Method and an apparatus for processing an audio signal

A method for processing an audio signal, comprising:

• receiving, by an audio processing apparatus, coding identification information indicating whether to apply a first coding scheme or a second coding scheme to a current frame;
• when the coding identification information indicates that the second coding scheme is applied to the current frame, receiving window type information indicating a particular window for the current frame, from among a plurality of windows;
• identifying that a current window is a stop_start window based on the window type information, wherein the stop_start window follows one of a long_start window, a short window and a window of the first coding scheme for a previous frame, wherein the stop_start window is followed by one of a long_stop window, a short window and a window of the first coding scheme for a following frame, wherein the stop_start window includes a gentle-gentle stop_start window, a gentle-steep stop_start window, a steep-gentle stop_start window and a steep-steep stop_start window;
• when the first coding scheme is applied to a previous frame, applying one of the gentle-gentle stop_start window and the gentle-steep stop_start window to the current frame;
• and
• when the first coding scheme is applied to a following frame, applying one of the gentle-gentle stop_start window and the steep-gentle stop_start window to the current frame,
• wherein:
• the gentle-gentle stop_start window comprise an ascending line with first slope and a descending line with the first slope,
• the gentle-steep stop_start window comprise an ascending line with the first slope and a descending line with second slope,
• the steep-gentle stop_start window comprise an ascending line with the second slope and a descending line with the first slope,
• the steep-steep stop_start window comprise an ascending line with the second slope and a descending line with the second slope, and
• the first slope is gentler than the second slope.

An apparatus for processing an audio signal, comprising:

• a de-multiplexer receiving coding identification information indicating whether to apply a first coding scheme or a second coding scheme to a current frame, and, when the coding identification information indicates that the second coding scheme is applied to the current frame, receiving window type information indicating a particular window for the current frame, from among a plurality of windows;
• and
• a second coding unit identifying that a current window is a stop_start window based on the window type information, wherein the stop_start window follows one of a long_start window, a short window and a window of the first coding scheme for a previous frame,
• wherein the stop_start window is followed by one of a long_stop window, a short window and a window of the first coding scheme for a following frame, wherein the stop_start window includes a gentle-gentle stop_start window, a gentle-steep stop_start window, a steep-gentle stop_start window and a steep-steep stop_start window, and, when the first coding scheme is applied to a previous frame, applying one of the gentle-gentle stop_start window and the gentle-steep stop_start window to the current frame, when the first coding scheme is applied to a following frame, applying one of the gentle-gentle stop_start window and the steep-gentle stop_start window to the current frame,
• wherein:
• the gentle-gentle stop_start window comprise an ascending line with first slope and a descending line with the first slope,
• the gentle-steep stop_start window comprise an ascending line with the first slope and a descending line with second slope,
• the steep-gentle stop_start window comprise an ascending line with the second slope and a descending line with the first slope,
• the steep-steep stop_start window comprise an ascending line with the second slope and a descending line with the second slope, and
• the first slope is gentler than the second slope.