RATE CONTROL APPARATUS FOR REAL-TIME IMAGE COMMUNICATION AND METHOD THEREOF

摘要

PURPOSE: A rate control apparatus for real-time image communication and a method thereof are provided to prevent buffer overflow or underflow of an encoder and a decoder, thereby improving reproduced image quality. CONSTITUTION: An initialization module(200) receives transfer rate of a channel and input frame per second of an image to be coded for setting up initial value required for rate control. A target bit calculation module(300) obtains and outputs target encoding bit number, the maximum permissible bit number, and the minimum permissible bit number by considering the current buffer state and transfer rate of the channel. A macro block rate control and encoding module(400) executes macro block rate control and encoding by using target encoding bit number, the maximum permissible bit number, and the minimum permissible bit number. A stuffing control module(800) compares macro block rate control, the size of bit stream from the macro block rate control and encoding module(400), the target encoding bit number for outputting stuffing bit stream. A buffer module(500) combines bit stream from the macro block rate control and encoding module(400) with stuffing bits from the stuffing control module(800) for storing the combined bits, outputs a buffer seizure state signal to the target bit calculation module(300), and transmits image information to a decoder. A frame skip module(600) receives the buffer seizure state signal for outputting a frame skip signal when buffer state exceeds specified limit. A control logic module(700) controls whole encoding procedure and receives the frame skip signal for determining whether the next input frame should be encoded.