Motorola Corporation

Northwestern University

Stephen N Levine

James C Brailean

Cheung Auyeung

Larry C Puhl

Kevin J O'Connell

Mark R Banham

Aggelos K Katsaggelos

James Joseph Kosmach

Ezzat A Dabbish

James C Baker

Michael P Metroka

Brett L Lindsley

Scott N Carney

Frederick D Dean

Harry M Bliss

John Paul Byrns

Gerald Edward Corrigan

Taner Ozcelik

Mary B Flanders

Guido M Schuster

Albert Joseph Leitich

Douglas C Dominiak

Robert J Irvine

A video bitstrean error resilient transcoder ( ), method ( ), video-phone, and video-communicator are provided wherein error resilience is implemented by verifying a syntax of a video bitstream and replacing the video bitstream between resynchronization markers with a valid syntax that is used by a decoder to produce a video sequence.

Video bitstream error resilient transcoder, method, video-phone, video-communicator and device

The present invention provides a method (200) and device (300) for error control of a video compressed sequence in which error protection for both random and burst channel errors is provided. The error control syntax (100) applies a fixed length packet synchronization system to variable length coded compressed video data, which provides the capability to limit error propagation within the decoded video bit stream. The fixed length packet control information provides information to decode compressed video data in both forward and reverse directions to allow for the recovery of correctly decoded video data within a decoded frame after long bursts of channel errors while reducing the overhead for error control. The error control method also provides video error detection which may be used for error concealment.

Method and device for error control of a macroblock-based video

A method (100, 200), device (300) and microprocessor (400) are provided for selectively compressing video frames of a motion compensated prediction-based video codec based on a predetermined set of compression techniques. An energy estimate of the current displaced frame difference, DFD, is used to compute a ratio between the estimate and a historical mean of energy estimates. The ratio is iteratively compared to a predetermined set of thresholds which are associated with the predetermined set of compression techniques. The comparisons are used to choose a technique based on the thresholds, and a technique is selected to be used for encoding the current DFD.

Method, device and microprocessor for selectively compressing video

The present invention provides a method (100, 200) and a device (300, 400, 600) for containing and concealing errors which occur in a transmitted video bitstream. Utilizing a plurality of predetermined scanning patterns, particular macroblocks are chosen per frame to have their intensity information encoded and transmitted. This approach provides an efficient method to limit the degradation to the visual quality of a video sequence decoded from a bitstream corrupted by an extended error burst. Concealment of areas within a video sequence that are affected by short error bursts and/or random errors is achieved by estimating the corresponding lost macroblock information from the remaining uncorrupted macroblocks. That is, for each lost macroblock a prediction of the intensity information is generated through the use of a motion vector from a neighboring uncorrupted macroblock.

Method and device for concealment and containment of errors in a

The present invention is method, rate controller, and system for preventing overflow and underflow of a decoder buffer in a video compression system. First, a plurality of quantized video bits is received from an encoder (102). The plurality of quantized video bits correspond to a video frame type. Then, a virtual buffer is created, in a rate controller, to model fullness of a decoder buffer, based on the quantized video bits, to produce a virtual buffer fullness (104). A quantization stepsize estimate is finally determined, in a rate controller, based on at least a first predetermined target bit allocation, the video frame type, and the virtual buffer fullness (106). The quantization step size estimate will prevent the overflow and underflow of a decoder buffer.

Method, rate controller, and system for preventing overflow and

The present invention provides a method (600) and system (100) for predicting a differential vector field. The method and system enable the detection and encoding of an area where motion compensating the past image frame to the current image frame, fails. Based on the DFD signal, the present invention detects regions where the motion compensation has failed (102). The boundaries of these regions are encoded and sent to the decoder (104). The intensity values contained in this region, by the current intensity frame, are also encoded and sent to the decoder. Based on the decoded region boundaries, the decoder decodes the intensity values and places them into the correct regions.

Method and system for improved motion compensation

The present invention is method and apparatus for preventing overflow and underflow of an encoder buffer in a video compression system. A virtual buffer is created in a rate controller to model the decoder buffer fullness (102). A sequence of bits is generated by an encoder (104). The encoder is controlled by the rate controller to prevent a decoder buffer underflow and overflow. Then, the sequence of bits is received by the encoder buffer to produce a bitstream (106). The bitstream corresponds to an instantaneous channel bitrate. The bitstream is transmitted from the encoder buffer to a decoder buffer following a delay (108). The delay is controlled by a rate controller to synchronize an encoder buffer fullness with a virtual buffer fullness (110). The synchronization prevents overflow and underflow of the encoder buffer.

Method and apparatus for preventing overflow and underflow of an encoder

Efficient and adaptable motion estimation between flames in a video sequence is achieved in a video compression system 100 by first performing a series of comparisons in a first region between a present video block of a present video frame and a comparison video block of a previously stored video frame based on a first search point displacement pattern 500. Then, similar comparisons are performed in a second and third region based on a second and third search point displacement pattern respectively 501, 502. A best match video block is determined as a result of the series of comparisons 503. The series of comparisons may be made for a predetermined number of video blocks 600 and video statistics may be collected for the comparisons 601. If the video statistics are unfavorable 602 or if a predetermined time has expired 603, then the region used for searching for a best match block may be changed.

Method for estimating motion in a video sequence

The present invention provides a method (100) and device (200) for allocating bits to video pictures in a video compression system. A sequence of video frames or pictures is received, and the number of bits used to compress a previously encoded frame and a signal-to-noise ratio for the immediately previously encoded video frame are determined. Rate distortion model parameters are updated. Then, first, second, and third deviations are determined. Finally, the bit allocation for the frame is determined based on the first number of bits used to compress a previously encoded frame, the first deviation, the second deviation, and the third deviation.

Method and device for determining bit allocation in a video compression

The extended error correction process of the present invention error corrects a data message that has been transmitted a plurality of times. The process first receives the data message at least twice, logically combining the first and second messages received to form an error indication word. The error indication word is then used to locate the error locations in each message after which some of the errors are complemented, depending on the total number of errors found. The message is then decoded and used for transmit power changes, channel reassignment, to release a call, etc.

Extended error correction of a transmitted data message

Whether to encode a present video block of an incoming video frame, i.e. intra code, or whether to encode the difference between the present video block of the incoming frame and a best match video block from a previously stored video frame, i.e. non-intra code, is determined in a video compression system 100. First the present video block is divided into a predetermined number of sub blocks 301. Then an average pixel value is calculated for each sub block 302 and used along with the individual pixel values of the sub block to determine sub block deviations 303. The sub block deviations are used to compute a present video block deviation 303. The present video block deviation is then compared with an error deviation 306 that is calculated based upon the present video block pixel values and the best match video block pixel values 305. If the comparison is favorable, then the difference between the present video block and the best match video block are encoded. If the comparison is unfavorable, then the present video block is encoded.

Method for determining whether to intra code a video block

There is provided a mechanism for block synchronization. It comprises: predeterminally arranging synchronization words about a point of interest, transmitting such arrangement, receiving that transmission having synchronization words predeterminally arranged about that point of interest, detecting at least part of those synchronization words, and locating the point of interest with reference to the arrangement of one detected word about another and their arrangement about the point of interest.

Permuted block synchronization

In a cellular radiotelephone communication system, there is provided a method and apparatus for reducing contention between a plurality of mobile units requesting system resources comprising the steps of A) receiving access requests from at least one of the plurality of mobile units, B) determining the number of attempted access requests (access request count); and C) altering system resources as a function of the access request count in order to reduce the likelihood of contending mobile units. An alternative embodiment suggests deriving timing advance information as well as access request count, correlating the access request count to the timing advance information, and altering system resources as a function of the correlation in order to reduce the likelihood of contention. Yet another embodiment suggests that the mobile unit take independent action, based upon its access request count, in order to reduce the likelihood of contention.

Contention reducing technique for a radio frequency communication system

There is provided a mechanism for error detection comprising: detecting the symmetry of error distributions over adjacent time intervals and muting of a radiotelephone in response to detected loss of substantial symmetry, unless errors are attributable to valid alternative detections. It is further characterized by: detecting the symmetry of error distributions over adjacent time intervals and muting a radiotelephone as a corrective response to detected consequential asymmetry or loss of substantial symmetry (unless errors are attributable to alternative detections of valid synchronization words) and cancelling any such corrective response upon subsequent alternative detections of valid synchronization words.

Error detection

The hand-off process of the present invention minimizes the number of hand-offs in radiotelephone system using smaller, elongated cells that may provide radiotelephone coverage in an urban environment along streets. While in the idle mode, the process of the present invention keeps track of the radiotelephone's direction of travel. When the radiotelephone is making a call, the base station process of the present invention keeps track of any fade condition that occurs, both short term and long term, and hands the radiotelephone off to another cell if one of these conditions occur.

Growing community of inventors

Itasca, IL, United States of America

Stephen N Levine