Showing papers on "Encoder published in 1996"

Unveiling turbo codes: some results on parallel concatenated coding schemes

Abstract: A parallel concatenated coding scheme consists of two simple constituent systematic encoders linked by an interleaver. The input bits to the first encoder are scrambled by the interleaver before entering the second encoder. The codeword of the parallel concatenated code consists of the input bits to the first encoder followed by the parity check bits of both encoders. This construction can be generalized to any number of constituent codes. Parallel concatenated schemes employing two convolutional codes as constituent codes, in connection with an iterative decoding algorithm of complexity comparable to that of the constituent codes, have been previously shown to yield remarkable coding gains close to theoretical limits. They have been named, and are known as, "turbo codes". We propose a method to evaluate an upper bound to the bit error probability of a parallel concatenated coding scheme averaged over all interleavers of a given length. The analytical bounding technique is then used to shed some light on some crucial questions, which have been floating around in the communications community since the proposal of turbo codes.

Digital Video: An introduction to MPEG-2

Abstract: From the Publisher: This book offers comprehensive coverage of the MPEG-2 audio / visual digital compression standard. The treatment includes the specifics needed to implement an MPEG-2 Decoder, including the syntax and semantics of the coded bitstreams. Since the MPEG-2 Encoders are not specified by the standard, and are actually closely held secrets of many vendors, the book only outlines the fundamentals of encoder design and algorithm optimization.

Design of parallel concatenated convolutional codes

Abstract: A parallel concatenated convolutional coding scheme consists of two constituent systematic: convolutional encoders linked by an interleaver. The information bits at the input of the first encoder are scrambled by the interleaver before entering the second encoder. The codewords of the parallel concatenated code consist of the information bits followed by the parity check bits of both encoders. Parallel concatenated codes (turbo codes), decoded through an iterative decoding algorithm of relatively low complexity, have been shown to yield remarkable coding gains close to theoretical limits. We characterize the separate contributions that the interleaver length and constituent codes give to the overall performance of the parallel concatenated code, and present some guidelines for the optimal design of the constituent convolutional codes.

Rate-distortion optimized mode selection for very low bit rate video coding and the emerging H.263 standard

Abstract: This paper addresses the problem of encoder optimization in a macroblock-based multimode video compression system. An efficient solution is proposed in which, for a given image region, the optimum combination of macroblock modes and the associated mode parameters are jointly selected so as to minimize the overall distortion for a given bit-rate budget. Conditions for optimizing the encoder operation are derived within a rate-constrained product code framework using a Lagrangian formulation. The instantaneous rate of the encoder is controlled by a single Lagrange multiplier that makes the method amenable to mobile wireless networks with time-varying capacity. When rate and distortion dependencies are introduced between adjacent blocks (as is the case when the motion vectors are differentially encoded and/or overlapped block motion compensation is employed), the ensuing encoder complexity is surmounted using dynamic programming. Due to the generic nature of the algorithm, it can be successfully applied to the problem of encoder control in numerous video coding standards, including H.261, MPEG-1, and MPEG-2. Moreover, the strategy is especially relevant for very low bit rate coding over wireless communication channels where the low dimensionality of the images associated with these bit rates makes real-time implementation very feasible. Accordingly, in this paper, the method is successfully applied to the emerging H.263 video coding standard with excellent results at rates as low as 8.0 Kb per second. Direct comparisons with the H.263 test model, TMN5, demonstrate that gains in peak signal-to-noise ratios (PSNR) are achievable over a wide range of rates.

Method and apparatus for tactilely responsive user interface

Abstract: A method and apparatus implementing a user interface device, such as a mouse or trackball, having electronically controllable tactile responsiveness which is flexibly programmable. The interface device includes at least two sets of wheels that move as the interface device is actuated. A servo motor (116) is attached to each of the at least two sets of wheels. A position encoder (118) is associated with each servo motor (116) and outputs position information to a controller (120).

Transcoding of MPEG bitstreams

Abstract: This paper discusses the problem of transcoding as it may occur in, for instance, the following situation. Suppose a satellite transmits an MPEG-compressed video signal at say 9 Mbit/s. This signal must be relayed at a cable head end. However, since the cable capacity is only limited, the cable head end will want to relay this incoming signal at a lower bit-rate of, say, 5 Mbit/s. The problem is how to convert a compressed video signal of a given bit-rate into a compressed video signal of a lower bit-rate. The specific transcoding problem discussed in this paper is referred to as bit-rate conversion. Basically, a transcoder used for such a purpose will consist of a cascaded decoder and encoder. It is shown in the paper that the complexity of this combination can be significantly reduced. The paper also investigates the loss of picture quality that may be expected when a transcoder is in the transmission chain. The loss of quality as compared to that resulting in the case of transmission without a transcoder is studied by means of computations using simplified models of the transmission chains and by means of using computer simulations of the complete transmission chain. It will be shown that the presence of two quantizers, i.e. cascaded quantization, in the transmission chain is the main cause of extra losses, and it will be shown that the losses in terms of SNR will be some 0.5 ? 1.0 dB greater than in the case of a transmission chain without a transcoder.

Gyrodometry: a new method for combining data from gyros and odometry in mobile robots

Abstract: This paper presents a very simple, yet very effective method for combining measurements from a gyro with measurements from wheel encoders (odometry). The method, called gyrodometry, has been developed based on a careful study of the physical interaction between the ground and the vehicle. We present experimental evidence that non-systematic odometry error sources (such as bumps) impact the vehicle only during very short periods; typically a fraction of a second for each encounter. During these short instances the readings from the gyro and from odometry differ significantly, while in the absence of large non-systematic errors the readings are very similar. Gyrodometry makes use of this observation by using odometry data only-most of the time, while substituting gyro data only during those brief instances during which the gyro and odometry data differ substantially. In this way the ill-effects of gyro drift are almost completely eliminated, and our method can thus make use of inexpensive gyros with large drift rates. Experimental data is presented that demonstrates the effectiveness of this approach.

Video teleconferencing system with digital transcoding

Abstract: A video teleconferencing system uses digital transcoding to obtain algorithm transcoding, transmission rate matching, and spatial mixing. The video teleconferencing system comprises a multipoint control unit (MCU) for allowing multiple audiovisual terminals, which send and receive compressed digital data signals, to communicate with each other in a conference. The MCU has a video processing unit (VPU) that performs algorithm transcoding, rate matching, and spatial mixing among the terminals within a conference. The VPU includes a time division multiplex pixel bus and a plurality of processors. Each processor is assignable to an audiovisual terminal in the conference and is coupled to the pixel bus. In a receive mode, each processor receives and decodes compressed video signals from its assigned terminal and puts the decoded signal onto the pixel bus. In a transmit mode, each processor receives from the pixel bus uncompressed video signals from any terminal in the conference. The uncompressed video signals are processed and encoded for transmission to the respective assigned terminal. Video encoding time due to motion displacement search is reduced by passing displacement information from the compressed video signals to the encoder to be used directly or as a seed for further refinements of the motion displacement field.

Post-compression hidden data transport

Abstract: Auxialiary data subband samples representing an auxiliary data signal (315) are transported in a subband-coded compressed digital audio signal without decompressing the data. A pre-existing packetized data stream (305) is provided to an input of an encoder (310). Subband audio samples (406) are extracted from the packet stream and normalized (408). The data to be transported modulates data carrier subbands (SPD0, SPD1, ---SPDN-1) including a pseudo-noise (PN) spread spectrum signal, each subband of which has a bandwidth corresponding to those of the digital audio signal. The modulated data carrier sequence is combined with the audio subband samples (SS1, SS2---SSN-1) to form a combined signal (452), then multiplexed (460) into pre-existing packet stream (407). In the decoder (368), the combined signal is demodulated to recover the auxiliary data signal (672). The recovered auxiliary data signal is carried substantially inaudibly in the audio signal and is spectrally shaped according to the audio signal to enhance concealment.

Transparent block skipping in object-based video coding systems

Abstract: A method implemented in an object-based video encoder or decoder uses shape information that describes the boundary of a group of pixels representing an object in a sequence of video frames to identify transparent blocks (e.g., macroblocks or blocks so that coding/decoding of these blocks can be skipped. In the object-based video coding method, encoders code shape separately from motion and texture, and shape information is available before the encoder/decoder codes/decodes texture and motion data. The encoder and decoder use this shape information to identify transparent macroblocks or blocks so that texture coding and possible motion coding can be skipped. This method for transparent block skipping reduces coding and decoding operations and reduces the number of bits needed to store a bitstream representing a compressed video sequence.

Digital data encoding in video signals using data modulated carrier signals at non-peaks in video spectra

Abstract: Digital information is encoded in the video portion of a television signal such that "n" (n is an integer) bits of the digital information are carried by each successive frame in a group of frames. The digital information is encoded by modulating a carrier signal, using, for example, either amplitude shift keying (ASK) or frequency shift keying (FSK), and the modulated carrier is then added to the video signal selectively, only in portions of the television program that (a) are not likely to be perceptible by a viewer, and (b) are of sufficient intensity to transmit the data. The video signal including the encoded digital data, may be transmitted, in real time, to a television receiver, or recorded for later playback. In either event, at a receiver, when the video signal containing the encoded information is displayed on a screen, the image is sensed or "viewed" by a photo detector, the output of which is applied to a band pass filter having a center frequency that corresponds to the oscillator frequency(s) in the encoder. The filter output is thresholded or FM detected, so that the receiver can recover the encoded data. By appropriately including checks bits and synchronization patterns, the bit stream output from the decoder can be synchronized, and the original encoded data recovered. Advantageously, the frequency of the oscillator in the ASK or FSK encoder is chosen so that the energy added to the video signal is in a portion of the frequency spectrum that otherwise contains little energy. This makes the added digital data imperceptible to a viewer. If desired, the same data may be repetitively encoded in several groups of frames, so as to increase the redundancy and thus the reliability of the overall system.

Portable 3-D scanning system and method for rapid shape digitizing and adaptive mesh generation

Abstract: A portable 3D scanning system collects 2D-profile data of objects using a combination of a laser-stripe positioning device and a video camera which detects the images of the laser stripe reflected from the object. The scanning system includes a laser-stripe generator, a video camera, a scanning mirror attached to a continuously rotating motor, an encoder or a photodiode operationally coupled to the motor, and associated electronics. As the rotating, scanning mirror reflects the laser stripe and variably positions the laser stripe across the object, the encoder or the photodiode generates signals indicating the angular position of the mirror. The video images of the reflected laser stripes are stored on a storage medium, while data relating to the angular positions of the laser stripes recorded in the video images are simultaneously stored on a storage medium. A computer subsequently synchronizes and processes the recorded laser stripe data with the angular-position data to generate a 3D model of the object by applying triangulation calculation and other post-scanning methods, e.g., multi-resolution analysis and adaptive-mesh generation. The multi-resolution analysis, which applies more points to resolve fine details and fewer points for smooth regions of the objects, leads to significant data compression. The adaptive mesh, which include connected polygonal elements and which may have multiple resolutions and tolerances, is generated by the adaptive-mesh generating routine.

CD player for reproducing signals from CD-OK and video CD

Abstract: A CD player for reproducing signals stored on CD-OK and video compact disks (VCD) includes a first controller for controlling CD-OK reproduction; a second controller for outputting audio and video data for CD-OK reproduction and a control signal for VCD reproduction; a decoder for restoring compressed video and audio data; a first storage for storing control data for processing CD-OK signals during CD-OK reproduction and for storing control data for processing VCD during VCD reproduction; a second storage for storing data for a still screen and superposed data of the CD-OK disk during CD-OK reproduction and for storing video and audio data during VCD reproduction; a first digital-to-analog converter for converting the CD-OK video data output from the second controller into an analog image signal; a second digital-to-analog converter for converting image data output from the decoder into an analog image signal; a first switch for selecting one of the image signals output from one of the digital-to-analog converters; a video encoder for converting the image signal output from the first switch into a composite image signal; and a second switch for selecting an audio output, thus integrating CD-OK and VCD reproduction circuits to reduce manufacturing costs for an integrated system.

Method and system to replace sections of an encoded video bitstream

Abstract: A method and system in which a section of a previously encoded digital bit stream is replaced with another section of encoded video. In order to remove a section of encoded video, it is necessary to determine the beginning and ending points of the encoded video in the digitally encoded bit stream. The addresses of the beginning and ending points of the encoded data cannot be simply looked up but are calculated by summing the bits consumed by each picture, the number of bits of the sequence header of each picture, the number of bits of each Group of Pictures (GOP) header, and all stuff bits. In order to encode the video which is to be inserted in place of the removed video, a process is performed which prevents decoding artifacts from appearing. This is accomplished by determining the last P-picture before the edit point and using it as a reference frame for frames after the edit point. Additionally, a short period of the original video encoded using its original quantizer values is included at the end of the video to be substituted. Alternatively, the encoder may be run so that an earlier encoded reference picture is not used. However, this requires extra bits to maintain picture quality because initial bidirectional frames of the substitute video will use only one reference frame instead of two.

Encoder/decoder buffer control for variable bit-rate channel

Abstract: Encoder/decoder buffer overflow and underflow encountered when employing actually variable or effectively variable bit-rate channels for communicating encoded video images and corresponding audio signals are overcome by adjusting the parameters of a video encoder in response to a representation of cell delay variation, i.e., jitter, determined at a remote decoder.

Low bit rate video encoder using overlapping block motion compensation and zerotree wavelet coding

Abstract: An apparatus and a concomitant method for encoding video frame sequences (input images) using overlapping block motion compensation in conjunction with zerotree wavelet coding. The method partitions each input image into a plurality of overlapping blocks and applies wavelet transform on the partitioned input image. Various optional quantization processes can be selectively applied to determine an optimal quantizer scale for each wavelet coefficient. Zerotree coding is then optionally applied to selectively prune the wavelet coefficients. Finally, the quantized coefficients are encoded into a bitstream.

System and method for lossless image compression

Abstract: A lossless image compression encoder/decoder system having a context determination circuit and a code table generator. The image compressor uses the context of a pixel to be encoded to predict the value of the pixel and determines a prediction error. The image compressor contains a context quantizer that quantizes the context of pixels. The image compressor counts the error values for each quantized context and uses these counts to generate context-specific coding tables for each quantized context. As it encodes a particular pixel, the encoder looks up the prediction error in the context-specific coding table for the context of the pixel and encodes that value. To decompress an image, the decompressor determines and quantizes the context of each pixel being decoded. The decompressor uses the same pixels as the compressor to determine the context. The decompressor retrieves from the context-specific coding table the error value corresponding to the coded pixel. The decompressor uses a predictor to predict the value of the pixel based on the context and adds the error value to determine the actual value of the pixel. In one embodiment the image compressor uses an alphabet extension, embedded in its context model, in specific low gradient contexts to reduce the redundancy of the encoding. Other systems and methods are disclosed.

Advances in residual vector quantization: a review

Abstract: Advances in residual vector quantization (RVQ) are surveyed. Definitions of joint encoder optimality and joint decoder optimality are discussed. Design techniques for RVQs with large numbers of stages and generally different encoder and decoder codebooks are elaborated and extended. Fixed-rate RVQs, and variable-rate RVQs that employ entropy coding are examined. Predictive and finite state RVQs designed and integrated into neural-network based source coding structures are revisited. Successive approximation RVQs that achieve embedded and refinable coding are reviewed. A new type of successive approximation RVQ that varies the instantaneous block rate by using different numbers of stages on different blocks is introduced and applied to image waveforms, and a scalar version of the new residual quantizer is applied to image subbands in an embedded wavelet transform coding system.

A rate-controlled digital video editing method and system which controls bit allocation of a video encoder by varying quantization levels

Abstract: A method and system for re-encoding frames of a digital video stream without changing the previously calculated bit length of the stream. A set of macroblocks at a time are re-encoded (292), the number of resulting bits is calculated (306, 368) and the deviation from an estimated number of bits is calculated (372), either set-by-set or cumulatively. Based on the accuracy (372), of the estimate (422) and the remaining number of sets of macroblocks (424) to re-encode, a correction factor (710) for the quantization level of the next set of macroblocks is chosen from a lookup table. The correction factor is added to the quantization level of the next set of macroblocks (712) and the results stored as the new quantization level of the set (706). This sequential process is done for all sets of macroblocks in the digital stream which are to be recorded according to changed image qualities (706. 708. 710. 712. 714).

System and method for lossless image compression having improved sequential determination of golomb parameter

Abstract: A lossless image compression encoder/decoder system having a context determination circuit and a code generator. The image compressor uses the context of a pixel to be encoded to predict the value of the pixel and determines a prediction error and maps the prediction error to a mapped value having a distribution suitable for Golomb encoding. The image compressor contains a context quantizer that quantizes the context of pixels. The image compressor determines a Golomb parameter based on the context and historical information gathered during the coding of an image. To avoid systematic prediction biases in an image, the image compressor adjusts the distribution of prediction residuals to a distribution suitable for Golomb coding. As it encodes a particular pixel, the encoder uses the Golomb parameter to determine a Golomb code for the prediction error and encodes that value. To decompress an image, the decompressor determines and quantizes the context of each pixel being decoded. The decompressor uses the same pixels as the compressor to determine the context. The decompressor uses the context and historical information gathered during the decompression of the image to determine a Golomb parameter for the context in which the pixel occured. The decompressor retrieves from the compressed image the code for the pixel. Using the Golomb parameter and the retrieved code, the decompressor determines the mapped value of the code. The decompressor then uses the inverse mapping to determine the error value. The decompressor uses a predictor to predict the value of the pixel based on the context and adds the error value to determine the actual value of the pixel. In one embodiment the image compressor uses an alphabet extension, embedded in its context model, in specific low gradient contexts to reduce the redundancy of the encoding. Other systems and methods are disclosed.

A novel bandwidth efficient coding scheme employing turbo codes

Abstract: We have investigated a novel bandwidth efficient channel coding scheme that has a code structure similar to binary turbo codes but employs Ungerboeck codes as component codes. The combination of turbo codes with powerful bandwidth efficient component codes leads to a straightforward encoder structure and allows iterative decoding in analogy to the binary turbo decoder. However, certain special conditions need to be met at the encoder, and the iterative decoder needs to be adapted to the decoding of the component Ungerboeck codes. The scheme has been investigated for 8 PSK and 16 QAM modulation, for which a first attempt at component code optimization was performed. Simulation results are presented and the scheme is compared with Ungerboeck codes on their own and also turbo codes with Gray mapping. The results show that the novel scheme is markedly superior at comparable complexity.

Compressed video transcoder

Abstract: Compressed video transcoding apparatus and methods are disclosed. One embodiment eliminates the need for reorder buffers by utilizing an encode order video decoder which decodes a first compressed video bit stream to provide a sequence of frames in an encode order suitable for direct encoding without further reordering. An encode order video encoder receives the sequence of frames in encode order and directly encodes the frames without further reordering to provide a second compressed video bit stream. Another embodiment utilizes a frame reorder device to reorder compressed frames of a first compressed video bit stream into an encode order such that a subsequent encoding operation after decoding the first compressed video bit stream can be performed without further reordering of the frames. The reordered compressed frames are decoded and applied in the encode order to an encoder which encodes the frames to provide a second compressed video bit stream. Another embodiment includes a decoder which decodes a first compressed video bit stream to provide a sequence of decoded frames. The sequence of decoded frames is applied to an encoder along with auxiliary information regarding the first compressed video bit stream. The encoder utilizes the auxiliary information to simplify encoding of the decoded frame sequence. The auxiliary information may include motion vectors, quantization scale, number of bits used, motion compensation mode and repeat field indications for the first compressed video bit stream.

Video encoder/decoder system

Abstract: A method and an apparatus for encoding an image signal. The apparatus includes an acquisition module disposed to receive the image signal. A first processor is coupled to the acquisition module. At least one encoder processor is coupled to the first processor. The at least one encoder processor produces an encoded image signal under control of the first processor. The method includes the steps of converting an input image signal into a predetermined digital format and transferring the digital format image signal to at least one encoder processor. The method further includes the step of applying, at the at least one encoder processor, a hierarchical vector quantization compression algorithm to the digitized image signal. At the next step, a resultant encoded bit stream generated by the application of the algorithm is collected. The method and apparatus of the present invention may be used in conjunction with an ordinary modem to transmit and/or receive audio, video sequences or still images.

Quasi-reprographics with variable embedded data with applications to copyright management, and distribution control

Abstract: A method and apparatus for quasi-reprographically replicating a source document. The source document is digitized, appropriate locations for embedded code are detected, and any embedded code located in the digitized document along with the detected locations are forwarded to a decoder. The decoder forwards the decoded information to a control unit which processes this information and forwards it to a encoder whereafter it is inserted in the digitized document. The hardcopy replication of the source document being substantially visually identical to the source document, even though new or additional embedded machine-readable data has been added or existing data has been changed. The process occurs without intervention by an operator and without knowledge of the operator producing the replicated documents.

Video coding/decoding apparatus which transmits different accuracy prediction levels

Abstract: A video coding/decoding apparatus comprises a prediction circuit that divides an input video signal into large regions and small regions in a hierarchical fashion and produces a prediction signal by performing prediction region by region, a subtracter for generating a prediction error signal for a prediction signal at the lowest level, a DCT circuit for coding a prediction error signal, a quantization circuit and a variable-length encoder, a variable-length encoder for coding the prediction mode and motion vector information obtained at each level from the prediction circuit, and a multiplexer for multiplexing the code strings obtained from the variable-length encoder and dividing them into the upper-layer and lower-layer code strings to output the code strings obtained at the variable-length encoder particularly as upper-layer code strings.

Variable length code detection in a signal processing system

Abstract: A group of incoming data stream bits having packed variable length code ("VLC") words is applied to an entropy code bit length searching module. The group of bits is replicated within a plurality of matching modules selectively distributed among entropy code bit length searching logic units. Each unit of entropy code bit length searching logic supports a VLC word table as characterized by, for example, standard compression formats such as MPEG-1, MPEG-2, H.261, and H.263. The matching modules are divided into groups within the entropy code bit length searching logic units. A group of matching modules is allocated to each VLC bit length represented in the associated VLC word supported table. A number of matching modules are allocated to each bit length equal to a minimum number of patterns unique to VLC words of a particular bit length. The matching modules compare an incoming data group to respective patterns. A detected match is indicated by an appropriately set group output signal. Each entropy code bit length searching logic unit includes a bit length encoder that receives the group output signals. The set group output signal indicates the bit length of a current VLC, and the bit length encoder encodes this information into a bit length code output signal. The bit length code signal is utilized by a shifter to parse a corresponding bit length of current data. The parsed current data may be directly applied to an address generator which generates an output signal for a decoding look up table.

Variable scaling of 16-bit fixed point fast fourier forward and inverse transforms to improve precision for implementation of discrete multitone for asymmetric digital subscriber loops

Abstract: A discrete multitone (DMT) digital subscriber loop (xDSL) telecommunication system has a transmitter portion including a bit encoder, inverse fast Fourier transform (FFT), parallel-to-serial converter, digital-to-analog converter and line driver for transmitting data signals to a twisted pair telephone line and a receiver portion including an analog-to-digital converter, serial-to-parallel converter, forward FFT and bit decoder for receiving data signals from the twisted pair telephone line. The FFT's are implemented in 19-bit precision using a fixed point 16-bit processor. At each FFT stage, the number of sign bits in the FFT input data is examined to determine whether overflow is possible during multiply and add operations. The input data is downscaled by right shifting one or two bits if overflow is possible. If downscaling occurred, the output data is rescaled after completion of the FFT operation. If overflow is not possible, no scaling is done. By using variable scaling to downscale only when necessary, better overall precision is maintained.

Video coding using motion compensation with polynomial motion vector fields

Abstract: This paper presents novel methods for motion compensated prediction and prediction error coding of video sequences. The scheme utilises segmentation of the video frames into nonregularly shaped segments composed of small square blocks which can be encoded with a very low number of bits. This two-step segmentation is obtained by quadtree-like splitting of image blocks followed by a motion assisted merging algorithm which yields segments characterised by uniformity of motion. Motion fields are compactly encoded using 2-D separable orthonormal polynomials. The number and order of these polynomials is established for each segment separately in an adaptive manner. To improve the efficiency of coding of the residual error, after motion compensated prediction the proposed scheme utilises the spatial properties of the prediction frame available in the encoder and the decoder. Results of the simulations described in this paper show that the presented scheme enables up to 45% bitrate reductions compared to the ITU-T Rec. H.263 video coder while achieving the same objective quality of coded video.

Video data encoder and decoder

Abstract: This invention relates to compression of prediction error in motion compensated video coding schemes. Prediction frame and motion vectors are used to extract useful information about the properties of the prediction error signal, e.g. its location, directionality, etc. This information does not need to be transmitted because the decoder of the proposed system includes means to extract this information. Information extracted by the encoder and decoder is used to adapt prediction error coding scheme which gives substantial bitrate reductions.

Hybrid hierarchical/full-search mpeg encoder motion estimation

Abstract: A computationally efficient hierarchical block-matching motion estimation technique, in conjunction with full-search block-matching, determines inter-frame motion for digital video data compression. In hierarchical block-matching, a filtered and decimated macroblock (16) is compared with macroblock sized subareas in a filtered and decimated search area (114). Comparing the original macroblock (16) with an augmented block (126) in the original search area (112), that corresponds to the best matching macroblock sized area in the search area (114), determines a motion vector. Operating parameters specify a search range in the search area (112) based on the type of frame being processed, i.e. P-frame (252) or B-frame (256), and, for B-frames (256), the distance of the B-frame (256) from the reference frame (254). A hierarchical block-matching search is performed if operating parameters specify a search range above an established threshold. A search range equal to or below the established threshold results in full-search block-matching.