# US 2022/0286103 A1 · Audio signal processing method and apparatus for controlling loudness level and dynamic range

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- Number: US 2022/0286103 A1
- Document ID: US20220286103A1
- Status: Published application
- Kind: A1
- Application number: 17/827,658
- Filed: 2022-05-27
- Published: 2022-09-08
- Earliest claimed: 2020-03-12
- Assignees: Gaudio Lab, Inc.
- Applicants: Gaudio Lab, Inc.
- Inventors: Hyunjoo CHUNG; Sangbae CHON; Hyunoh OH; Jeonghun SEO
- Web page: https://patentgrep.com/patent/US20220286103A1

## CPC

- H03G 3/3005: {in amplifiers suitable for low-frequencies, e.g. audio amplifiers (H03G3/32, H03G3/34 take precedence)}
- H03G 7/002: {in untuned or low-frequency amplifiers, e.g. audio amplifiers (H03G7/007, H03G7/001, H03G7/008, H03G7/02, H03G7/06 take precedence)}
- H03G 7/007: {of digital or coded signals}
- H04R 1/1083: {Reduction of ambient noise (active noise reduction per se G10K11/175; protective devices for the ear, e.g. providing acoustic protection A61F11/06)}
- G06F 16/683: using metadata automatically derived from the content
- H04R 2430/01: Aspects of volume control, not necessarily automatic, in sound systems
- H03G: CONTROL OF AMPLIFICATION
- H04R: LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS (producing sounds with frequency not determined by supply frequency G10K)
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)

## Abstract

Disclosed is a method of operating an audio signal processing apparatus playing content including an audio signal. The method includes receiving the audio signal, receiving metadata including information related to a loudness of the audio signal, the metadata including loudness distribution information indicating, for each of a plurality of steps separated according to a loudness magnitude, a ratio between an amount of the audio signal corresponding to each of the plurality of steps of the audio signal and a total amount of the audio signal, and adjusting the loudness of the audio signal based on the metadata.

## Claims

### Claim at position 1

1-20. (Cancelled).

### Claim 21

A method of operating an audio signal processing apparatus playing content including an audio signal, the method comprising:
receiving the audio signal;
receiving metadata including information related to a loudness of the audio signal, the metadata including loudness distribution information, for each of a plurality of steps separated according to a loudness magnitude, indicating a ratio between an amount of an audio signal corresponding to each of the plurality of steps of the audio signal and a total amount of the audio signal; and
adjusting the loudness of the audio signal based on the metadata,
wherein a value of the ratio for each of the plurality of steps is encoded with a variable length,
wherein the metadata includes information indicating a type of loudness that is a reference to the loudness distribution information.

### Claim 22 (depends on 21)

The method of claim 21, wherein the metadata includes a bit string including the value of the ratio corresponding to each of the plurality of steps separated according to the loudness magnitude, and
the bit string includes an ending flag repeatedly positioned by a predetermined number and indicating an end of bits representing the ratio corresponding to each of plurality of steps.

### Claim 23 (depends on 22)

The method of claim 22, wherein the adjusting the loudness of the audio signal based on the metadata includes obtaining the value of the ratio for each of the plurality of steps by using a bit operation below.
Syntax
No. of bytes
value = readFlexible( )
{
value = 0;
for (n=0; n<5; n++) {
byte;
1
value += (0x7F & byte) << (7 * n);
if (!(0x80 & byte)) break;
}
return value:
}

### Claim 24 (depends on 21)

The method of claim 21, wherein the type of loudness is classified according to a length of a time interval in which the loudness is measured.

### Claim 25 (depends on 21)

The method of claim 21, wherein the adjusting the loudness of the audio signal based on the metadata includes adjusting the loudness of the audio signal based on the loudness distribution information and a characteristic of nonlinear processing applied to the audio signal.

### Claim 26 (depends on 25)

The method of claim 25, wherein the nonlinear processing includes dynamic range control (DRC).

### Claim 27 (depends on 25)

The method of claim 25, wherein the adjusting the loudness of the audio signal based on the loudness distribution information and the characteristic of the nonlinear processing applied to the audio signal includes adjusting the loudness based on a difference between a target loudness and a value obtained by adding a loudness deviation caused by the nonlinear processing to the loudness of the audio signal.

### Claim 28

A method of generating metadata for content including an audio signal, the method comprising:
obtaining loudness distribution information of the audio signal, the loudness distribution information indicating, for each of a plurality of steps separated according to a loudness magnitude, a ratio between an amount of the audio signal corresponding to each of the plurality of steps of the audio signal and a total amount of the audio signal; and
inserting the loudness distribution information in the metadata,
wherein a value of the ratio for each of the plurality of steps is encoded with a variable length,
wherein the metadata includes information indicating a type of loudness that is a reference to the loudness distribution information.

### Claim 29 (depends on 28)

The method of claim 28, wherein the metadata includes a bit string including the audio signal ratio corresponding to each of the plurality of steps separated according to the loudness magnitude, and
the bit string includes an ending flag repeatedly positioned by a predetermined number and indicating an end of bits representing the audio signal ratio corresponding to each step.

### Claim 30 (depends on 29)

The method of claim 29, wherein the ending flag is repeatedly positioned every 8 bits in the bit string.

### Claim 31 (depends on 28)

The method of claim 28, wherein the type of loudness is classified according to a length of a time interval in which the loudness is measured.

### Claim 32

An audio signal processing apparatus playing content including an audio signal, the audio signal processing apparatus comprising:
a receiver receiving the audio signal; and
a processor controlling the audio signal processing apparatus, wherein the processor is configured to:
receive metadata including information related to a loudness of the audio signal, the metadata including loudness distribution information indicating, for each of a plurality of steps separated according to a loudness magnitude, a ratio between an amount of an audio signal corresponding to each of the plurality of steps of the audio signal and a total amount of the audio signal; and
adjust the loudness of the audio signal based on the metadata, ,
wherein a value of the ratio for each of the plurality of steps is encoded with a variable length,
wherein the metadata includes information indicating a type of loudness that is a reference to the loudness distribution information.

### Claim 33 (depends on 32)

The audio signal processing apparatus of claim 32, wherein the metadata includes a bit string including the value of the ratio corresponding to each of the plurality of steps separated according to the loudness magnitude, and
the bit string includes an ending flag repeatedly positioned by a predetermined number and indicating an end of bits representing the ratio corresponding to each step.

### Claim 34 (depends on 33)

The audio signal processing apparatus of claim 33, wherein the processor is configured to obtain a value of the ratio for each of the plurality of the steps by using a bit operation below.
Syntax
No. of bytes
value = readFlexible( )
{
value = 0;
for (n=0; n<5; n++) {
byte;
1
value += (0x7F & byte) << (7 * n);
if (!(0x80 & byte)) break;
}
return value:
}