Question: In the EVS (Enhanced Voice Services) codec, what determines the selection between ALFE (Adaptive Low Frequency Emphasis) algorithm 1 and ALFE algorithm 2 for enhancing low-frequency performance?
Option 1: The choice of arithmetic coding algorithm and the bit-rate (e.g., 9.6 kbps, 48 kbps and above for Algorithm 1, and 13.2 to 32 kbps for Algorithm 2)
Option 2: The type of MDCT (Modified Discrete Cosine Transform) quantization used in the encoder
Option 3: The number of spectral lines amplified prior to quantization
Option 4: The LPC (Linear Predictive Coding) frequency-band gains alone
Explanation: The selection between Algorithm 1 and Algorithm 2 depends on both the choice of arithmetic coding algorithm and the bit-rate at which the codec operates, ensuring optimal low-frequency enhancement across various operational conditions.