Encoding an information signal

Patent metadata

Field	Value
Publication number	US-RE50654-E
Application number	US-202318225488-A
Country	US
Kind code	E1
Filing date	Jul 24, 2023
Priority date	Oct 18, 2006
Publication date	Nov 4, 2025
Grant date	Nov 4, 2025

Abstract

The transient problem may be sufficiently addressed, and for this purpose, a further delay on the side of the decoding may be reduced if a new SBR frame class is used wherein the frame boundaries are not shifted, i.e. the grid boundaries are still synchronized with the frame boundaries, but wherein a transient position indication is additionally used as a syntax element so as to be used, on the encoder and/or decoder sides, within the frames of these new frame class for determining the grid boundaries within these frames.

First claim

The invention claimed is:

1 . An encoder comprising
a low-frequency portion encoder for encoding a low-frequency portion of an information signal in units of frames of the information signal; a localizer for localizing transients within the information signal; an associator for, as a function of the localization, associating a respective reconstruction mode from among at least two possible reconstruction modes with the frames of the information signal, and, for frames which have associated therewith a first one of the at least two possible reconstruction modes, associating a respective transient position indication with these frames; a generator for generating a representation of a spectral envelope of a high-frequency portion of the information signal in a temporal grid which depends on reconstruction modes associated with the frames, such that frames which have the first one of the at least two possible reconstruction modes associated therewith, the frame boundaries of these frames coincide with grid boundaries of the grid, and the grid boundaries of the grid within these frames depend on the transient position indication; and a combiner for combining the encoded low-frequency portion, the representation of the spectral envelope and information on the associated reconstruction modes and the transient position indications into an encoded information signal, wherein at least one of the low-frequency portion encoder, the localizer, the associator, the generator and the combiner comprises a hardware implementation.

2 . The encoder as claimed in claim 1 , wherein the generator is formed such that the grid boundaries within the frame, which have the first one of the at least two possible reconstruction modes associated therewith, are located such that they specify at least a first grid area whose position within the respective frame depends on the transient position indication, and whose temporal extension is smaller than ⅓ of a length of the frames, as well as a second and/or a third grid area(s) which take(s) up the remaining part of the respective frame from the first grid area to the frame boundary, which is leading in terms of time and/or trailing in terms of time, of the respective frame.

3 . The encoder as claimed in claim 2 , wherein the generator and the combiner are formed to introduce, for a frame having the first reconstruction mode associated with it which comprises three grid areas and wherein the first grid area among the three grid areas is closer to a preceding frame than a predetermined value, one or several spectral envelope values describing the spectral envelope with a respective frequency resolution, only for the first and third grid areas, into the encoded information signal, and to introduce no spectral envelope value into the encoded information signal for the second grid area of this frame.

4 . The encoder as claimed in claim 2 , wherein the generator and the combiner are formed to introduce, for a frame having the first reconstruction mode associated with it, which comprises only two grid areas and wherein the first grid area borders on the frame boundary which is trailing in terms of time, one or several spectral envelope values, for both grid areas, said one or several spectral envelope value(s) describing the spectral envelope with a respective frequency resolution, into the encoded information signal, and to also use, for determining the spectral envelope value(s) for the first grid area, parts of the information signal located in the extension grid area in the subsequent frame which borders on the trailing frame boundary, and to shorten a grid area, which is leading in terms of time, of the subsequent frame as is specified by the reconstruction mode of the subsequent frame, so as to start only at the extension grid area.

5 . The encoder as claimed in claim 3 , wherein the generator and the combiner are formed to introduce one or several spectral envelope values into the encoded information signal for a frame having the second reconstruction mode associated with it or having the first reconstruction mode associated with it, but for which neither the condition that it comprises three grid areas and that, at the same time, the first grid area among the three grid areas is located closer to the preceding frame than the predetermined value, nor the condition that it comprises only two grid areas and that, at the same time, the first grid area borders on the frame boundary which is trailing in terms of time, are fulfilled, for each grid area of this frame.

6 . The encoder as claimed in claim 2 , wherein the generator is formed such that the first grid area borders on the frame boundary, leading in terms of time, of the respective frame if there is no second grid area, and wherein the first grid area borders on the frame boundary, trailing in terms of time, of the respective frame if no third grid area exists.

7 . The encoder as claimed in claim 1 , wherein the generator is formed such that the grid boundaries within frames which have the second of the at least two possible reconstruction modes associated with them are located such that they are equally distributed over time, so that these frames only comprise one grid area or are subdivided into equally sized grid areas.

8 . The encoder as claimed in claim 1 , wherein the associator is formed to associate a frame subdivision number indication with each frame which has the second of the at least two possible reconstruction modes associated with it, the generator being formed such that the grid boundaries within these frames subdivide these frames into a number of grid areas, said number depending on the respective frame subdivision number indication.

9 . The encoder as claimed in claim 1 , wherein the generator is formed such that the frame boundaries of the frames coincide with grid boundaries of the grid independently of the possible reconstruction modes associated with the frames.

10 . The encoder as claimed in claim 1 , wherein the generator comprises an analysis filter bank which generates a set of spectral values for each filter bank time slot of the information signal, each frame with a length of several filter bank time slots, and the generator further comprising an averager for averaging the energy spectral values in the resolution of the grid.

11 . A decoder comprising
an extractor for extracting, from the an encoded information signal, an encoded low-frequency portion of an information signal, a representation of a spectral envelope of a high-frequency portion of the information signal, information on reconstruction modes associated with frames of the information signal and corresponding with one, respectively, of at least two possible reconstruction modes, and transient position indications associated with frames, in each case, which have a first one of the at least two possible reconstruction modes associated with them; a low-frequency portion decoder for decoding the encoded low-frequency portion of the information signal in units of frames of the information signal; a provider for providing a preliminary high-frequency portion signal on the basis of the decoded low-frequency portion; and an adaptor for spectrally adapting the preliminary high-frequency portion signal to the spectral envelopes envelope by means of spectral weighting of the preliminary high-frequency portion signal as a function of the representation of the spectral envelopes envelope in a temporal grid which depends on the reconstruction modes associated with the frames, such that for frames having the first one of the at least two possible reconstruction modes associated with them, the frame boundaries of these frames coincide with gr

Assignees

• Fraunhofer Ges Forschung

Inventors

• Schnell Markus
• Schuldt Michael
• Lutzky Manfred
• Jander Manuel

Classifications

• G10L21/038 Primary

  using band spreading techniques · CPC title