An 8 kbit/s LD-CELP with improved excitation and perceptual modelling

An excitation modeling based on a multitap adaptive or fixed codebook is proposed for low-delay encoding of speech signals. The algorithm can produce high-quality speech at bit rates of 8 kbit/s, but it is still lacking the toll quality of LD-CELP (low-delay code excited linear prediction) at 16 kbit/s. A simplified vector quantization search procedure was incorporated to reduce the complexity with little subjective degradation. The performance results indicated a need for several types of efficient excitation modeling, depending on the nature of the input signal.<>