Method and apparatus for concealing frame error and method and apparatus for audio decoding
Disclosed is a frame error concealment (FEC) method. The method includes: selecting an FEC mode based on states of a current frame and a previous frame of the current frame in a time domain signal generated after time-frequency inverse transform processing; and performing corresponding time domain error concealment processing on the current frame based on the selected FEC mode, wherein the current frame is an error frame or the current frame is a normal frame when the previous frame is an error frame.
1. A frame error concealment method comprising:
selecting one mode from among a plurality of modes associated with repetition and smoothing, for a frame in a time domain signal generated after time-frequency inverse transform processing; and
performing a corresponding time domain error concealment processing on the frame based on the selected mode,
wherein the frame is classified as a current error frame or a next good frame after a single error frame or a next good frame after a burst error frame, and
wherein the plurality of modes include a first mode related to the current error frame, a second mode related to the next good frame after the single error frame, and a third mode related to the next good frame after the burst error frame.
2. The method of claim 1 , further comprising performing a frequency domain error concealment processing on the frame when the frame is an error frame before the time-frequency inverse transform processing.
3. The method of claim 1 , wherein the performing of the time domain error concealment processing when the selected mode corresponds to the first mode, comprises:
performing windowing processing on a signal of the current error frame after the time-frequency inverse transform processing;
repeating a signal before two frames at a beginning part of the current error frame after the time-frequency inverse transform processing;
performing overlap and add (OLA) processing on the signal repeated at the beginning part of the current error frame and the signal of the current error frame; and
performing OLA processing by applying a smoothing window having a predetermined overlap duration between a signal of a previous frame and the signal of the current error frame.
4. The method of claim 1 , wherein the performing of the time domain error concealment processing when the selected mode corresponds to the second mode, comprises:
selecting a length of an overlap duration of a smoothing window to be applied in smoothing processing; and
performing overlap and add (OLA) processing by applying the selected smoothing window between a signal of the single error frame and a signal of the next good frame after the time-frequency inverse transform processing.
5. The method of claim 1 , wherein the performing of the time domain error concealment processing when the selected mode corresponds to the third mode, comprises:
copying a part corresponding to a next frame in a signal of the next good frame to a beginning part of the next good frame after the time-frequency inverse transform processing;
performing overlap and add (OLA) processing by applying a smoothing window to a signal of the burst error frame and a signal copied from the future after the time-frequency inverse transform processing;
performing OLA processing while removing a discontinuity by applying a smoothing window having a predetermined overlap duration between a signal replaced in the burst error frame and the signal of the next good frame.
6. The method of claim 1 , wherein when the mode is selected by considering stationary information of the current frame.