Processor for processing an audio signal, comprising: an analyzer for deriving a window control signal from the audio signal, the window control signal indicating a change from a first asymmetric window comprising a first overlap portion and a second overlap portion to a second window comprising a first overlap portion, the second overlap portion of the first asymmetric window overlapping with the first overlap portion of the second window, the first overlap portion of the first asymmetric window preceding the second overlap portion of the first asymmetric window, or the window control signal indicating a change from a third window comprising a second overlap portion to a fourth asymmetric window comprising a first overlap portion and a second overlap portion, the second overlap portion of the third window overlapping with the first overlap portion of the fourth asymmetric window, the first overlap portion of the fourth asymmetric window preceding the second overlap portion of the fourth asymmetric window, wherein the second window is shorter than the first asymmetric window, or wherein the third window is shorter than the fourth asymmetric window; a window constructor for constructing the second window using the first overlap portion of the first asymmetric window, wherein the window constructor is configured to determine the first overlap portion of the second window using a truncated first overlap portion of the first asymmetric window, or for constructing the third window using the second overlap portion of the fourth asymmetric window, wherein the window constructor is configured to calculate the second overlap portion of the third window using a truncated second overlap portion of the fourth asymmetric window; and a windower for applying the first asymmetric window and the second window or the third window and the fourth asymmetric window to obtain windowed audio signal portions. an analyzer for deriving a window control signal from the audio signal, the window control signal indicating a change from a first asymmetric window comprising a first overlap portion and a second overlap portion to a second window comprising a first overlap portion, the second overlap portion of the first asymmetric window overlapping with the first overlap portion of the second window, the first overlap portion of the first asymmetric window preceding the second overlap portion of the first asymmetric window, or the window control signal indicating a change from a third window comprising a second overlap portion to a fourth asymmetric window comprising a first overlap portion and a second overlap portion, the second overlap portion of the third window overlapping with the first overlap portion of the fourth asymmetric window, the first overlap portion of the fourth asymmetric window preceding the second overlap portion of the fourth asymmetric window, wherein the second window is shorter than the first asymmetric window, or wherein the third window is shorter than the fourth asymmetric window; the window control signal indicating a change from a first asymmetric window comprising a first overlap portion and a second overlap portion to a second window comprising a first overlap portion, the second overlap portion of the first asymmetric window overlapping with the first overlap portion of the second window, the first overlap portion of the first asymmetric window preceding the second overlap portion of the first asymmetric window, or the window control signal indicating a change from a third window comprising a second overlap portion to a fourth asymmetric window comprising a first overlap portion and a second overlap portion, the second overlap portion of the third window overlapping with the first overlap portion of the fourth asymmetric window, the first overlap portion of the fourth asymmetric window preceding the second overlap portion of the fourth asymmetric window, wherein the second window is shorter than the first asymmetric window, or wherein the third window is shorter than the fourth asymmetric window; a window constructor for constructing the second window using the first overlap portion of the first asymmetric window, wherein the window constructor is configured to determine the first overlap portion of the second window using a truncated first overlap portion of the first asymmetric window, or for constructing the third window using the second overlap portion of the fourth asymmetric window, wherein the window constructor is configured to calculate the second overlap portion of the third window using a truncated second overlap portion of the fourth asymmetric window; and for constructing the second window using the first overlap portion of the first asymmetric window, wherein the window constructor is configured to determine the first overlap portion of the second window using a truncated first overlap portion of the first asymmetric window, or for constructing the third window using the second overlap portion of the fourth asymmetric window, wherein the window constructor is configured to calculate the second overlap portion of the third window using a truncated second overlap portion of the fourth asymmetric window; and a windower for applying the first asymmetric window and the second window or the third window and the fourth asymmetric window to obtain windowed audio signal portions.