MPEG-4 is the multimedia standard for combining interactivity, natural and synthetic digital video, audio and computer-graphics Typical applications are: internet, video conferencing, mobile videophones, multimedia cooperative work, teleteaching and games With MPEG-4 the next step from block-based video (ISO/IEC MPEG-1, MPEG-2, CCITT H261, ITU-T H263) to arbitrarily-shaped visual objects is taken This significant step demands a new methodology for system analysis and design to meet the considerably higher flexibility of MPEG-4 Motion estimation is a central part of MPEG-1/2/4 and H261/H263 video compression standards and has attracted much attention in research and industry, for the following reasons: it is computationally the most demanding algorithm of a video encoder (about 60-80% of the total computation time), it has a high impact on the visual quality of a video encoder, and it is not standardized, thus being open to competition Algorithms, Complexity Analysis, and VLSI Architectures for MPEG-4 Motion Estimation covers in detail every single step in the design of a MPEG-1/2/4 or H261/H263 compliant video encoder: Fast motion estimation algorithms Complexity analysis tools Detailed complexity analysis of a software implementation of MPEG-4 video Complexity and visual quality analysis of fast motion estimation algorithms within MPEG-4 Design space on motion estimation VLSI architectures Detailed VLSI design examples of (1) a high throughput and (2) a low-power MPEG-4 motion estimator Algorithms, Complexity Analysis and VLSI Architectures for MPEG-4 Motion Estimation is an important introduction to numerous algorithmic, architectural and system design aspects of the multimedia standard MPEG-4 As such, all researchers, students and practitioners working in image processing, video coding or system and VLSI design will find this book of interest

Algorithms, Complexity Analysis and VLSI Architectures for MPEG-4 Motion Estimation

The three-step search (TSS) algorithm for block-matching motion estimation, due to its simplicity, significant computational reduction, and good performance, has been widely used in real-time video applications. A new search algorithm is proposed for further reduction of computational complexity for motion estimation. It is shown that the proposed algorithm is simple and efficient and requires about one half of the computation for the TSS while keeping the same regularity and good performance.

A simple and efficient search algorithm for block-matching motion estimation

Variable block-size motion estimation (VBSME) has become an important video coding technique, but it increases the difficulty of hardware design. In this paper, we use inter-/intra-level classification and various data flows to analyze the impact of supporting VBSME in different hardware architectures. Furthermore, we propose two hardware architectures that can support traditional fixed block-size motion estimation as well as VBSME with less chip area overhead compared to previous approaches. By broadcasting reference pixel rows and propagating partial sums of absolute differences (SADs), the first design has the fewer reference pixel registers and a shorter critical path. The second design utilizes a two-dimensional distortion array and one adder tree with the reference buffer that can maximize the data reuse between successive searching candidates. The first design is suitable for low resolution or a small search range, and the second design has advantages of supporting a high degree of parallelism and VBSME. Finally, we propose an eight-parallel SAD tree with a shared reference buffer for H.264/AVC integer motion estimation (IME). Its processing ability is eight times of the single SAD tree, but the reference buffer size is only doubled. Moreover, the most critical issue of H.264 IME, which is huge memory bandwidth, is overcome. We are able to save 99.9% off-chip memory bandwidth and 99.22% on-chip memory bandwidth. We demonstrate a 720-p, 30-fps solution at 108 MHz with 330.2k gate count and 208k bits on-chip memory

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Analysis and architecture design of variable block-size motion estimation for H.264/AVC

Block matching motion estimation is the heart of video coding systems. During the last two decades, hundreds of fast algorithms and VLSI architectures have been proposed. In this paper, we try to provide an extensive exploration of motion estimation with our new developments. The main concepts of fast algorithms can be classified into six categories: reduction in search positions, simplification of matching criterion, bitwidth reduction, predictive search, hierarchical search, and fast full search. Comparisons of various algorithms in terms of video quality and computational complexity are given as useful guidelines for software applications. As for hardware implementations, full search architectures derived from systolic mapping are first introduced. The systolic arrays can be divided into inter-type and intra-type with 1-D, 2-D, and tree structures. Hexagonal plots are presented for system designers to clearly evaluate the architectures in six aspects including gate count, required frequency, hard-ware utilization, memory bandwidth, memory bitwidth, and latency. Next, architectures supporting fast algorithms are also reviewed. Finally, we propose our algorithmic and architectural co-development. The main idea is quick checking of the entire search range with simplified matching criterion to globally eliminate impossible candidates, followed by finer selection among potential best matched candidates. The operations of the two stages are mapped to the same hardware for resource sharing. Simulation results show that our design is ten times more area-speed efficient than full search architectures while the video quality is competitively the same.

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Survey on Block Matching Motion Estimation Algorithms and Architectures with New Results

Power consumption is very critical for portable video applications such as portable videophone and digital camcorder. Motion estimation (ME) in the video encoder requires a huge amount of computation, and hence consumes the largest portion of power. We propose a novel method of reducing power consumption of the ME by adaptively changing the pixel resolution during the computation of the motion vector. The pixel resolution is changed by masking or truncating the least significant bits of the pixel data, which is governed by the bit-rate control mechanism. Experimental results show that on average more than 4 bits ran be truncated without significantly affecting the picture quality. This results in more than 60% reduction in power consumption.

Low-power VLSI design for motion estimation using adaptive pixel truncation

The paper describes fully pipelined parallel architectures for the 3-step hierarchical search block-matching algorithm, a fast motion estimation algorithm for video coding. The advantage of this algorithm was completely utilized by use of intelligent data arrangement and memory configuration. Techniques for reducing interconnections and external memory accesses were also developed. Because of their low costs, high speeds, and low memory bandwidth requirements, the proposed 3-PE, 9-PE, and 27-PE architectures provide efficient solutions for real-time motion estimations required by video applications of various data rates, from low bit-rate video to HDTV systems. >

Liang-Gee

Papers

Parallel architectures for 3-step hierarchical search block-matching algorithm