Question: In EVS (Enhanced Voice Services) codec, how are the pitch lag index and gain index represented when the LTP (Long-Term Prediction) flag is set to one?
Option 1: Pitch Lag Index: Signed 8-bit integer, Gain Index: Unsigned 4-bit integer
Option 2: Pitch Lag Index: Unsigned 9-bit integer, Gain Index: Signed 3-bit integer
Option 3: Pitch Lag Index: Signed 16-bit integer, Gain Index: Unsigned 2-bit integer
Option 4: Pitch Lag Index: Unsigned 9-bit integer, Gain Index: Unsigned 2-bit integer
Explanation: According to the EVS codec specifications for LTP (Long-Term Prediction), when the LTP flag is enabled, the pitch lag index is transmitted as an unsigned 9-bit integer to capture various pitch periods, while the gain index is represented as an unsigned 2-bit integer, balancing precision and bit rate for effective voice compression without compromising voice quality.