Computational improvement for G.729 standard

G.729 is a CS-ACELP-based standard for 8 kbit/s speech compression and is defined by the ITU. In the G.729 encoding phase, the open-loop pitch T_op is estimated for each frame to reduce the computation required to search for the best adaptive codebook delay. However, >25% CPU time is required for the open-loop pitch analysis. The weighted delta-LSP (WD-LSP) function is employed here to reduce the computation required for open-loop pitch analysis. An 81% saving is made in the computation of T_op. A total computational saving of 21% for the encoding phase is achieved and the speech quality still sounds good (MOS=3.5)