Method and apparatus of encoding/decoding video data using bitrate adaptive binary arithmetic coding

An apparatus and a method for bit rate-adaptive binary arithmetic encoding/decoding of video data are provided to perform the binary arithmetic encoding/decoding by determining the maximum length of a prefix, an order of an exponential golomb code and the number of contexts in which binarization is performed according to a compression bit rate of the video data, thereby obtaining high encoding efficiency irrespective of a range of a required compression bit rate. An apparatus for binary arithmetic encoding of video data comprises the followings: a bit rate adaptive unit(130) for determining the maximum length of a prefix by using a compression bit rate of the video data; a binarization unit(140) for performing binarization by dividing the video data into the prefix and a suffix according to the determined maximum length of the prefix; and an arithmetic encoding unit(160) for performing arithmetic encoding of the video data in which the binarization is performed. The compression bit rate of the video data is detected by using a quantization step size.