| 摘要 |
PURPOSE:To encode pitch information at a high quality and low pitch rate by causing an encoder to follow the change of a pitch mechanism in a frame while the linear coupling of reference sound signals is formed and performing efficient quantization. CONSTITUTION:An encoder is constituted of a linear forecasting analyzer 110, pitch predicting analyzer 120 which performs pitch extraction, reference sound component calculator 130, sound varying component calculator 140, quantizer 145, and multiplexer 150. Pitch variation in a frame is absorbed in such a way that a reference reproduced sound signal which represents the average characteristic of the basic period length of sound signals in the frame is synthesized and input sound signals are represented by the linear sum of the reference reproduced sound signal, and then, factors and phase components for forming this linear coupling are found so that the pitch variation of input sounds can be followed faithfully. In addition, when a linear coupling factor is quantized, the correlation between the linear coupling factor and reference period information is utilized. Therefore, pitch information can be encoded at a high quality and low pitch rate. |
