Question: In the context of Enhanced Voice Services (EVS) codec, specifically for transient frames utilizing MDCT-based TCX, what transformation process is applied to each sub-frame (TCX5 or TCX10) after determining the transform and overlap length configuration?
Option 1: Forward Discrete Cosine Transform (FDCT) with TDA
Option 2: Inverse Modified Discrete Cosine Transform (Inverse MDCT) implemented using IDCTIV and inverse TDA
Option 3: Short-Term Fourier Transform (STFT) with overlap-add
Option 4: Adaptive Windowed DFT (Discrete Fourier Transform)
Explanation: The correct answer, Inverse MDCT implemented using IDCTIV and inverse TDA, is specific to the handling of transient frames in EVS codec for efficient voice signal processing. This process is crucial for maintaining audio quality during transient audio segments. The use of inverse MDCT, as opposed to forward transforms or other types like STFT or DFT, highlights its role in decoding or synthesis stages of audio coding, aligning with the detailed algorithmic descriptions typical of telecom standards for voice services.