Memory-less gain quantization in the EVS codec

The recent standard on Enhanced Voiced Services (EVS) contains two memory-less gain coding mechanisms achieving better performance than the prediction-based techniques used in 3GPP AMR-WB and ITU-T G.729 codecs. The EVS gain encoder uses joint vector quantization without the need of information from previous frames. Inter-frame prediction is replaced by alternative schemes based on sub-frame prediction or estimated average target signal energy. This eliminates the propagation of error inside the adaptive codebook and reduces the risk of artifacts in the recovery stage after frame error concealment. The results show that the EVS codec outperforms AMR-WB at all bitrates while keeping the same amount of bits required for gain quantization.