public class BandDetector
A simple energy-based detector for upsampled audio. Could be used to detect
bandwidth issues leading to the accuracy issues.
The detector simply looks for energies in different mel bands and using the
threshold it decides if we have cut of the frequencies signal. On every frame
we find the maximum energy band, then we just control that energy doesn't
fall too fast in upper bands.
A paper on the subject is "DETECTING BANDLIMITED AUDIO IN BROADCAST TELEVISION SHOWS"
by by Mark C. Fuhs, Qin Jin and Tanja Schultz where spline approximation is proposed
for detection. However, the paper seems to contain a fundamental flaw. The
decision is made on average spectrum, not per-frame. This probably leads
to omission of the events in high frequency which might signal about wide band.