| 摘要 |
PURPOSE:To obtain an excellent decoded sound by quantizing coefficient data, obtained by converting voice orthogonally, according to spectrum envelope information of the voice data and pitch information on the low frequency component of the voice data. CONSTITUTION:The pitch information is found from only DCT coefficient data of, for example, 4kHz in consideration of the fact that the pitch structure (periodic microstructure) of the voice data is hard to appear normally above 3 - 4kHz. Consequently, data obtained by processing only the low frequency <=4kHz of the output of a squaring arithmetic circuit 8 through the reverse fast Fourier transformation of a low-frequency inverse fast Fourier transform (IFFT) circuit 20 is sent to a pitch arithmetic circuit 11 while the output of a full IFFT circuit 9 is sent to a prediction coefficient arithmetic circuit 10 as it is. Consequently, the excellent decoded sound is obtained. |
