Apparatus for encoding and decoding of integrated speech and audio

1. An encoding apparatus for integrally encoding a speech signal and an audio signal, the encoding apparatus comprising:

a module selection unit to analyze a characteristic of an input signal and to select a first encoding module for encoding a current frame of the input signal;

a speech encoding unit to encode the input signal according to a selection of the module selection unit and to generate a speech bitstream;

an audio encoding unit to encode the input signal according to the selection of the module selection unit and to generate an audio bitstream;

a module buffer to transmit information of a second encoding module corresponding to a previous frame of the current frame to the speech encoding unit and the audio encoding unit; and

a bitstream generation unit to generate an output bitstream from the speech encoding unit or the audio encoding unit according to the selection of the module selection unit,

wherein, when an overlap operation between the previous frame and the current frame occurs, the speech encoding unit encodes a half sample of the previous frame having a speech characteristic as additional information to decode a current frame having an audio characteristic according to MDCT(Modified Discrete Cosine Transform) at a decoding apparatus,

wherein the bitstream generation unit generates the output bitstream including module information for the current frame selected by the module selection unit, the speech bitstream generated from the speech encoding unit and the audio bitstream generated from the audio encoding unit.

2. The encoding apparatus of claim 1 , wherein the module selection unit extracts the module information of the selected first encoding module and transmits the module information to the bitstream generation unit.

3. The encoding apparatus of claim 1 , wherein the speech encoding unit comprises:

a first speech encoder to encode the input signal to a Code Excitation Linear Prediction (CELP) structure when the first encoding module is identical to the second encoding module; and

an encoding initialization unit to determine an initial value for encoding of the first speech encoder when the first encoding module is different from the second encoding module.

4. The encoding apparatus of claim 3 , wherein:

when the first encoding module is identical to the second encoding module, the first speech encoder encodes the input signal using an internal initial value of the first speech encoder, and

when the first encoding module is different from the second encoding module, the first speech encoder encodes the input signal using an initial value that is determined by the encoding initialization unit.

5. The encoding apparatus of claim 3 , wherein the encoding initialization unit comprises:

a Linear Predictive Coder (LPC) analyzer to calculate an LPC coefficient with respect to the previous input signal;

a Linear Spectrum Pair (LSP) converter to convert the calculated LPC coefficient to an LSP value;

an LPC residual signal calculator to calculate an LPC residual signal using the previous input signal and the LPC coefficient; and

an encoding initial value decision unit to determine the initial value for encoding of the first speech encoder using the LPC coefficient, the LSP value, and the LPC residual signal.

6. The encoding apparatus of claim 1 , wherein the audio encoding unit comprises:

a first audio encoder to encode the input signal through a Modified Discrete Cosine Transform (MDCT) operation when the first encoding module is identical to the second encoding module;

a second speech encoder to encode the input signal to a CELP structure when the first encoding module is different from the second encoding module;

a second audio encoder to encode the input signal through the MDCT operation when the first encoding module is different from the second encoding module; and

a multiplexer to select one of an output of the first audio encoder, an output of the second speech encoder, and an output of the second audio encoder to generate the output bitstream.

7. The encoding apparatus of claim 6 , wherein, when the first encoding module is different from the second encoding module, the second speech encoder encodes an input signal corresponding to a front half sample of the current frame.

8. The encoding apparatus of claim 6 , wherein the second audio encoder comprises:

a zero input response calculator to calculate a zero input response with respect to an LPC filter after terminating an encoding operation of the second speech encoder;

a first converter to convert, to zero, an input signal corresponding to a front ½ sample of the current frame; and

a second converter to subtract the zero input response from an input signal corresponding to a rear half sample of the current frame, wherein

the second audio encoder encodes a converted signal of the first converter and a converted signal of the second converter.

9. A decoding apparatus for integrally decoding a speech signal and an audio signal, the decoding apparatus comprising:

a module selection unit to analyze a characteristic of an input bitstream and to select a first decoding module for decoding a current frame of the input bitstream;

a speech decoding unit to decode the input bitstream according to a selection of the module selection unit and to generate a speech signal;

an audio decoding unit to decode the input bitstream according to the selection of the module selection unit and to generate an audio signal;

a module buffer to transmit information of a second decoding module corresponding to a previous frame of the current frame to the speech decoding unit and the audio decoding unit; and

an output generation unit to select one of the speech signal of the speech decoding unit and the audio signal of the audio signal according to the selection of the module selection unit and to output an output signal,

wherein the speech decoding unit decodes a half sample of a previous frame having a speech characteristic as additional information,

wherein, when an overlap operation between the previous frame and the current frame occurs, the audio decoding unit decodes a current frame according to MDCT(Modified Discrete Cosine Transform) by compensating the current frame based on the additional information.

10. The decoding apparatus of claim 9 , wherein the speech decoding unit comprises:

a first speech decoder to decode the input stream to a CELP structure when the first decoding module is identical to the second decoding module; and

a decoding initialization unit to determine an initial value for decoding of the first speech decoder when the first decoding module is different from the second decoding module.

11. The decoding apparatus of claim 10 , wherein:

when the first decoding module is identical to the second decoding module, the first speech decoder decodes the input bitstream using an internal initial value of the first speech decoder, and

when the first decoding module is different from the second decoding module, the first speech decoder decodes the input bitstream using an initial value that is determined by the decoding initialization unit.

12. The decoding apparatus of claim 9 , wherein the decoding initialization unit comprises:

an LPC analyzer to calculate an LPC coefficient with respect to the previous output signal;

an LSP converter to convert the calculated LPC coefficient to an LSP value;

an LPC residual signal calculator to calculate an LPC residual signal using the previous output signal and the LPC coefficient; and

a decoding initial value decision unit to determine the initial value for decoding of the first speech decoder using the LPC coefficient, the LSP value, and the LPC residual signal.

13. The decoding apparatus of claim 9 , wherein the audio decoding unit comprises:

a first audio decoder to decode the input bitstream through an Inverse MDCT (IMDCT) operation when the first decoding module is identical to the second decoding module;

a second speech decoder to decode the input bitstream to a CELP structure when the first decoding module is different from the second decoding module;

a second audio decoder to decode the input bitstream through the IMDCT operation when the first decoding module is different from the second decoding module; and

a signal restoration unit to calculate a final output from an output of the second speech decoder and an output of the second audio decoder; and

an output selector to select and output one of an output of the signal restoration unit and an output of the first audio decoder.

14. The decoding apparatus of claim 13 , wherein, when the first decoding module is different from the second decoding module, the second speech decoder decodes an input bitstream corresponding to a front half sample of the current frame to output an input signal.

15. The decoding apparatus of claim 13 , wherein the signal restoration unit determines the output of the second speech decoder as an output signal corresponding to a front half sample of the current frame.