Question: In the Adaptive Multi-Rate (AMR) speech codec, how does the frequency of Linear Prediction (LP) analysis differ between the 12.2 kbit/s mode and the lower modes (e.g., 10.2, 7.95 kbit/s) in terms of speech frame processing?
Option 1: LP analysis is performed once per speech frame in all modes.
Option 2: LP analysis is performed twice per speech frame only in the lower modes.
Option 3: The frequency of LP analysis is mode-dependent, with twice per frame for 12.2 kbit/s and once per frame for other mentioned modes.
Option 4: LP analysis occurs thrice per speech frame for all modes except 12.2 kbit/s, where it's done twice.
Explanation: According to the specifications, the 12.2 kbit/s mode performs Linear Prediction (LP) analysis twice per speech frame, whereas the lower modes (e.g., 10.2, 7.95 kbit/s) perform LP analysis once per speech frame. This distinction highlights how different bitrate modes in AMR adapt their processing to balance quality and resource utilization.