APPARATUS FOR DECODING MOTION PICTURE OF VARIABLE BIT RATE WITH THE FUNCTION OF VARIABLE SPEED, HIGH SPEED REPRODUCTION

摘要

A variable bit rate MPEG2 video decoder having a variable rate fast playback function includes a variable rate fast playback processor with a portion determining the fullness of a video buffer according to the amount of data input to and output from the video buffer; a fast playback rate controller for calculating a variable rate control parameter S representing the number of bi-directional predicted (B) pictures to be restored within one group of pictures (GOP) for the fast playback mode and a parameter D representing the sequence of B pictures to be restored during the fast playback mode according to the total number (T) of pictures and the number (N) of B pictures within one GOP and the buffer's fullness output from the portion for determining the fullness of the video buffer; and an effective data detector and transmitter for detecting a picture start code to detect data of a picture layer, classifying data of pictures and counting the number of B pictures to transmit effective data for the fast playback mode according to the variable rate control parameter S and the parameter D representing the sequence of B pictures. Accordingly, B pictures to be restored during the fast playback are arranged in sequence based on the buffer's fullness.