Question: In EVS (Enhanced Voice Services) codec, how is the LPC synthesis filter applied to the excitation signal for bitrates above 24.4 kb/s?
Option 1: Using a single LPC synthesis filter across the entire frame.
Option 2: Applying the LPC synthesis filter in four subframes based on specific criteria.
Option 3: Skipping LPC synthesis for high bitrate to reduce computational complexity.
Option 4: Doubling the LPC synthesis filters for enhanced quality.
Explanation: For bitrates above 24.4 kb/s, the EVS codec utilizes a more detailed processing approach by dividing the signal into subframes. This allows for more precise spectral shaping of the noise-added excitation, enhancing voice quality at higher bitrates. Applying the LPC synthesis filter in four subframes (as per specific criteria) enables this improved handling, making Option 2 the correct choice.