High-band speech coding apparatus and high-band speech decoding apparatus in wide-band speech coding/decoding system and high-band speech coding and decoding method performed by the apparatuses

A wideband speech encoding system comprising:

• a band division unit dividing a speech signal into a high-band speech signal and a low-band speech signal;
• a low-band speech signal encoding apparatus encoding the low-band speech signal received from the band division unit and outputting a pitch value of the low-band speech signal that is detected through the encoding;
• and
• a high-band speech signal encoding apparatus encoding the high-band speech signal using the high-band and low-band speech signals received from the band division unit and the pitch value of the low-band speech signal.

A high-band speech decoding apparatus comprising:

• a first decoding unit decoding a high-band speech signal based on a combination of a harmonic structure and a stochastic structure using received first decoding information;
• a second decoding unit decoding the high-band speech signal based on a stochastic structure using received second decoding information;
• and
• a switch outputting one of the decoded high-band speech signals received from the first and second decoding units according to received mode selection information.

A wideband speech decoding system comprising:

• a high-band speech signal decoding apparatus decoding a high-band speech signal using decoding information received via a channel using one of a stochastic structure and a combination of a harmonic structure and the stochastic structure;
• a low-band speech signal decoding apparatus decoding a low-band speech signal using decoding information received via the channel;
• and
• a band combination unit combining the decoded high-band speech signal with the decoded low-band speech signal to output a decoded speech signal.

A high-band speech encoding method in a wideband speech encoding system, comprising:

• determining whether a high-band speech signal and a low-band speech signal have harmonic components;
• encoding the high-band speech signal based on a combination of a harmonic structure and a stochastic structure when both the high-band and low-band speech signals have harmonic components;
• and
• encoding the high-band speech signal based on a stochastic structure when any one of the high-band and low-band speech signals does not have a harmonic component.

A high-band speech decoding method, comprising:

• analyzing mode selection information included in received decoding information;
• decoding a high-band speech signal based on the received decoding information using a combination of a harmonic structure and a stochastic structure when the mode selection information represents a mode in which a harmonic structure and a stochastic structure are combined;
• and
• decoding the high-band speech signal based on the received decoding information using a stochastic structure when the mode selection information represents a stochastic structure.