quality of the transmitted vector quantized data is a function of the number of levels in the second codebook.

Method for selecting reproduction quality of transmitted vector

A method and apparatus for processing fields of a video signal that are to be combined into a frame, compressed and communicated over a digital communications system. The processing technique increases the spatial correlation between pixels at a cost of slightly reduced resolution in areas of the frame where there is movement. The method employs a motion detector to separate moving and non-moving areas of the frame. A simple combination of lines from a first field and a second field can be used in static areas. In moving areas, a digital filter is applied to the fields to increase correlation in the resulting field. A digital compression technique such as vector quantization is applied to the resulting frame-based signal.

Motion filter for digital television system

A method and apparatus is disclosed wherein fixed rate vector quantized data is transmitted from a first location to a second location via a first medium. The fixed rate vector quantized data is received at the second location and transformed to variable rate vector quantized data. Then, the transformed variable rate vector quantized data is transmitted to a third location via a second medium. At the third location, the variable rate vector quantized data may be received, and if desired, transformed back to fixed rate form. A distortion adaptive vector quantization method is employed to transform the fixed rate vector quantization data to variable rate vector quantization data.

Method and apparatus for transforming between fixed-rate vector

A vector quantization me employs mirrored input vectors to increase the reproduction quality of transmitted vector quantized data. A codevector is selected from a vector quantization codebook for each possible orientation of an input vector. The codevector having the smallest distortion relative to the input vector is selected for transmission. An identification code identifying the selected orientation is also transmitted.

Vector quantization method employing mirrored input vectors to search

A variable rate vector quantization method employs a tree structured codebook. The level of the codebook from which codevectors are selected is determined by a threshold. The threshold varies according to the fullness of a buffer which stores vector quantized data to be transmitted.

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North Logan, UT, United States of America

Paul D Israelsen