Showing papers on "Inter frame published in 1998"

Continuously adaptive digital video compression system and method for a web streamer

Abstract: A cost effective continuously adaptive digital video system and method for compressing color video data for moving images The method describes capturing an analog video frame and digitizing the image into a preferred source input format for compression using a combination of unique lossy and lossless digital compression techniques including subband coding, wavelet transforms, motion detection, run length coding and variable length coding The system includes encoder and decoder (CODEC) sections for compression and decompression of visual images to provide high compression with good to excellent video quality The compressed video data provides a base video layer and additional layers of video data that are multiplexed with compressed digital audio to provide a data stream that can be packetized for distribution over inter or intranets, including wireless networks over local or wide areas The (CODEC) system continuously adjusts the compression of the digital images frame by frame in response to comparing the available bandwidth on the data channel to the available bandwidth on the channel for the previous frame to provide an output data stream commensurate with the available bandwidth of the network transmission channel and with the receiver resource capabilities of the client users The compression may be further adjusted by adjustment of the frame rate of the output data stream

Method and apparatus for increasing video frame rate

Abstract: Synthesizing of video frames that have been dropped by a video encoder is achieved by interpolating between decoded frames at a decoder. The method consists of successive refinement stages that increase in computational complexity. Starting with a spatio-temporal median filtering approach, each stage uses information that improves the quality of the interpolated frames, such as bit stream motion information, decoder-based motion estimation and motion-based state segmentation of regions. By using more computational resources, each of these stages results in an improved quality of interpolated video. The motion compensation techniques are based on block-based motion estimation of the kind used by block-transform based video encoders. More accurate motion estimates are obtained by using a combination of forward and backward block motion estimation. The method is further extended by incorporating global/local motion estimation based on the segmentation information, and employing image warping techniques to compensate for motion resulting from deformations.

Real-time encoding of video sequence employing two encoders and statistical analysis

Abstract: Method, system and computer program product are provided for adaptively encoding in hardware, software or a combination thereof a sequence of video frames in real-time. A first encoding subsystem analyzes the sequence of video frames to derive information on at least one characteristic thereof, such as motion statistics, non-motion statistics, scene change statistics, or scene fade statistics. The gathered information may be either an intraframe characteristic or an interframe characteristic. A control processor is coupled to the first encoding subsystem to automatically analyze the gathered information in real time and dynamically produce a set of control parameters. A second encoding subsystem, coupled to the control processor, then encodes each frame of the sequence of video frames employing the corresponding set of control parameters.

Method for tracking a video object in a time-ordered sequence of image frames

Abstract: A method for tracking a video object in a time-ordered sequence of image frames, comprises the steps of (a) identifying the object to be tracked in a first frame and determining its shape in the first frame; (b) selecting another frame, referred to as the last frame and identifying the shape of the object in the last frame; (c) selecting a number of intermediate frames between the first and last frames; (d) automatically identifying the shape of the object in the intermediate frames; and (e) interpolating between all of the frames in the sequence so as to determine the trajectory of the object in all of the frames

Dynamic frame-skipping in video transcoding

Abstract: This paper investigates the dynamic frame skipping strategy in video transcoding. To speed up the operation, a video transcoder usually reuses the decoded motion vectors to reencode the video sequences at a lower bit-rate. When frame skipping is allowed in a transcoder, those motion vectors can not be reused because the motion vectors of the current frame is no longer estimated from the immediate past frame. To reduce the computational complexity of motion vectors reestimation, a bilinear interpolation approach is developed to overcome this problem. Based on these interpolated motion vectors, the search range can be much reduced. Furthermore, we propose a frame rate control scheme which can dynamically adjust the number of skipped frames according to the accumulated magnitude of the motion vectors. As a result, the decoded sequence can present much smoother motion.

POCS-based error concealment for packet video using multiframe overlap information

Abstract: This paper proposes a new error concealment algorithm for packet video, effectively eliminating error propagation effects. Most standard video codecs use motion compensation to remove temporal redundancy. With such motion-compensated interframe processing, any packet loss may generate serious error propagation over more than ten consecutive frames. This kind of error propagation leads to perceptually annoying artifacts. Thus, proper error concealment algorithms need to be used to reduce this effect. The proposed algorithm adopts a one-pixel block overlap structure. With the redundancy information from the damaged frame and the following frames, the proposed POCS-based method can have consistently high performance in error concealment. According to the experimental results, the proposed algorithm can successfully eliminate visible error propagation. In addition, the proposed algorithm is very robust. Experimental results show that it can have good error concealment results, even when the damaged frame loses all the DCT coefficients.

Method and apparatus for playing an MPEG data file backward

Abstract: The present invention has been made in consideration of linear reverse playback of MPEG video data and has particular applications to video special effect editing. According to one aspect of the present invention, the disclosed system uses a minimum number of frame storage to buffer decompressed I and P frames so as to decompress B frames in a reverse order and subsequently display the B frames. Every time, it comes to display the decompressed I and P frames buffered in the frame storage, an I frame or a P frame in a group of picture (GOP) prior to current GOP is decompressed and buffered into one of the frame storage that becomes available when the content therein has been retrieved for display. The cyclic use of the frame storage and the time that would be otherwise spent for decompressing B frames guarantees a linear reverse playback of MPEG video data without showing retardant visual effects that often result from non-even decoding processes in displaying compressed frames.

Multiple display synchronization apparatus and method

Abstract: A method of synchronizing, at a system frame display rate, a first set of frames displayed by a first monitor with a second set of frames by a second monitor, utilizes frame production rates of the two sets of frames to set the system frame display rate. More particularly, the first set of frames are produced at a first frame production rate by a first graphics engine, and the second set of frames are produced at a second frame production rate by a second graphics engine. The first frame production rate and second frame production rate first are compared to determine which frame production rate is slower. The system frame display rate then is set to be no greater than the slower of the two frame production rates.

Device and method for converting frame rate

Abstract: Device and method for converting a frame rate, is disclosed, in which a motion compensated frame is newly produced in converting a frame rate, particularly, in a digital TV of a PAL or NTSC system, a motion component compensated separate frame is provided between frames and displayed to horizontal/vertical synchronizing signals two times faster than an original frequency for eliminating flicker, and in a case when a video signal of a film rate is converted into a video signal of a frame rate of PAL or NTSC system, motion component compensated new frames are produced for converting the frame rate for preventing blurring occurred in motion portions. And, by differently compensating motion components of N frames inserted between two frames and processing the frames in real time, a slow motion can be displayed smoothly without any separate memory.

Increased video playback framerate in low bit-rate video applications

Abstract: A method comprising selecting a number of blocks of a frame pair and synthesizing an interpolated frame based on those selected blocks of the frame pair. Additionally, the synthesis of the interpolated frame is aborted upon determining the interpolated frame has an unacceptable quality.

Encoding digital signals

Abstract: A motion factor coding apparatus receives an input video signal which is applied to a subtractor and to a motion estimator which generates motion vectors for the current frame relative to a reference frame that is stored in the motion estimator. The motion vectors are passed to a buffer which are then iteratively update in a re-estimator. The number of iterations can be set to a fixed number or can be controlled by measuring the effect of each successive update on the motion. When a satisfactory number of iterations is reached, update motion vectors are passed to a motion compensator which generates a predicted frame which is applied as another input to the subtractor where the predicted frame is subtracted from the current frame in the input digital video signal. The subtraction removes temporal redundancy in the signal.

Optimizing block size in motion-compensated video coding

Abstract: Despite the widespread experience with block-based video coders, there is little analysis or theory that quantitatively explains the effect of block size on encoding bit rate, and ordinarily the block size for a coder is chosen based on empirical experiments on video sequences of interest. In this work, we derive a procedure to determine the optimal block size that minimizes the encoding rate for a typical block-based video coder. To do this, we analytically model the effect of block size and derive expressions for the encoding rates for both motion vectors and difference frames as functions of block size. Minimizing these expressions leads to a simple formula that indicates how to choose the block size in these types of coders. This formula also shows that the best block size is a function of the accuracy with which the motion vectors are encoded and several parameters related to key characteristics of the video scene, such as image texture, motion activity, interframe noise, and coding distortion. We implement the video coder and use our analysis to optimize and explain its performance on real video frames.

Fractal coding of video sequence using circular prediction mapping and noncontractive interframe mapping

Abstract: We propose a novel algorithm for fractal video sequence coding, based on the circular prediction mapping and the noncontractive interframe mapping. The proposed algorithm can effectively exploit the temporal correlation in real image sequences, since each range block is approximated by the domain block in the adjacent frame, which is of the same size as the range block. The computer simulation results demonstrate that the proposed algorithm provides very promising performance at low bit rate, ranging from 40-250 kbyte/s.

Preprocessing process and device for motion estimation

Abstract: The invention relates to a method of preprocessing a video image sequence consisting of a succession of interlaced frames for estimating motion between a first and a second frame, characterized in that a temporal filtering is performed on the basis of at least two input frames so as to deliver each of the two frames utilized by the motion estimator. The applications relate to motion estimators, in the field of video image compression or the conversion of television standards.

Real-time variable bit rate encoding of video sequence employing statistics

Abstract: Method, system and computer program product are provided for adaptively encoding in hardware, software or a combination thereof a sequence of video frames in real-time. Pre-encode perceptual activity measurement processing is employed to derive statistics on each frame of the sequence of video frames to be encoded. The statistics are used by variable bit rate logic to obtain a number of bits to be used in encoding each frame. The number of bits to be used is provided to a single encoding engine, which encodes the sequence of video frames and produces a constant quality, variable bit rate bitstream output. The pre-encode processing employs a regulator as the global data flow control and synchronization for the encoder. Perceptual activity analysis on each frame of the sequence of video frames can derive information on, for example, shading, scene change, fade, color, motion and/or edge presence within the frame. Voting gives greater weight to the presence of certain characteristics within the frame.

Motion image coding apparatus adaptively controlling reference frame interval

Abstract: A motion image coding apparatus providing enhanced image quality as compared with the prior art includes a coding unit for coding first, second and third frames, a prediction efficiency calculating circuit for calculating prediction efficiency in inter-frame prediction, in coding by the coding unit using said first or second frame as a reference frame, and a reference frame interval determining circuit for determining a reference frame interval which is a time interval between the first and second frames, time interval between the second frames and time interval between the first frames.

Deinterlacing a video signal using a motion detector

Abstract: Deinterlacing a video signal using a motion detector is disclosed. In one embodiment, a divider, a comparator, and an interpolator deinterlace a video signal and reduce combing artifacts. The divider forms a ratio of inter-field activity to intra-field activity in a video frame. The ratio is compared to an empirically determined threshold. If the ratio is greater than the threshold, then there is motion in the frame and the second field is interpolated from the first field. If the ratio is less than the threshold, then there is no motion in the frame and no change is made to the frame.

Method and device for noise reduction

Abstract: A method of reducing noise in a video signal which includes a plurality of video frames being composed of a plurality of pixels, the method comprising the steps of: comparing video information contained in a current video frame and a plurality of temporally adjacent video frames; selecting from the current video frame and the adjacent video frames the video information that according to a predetermined condition is likely to be correct for the current video frame; and finally assigning the selected video information to the current video frame to thereby produce a video frame wherein noise has been reduced.

Video display method and apparatus with synchronized video playback and weighted frame creation

Abstract: A video display apparatus and method for displaying decoded video frames from an encoded video stream utilizes a display time difference determinator that detects a frame display time difference, on a per frame basis if desired, between a refresh rate based frame display time, and a video playback frame rate display time to generate frame display time difference data. This is done on a continuous basis to detect synchronization problems between video data that is to be displayed simultaneously with non-video data on a display device such as a progressive display screen. A pixel blender blends pixel data from an adjacent frame, such as an already reconstructed previous frame or next frame, to create a temporally adjusted frame based on the determined frame display time difference data.

Delay balanced video encoder system

Abstract: A process and apparatus for encoding are provided, wherein fields of a digital signal are processed to detect repeat fields. Adjacent pairs of the non-repeated fields are organized into frames. A determination is made whether to encode each of the frames as an intraframe, a predicted frame or a bidirectionally predicted frame. The frames are encoded in a specific, predefined order relative to the order of capture of the frames and the type of frame. After each bidirectionally predicted frame that immediately precedes one of the detected repeat fields, encoding of a frame is delayed for one field time. Encoding is paused after encoding each reference frame that is the very next reference frame to be encoded after a second reference frame, which second reference frame immediately precedes one of the detected repeat fields. A process and apparatus for statistically multiplexing multiple encoded digital video signals are also provided. Statistics are gathered for one or more of the encoded digital video signals and bit rates are allocated for transmitting one or more of the digital video signals as encoded. One of the digital video signals is encoded to produce a certain number of bits for each encoded picture in accordance with a decoder buffer model having a predefined size and filling at a certain bit rate, which is updated with the bit rate allocated to the one digital video signal. The update is delayed by a number of field display times depending on the number of times encoding pauses, and a presumed number of times decoding pauses, as a result of the detected repeat fields.

Motion vector re-estimation and dynamic frame-skipping for video transcoding

Abstract: This paper investigates the dynamic frame-skipping strategy in video transcoding. To speed up the operation, a video transcoder usually reuses the decoded motion vectors to reencode the video sequences at a lower bit-rate. When frame-skipping is allowed in a transcoder, those motion vectors can not be reused because the motion vectors of the current frame is no longer estimated from the immediate past frame. To reduce the computational complexity of motion vectors re-estimation, a bilinear interpolation approach is developed to overcome this problem. Based on these interpolated motion vectors, the search range can be much reduced. Furthermore, we propose a frame rate control scheme which can dynamically adjust the number of skipped frames according to the accumulated magnitude of motion vectors. As a result, the decoded sequence can present much smoother motion.

Video signal coding systems and processes using adaptive quantization

Abstract: A compression system and process employs a group of quantizers (or set of predefined quantized values) and involves the selection of the quantizers for each video frame or frame portion. For each frame portion, a selection of the most appropriate quantizer is made. The selection of which quantizer from the selection group is most appropriate for coding of a video frame or frame portion is based on a formula which takes account both the distortion (accuracy) and bit rate characteristics of each quantizer. The quantizer that exhibits the best combined distortion and bit rate characteristics is selected for coding the frame or frame portion. A similar formula, based on both distortion and bit rate characteristics, is used to select the particular quantization value within the quantizer set for each video signal value being coded.

Video signal coding method

Abstract: A video signal coding method is provided which finds proper decision curves according to characteristics of input frames and encodes the optimal macroblock by using the decision curves instead of a fixed motion/no-motion compensation curve and intra/inter coding curve. The optimal mode is selected for each macroblock of input frame and it is determined through a step of judging whether the input frame is intra mode using a given function, a step of judging whether the input frame is inter mode when it is not intra mode using a given function, a step of controlling quantizer using a predetermined critical value when it is not inter mode, and step of performing skip when the quantizer controlling step is not carried out.

Coding an intra-frame upon detecting a scene change in a video sequence

Abstract: A method and apparatus is described for encoding a video sequence of frames. Each frame in the video sequence is organized in blocks of pixels. A scene change is detected when a current frame in the video sequence is substantially different from a previous frame. When it is determined that the current frame is the change in scene, the current frame is coded to be an intra frame with each block of pixels of the intra frame is being an intra-coded block. Coding the sequence of frames produces a compressed bit stream having a coded intra frame at each scene change. Each coded intra frame provides an access point in the bit stream from which a storyboard of the scenes in the video sequence can be generated.

Repeat field detection using checkerboard pattern

Abstract: The present invention is directed to a method for encoding an uncompressed digital video bit stream. The video bit stream comprises successive frames, each of which includes one or more odd fields and one or more even fields. Such frames with more than two fields may result from a telecine process as discussed above. The inventive method comprises the steps of capturing successive frames of said video bit stream in an encoder system, determining statistics for each frame to make an encoding decision for the frame, the statistics for each frame being determined in a single field time, using a statistically valid subset of pixels from the frame, and encoding the frame in said encoding system in a manner responsive to said encoding decision to generate an encoded bit stream. In a preferred embodiment of the invention, the statistically valid subset of pixels has a checkerboard pattern. Illustratively, the encoding decision involves dropping a repeated field in a frame and inserting a repeat field flag into the encoded bit stream.

Dynamically determining group of picture size during encoding of video sequence

Abstract: Method, system and computer program product are provided for dynamically determining group of picture (GOP) size as a function of picture change activity within a sequence of video frames. Image statistics on one or more intraframe characteristics of the sequence of video frames is compared to a preset threshold for deciding whether to continue within an existing GOP or to begin a new GOP. A frame of the sequence of video frames is intra-coded, and each of a variable number of subsequent frames is bi-directionally predictive-coded (B). Each B frame subsequent to the I frame is encoded employing forward prediction motion estimation only from the I frame. When a predefined picture degradation occurs, a new GOP is initiated. One example of an intraframe characteristic to be monitored is the number of intra-coded macroblocks within each B coded frame. This number is compared against a threshold number, which may be a percentage of the total number of macroblocks within the frame.

Flexible beam sequencing for 3-dimensional ultrasound imaging

Abstract: A method of generating data compatible with forming a three-dimensional ultrasonic image includes selecting different frame rates for generating patterns of image information and frames of non-imaging information, such as motion information. The frame rates may be independently determined, based upon the desired characteristics of the two types of frames. Typically, image frames and motion frames are formed concurrently, with the formation of each motion frame overlapping the formation of more than one image frame, i.e., motion frames have a lower frame rate than image frames. After a sufficient number of image and motion frames have been generated, the image frames and the motion data are spatially coordinated to provide a three-dimensional flow image of a region of interest. In one approach, the spatial coordination of motion frames is implemented by incorporating the motion frames in a non-parallel relationship with the image frames. In a more accurate approach, the motion information is incorporated on a value-by-value basis into the image frames.

Continuous synchronization adjustment in a telecommunications system

Abstract: A continuous synchronization adjustment algorithm (100) is described, which continuously synchronizes frames used in digital synchronous transmissions. By letting the receiver continuously adjust (122, 126) the assumed frame position, rather than adjusting only once per frame as conventionally done, a significant increase in bit error rate can be achieved. When an incorrect single sync bit is detected (114) in a frame, thereafter during the rest of the frame, the single sync bit positions that would result from an advance or delay of the frame position (e.g., due to a bit slip in the frame) are checked (120). The frame position is then adjusted (122, 126) immediately, without waiting for the beginning of the next frame. Consequently, there is a significant decrease in the number of data bits that are interpreted incorrectly or disregarded. As such, the bit error rate resulting from the present continuous algorithm is significantly improved over that resulting from prior synchronization algorithms.

Video encoder having reduced memory bandwidth requirements

Abstract: A video encoder typically includes a preprocessor, a frame store, a motion compensator, and a compression module. The preprocessor converts an incoming digital video signal to image macroblocks. The frame store stores the macroblocks from anchor frames, and the motion compensator searches neighborhoods in anchor frames for best matches to macroblocks from a current frame. The compression module receives a vector from the motion compensator indicative of the best match and uses it to compress the macroblocks from the current frame. The compressed macroblocks are provided as components of a compressed video output bitstream. To perform the neighborhood search, the motion compensator accesses many neighborhood macroblocks from the anchor frame for each macroblock from the current frame. To reduce the number of memory accesses, the motion compensator caches the neighborhood macroblocks. Since the search neighborhoods for adjacent macroblocks overlap, caching is effective. The effectiveness of caching may be increased by altering the order in which macroblocks from the current anchor frame are processed. This advantageously reduces the number of neighbourhood macroblocks from the anchor frame added to the cache for each neighborhood search, thereby providing for reduced requirement for memory bandwidth of the frame store.