Question: In EVS (Enhanced Voice Services) decoding, when a lost frame is partially reconstructed using redundant information from future frames, how are the decoding parameters (e.g., LSP, adaptive codebook gain) of the current frame primarily determined if it or its preceding frame is a partial redundant frame?
Option 1: Solely based on the signal type and decoding parameters from previous frames.
Option 2: Exclusively using the coding scheme of the current frame without referencing other frames.
Option 3: By first obtaining the decoding parameters from the current frame and then post-processing them with parameters from both previous and future frames relative to the current frame position.
Option 4: Through concealment mode derivation, ignoring available bitstream parameters.
Explanation: This is correct because, according to the EVS decoding process for partial redundant frames, the initial step involves obtaining the decoding parameters (like LSP, gains) directly from the current frame. These are then refined (post-processed) by considering not just the context from previous frames but also leveraging information available from future frames relative to the current frame's position. This approach enhances the accuracy of the reconstructed signal.