Video decoder including a scale-down function for scaling down an image and method thereof

摘要

A compression video decoder and a method thereof, which decodes a standard compressed and encoded video stream, directly outputs the decoded image according to a screen size of a display device without using a special scale-down block for scaling down the image, increases a speed by reducing computational complexity for scaling down the image, maintains quality of the original image, and minimizes distortion. The compression video decoder for decoding the compressed and encoded video stream according to a video compression method using discrete cosine transform (DCT) and motion compensation (MC), includes an inverse discrete cosine transform (IDCT) block for extracting an NxN block DCT image in an image scale-down ratio according to DC coefficients from an 8x8 block DCT image which has been obtained from the compressed and encoded video stream and will be IDCT-processed, multiplying the respective coefficients by N/8, and performing the IDCT thereon, and an MC block for performing the MC by using the IDCT-processed reference image and the current image, and reducing a magnitude of a motion vector and a range of the MC at a ratio of N:8.