Coded Domain Level Control for The AMR Speech Codec

This paper presents a coded domain level control technique for the adaptive multi-rate (AMR) speech codec. Level control in the coded domain is done by directly modifying quantized speech parameters. The advantage of the method is an accurate speech level control with minimized system complexity and end-to-end delay when tandem coding can be avoided completely. Requantization optimization functions are derived for scalar and vector quantization of relevant parameters. The experimental results show that the presented technique makes possible to apply a desired gain in the coded domain maintaining high speech quality