Michael Bakhmutsky

METHOD OF CONCURRENT MULTIPLE-MODE MOTION ESTIMATION FOR DIGITAL VIDEO

This paper describes a method of motion estimation that determines the optimum prediction mode, along with the resulting motion vectors, as a part of the estimation process. It supports all six prediction modes that are allowed by the Main Profile of the MPEG-2 video coding standard, including the dual-prime modes, for frame and field picture types. If implemented on a processor whose architecture is optimized for the required operations, its computational complexity will not be much greater than that of conventional single-mode motion estimation.

Effective half-pel motion compensation and estimation scheme for digital video

Half-pel motion compensation, unlike its full-pel counterpart, requires the availability of up to four pixels from the reference picture to generate each compensated pixel. To compensate a 16 X 16 macroblock, a 17 X 17 array of pixels is needed. The number of memory access cycles necessary to process a macroblock, if half-pel motion compensation is employed, is greater than the number otherwise needed by 33, or 13% of the macroblock size. In some motion prediction modes, two 17 X 9 pixel arrays are used, and the number of additional cycles increases to 50, or 20% of the macroblock size. This affects the timing requirements for digital video decoding. In particular, a clock frequency higher than the pixel rate is required, as is buffering for pixel data to convert between the two rates. This paper considers the above problem and presents a method of reference picture memory access that eliminates the additional processing time required for half-pel motion compensation.