Patent ID: 7318024
Filing Date: 2008-01-08
Classification: G10L

Abstract:
1. A speech communication code conversion method of converting a first code string of a speech signal into a second code string of the speech signal, said method comprising the steps of: a first step of obtaining a first line spectral pair from a code corresponding to a linear prediction coefficient out of said first code string, said first code string codable in a first coding and decoding system, a second step of storing and holding said first line spectral pair as a second line spectral pair, a third step of calculating, from said first line spectral pair, said second line spectral pair, a third line spectral pair sequentially read from a table in which a plurality of line spectral pairs are stored in advance, and a fourth line spectral pair selected, and stored and held among the third line spectral pairs read in the past from said table, an evaluation value for each said third line spectral pair, and a fourth step of selecting said third line spectral pair for which said evaluation value is the minimum from said table to output a code corresponding to said selected third line spectral pair as a converted code corresponding to a linear prediction coefficient in the second code string, and a fifth step of storing and holding said selected third line spectral pair as the fourth line spectral pair, wherein said converted code is decodable by a linear prediction coefficient decoding method in a second coding and decoding system such that the speech signal is interpretable by said first coding and decoding system and said second coding and decoding system.