A method of decoding an audio signal, comprising: receiving, by a downmix decoding unit, an audio signal including a downmix signal (Xm) in the Modified Discrete Cosine Transform, MDCT, domain; receiving, by a plural-channel decoding unit, spatial information (SI3, SI4); converting, by a first domain converting unit, the downmix signal (Xm) from the MDCT domain into the time domain, and converting, by a second downmix converting unit, the downmix signal (Xm) from the MDCT domain into the quadrature mirror filter, QMF, domain; receiving, by the plural-channel decoding unit, the downmix signal converted into the time domain or the downmix signal converted into the QMF domain; and when i) the downmix signal is received from the time domain and when ii) the downmix signal and the spatial information are matched together with time synchronization in the QMF domain: - domain converting, by a third domain converting unit, the downmix signal converted into the time domain to a downmix signal of the QMF domain; and - generating, by a plural-channel generating unit a plural-channel audio signal by combining the downmix signal of the QMF domain with the spatial information; and when i) the downmix signal is received from the QMF domain and when ii) time synchronization between the spatial information and the downmix signal is matched in the time domain in encoding: - compensating, by a signal delay processing unit, the downmix signal converted into the QMF domain for a mismatched time synchronization by lagging the downmix signal converted into the QMF domain by a time synchronization difference, the time synchronization difference being a difference between a delay time generated from the second domain converting unit and a total of a delay time generated from the first domain converting unit and a delay time generated from the third domain converting unit; and - generating, by the plural-channel generating unit a plural-channel audio signal by combining the lagged downmix signal converted into the QMF domain (XQ2') with the spatial information after completion of the compensating time delay. receiving, by a downmix decoding unit, an audio signal including a downmix signal (Xm) in the Modified Discrete Cosine Transform, MDCT, domain; receiving, by a plural-channel decoding unit, spatial information (SI3, SI4); converting, by a first domain converting unit, the downmix signal (Xm) from the MDCT domain into the time domain, and converting, by a second downmix converting unit, the downmix signal (Xm) from the MDCT domain into the quadrature mirror filter, QMF, domain; receiving, by the plural-channel decoding unit, the downmix signal converted into the time domain or the downmix signal converted into the QMF domain; and when i) the downmix signal is received from the time domain and when ii) the downmix signal and the spatial information are matched together with time synchronization in the QMF domain: - domain converting, by a third domain converting unit, the downmix signal converted into the time domain to a downmix signal of the QMF domain; and - generating, by a plural-channel generating unit a plural-channel audio signal by combining the downmix signal of the QMF domain with the spatial information; and - domain converting, by a third domain converting unit, the downmix signal converted into the time domain to a downmix signal of the QMF domain; and - generating, by a plural-channel generating unit a plural-channel audio signal by combining the downmix signal of the QMF domain with the spatial information; and when i) the downmix signal is received from the QMF domain and when ii) time synchronization between the spatial information and the downmix signal is matched in the time domain in encoding: - compensating, by a signal delay processing unit, the downmix signal converted into the QMF domain for a mismatched time synchronization by lagging the downmix signal converted into the QMF domain by a time synchronization difference, the time synchronization difference being a difference between a delay time generated from the second domain converting unit and a total of a delay time generated from the first domain converting unit and a delay time generated from the third domain converting unit; and - generating, by the plural-channel generating unit a plural-channel audio signal by combining the lagged downmix signal converted into the QMF domain (XQ2') with the spatial information after completion of the compensating time delay. - compensating, by a signal delay processing unit, the downmix signal converted into the QMF domain for a mismatched time synchronization by lagging the downmix signal converted into the QMF domain by a time synchronization difference, the time synchronization difference being a difference between a delay time generated from the second domain converting unit and a total of a delay time generated from the first domain converting unit and a delay time generated from the third domain converting unit; and - generating, by the plural-channel generating unit a plural-channel audio signal by combining the lagged downmix signal converted into the QMF domain (XQ2') with the spatial information after completion of the compensating time delay.