software motion picture (DEC) (SMP)

Software Motion Picture(SMP) is a compression method for moving images and digital video developed by Digital Equipment ( DEC). The software-based compression algorithm works lossy and is executable on all Windows platforms.

Software Motion Picture was developed for simple network applications. With a resolution of 320 x 240 pixels, a color depth of 8 bits and a frame rate of 15 frames/s, the quality is adapted to communication applications. Compression by a factor of about 9:1 achieves data rates of about 1 Mbit/s for video and 100 kbit/s for audio.

SMP compression works on a block-by-block basis, first determining the luminance and chrominance values using color subsampling. Then the 16-bit data blocks for chrominance are halved to 8 bits by averaging the color values of adjacent pixels. The luminance component is divided into blocks consisting of 4x4 pixels. The data size of the blocks is reduced by averaging the gray values.