Patent ID: 7079581

Claim:
An encoder comprising: an encoding unit for performing a predetermined image conversion on present video data to be encoded and encoding the video data into a variable bit rate by quantizing the conversion result; and a variable bit rate controller for allocating an overall bit estimate of the video data, which is to be stored in a system, to each frame according to a variation in video recording time, detecting the complexity of frames based on a difference between pixels of the encoded video data, and determining a quantization factor using the detected complexity, wherein the variable bit rate controller comprises: a complexity calculator for allocating the overall bit estimate to each frame according to a variation in video recording time, and detecting the complexity of frames with a difference between pixels of the previous video data and the present video data; a target bit rate decision unit for determining a target bit rate to be stored in each frame in accordance with the detected complexity; a scene change detector for detecting a scene change in the present video data in accordance with the detected complexity; a group-of-picture (GOP) selector for grouping frames of the present video data into GOP having frames of similar complexity; a rate distortion function updating unit for updating a rate distortion function, which is to be used in calculating the quantization factor, according to the grouping result; and a quantization factor decision unit for calculating the quantization factor with the complexity, the bit estimate, the target bit rate, and parameters updated by the rate distortion function updating unit.