Figure 5
From: An Overview of the Coding Standard MPEG-4 Audio Amendments 1 and 2: HE-AAC, SSC, and HE-AAC v2
Illustration of missing sinusoidal components in the high-band (if no additional sinusoidal signals are added in the decoder). This can be used for an analysis-by-synthesis method in the SBR encoder in order to assess where a sinusoid should be added on the decoder side. The upper panel shows the spectrum of the input signal (a glockenspiel signal), and the lower panel shows a spectrum of the signal obtained after HF generation based on the low-band signal without adding separate sinusoids. The SBR range covers the frequency range from 5.5 kHz to 15 kHz.