A SOT based digital audio coder using reference frame ordering method

In SOT based coding methods, ordering of the coefficients could affect coding efficiency. A small coefficient placed close to tree root usually reduces the coding efficiency significantly. Hence, a good reordering scheme for a SOT is critical. In digital audio coding, information of neighboring frames is usually highly correlated. Based on this property, a SOT based audio coding scheme with a coefficient reordering method is proposed. The proposed coder may have the coefficients of the current frame reordered depending on the decoded results of some previous frames. The coding qualities of the proposed coder and MPEG-4 AAC coder are compared using ODG (Objective Differential Grade) on a variety of sound sources.