Parameter update method for entropy coding and decoding of conversion coefficient level, and entropy coding device and entropy decoding device of conversion coefficient level using same
Methods and apparatuses for decoding and encoding video are provided. A method includes obtaining bit strings corresponding to current transformation coefficient level information by arithmetic decoding a bitstream based on a context model that indicates a probability as to whether a bit from a bit string is a one or a zero, updating or maintaining a previous binarization parameter based on a comparison of a predetermined value and a size of a previous transformation coefficient, obtaining the current transformation coefficient level information by performing de-binarization of the bit strings using the determined current binarization parameter, and generating a size of a current transformation coefficient using the current transformation coefficient level information.
1. A method of decoding video, the method comprising:
obtaining a bin string corresponding to current transformation coefficient level information by arithmetic decoding a bitstream;
determining a current binarization parameter, for determining a prefix bin string from the bin string, to be one of (i) a previous binarization parameter and (ii) an updated value of the previous binarization parameter obtained by adding n to the previous binarization parameter, where n is an integer, and n is equal to or greater than 1, based on a comparison between a predetermined value that is proportional to the previous binarization parameter and a value of a previous transformation coefficient;
obtaining the current transformation coefficient level information by de-binarizing a binary value of the prefix bin string using the determined current binarization parameter;
determining a value of the current transformation coefficient using the current transformation coefficient level information; and
decoding data included in a transformation unit using reverse transformation based on the value of the current transformation coefficient in the transformation unit,
wherein, when the value of the previous transformation coefficient is equal to or smaller than the predetermined value, the current binarization parameter is determined to be the previous binarization parameter, and
when the value of the previous transformation coefficient is larger than the predetermined value, the current binarization parameter is determined to be the updated value.
2. The method of claim 1 , wherein n is equal to 1.
3. The method of claim 1 , wherein the obtaining comprises:
de-binarizing the binary values of the prefix bin string and binary values of a suffix bin string from among the bin string using the determined current binarization parameter.
4. The method of claim 1 , wherein the predetermined value is exponentially proportional to the previous binarization parameter.
5. The method of claim 1 , wherein the previous binarization parameter is for determining a previous prefix bin string from a previous bin string corresponding to a previous transformation coefficient level indicating a size of a previous transformation coefficient.