Question: When switching from primary modes to AMR-WB IO in EVS (Enhanced Voice Services) codec, what happens to the bass post-filter and formant post-filter in the first AMR-WB IO frame?
Option 1: Both bass post-filter and formant post-filter are always employed for enhanced quality.
Option 2: The bass post-filter is employed, but the formant post-filter is not in the first frame.
Option 3: The formant post-filter is employed, but the bass post-filter is not in the first frame.
Option 4: Neither the bass post-filter nor the formant post-filter is employed in the first AMR-WB IO frame.
Explanation: This is correct because, according to the specified behavior for switching to AMR-WB IO mode in EVS codec, both the bass post-filter and the formant post-filter are specifically not used in the first frame of this mode. This ensures a defined transition from the primary modes to AMR-WB IO, potentially simplifying the adaptation process or reducing computational overhead at the start of the new mode.