Question: In EVS (Enhanced Voice Services) decoding, specifically for SID (Silence Insertion Description) frames in FD-CNG (Fullband Discontinuous CELP Noise), how are the decoded SID parameters distributed in terms of describing background noise energy?
Option 1: Entirely across CLDFB (Cascade Lattice Differential Feedback) bands, covering both core and extended bandwidths uniformly.
Option 2: Solely within FFT (Fast Fourier Transform) bins limited to the core bandwidth, excluding higher frequency bands.
Option 3: Across two segments: the first set of parameters in FFT bins for the core bandwidth, and the remaining parameters in CLDFB bands above the core bandwidth.
Option 4: Dynamically allocated between FFT bins and CLDFB bands based on the detected noise type (e.g., white, pink, etc.).
Explanation: This is correct because, as per the EVS decoding process for SID frames in FD-CNG, the background noise energy description is split. The initial parameters focus on the core bandwidth using FFT bins to capture detailed spectral energy within this primary range. The subsequent parameters then address the broader spectral energy but in CLDFB bands, which efficiently cover the higher frequency ranges beyond the core bandwidth, ensuring comprehensive noise characterization without redundancy.