An adaptive multi-rate speech codec based on MP-CELP coding algorithm for ETSI AMR standard

This paper proposes a speech codec based on the multi-pulse based CELP (MP-CELP) coding and convolutional coding algorithms for the ETSI adaptive multi-rate (AMR) standard. The codec operates at several speech coding rates, maintaining a fixed gross rate including speech and channel coding for the full-rate (FR) and half-rate (HR) channel modes. MP-CELP has great features of easily changing the speech coding rate by controlling the parameters such as the number of pulses and other parameters. Subjective tests show that the proposed AMR codec in the FR channel mode achieves higher performance than that of the enhanced FR codec, and the proposed codec in the HR channel mode gives a comparable coding quality to that by the full-rate codec, by selecting an optimal coding rate for each channel condition. T-tests based on the test results also show that the proposed speech codec meets about 80% of the seventeen requirements, which are selected from the AMR standard study report. Therefore, the proposed codec is promising for the AMR standard.