Low complexity bit allocation algorithm with psychoacoustical optimisation

This paper describes a full-rate (FR) candidate speech codec for a new Adaptive Multi-Rate (AMR) codec standard. The proposed codec is a multi-rate codec, operating in various modes that have different bit-rate partitionings between source and channel coding. The source coding is based on Algebraic Code Excited Linear Predictive Coding (ACELP). Convolutional coding is used for the channel coding. Subjective tests show that at poor channel error conditions with low C/I-ratios of 7 dB, the lowest mode of the proposed codec produces speech quality comparable to G.728 in clean channel condition. The codec also provides substantial improvement on error robustness over the Enhanced Full Rate (EFR) GSM codec, by selecting an optimal coding rate to suit the channel condition. The codec performance passes twenty-six out of the twenty-nine test conditions, conducted according to [2]. Therefore, the proposed codec has passed the ETSI qualification test.