Question: In EVS (Enhanced Voice Services) codec, when transitioning from CELP to MDCT coding mode, what issue arises at the beginning of the MDCT encoded frame due to the preceding CELP encoded frame?
Option 1: Insufficient Bitrate Allocation
Option 2: Increased Packet Loss Susceptibility
Option 3: Incompatibility with Upstream Network Elements
Option 4: Aliasing Distortion Affecting Proper Reconstruction
Explanation: When switching from CELP (Code-Excited Linear Prediction) to MDCT (Modified Discrete Cosine Transform) coding mode in EVS, the absence of a preceding MDCT frame introduces aliasing. This aliasing specifically affects the proper reconstruction of the initial portion of the MDCT encoded frame. Understanding this issue is crucial for managing voice quality transitions between these coding modes in telecommunications networks.