Method for measuring HOA loudness level and device for measuring HOA loudness level

Patent metadata

Field	Value
Publication number	US-9832584-B2
Application number	US-201414761109-A
Country	US
Kind code	B2
Filing date	Jan 9, 2014
Priority date	Jan 16, 2013
Publication date	Nov 28, 2017
Grant date	Nov 28, 2017

Abstract

The invention relates to Higher-Order Ambisonics (HOA) Content Loudness Level Adjustment. A method for adjusting a loudness level of a HOA audio signal on a transmitting side comprises steps of measuring loudness of only the W-channel of the HOA audio signal, and leveling HOA master gain for all channels of the HOA signal according to the measured loudness of the W-channel.

First claim

The invention claimed is:

1. A method for adjusting a loudness level of a Higher Order Ambisonics (HOA) formatted 3D audio signal, the 3D audio signal having at least a coefficient channel with coefficients of 0 th order and one or more coefficient channels with coefficients of an order higher than zero, the method comprising:
measuring loudness of the coefficient channel with coefficients of 0 th order of the 3D audio signal; and
level adjusting a master gain for all coefficient channels of the 3D audio signal according to the measured loudness of the coefficient channel with coefficients of 0 th order, wherein a level adjusted HOA signal is obtained.

2. The method of claim 1 , further comprising steps of rendering the 3D audio signal, wherein a normalized rendering matrix is used, and monitoring the loudness of the rendered signal.

3. The method according to claim 2 , wherein the rendering uses a rendering matrix that is normalized with a normalization factor D n , according to

D
n

=

D
e

(

N
+
1

)

,

wherein D e is the energy preserving rendering matrix, or according to

D
n

=

D




D




fro

,

wherein D is an approximately energy preserving rendering matrix.

4. The method according to claim 2 , wherein the rendering uses a rendering matrix that is normalized with a normalization factor {circumflex over (D)} n according to

D
^

n

=

D




Dy




2
2

,

wherein y is a HOA test signal composed of Spherical Harmonics of direction Ω c and D is an approximately energy preserving rendering matrix.

5. The method according to claim 1 , further comprising rendering the signal resulting from said level adjusting step and transmitting the rendered signal, wherein the rendering uses an energy preserving rendering matrix that is normalized with a normalization factor according to

D
n

=

D




D




fro

or according to

D
^

n

=

D




Dy




2
2

,

wherein D is an approximately energy preserving rendering matrix and y is a HOA test signal composed of Spherical Harmonics of direction Ω c .

6. The method according to claim 1 , further comprising transmitting, receiving and rendering the signal resulting from said level adjusting step, wherein the rendering after transmitting and receiving uses an energy preserving rendering matrix that is normalized with a normalization factor according to

D
n

=

D




D




fro

or according to

D
^

n

=

D




Dy




2
2

,

wherein D is an approximately energy preserving rendering matrix and y is a HOA test signal composed of Spherical Harmonics of direction Ω c .

7. The method according to claim 1 , wherein the measuring loudness of the coefficient channel and level adjusting a master gain are performed on a transmitting side, before a step of transmission or storage.

8. The method of claim 1 , wherein said measuring loudness results in momentary, short-term and integrated loudness measures that are input to the level adjusting.

9. A device for loudness level adjustment for Higher Order Ambisonics (HOA) formatted 3D audio signals, the 3D audio signal having at least a coefficient channel with coefficients of 0 th order and one or more coefficient channels with coefficients of an order higher than zero, the device comprising:
a loudness measuring unit for measuring loudness of the coefficient channel with coefficients of 0 th order; and
a master gain unit for regulating gain of all coefficient channels of the 3D audio signal according to the measured loudness received from the loudness measuring unit, the master gain unit providing a level adjusted HOA signal.

10. The device of claim 9 , further comprising a monitoring unit for rendering the level adjusted HOA signal, wherein a normalized rendering matrix is used, and for

Assignees

• Dolby Laboratories Licensing Corp

Inventors

• Boehm Johannes
• Keiler Florian

Classifications

• H04S3/008 Primary

  in which the audio signals are in digital form, i.e. employing more than two discrete digital channels (data reduction aspects thereof based on psychoacoustics G10L19/02) · CPC title

• H04S2400/13

  Aspects of volume control, not necessarily automatic, in stereophonic sound systems · CPC title

• H04S2420/11

  Application of ambisonics in stereophonic audio systems · CPC title

• H04S2400/15

  Aspects of sound capture and related signal processing for recording or reproduction · CPC title

• H03G9/005

  of digital or coded signals · CPC title