A packet loss recovery technique with line spectral frequency modification in 3GPP EVS codec

This paper examines a method for controlling the energy of decoded signal at the recovery frame from a packet loss. Our observation unveiled that a packet loss before speech onset causes sudden increase in the amplitude of the decoded signal at the recovery frame when predictive quantization of line spectral frequency is used. To mitigate the artifact caused by the overshoot, a detector of the overshoot is proposed as well as a method that controls the amplitude of the decoded signal by adjusting distances of adjacent line spectral frequencies. This technology is implemented in the enhanced voice services (EVS) codec which is the latest 3GPP speech and audio codec standard.