Unsampled hd mpeg video and half-pel motion compensation

Abstract

A high definition digital video presentation system is provided with an interpolator which upsamples standard resolution MPEG pictures to higher resolution, preferably to double the number of pixels in both the vertical and horizontal dimensions. The upsampling is performed after the decoding and transformation of the incoming picture and prior to the buffering of the picture data or the performance of motion compensation by which pixel data are copied from previously received pictures. In the preferred embodiment, frame pictures are decoded, upsampled and stored in full frame picture buffers, preferably, in two buffers, one to be copied into each field of subsequent pictures in the performance of motion compensation. Interpolation may be by frame, where intervening lines of pixels are interpolated from the pixels of adjacent odd and even lines, and by field, where an intervening odd (or even) line of pixels is interpolated from the pixels of each pair of adjacent even (or odd) lines. With frame interpolation, both buffers are stored with a frame interpolated upsampled picture, while with field interpolation, one buffer is stored with a picture interpolated only from even lines and one is stored with a picture interpolated only from odd lines. The decision to interpolate by frame or by field is made macroblock-by-macroblock by the processor based on an analysis of received data to provide the method that most accurately interpolates the intervening pixels. With the upsampled pictures stored in the buffers, no further half-pel interpolation is required for half-pel motion compensation of new pixels, which is carried out by directly copying original or previously interpolated pixels. Preferably pixels at original pixel positions are, however, interpolated from only original pixel data according to MPEG techniques.