Dynamic strategy for window splitting, parameters estimation and interpolation in spatial parametric audio coders

In most parametric stereo audio coders, sets of spatial parameters are extracted from the audio channels in a time-frequency domain. In order to reduce the amount of data, the parameters plane is highly down-sampled, and transmitted together with a mono downmix. Then, in the decoding process, it is necessary to interpolate the upmix matrix computed from these parameters. Usually, this is done in the same way for each portion of signal, regardless of its nature. In this article, we propose a dynamic strategy of window splitting, estimation of the parameters and interpolation of the upmix matrix based on transient detection in the audio signal. Subjective tests show an improvement when applied to the new stereo parametric tool from MPEG USAC.