Method and apparatus for concealing frame error and method and apparatus for audio decoding

1. A frame error concealment method comprising:

when a current frame is classified as an error frame, performing a frequency domain error concealment processing on the current frame to generate spectral coefficients of the current frame;

generating a time domain signal of the current frame based on a time-frequency inverse transform; and

when the current frame is classified as the error frame or a next good frame after the error frame, performing a corresponding time domain error concealment processing on the time domain signal of the current frame by using a mode from among a plurality of modes including at least one mode associated with repetition and smoothing,

wherein the mode from among the plurality of modes is selected according to whether the current frame is stationary.

2. The method of claim 1 , wherein the plurality of modes include a first mode related to the error frame, a second mode related to the next good frame after a single error frame, and a third mode related to the next good frame after a burst error frame.

3. The method of claim 1 , wherein the performing the corresponding time domain error concealment processing when the mode from among the plurality of modes corresponds to a mode related to the error frame comprises performing windowing processing on the time domain signal of the current frame, repeating a time domain signal of a frame that is two frames previous to the current frame to a beginning part of the current frame, performing overlap and add (OLA) processing on a time domain signal of the current frame obtained from a result of the repeating and the time domain signal of the current frame, and performing smoothing processing by applying a smoothing window between a time domain signal of a previous frame and a time domain signal of the current frame obtained from a result of the OLA processing and performing OLA processing.

4. The method of claim 1 , wherein the performing the corresponding time domain error concealment processing when the mode from among the plurality of modes corresponds to a mode related to the next good frame after a single error frame comprises smoothing the current frame by applying a smoothing window between a time domain signal of a previous frame and the time domain signal of the current frame.

5. The method of claim 1 , wherein the performing the corresponding time domain error concealment processing when the mode from among the plurality of modes corresponds to a mode related to the next good frame after a burst error frame comprises copying a part used for a next frame in the time domain signal of the current frame to a beginning part of the current frame, down scaling the current frame obtained from a result of the copying, smoothing the down scaled current frame by applying a first smoothing window to a time domain signal of a previous frame and a time domain signal of the beginning part obtained from a result of the copying in the down scaled current frame, and performing OLA processing by applying a second smoothing window between a time domain signal of the previous frame obtained from a result of the smoothing and the time domain signal of the down scaled current frame.

6. A frame error concealment apparatus comprising:

at least one processing device configured to:

when a current frame is classified as an error frame, perform a frequency domain error concealment processing on the current frame to generate spectral coefficients of the current frame;

generate a time domain signal of the current frame based on a time-frequency inverse transform; and

when the current frame is classified as the error frame or a next good frame after the error frame, perform a corresponding time domain error concealment processing on the time domain signal of the current frame by using a mode from among a plurality of modes including at least one mode associated with repetition and smoothing,

wherein the mode from among the plurality of modes is selected according to whether the current frame is stationary.

7. The apparatus of claim 6 , wherein the plurality of modes include a first mode related to the error frame, a second mode related to the next good frame after a single error frame, and a third mode related to the next good frame after a burst error frame.

8. The apparatus of claim 6 , wherein the at least one processing device is configured to perform the corresponding time domain error concealment processing when the mode from among the plurality of modes corresponds to a mode related to the error frame, by performing windowing processing on the time domain signal of the current frame, repeating a time domain signal of a frame that is two frames previous to the current frame to a beginning part of the current frame, performing overlap and add (OLA) processing on a time domain signal of the current frame obtained from a result of the repeating and the time domain signal of the current frame, and performing smoothing processing by applying a smoothing window between a time domain signal of a previous frame and a time domain signal of the current frame obtained from a result of the OLA processing and performing OLA processing.

9. The apparatus of claim 6 , wherein the at least one processing device is configured to perform the corresponding time domain error concealment processing when the mode from among the plurality of modes corresponds to a mode related to the next good frame after a single error frame, by smoothing the current frame by applying a smoothing window between a time domain signal of a previous frame and the time domain signal of the current frame.

10. The apparatus of claim 6 , wherein the at least one processing device is configured to perform the corresponding time domain error concealment processing when the mode from among the plurality of modes corresponds to a mode related to the next good frame after a burst error frame, by copying a part used for a next frame in the time domain signal of the current frame to a beginning part of the current frame, down scaling the current frame obtained from a result of the copying, smoothing the down scaled current frame by applying a first smoothing window to a time domain signal of a previous frame and a time domain signal of the beginning part obtained from a result of the copying in the down scaled current frame, and performing OLA processing by applying a second smoothing window between a time domain signal of the previous frame obtained from a result of the smoothing and the time domain signal of the down scaled current frame.