1. Field of the Invention
The present general inventive concept relates to a method and apparatus to decode a voice signal or an audio signal, and more particularly, to a frame error concealment method and apparatus to conceal a frame error generated in a decoded signal.
2. Description of the Related Art
When packets are lost or distorted during transmission of an encoded audio signal over a wired/wireless network, an error may be generated in a frame of a decoded audio signal due to a transmission error. Unless the generated error is properly handled, the sound quality of the audio signal degrades in the frame having the error. Moreover, since a decoder reconstructs a signal using prediction, the generated error continuously propagates to the next frame and the sound quality of the audio signal also degrades in the next frame. Accordingly, it is important to efficiently conceal a frame error in order to prevent the sound quality of a reconstructed audio signal from degrading.
There are various frame error concealment methods such as a muting method, a repetition method, an interpolation method, an extrapolation method, and a regression analysis method. The muting method reduces volume in a frame having an error, which will be referred to hereinafter as an error frame (EF), thereby alleviating the influence of the error upon an output signal. The repetition method reconstructs a signal of the EF by repetitively reproducing a previous good frame (PGF) of the EF. The interpolation method predicts a parameter of the EF by interpolating a parameter of the PGF and a parameter of a next good frame (NGF). The extrapolation method obtains the parameter of the EF by extrapolating the parameter of the PGF. The regression analysis method obtains the parameter of the EF by regressively analyzing the parameter of the PGF.
Conventionally, however, since the EF has been reconstructed for any type of input signal using the same method, the frame error cannot be efficiently concealed, causing degradation in sound quality.