Question: In the context of EVS (Enhanced Voice Services) codec, how are filter memories updated during the encoding process?
Option 1: By incorporating both adaptive codebook contribution and Gaussian noise excitation.
Option 2: Solely based on the adaptive codebook contribution without considering Gaussian noise excitation.
Option 3: Without any adaptive codebook contribution, but excluding Gaussian noise excitation from the update process.
Option 4: By directly using the previous subframe's signal target, ignoring both adaptive and Gaussian contributions.
Explanation: The correct approach for updating filter memories in EVS codec, as per the detailed algorithmic description, explicitly excludes the adaptive codebook contribution while also not taking into account the Gaussian noise excitation for both the update and computing the next subframe's signal target. This ensures a specific handling of memory updates to optimize voice service quality.