MPEG-4: an object-based multimedia coding standard supporting mobile applications
Mobile Networks and Applications - Special issue: mobile multimedia communications
Multihypothesis Motion Stimation for Video Coding
DCC '01 Proceedings of the Data Compression Conference
Fast motion estimation within the H.264 codec
ICME '03 Proceedings of the 2003 International Conference on Multimedia and Expo - Volume 3 (ICME '03) - Volume 03
Algorithm for computer control of a digital plotter
IBM Systems Journal
Multi-hypothesis motion compensation for low bit-rate video coding
ICASSP'93 Proceedings of the 1993 IEEE international conference on Acoustics, speech, and signal processing: image and multidimensional signal processing - Volume V
Image sequence coding using multiple-level segmentation and affine motion estimation
IEEE Journal on Selected Areas in Communications
Efficiency analysis of multihypothesis motion-compensated prediction for video coding
IEEE Transactions on Image Processing
A parametric solution for optimal overlapped block motion compensation
IEEE Transactions on Image Processing
IEEE Transactions on Circuits and Systems for Video Technology
Motion optimization of ordered blocks for overlapped block motion compensation
IEEE Transactions on Circuits and Systems for Video Technology
Long-term memory motion-compensated prediction
IEEE Transactions on Circuits and Systems for Video Technology
Rate-constrained multihypothesis prediction for motion-compensated video compression
IEEE Transactions on Circuits and Systems for Video Technology
Overview of the H.264/AVC video coding standard
IEEE Transactions on Circuits and Systems for Video Technology
Context-based adaptive binary arithmetic coding in the H.264/AVC video compression standard
IEEE Transactions on Circuits and Systems for Video Technology
Affine multipicture motion-compensated prediction
IEEE Transactions on Circuits and Systems for Video Technology
Adaptive interpolation filters and high-resolution displacements for video coding
IEEE Transactions on Circuits and Systems for Video Technology
Modeling Quantization of Affine Motion Vector Coefficients
IEEE Transactions on Circuits and Systems for Video Technology
Shape-adaptive DCT for generic coding of video
IEEE Transactions on Circuits and Systems for Video Technology
Efficiency of shape-adaptive 2-D transforms for coding of arbitrarily shaped image segments
IEEE Transactions on Circuits and Systems for Video Technology
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While many recent international video coding standards, especially H.264/MPEG-4 AVC, leverage block size adaptivity in motion estimation, the rate-distortion boundary can be pushed further by allowing even more freedom in the partitioning process of inter pictures. Adaptive-shape partitioning, which allows blocks to be partitioned along a straight line that runs through the block at a freely chosen angle and position, complements the regular subblock partitioning, allowing the encoder to better adapt to the local characteristics of the motion activity in a video sequence. However, the technique demands excessive encoder resources to exhaust the large search space. This paper is the result of an investigation into the relative rate-distortion importance of the various adaptive-shape modes, both in terms of the angle of the partition boundary and of its location within a block. We find that a significant reduction of the search space with a factor of up to 40 can be accomplished, while retaining 50 to 90% of the compression gain obtained in the state of the art. This allows encoders to operate at much lower complexity levels and also reduces the signaling overhead associated with adaptive-shape partitioning. Based on our observations, we formulate a number of approaches to trade off compression performance against encoder complexity. Furthermore we discuss the use of various schemes of overlapping motion estimation along the partition boundary, an aspect which is currently left unaddressed in the literature on adaptive-shape partitioning. We introduce the use of shape-adaptive transforms for the motion compensated signal, to avoid the condition that arises with adaptive-shape partitioning where a partition boundary lies inside a transform block. The result is a reduction in ringing artifacts while maintaining objective quality.