# US 8,930,199 B2 · Method and an apparatus for processing an audio signal

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- Number: US 8,930,199 B2
- Document ID: US8930199B2
- Status: Granted
- Kind: B2
- Application number: 13/391,992
- Filed: 2010-09-17
- Published: 2012-09-20
- Granted: 2015-01-06
- Earliest claimed: 2009-09-17
- Assignees: Industry-Academic Cooperation Foundation, Yonsei University
- Applicants: Hyen-O Oh; Chang Heon Lee; Hong Goo Kang; Jeongook Song
- Inventors: Hyen-O Oh; Chang Heon Lee; Hong Goo Kang; Jeongook Song
- Web page: https://patentgrep.com/patent/US8930199B2

## CPC

- G10L 19/00: Speech or audio signals analysis-synthesis techniques for redundancy reduction, e.g. in vocoders; Coding or decoding of speech or audio signals, using source filter models or psychoacoustic analysis (in musical instruments G10H)
- G10L 19/04: using predictive techniques
- G10L 19/18: Vocoders using multiple modes
- G10L 19/022: Blocking, i.e. grouping of samples in time; Choice of analysis windows; Overlap factoring
- G10L 19/167: {Audio streaming, i.e. formatting and decoding of an encoded audio signal representation into a data stream for transmission or storage purposes}
- G11B 20/00007: {Time or data compression or expansion (audio compression based on psychoacoustics G10L19/00; data processing for reproducing audio data at different playback speeds G10L21/04; video compression H04N19/00; data compression per se H03M7/30)}
- G11B 2020/00028: {Advanced audio coding [AAC]}
- G11B 2020/10546: {specifically adapted for audio data}
- G10L: SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING
- G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R)

## Abstract

A method of processing an audio signal is disclosed. The present invention includes 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 long stop window based on the window type information, wherein the long stop window is followed by only long window of a following frame, wherein the long stop window includes a gentle long stop window and a steep long stop window; and, when the first coding scheme is applied to a previous frame, applying the gentle long stop window to the current frame, wherein: the gentle long stop window comprise an ascending line with first slope, the steep long stop window comprise an ascending line with second slope, and, the first slope is gentler than the second slope.

## Claims

### Claim 1

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 based on linear-prediction domain or a second coding scheme based on frequency domain to a current frame;
when the coding identification information indicates that the second coding scheme based on frequency domain 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 long_stop window based on the window type information, wherein the long_stop window is followed by only_long window of a following frame, wherein the long_stop window comprises an ascending line; and,
determining a slope of the ascending line to be either a first slope or a second slope according to a previous frame,
wherein the ascending line is determined to be the first slope gentler than the second slope when the first coding scheme based on linear-prediction domain is applied to the previous frame, and is determined to be the second slope when the first coding scheme based on linear-prediction domain is not applied to the previous frame,
wherein the first slope is gentler than the second slope, and
wherein a width of the long_stop window is 2N (where N is frame length) regardless of whether the ascending line is determined to be the first slope or not.

### Claim 2 (depends on 1)

The method of the claim 1, wherein a width of the first slope is equal to two-times a width of the second slope.

### Claim 3 (depends on 1)

The method of claim 1, wherein a width of the first slope corresponds to N/4 (where N is frame length).

### Claim 4 (depends on 1)

The method of claim 1, wherein a width of the first slope corresponds to 256 samples, and wherein a width of the first slope is equal to ⅛ of length of the long_stop window.

### Claim 5 (depends on 1)

The method of claim 1, wherein the only_long window is horizontal-symmetry, and the long_stop window is horizontal-asymmetry, the long_stop window has zero part in a left half.

### Claim 6 (depends on 1)

The method of claim 1, wherein center point of the ascending line with the first slope or the second slope is at N/2 distance from a start point of the long_stop window (where N is frame length).

### Claim 7

An apparatus for processing an audio signal, comprising:
a de-multiplexer receiving coding identification information indicating whether to apply a first coding scheme based on linear-prediction domain or a second coding scheme based on frequency domain to a current frame, and when the coding identification information indicates that the second coding scheme based on frequency domain 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 and identifying that a current window is a long_stop window based on the window type information, wherein the long_stop window is followed by only_long window of a following frame, wherein the long_stop window comprises an ascending line and, determining a slope of the ascending line to be either a first slope or a second slope according to a previous frame,
wherein the ascending line is determined to be the first slope gentler than the second slope when the first coding scheme based on linear-prediction domain is applied to the previous frame, and is determined to be the second slope when the first coding scheme based on linear-prediction domain is not applied to the previous frame,
wherein the first slope is gentler than the second slope, and
wherein a width of the long_stop window is 2N (where N is frame length) regardless of whether the ascending line is determined to be the first slope or not.

### Claim 8 (depends on 7)

The apparatus of the claim 7, wherein a width of the first slope is equal to two-times a width of the second slope.

### Claim 9 (depends on 7)

The apparatus of claim 7, wherein a width of the first slope corresponds to N/4 (where N is frame length).

### Claim 10 (depends on 7)

The apparatus of claim 7, wherein a width of the first slope corresponds to 256 samples, and wherein a width of the first slope is equal to ⅛ of length of the long_stop window.

### Claim 11 (depends on 7)

The apparatus of claim 7, wherein the only_long window is horizontal-symmetry, and the long_stop window is horizontal-asymmetry, the long_stop window has zero part in a left half.

### Claim 12 (depends on 7)

The apparatus of claim 7, wherein center point of the ascending line with the first slope or the second slope is at N/2 distance from a start point of the long_stop window (where N is frame length).