Speech coding method and apparatus for coding an input speech signal based on whether the input speech signal is wideband or narrowband

• US 8,260,621 B2
• Filed: 03/31/2010
• Issued: 09/04/2012
• Est. Priority Date: 04/04/2003
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Miseki, Kimio
• Primary Examiner(s): Smits, Talivaldis Ivars
• Application Number:
  US12/751,421
• Publication Number:
  US 20100250245A1
• Time in Patent Office: 888 Days
• Field of Search: None
• US Class Current: 704/500
• CPC Class Codes: G10L 19/18 Vocoders using multiple modes

Abstract

A wideband speech coding apparatus comprises a wideband speech coding unit configured to code an input speech signal at a bit rate which is set in advance in accordance with a wideband speech signal. The apparatus further comprises an identification unit configured to identify whether the input speech signal is a wideband speech signal or a narrowband speech signal. The apparatus further comprises a control unit configured to cause the wideband speech coding unit to code the input speech signal, when the identification unit identifies that the input speech signal is the wideband speech signal, and to cause the wideband speech coding unit to raise the bit rate to code the input speech signal, when the identification unit identifies that the input speech signal is the narrowband speech signal. The apparatus further comprises an output unit to output the input speech signal coded by the wideband speech coding unit.

Claims

1. A wideband speech coding apparatus, comprising:

a wideband speech coding unit configured to code an input speech signal at a bit rate which is set in advance in accordance with a wideband speech signal;

an identification unit configured to identify whether the input speech signal is a wideband speech signal or a narrowband speech signal;

a control unit configured to cause the wideband speech coding unit to code the input speech signal, when the identification unit identifies that the input speech signal is the wideband speech signal, and to cause the wideband speech coding unit to raise the bit rate to code the input speech signal, when the identification unit identifies that the input speech signal is the narrowband speech signal; and

an output unit to output the input speech signal coded by the wideband speech coding unit.

2. The wideband coding apparatus according to claim 1, further comprising a detection unit for detecting speech activity of the input speech signal, wherein the control unit performs a control for causing the coding unit to code the input speech signal, only when the identification unit identifies that the input speech signal is the narrowband speech signal, and the detection unit detects that the speech activity of the input speech signal is higher than a predetermined level.

3. A wideband speech coding apparatus, comprising:

a wideband speech coding unit configured to code an input speech signal at a bit rate which is set in advance in accordance with a wideband speech signal;

an identification unit configured to identify whether a sampling rate of the input speech signal is a first sampling rate to be applied to the wideband speech signal or a second sampling rate to be applied to the narrowband speech signal;

a control unit configured to cause the wideband speech coding unit to lower the bit rate to code the input speech signal, when the identification unit identifies that the sampling rate of the input speech signal is the first sampling rate, and to cause the wideband speech coding unit to raise the bit rate to code the input speech signal, when the identification unit identifies that the sampling rate of the input speech signal is the second sampling rate; and

an output unit to output a result of coding by the wideband speech coding unit.

8. The wideband coding apparatus according to claim 3, further comprising a detection unit for detecting speech activity of the input speech signal, wherein the control unit performs a control for causing the coding unit to code the input speech signal, only when the identification unit identifies that the input speech signal is the narrowband speech signal, and the detection unit detects that the speech activity of the input speech signal is higher than a predetermined level.

4. A wideband speech coding apparatus which causes an input speech signal to be represented by spectrum parameters and an excitation signal, and codes the spectrum parameters and the excitation signal, the wideband speech coding apparatus comprising:

a spectrum parameter coding unit configured to extract the spectrum parameters from the input speech signal, and coding the extracted spectrum parameters;

an identification unit configured to identify whether the input speech signal is a wideband speech signal or a narrowband speech signal;

a control unit configured to set a spectrum parameter degree in the spectrum parameter coding unit, when the identification unit identifies that the input speech signal is the wideband speech signal, and to lower the spectrum parameter degree in the spectrum parameter coding unit, when the identification unit identifies that the input signal is the narrowband speech signal;

a converter configured to convert a sampling rate of the input speech signal to a predetermined sampling rate for wideband speech coding; and

an output unit to output a result of coding by the spectrum parameter coding unit.

5. A wideband speech coding apparatus which causes an input speech signal to be represented by spectrum parameters and an excitation signal, and codes the spectrum parameters and the excitation signal, the wideband speech coding apparatus comprising:

a spectrum parameter coding unit configured to extract the spectrum parameters from the input speech signal, and coding the extracted spectrum parameters;

an identification unit configured to identify whether a sampling rate of the input speech signal is a first sampling rate to be applied to a wideband speech signal or a second sampling rate to be applied to a narrowband speech signal;

a control unit configured to set a spectrum parameter degree in the spectrum parameter coding unit, when the identification unit identifies that the sampling rate of the input speech signal is the first sampling rate, and to lower the spectrum parameter degree in the spectrum parameter coding unit, when the identification unit identifies that the sampling rate of the input signal is the second sampling rate;

a converter configured to convert the sampling rate of the input speech signal to a predetermined sampling rate for wideband speech coding; and

an output unit to output a result of coding by the spectrum parameter coding unit.

6. A wideband speech coding method of causing an input speech signal to be represented by spectrum parameters and an excitation signal, and coding the spectrum parameters and the excitation signal, the wideband speech coding method comprising:

a process of identifying whether the input speech signal is a wideband speech signal or a narrowband speech signal;

a process of coding the spectrum parameter with a spectrum parameter degree which is set in advance in accordance with the wideband speech signal, when it is identified that the input speech signal is the wideband speech signal;

a process of lowering, when it is identified that the input speech signal is the narrowband speech signal, the spectrum parameter degree and then coding the spectrum parameters with the lowered spectrum parameter degree;

a process of converting a sampling rate of the input speech signal to a predetermined sampling rate for wideband speech coding; and

a process of outputting a result of coding in the coding process and the lowering and coding process which is executed.

7. A wideband speech coding method of causing an input speech signal to be represented by spectrum parameters and an excitation signal, and coding the spectrum parameters and the excitation signal, the wideband speech coding method comprising:

a process of identifying whether a sampling rate of the input speech signal is a first sampling rate to be applied to a wideband speech signal or a second sampling rate to be applied to a narrowband speech signal;

a process of coding the spectrum parameters with a spectrum parameter degree which is set in advance in accordance with the first sampling rate, when it is identified that the sampling rate of the input speech signal is the first sampling rate;

a process of lowering, when it is identified that the sampling rate of the input speech signal is the second sampling rate, the spectrum parameter degree and then coding the spectrum parameters with the lowered spectrum parameter degree;

a process of converting the sampling rate of the input speech signal to a predetermined sampling rate for wideband speech coding; and

a process of outputting a result of coding in the coding process and the lowering and coding process which is executed.

9. A wideband speech coding method comprising:

a process of coding an input speech signal at a bit rate which is set in advance in accordance with a wideband speech signal;

a process of identifying whether the input speech signal is the wideband speech signal or a narrowband speech signal;

a process of lowering the bit rate and coding the input speech signal at the lowered bit rate, when it is identified that the input speech signal is the wideband speech signal;

a process of raising the bit rate and coding the input speech signal at the raised bit rate, when it is identified that the input speech signal is the narrowband speech signal; and

a process of outputting a result of coding in the coding process.

10. The wideband coding method according to claim 9, further comprising:

a process of detecting activity of the input speech signal; and

a process of coding the input speech signal at the second bit rate, only when it is identified that the input speech signal is the narrowband speech signal, and it is also identified based on the process of detecting the activity of the input speech signal that speech activity of the input speech signal is higher than a predetermined level.

11. A wideband speech coding method comprising:

a process of coding an input speech signal at a bit rate which is set in advance in accordance with a wideband speech signal;

a process of identifying whether a sampling rate of the input speech signal is a first sampling rate to be applied to the wideband speech signal or a second sampling rate to be applied to a narrowband speech signal;

a process of lowering the bit rate and coding the input speech signal at the lowered bit rate, when it is identified that the sampling rate of the input speech signal is the first sampling rate;

a process of raising the bit rate and coding the input speech signal at the raised bit rate, when it is identified that the sampling rate of the input speech signal is the second sampling rate; and

a process of outputting a result of coding in the coding process.

12. The wideband coding method according to claim 11, further comprising:

a process of detecting activity of the input speech signal; and

a process of coding the input speech signal at the second bit rate, only when it is identified that the input speech signal is the narrowband speech signal, and it is also identified based on the process of detecting the activity of the input speech signal that speech activity of the input speech signal is higher than a predetermined level.