Question: In the EVS (Enhanced Voice Services) codec, during MDCT to CELP transition 3 (MC3), how are the previous quantized end-frame LSP/LSF and the quantized mid-frame LSP/LSF handled in relation to the current frame?
Option 1: They are updated using predictive modeling based on past frames.
Option 2: They are set to the current quantized end-frame LSP/LSF values, effectively synchronizing them.
Option 3: They are reset to predetermined default values (typically 0) like other CELP state variables.
Option 4: They are left unchanged from their previous values without any adjustment.
Explanation: During the MC3 transition in EVS codec, to ensure a smooth and synchronized state, the previous quantized end-frame LSP/LSF and the quantized mid-frame LSP/LSF are specifically set to match the current quantized end-frame LSP/LSF. This approach helps in maintaining consistency across frames during the transition, which is crucial for voice quality.