Patent ID: 8503535
Filing Date: 2013-08-06
Classification: G10L,H04N

Abstract:
1. A method for improving the encoding efficiency for an audio signal, wherein said signal is processed using an integer-reversible transform for each block of samples of said signal, which integer transform is carried out using lifting steps which represent sub-steps of said integer transform and which lifting steps include rounding operations, and wherein noise shaping for the rounding errors resulting from said lifting steps is performed, said method comprising the step: integer transforming said sample blocks using lifting steps and adaptive noise shaping for at least some of said lifting steps, said transform providing corresponding blocks of transform coefficients and wherein in said noise shaping performs rounding noise from low-level magnitude transform coefficients in a current one of said transformed blocks is decreased whereas rounding noise from high-level magnitude transform coefficients in said current transformed block is increased, and wherein filter coefficients of a corresponding noise shaping filter are derived from said audio signal samples on a frame-by-frame basis, wherein in addition a noise shaping pre-filter is arranged upstream said integer transforming.