Apparatus and method for processing an audio signal using patch border alignment

Patent metadata

Field	Value
Publication number	US-9305557-B2
Application number	US-201213604336-A
Country	US
Kind code	B2
Filing date	Sep 5, 2012
Priority date	Mar 9, 2010
Publication date	Apr 5, 2016
Grant date	Apr 5, 2016

Abstract

Apparatus for processing an audio signal to generate a bandwidth extended signal having a high frequency part and a low frequency part using parametric data for the high frequency part, the parametric data relating to frequency bands of the high frequency part includes a patch border calculator for calculating a patch border such that the patch border coincides with a frequency band border of the frequency bands. The apparatus further includes a patcher for generating a patched signal using the audio signal and the patch border.

First claim

The invention claimed is:

1. An apparatus for processing an audio signal to generate a bandwidth extended signal comprising a high frequency part and a low frequency part using parametric data for the high frequency part, the parametric data relating to frequency bands of the high frequency part, comprising:
a patch border calculator for calculating a patch border of a plurality of patch borders such that the patch border coincides with a frequency band border of the frequency bands of the high frequency part; and
a patcher for generating a patched signal using the audio signal and the patch border, wherein the patch borders relate to the high frequency part of the bandwidth extended signal;
wherein the patch border calculator is configured for:
calculating a frequency table defining the frequency bands of the high frequency part using the parametric data or further configuration input data;
setting a target synthesis patch border different from the patch border using at least one transposition factor;
searching, in the frequency table, for a matching frequency band comprising a matching border coinciding with the target synthesis patch border within a predetermined matching range, or searching for the frequency band comprising a frequency band border being closest to the target synthesis patch border; and
selecting the matching frequency band as the patch border, wherein the matching frequency band comprises a matching border coinciding with the target synthesis patch border within a predetermined matching range or comprises a frequency band border being closest to the target synthesis patch border.

2. The apparatus in accordance with claim 1 , in which the patch border calculator is configured to calculate patch borders for three different transposition factors such that each patch border coincides with a frequency band border of the frequency bands of the high frequency part, and
in which the patcher is configured to generate the patched signal using the three different transposition factors so that a border between adjacent patches coincides with a border between two adjacent frequency bands.

3. The apparatus in accordance with claim 1 , in which the patch border calculator is configured to calculate the patch border as a frequency border in a synthesis frequency range corresponding to the high frequency part, and
wherein the patcher is configured to select a frequency portion of the low band part using a transposition factor and the patch border.

4. The apparatus in accordance with claim 1 , further comprising:
a high frequency reconstructor for adjusting the patched signal using the parametric data, the high frequency reconstructor being configured for calculating, for a frequency band or a group of frequency bands, a gain factor to be used for weighting the corresponding frequency band or groups of frequency bands of the patched signal.

5. The apparatus in accordance with claim 1 , in which the predetermined matching range is set to a value smaller than or equal to five QMF bands or 40 frequency bins of the high frequency part.

6. The apparatus in accordance with claim 1 , in which the parametric data comprise a spectral envelope data value, wherein, for each frequency band, a separate spectral envelope data value is given, wherein the apparatus further comprises a high frequency reconstructor for spectral envelope adjusting each band of the patched signal using the spectral envelope data value for this band.

7. The apparatus in accordance with claim 1 , in which the patch border calculator is configured for searching for the highest border in the frequency table that does not exceed a bandwidth limit of a high frequency regenerated signal for a transposition factor, and to use the found highest border as the patch border.

8. The apparatus in accordance with claim 7 , in which the patch border calculator is configured to receive, for each transposition factor of the plurality of different transposition factors, a different target patch border.

9. The apparatus in accordance with claim 1 , further comprising a limiter tool for calculating limiter bands used in limiting gain values for adjusting the patched signals, the apparatus further comprising a limiter band calculator configured to set a limiter border so that at least a patch border determined by the patch border calculator is set as a limiter border as well.

10. The apparatus in accordance with claim 9 , in which the limiter band calculator is configured to calculate further limiter borders so that the further limiter borders coincide with frequency band borders of the frequency bands of the high frequency part.

11. The apparatus in accordance with claim 1 , in which the patcher is configured for generating multiple patches using different transposition factors,
in which the patch border calculator is configured to calculate the patch borders of each patch of the multiple patches so that the patch borders coincide with different frequency band borders of the frequency bands of the high frequency part,
wherein the apparatus further comprises an envelope adjuster for adjusting an envelope of the high frequency part after patching or for adjusting the high frequency part before patching using scale factors comprised by the parametric data given for scale factor bands.

12. A method of processing an audio signal to generate a bandwidth extended signal comprising a high frequency part and a low frequency part using parametric data for the high frequency part, the parametric data relating to frequency bands of the high frequency part, comprising:
calculating a patch border such that the patch border of a plurality of patch borders coincides with a frequency band border of the frequency bands of the high frequency part; and
generating a patched signal using the audio signal and the patch border, wherein the patch borders relate to the high frequency part of the bandwidth extended signal,
wherein said calculating a patch border comprises:
calculating a frequency table defining the frequency bands of the high frequency part using the parametric data or further configuration input data;
setting a target synthesis patch border different from the patch border using at least one transposition factor;
searching, in the frequency table, for a matching frequency band comprising a matching border coinciding with the target synthesis patch border within a predetermined matching range, or to search for the frequency band comprising a frequency band border being closest to the target synthesis patch border; and
selecting the matching frequency band as the patch border, wherein the matching frequency band comprises a matching border coinciding with the target synthesis patch border within a predetermined matching range or comprises a frequency band border being closest to the target synthesis patch border.

13. A non-transitory storage medium having stored thereon a computer program comprising a program code for performing when running on a computer, the method of processing an audio signal to generate a bandwidth extended signal comprising a high frequency part and a low frequency part using parametric data for the high frequency part, the parametric data relating to frequency bands of the high frequency part, said method comprising:
calculating a patch border such that the patch border of a plurality of patch borders coincides with a frequency band border of the frequency bands of the high frequency part; and
generating a patched signal using the audio signal and the patch border, wherein the patch borders relate to the high frequency part of the bandwidth extended signal,
wherein said calculatin

Assignees

• Nagel Frederik
• Disch Sascha
• Wilde Stephan
• Villemoes Lars
• Ekstrand Per
• Fraunhofer Ges Forschung
• Dolby Int Ab

Inventors

• Nagel Frederik
• Disch Sascha
• Wilde Stephan
• Villemoes Lars
• Ekstrand Per

Classifications

• G10L21/038

  using band spreading techniques · CPC title

• G10L19/008 Primary

  Multichannel audio signal coding or decoding using interchannel correlation to reduce redundancy, e.g. joint-stereo, intensity-coding or matrixing · CPC title

• G10L19/0204 Primary

  using subband decomposition · CPC title

• G10L21/04

  Time compression or expansion · CPC title

• G10L21/0232 Primary

  Processing in the frequency domain · CPC title