Direct estimation of frequency from MDCT-encoded files
The Modified Discrete Cosine Transform (MDCT) is a broadlyused transform for audio coding, since it allows an orthogonal time-frequency transform without blocking effects. In this article, we show that the MDCT can also be used as an analysis tool. This is illustrated by extracting the frequency of a pure sine wave with some simple combinations of MDCT coefficients. We studied the performance of this estimation in ideal (noiseless) conditions, as well as the influence of additive noise (white noise / quantization noise). This forms the basis of a low-level feature extraction directly in the compressed domain.