Patent ID: 8271267

Claim:
A scalable speech coding apparatus having a mixed structure, the apparatus comprising: a band divider to divide a speech input signal into a low-band signal and a high-band signal according to a specific frequency, and outputting the low-band signal and the high-band signal; a low-band coder to output a low-band first index by coding the low-band signal, to transmit information required for coding the high-band signal to a high-band coder, and to transmit a error signal obtained from the low-band signal and a signal generated during coding the low-band signal; a high-band coder to output a high-band second index obtained when the high-band signal is coded by using information received from the low-band coder, and to transmit a second error signal obtained from the high-band signal and a signal generated during coding the high-band signal; a wide-band coder to obtain a wide-band third index from the first and second error signals using a modified discrete cosine transform (MDCT); and a bit-stream generator to output a scalable bit-stream composed of the low-band first index received from the low-band coder, the high-band second index received from the high-band coder, and the wide-band third index received from the wide-band coder.