Question: What happens to the Adaptive Codebook state during internal sampling rate switching between 12.8 kHz and a frequency other than 16 kHz in CELP mode, according to 3GPP EVS (Enhanced Voice Services) codec specifications?
Option 1: The adaptive codebook is resampled using a predefined method.
Option 2: The adaptive codebook is reset with zeros.
Option 3: The adaptive codebook state remains unchanged.
Option 4: The LPC synthesis filter state is used to update the adaptive codebook.
Explanation: According to the EVS codec specifications for seamless transitions and internal sampling rate switching, if the switch involves a sampling rate different from both 12.8 kHz and 16 kHz, the adaptive codebook state is reset with zeros to ensure compatibility and prevent errors in audio decoding. This highlights the importance of managing memory states during dynamic changes in telecom networks to maintain voice service quality.