Question: In a codec for Enhanced Voice Services (EVS), when switching from wideband to super wideband for multi-mode FD BWE or MDCT core, how are coefficients adjusted in each respective domain?
Option 1: Coefficients in both frequency and temporal domains are adjusted using a fixed gain.
Option 2: Frequency domain coefficients are faded with a factor, while temporal domain coefficients remain unchanged.
Option 3: Temporal domain global gain is amplified without fading for seamless switching.
Option 4: Frequency domain coefficients are faded using a factor, and when operating with TBE, the temporal domain's global gain is also faded using the same factor.
Explanation: This correct answer reflects the nuanced handling of coefficient adjustments during wideband to super wideband switching in EVS codecs. Specifically, it highlights the differentiated approach based on the operational mode (FD BWE/MDCT core vs. TBE), ensuring a smooth transition by fading coefficients in the frequency domain and, for TBE, similarly adjusting the global gain in the temporal domain.