US Patent 8489884 Methods and apparatus for generating signatures

Methods, apparatus, and articles of manufacture for media monitoring are disclosed. In particular, the example methods, apparatus, and articles of manufacture generate signatures. Initially, a first plurality of filtered values are identified by performing a wavelet transform on a first frame of media samples. A first energy value is determined based on a first portion of the first plurality of filtered values, and a second energy value is determined based on a second portion of the first plurality of filtered values. A first descriptor of the first frame of media samples is determined based on a comparison of the first energy value and the second energy value. A first signature is generated based on the first descriptor.