A Sub 100 mW H.264 MP@L4.1 Integer-Pel Motion Estimation Processor Core for MBAFF Encoding with Reconfigurable Ring-Connected Systolic Array and Segmentation-Free, Rectangle-Access Search-Window Buffer

Yuichiro MURACHI  Junichi MIYAKOSHI  Masaki HAMAMOTO  Takahiro IINUMA  Tomokazu ISHIHARA  Fang YIN  Jangchung LEE  Hiroshi KAWAGUCHI  Masahiko YOSHIMOTO  

IEICE TRANSACTIONS on Electronics   Vol.E91-C   No.4   pp.465-478
Publication Date: 2008/04/01
Online ISSN: 1745-1353
DOI: 10.1093/ietele/e91-c.4.465
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Advanced Technologies in Digital LSIs and Memories)
low power,  motion estimation,  H.264,  systolic array,  MBAFF,  SRAM,  

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We describe a sub 100-mW H.264 MP@L4.1 integer-pel motion estimation processor core for low power video encoder. It supports macro block adaptive frame field (MBAFF) encoding and bi-directional prediction for a resolution of 19201080 pixels at 30 fps. The proposed processor features a novel hierarchical algorithm, reconfigurable ring-connected systolic array architecture and segmentation-free, rectangle-access search window buffer. The hierarchical algorithm consists of a fine search and a coarse search. A complementary recursive cross search is newly introduced in the coarse search. The fine search is adaptively carried out, based on an image analysis result obtained by the coarse search. The proposed systolic array architecture minimizes the amount of transferred data, and lowers computation cycles for the coarse and fine searches. In addition, we propose a novel search window buffer SRAM that has instantaneous accessibility to a rectangular area with arbitrary location. The processor core has been designed with a 90 nm CMOS design rule. Core size is 2.52.5 mm2. One core supports one-reference-frame and dissipates 48 mW at 1 V. Two core configuration consumes 96 mW for two-reference-frame search.