An Efficient Codebook for the SCELP Low Delay Audio Codec

The SCELP (spherical code excited linear prediction) audio codec has recently been proposed as a new candidate for low delay audio coding based on linear prediction (LP). The new codec applies closed-loop vector quantization employing a spherical code in a gain shape manner. The spherical code is based on the apple-peeling code construction rule and in general does not require a codebook table for the encoding and decoding process. In this contribution, however, we propose to employ auxiliary information gathered in advance to reduce the computational encoding and decoding complexity at runtime significantly. This auxiliary information can be considered as the SCELP codebook. Due to the consideration of the characteristics of the apple-peeling code construction principle, this codebook can be stored very efficiently in read-only-memory. With the proposed principle, low computational as well as low memory complexity can be achieved simultaneously in the SCELP codec