Improvement and implementation of G.729.1 speech coding algorithm
Liu Li · Microcomputer & its Applications · 2010
This paper describes an efficient algorithm for implementing MDCT/IMDCT of length N=5×2m (m≥2) in G.729.1. The algorithm has implemented in float-point on the platform of cygwin. It utilizes a mapping of MDCT of size N into N/2-point DCT-IV and DCT-Ⅱ with isolated premultiplications, which are subsequently moved in the windowing stage. The window is piece-wise symmetric, and can be store N/2 words. The algorithm also uses an efficient factorization of 5 point DCT-Ⅱ which requires only 4 multiplications. This algorithm offers practically appreciable reduction in complexity and memory usage.