Apparatus and method for generating an encoded signal or for decoding an encoded audio signal using a multi overlap portion

An apparatus for decoding an encoded audio or image signal, comprising an encoded first frame and an encoded second frame, comprising:

• a processor for processing the first encoded frame and the second encoded frame to acquire a first frame of spectral values and a second frame of spectral values, the first and second frames comprising an aliasing portion;
• a time converter for applying a transform to the first frame of spectral values using a first window function to acquire a first block of samples, for applying another transform to a first portion of the second frame of spectral values using a second window function, and for applying another one or more transforms to a second portion of the second frame of spectral values using one or more third window functions to acquire a second block of samples,
• wherein the first window function, the second window function and the third window function form a multi-overlap region;
• and
• a post-processor for post-processing the second block of samples using a folding-out operation to acquire a post-processed second block of samples comprising a portion of the second block of samples overlapping with the first block of samples in the multi-overlap region, for windowing the post-processed second block of samples using an auxiliary window function, and for overlap-adding the windowed post-processed second block of samples and the first block of samples to acquire a decoded audio or image signal.

A method for generating an encoded audio or image signal, comprising:

• generating a window sequence information for windowing an audio or image signal, the window sequence information indicating a first window function for generating a first frame of spectral values, a second window function and at least one third window function for generating a second frame of spectral values comprising a first and a second portion, wherein the first window function, the second window function and the one or more third window functions overlap within a multi-overlap region;
• windowing a second block of samples corresponding to the second window function and the one or more third window functions using an auxiliary window function to acquire a second block of windowed samples;
• preprocessing the second block of windowed samples using a folding-in operation of a portion of the second block overlapping with a first block into the multi-overlap portion to acquire a preprocessed second block of windowed samples comprising a modified multi-overlap portion;
• applying an aliasing-introducing transform to the first block of samples using the first window function to acquire the first frame of spectral values, applying another aliasing-introducing transform to a first portion of the preprocessed second block of windowed samples using the second window function to acquire a first portion of spectral values of the second frame, and applying another one or more aliasing-introducing transforms to a second portion of the preprocessed second block of windowed samples using the one or more third window functions to acquire a second portion of spectral values of the second frame;
• and
• processing the first frame and the second frame to acquire encoded frames of the audio or image signal.

A method for decoding an encoded audio or image signal, comprising an encoded first frame and an encoded second frame, comprising:

• processing the first encoded frame and the second encoded frame to acquire a first frame of spectral values and a second frame of spectral values, the first and second frames comprising an aliasing portion;
• applying a transform to the first frame of spectral values using a first window function to acquire a first block of samples, applying another transform to a first portion of the second frame of spectral values using a second window function, and applying another one or more transforms to a second portion of the second frame of spectral values using one or more third window functions to acquire a second block of samples,
• wherein the first window function, the second window function and the third window function form a multi-overlap region;
• and
• post-processing the second block of samples using a folding-out operation to acquire a post-processed second block of samples comprising a portion of the second block of samples overlapping with the first block of samples in the multi-overlap region, windowing the post-processed second block of samples using an auxiliary window function, and overlap-adding the windowed post-processed second block of samples and the first block of samples to acquire a decoded audio or image signal.