| 摘要 |
A digital media decoder comprises a data storage buffer for storing encoded digital media data; and a processor configured to: receive a set of compressed symbols describing a series of transform coefficients; uncompress the symbols; and reconstruct the series of transform coefficients by analysing the set of uncompressed symbols. The set of compressed symbols comprises jointly-coded symbols encoded from a set of code tables according to a context model. Each jointly-coded symbol describes a non-zero level from the series of transform coefficients and whether there are zero-value coefficients following the non-zero level. Also disclosed is a method of encoding a series of transform coefficients for a block representing digital media data comprising using a computing device that implements an encoder, representing the series of transform coefficients as a series of symbols. A given symbol of the series of symbols represents (a) an indication of a non-zero coefficient from the series of transform coefficients and (b) an indication of whether the non-zero coefficient is a last non-zero coefficient for the block and, if not the last non-zero coefficient for the block, an indication of a length of a run of subsequent zero-value coefficients for the block; and for each symbol in the series of symbols, sending the symbol to be encoded in a compressed bit stream. Also disclosed is a method of decoding compressed digital media data comprising receiving a bit stream comprising compressed jointly-coded symbol. Each encoded from a set of code tables according to a context model. The bit stream includes an initial jointly-coded symbol from the jointly coded symbols. The method of decoding further comprises decoding the jointly-coded symbols. The decoding includes decoding the initial jointly-coded symbol to determine a first indication for a run of initial transform coefficient zeros, a second indication for a non-zero transform coefficient level, and third indication for whether the non-zero transform coefficient level is a last non-zero transform coefficient level and, if not, a run of subsequent transform coefficient zeros. The method of decoding further comprises reconstructing a set of transform coefficients from decoded levels and runs of transform coefficient zeros. |
