Reconstruction of audio channels with direction parameters indicating direction of origin

• US 9,015,051 B2
• Filed: 02/01/2008
• Issued: 04/21/2015
• Est. Priority Date: 03/21/2007
• Status: Active Grant

• Current Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V.
• Original Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V.
• Inventors: Pulkki, Ville
• Primary Examiner(s): Lerner, Martin
• Application Number:
  US12/532,401
• Publication Number:
  US 20100169103A1
• Time in Patent Office: 2,636 Days
• Field of Search: 704/205, 704/225, 704/278, 704/500, 381/1, 381/23, 381/92, 381/17, 381/19
• US Class Current: 704/278
• CPC Class Codes: H04R 27/00 Public address systems circuits for preventing acoustic reaction H04R3/02; circuits for distributing signals to loudspeakers H04R3/12; monitoring or testing arrangements for public address systems H04R29/007; amplifiers H03F
• CPC Class Codes: H04S 2400/11 Positioning of individual sound objects, e.g. moving airplane, within a sound field H04S2420/13 takes precedence
• CPC Class Codes: H04S 2400/13 Aspects of volume control, not necessarily automatic, in stereophonic sound systems
• CPC Class Codes: H04S 2420/07 Synergistic effects of band splitting and sub-band processing
• CPC Class Codes: H04S 2420/11 Application of ambisonics in stereophonic audio systems
• CPC Class Codes: H04S 7/302 Electronic adaptation of stereophonic sound system to listener position or orientation H04S7/301 takes precedence
• CPC Class Codes: H04S 7/305 Electronic adaptation of stereophonic audio signals to reverberation of the listening space H04S7/301 takes precedence

Abstract

An audio signal having at least one audio channel and associated direction parameters indicating a direction of origin of a portion of the audio channel with respect to a recording position is reconstructed to derive a reconstructed audio signal. A desired direction of origin with respect to the recording position is selected. The portion of the audio channel is modified for deriving a reconstructed portion of the reconstructed audio signal, wherein the modifying includes increasing an intensity of the portion of the audio channel having direction parameters indicating a direction of origin close to the desired direction of origin with respect to another portion of the audio channel having direction parameters indicating a direction of origin further away from the desired direction of origin.

Claims

1. A method for reconstructing an audio signal to obtain a reconstructed audio signal, the method comprising:

receiving the audio signal, the audio signal comprising at least one audio channel and a first associated direction parameter indicating a first direction of origin of a first portion in a first frequency band of a frame of the at least one audio channel with respect to a recording position and a second associated direction parameter indicating a second direction of origin of a second portion in a second frequency band of the frame of the at least one audio channel with respect to the recording position,

wherein the first associated direction parameter is different from the second associated direction parameter, wherein the first direction of origin is different from the second direction of origin, and wherein the first frequency band is different from the second frequency band;

selecting, by a selector, a set direction of origin with respect to the recording position to obtain a selected set direction of origin; and

modifying, by a modifier, the first portion in the first frequency band of the frame of the at least one audio channel and the second portion in the second frequency band of the frame of the at least one audio channel for deriving a reconstructed portion in the first frequency band and the second frequency band of the reconstructed audio signal for the frame of the at least one audio channel, wherein the modifying comprises increasing an intensity of the first portion in the first frequency band of the frame of the at least one audio channel, when the first direction parameter associated with the first frequency band of the first portion of the at least one audio channel indicates the first direction of origin close to the selected set direction of origin with respect to the second frequency band of the second portion of the frame of the at least one audio channel for which the second associated direction parameter indicates the second direction of origin further away from the selected set direction of origin,

wherein at least one of the selector and the modifier comprises a hardware implementation.

2. The method of claim 1, wherein the selecting comprises:

reading the set direction from a memory.

3. The method of claim 1, in which the modifying comprises deriving a scaling factor for the first and the second portions of the at least one audio channel such that a scaled first portion of the at least one audio channel comprising the first associated direction parameter indicating the first direction of origin close to the set direction of origin comprises an increased intensity with respect to a second scaled portion of the at least one audio channel comprising the second associated direction parameter indicating the second direction of origin further away from the set direction of origin, wherein the first scaled portion is derived by multiplying the first portion of the at least one audio channel with the first scaling factor, and wherein the second scaled portion is derived by multiplying the second portion of the at least one audio channel with the second scaling factor.

4. The method of claim 1, further comprising:

deriving a frequency representation of the frame of the at least one audio channel to obtain the first portion and the second portion having the first and the second frequency bands, respectively.

5. The method of claim 4, wherein the first frequency band has a first bandwidth, wherein the second frequency band has a second bandwidth, and wherein the first bandwidth is different from the second bandwidth.

6. The method of claim 1, wherein selecting of the set direction of origin comprises receiving input parameters indicating the set direction as a user input.

7. The method of claim 1, wherein selecting the set direction comprises receiving direction parameters associated to the audio signal, the direction parameters indicating the set direction.

8. The method of claim 1, wherein selecting the set direction comprises determining the direction of origin of a finite width frequency interval of the at least one audio channel.

9. The method of claim 1, further comprising:

receiving a first diffuseness parameter associated to the at least one audio channel and a second diffuseness parameter associated to the at least one audio channel, the first diffuseness parameter indicating a first diffuseness of the first portion of the at least one audio channel, and the second diffuseness parameter indicating a second diffuseness of the second portion of the at least one audio channel, the second diffuseness being different from the first diffuseness; and

wherein the modifying of the first or second portion of the at least one audio channel comprises decreasing an intensity of the first portion of the at least one audio channel comprising the first diffuseness parameter indicating the first diffuseness with respect to the second portion of the at least one audio channel comprising the second diffuseness parameter indicating the second diffuseness, the second diffuseness being lower than the first diffuseness.

10. The method of claim 1, further comprising:

up-mixing the at least one audio channel to multiple channels for playback via a loudspeaker system comprising multiple loudspeakers, wherein each of the multiple channels comprises a channel portion corresponding to the first portion of the at least one audio channel and to the second portion of the at least one audio channel.

11. The method of claim 10, in which the modifying comprises increasing the intensity of each of up-mixed first channel portions up-mixed from the first portion of the at least one audio channel comprising the first associated direction parameter indicating the first direction of origin being close to the set direction of origin with respect to up-mixed second channel portions of the multiple channels up-mixed from the second portion of the at least one audio channel comprising the second associated direction parameter indicating the second direction of origin further away from the set direction of origin.

12. The method of claim 11, further comprising:

panning the amplitude of the up-mixed first and second channel portions such that a perceived direction of origin of reconstructed first and second channel portions corresponds to the direction of origin when played back using a predetermined loudspeaker set-up.

13. A method for enhancing a directional perception of an audio signal, the method comprising:

deriving, by a signal generator, at least one audio channel and a first associated direction parameter indicating a first direction of origin of a first portion in a first frequency band of a frame of the at least one audio channel with respect to a recording position, and a second associated direction parameter indicating a second direction of origin of a second portion in a second frequency band of the frame of the at least one audio channel with respect to the recording position,

wherein the first associated direction parameter is different from the second associated direction parameter, wherein the first direction of origin is different from the second direction of origin, and wherein the first frequency band is different from the second frequency band;

selecting, by a selector, a set direction of origin with respect to the recording position to obtain a selected set direction of origin; and

modifying, by a modifier, the first portion in the first frequency band of the frame of the at least one audio channel and the second portion in the second frequency band of the frame of the at least one audio channel for deriving a reconstructed portion in the first frequency band and the second frequency band of the reconstructed audio signal for the frame of the at least one audio channel, wherein the modifying comprises increasing an intensity of the first portion in the first frequency band of the frame of the at least one audio channel, when the first direction parameter associated with the first frequency band of the first portion of the at least one audio channel indicates the first direction of origin close to the selected set direction of origin with respect to the second frequency band of the second portion of the frame of the at least one audio channel for which the second associated direction parameter indicates the second direction of origin further away from the selected set direction of origin,

wherein at least one of the signal generator, the selector and the modifier comprises a hardware implementation.

14. An audio decoder apparatus for reconstructing an audio signal to obtain a reconstructed audio signal, comprising:

an input adapted to receive the audio signal, the audio signal comprising at least one audio channel and a first associated direction parameter indicating a first direction of origin of a first portion in a first frequency band of a frame of the at least one audio channel with respect to a recording position, and a second associated direction parameter indicating a second direction of origin of a second portion in a second frequency band of the frame of the at least one audio channel with respect to the recording position,

wherein the first associated direction parameter is different from the second associated direction parameter, wherein the first direction of origin is different from the second direction of origin, and wherein the first frequency band is different from the second frequency band;

a direction selector adapted to select a set direction of origin with respect to the recording position to obtain a selected set direction of origin; and

an audio portion modifier configured for modifying the first portion in the first frequency band of the frame of the at least one audio channel and the second portion in the second frequency band of the frame of the at least one audio channel for deriving a reconstructed portion in the first frequency band and the second frequency band of the reconstructed audio signal for the frame of the at least one audio channel, wherein the modifying comprises increasing an intensity of the first portion in the first frequency band of the frame of the at least one audio channel, when the first direction parameter associated with the first frequency band of the first portion of the at least one audio channel indicates the first direction of origin close to the selected set direction of origin with respect to the second frequency band of the second portion of the frame of the at least one audio channel for which the second associated direction parameter indicates the second direction of origin further away from the selected set direction of origin,

wherein at least one of the input, the direction selector and the audio portion modifier comprises a hardware implementation.

15. An audio encoder apparatus for enhancing a directional perception of an audio signal, the audio encoder comprising:

a signal generator adapted to derive at least one audio channel and a first associated direction parameter indicating a first direction of origin of a first portion in a first frequency band of a frame of the at least one audio channel with respect to a recording position, and a second associated direction parameter indicating a second direction of origin of a second portion in a second frequency band of the frame of the at least one audio channel with respect to the recording position,

wherein the first associated direction parameter is different from the second associated direction parameter, wherein the first direction of origin is different from the second direction of origin, and wherein the first frequency band is different from the second frequency band;

a direction selector adapted to select a set direction of origin with respect to the recording position to obtain a selected set direction of origin; and

a signal modifier configured for modifying the first portion in the first frequency band of the frame of the at least one audio channel and the second portion in the second frequency band of the frame of the at least one audio channel for deriving a reconstructed portion in the first frequency band and the second frequency band of the reconstructed audio signal for the frame of the at least one audio channel, wherein the modifying comprises increasing an intensity of the first portion in the first frequency band of the frame of the at least one audio channel, when the first direction parameter associated with the first frequency band of the first portion of the at least one audio channel indicates the first direction of origin close to the selected set direction of origin with respect to the second frequency band of the second portion of the frame of the at least one audio channel for which the second associated direction parameter indicates the second direction of origin further away from the selected set direction of origin,

wherein at least one of the signal generator, the direction selector and the signal modifier comprises a hardware implementation.

16. A system for enhancement of a reconstructed audio signal, the system comprising:

an audio encoder adapted to derive an audio signal comprising at least one audio channel and a first associated direction parameter indicating a first direction of origin of a first portion in a first frequency band of a frame of the at least one audio channel with respect to a recording position, and a second associated direction parameter indicating a second direction of origin of a second portion in a second frequency band of the frame of the at least one audio channel with respect to the recording position,

wherein the first associated direction parameter is different from the second associated direction parameter, wherein the first direction of origin is different from the second direction of origin, and wherein the first frequency band is different from the second frequency band;

a direction selector adapted to select a set direction of origin with respect to the recording position to obtain a selected set direction of origin; and

an audio decoder comprising an audio portion modifier configured for modifying the first portion in the first frequency band of the frame of the at least one audio channel and the second portion in the second frequency band of the frame of the at least one audio channel for deriving a reconstructed portion in the first frequency band and the second frequency band of the reconstructed audio signal for the frame of the at least one audio channel, wherein the modifying comprises increasing an intensity of the first portion in the first frequency band of the frame of the at least one audio channel, when the first direction parameter associated with the first frequency band of the first portion of the at least one audio channel indicates the first direction of origin close to the selected set direction of origin with respect to the second frequency band of the second portion of the frame of the at least one audio channel for which the second associated direction parameter indicates the second direction of origin further away from the selected set direction of origin,

wherein at least one of the audio encoder, the direction selector, the audio decoder, and the audio portion modifier comprises a hardware implementation.

17. A non-transitory storage medium having stored thereon a computer program for, when running on a computer, implementing a method for reconstructing an audio signal to obtain a reconstructed audio signal, the method comprising:

receiving the audio signal, the audio signal comprising at least one audio channel and a first associated direction parameter indicating a first direction of origin of a first portion in a first frequency band of a frame of the at least one audio channel with respect to a recording position, and a second associated direction parameter indicating a second direction of origin of a second portion in a second frequency band of the frame of the at least one audio channel with respect to the recording position,

wherein the first associated direction parameter is different from the second associated direction parameter, wherein the first direction of origin is different from the second direction of origin, and wherein the first frequency band is different from the second frequency band;

selecting a set direction of origin with respect to the recording position to obtain a selected set direction of origin; and

modifying the first portion in the first frequency band of the frame of the at least one audio channel and the second portion in the second frequency band of the frame of the at least one audio channel for deriving a reconstructed portion in the first frequency band and the second frequency band of the reconstructed audio signal for the frame of the at least one audio channel, wherein the modifying comprises increasing an intensity of the first portion in the first frequency band of the frame of the at least one audio channel, when the first direction parameter associated with the first frequency band of the first portion of the at least one audio channel indicates the first direction of origin close to the selected set direction of origin with respect to the second frequency band of the second portion of the frame of the at least one audio channel for which the second associated direction parameter indicates the second direction of origin further away from the selected set direction of origin.

18. A non-transitory storage medium having stored thereon a computer program for, when running on a computer, implementing a method for enhancing a directional perception of an audio signal, the method comprising:

deriving at least one audio channel and associated direction parameters indicating a first direction of origin of a first portion in a first frequency band of a frame of the at least one audio channel with respect to a recording position, and a second associated direction parameter indicating a second direction of origin of a second portion in a second frequency band of the frame of the at least one audio channel with respect to the recording position,

wherein the first associated direction parameter is different from the second associated direction parameter, wherein the first direction of origin is different from the second direction of origin, and wherein the first frequency band is different from the second frequency band;

selecting a set direction of origin with respect to the recording position to obtain a selected set direction of origin; and

modifying the first portion in the first frequency band of the frame of the at least one audio channel and the second portion in the second frequency band of the frame of the at least one audio channel for deriving a reconstructed portion in the first frequency band and the second frequency band of the reconstructed audio signal for the frame of the at least one audio channel, wherein the modifying comprises increasing an intensity of the first portion in the first frequency band of the frame of the at least one audio channel, when the first direction parameter associated with the first frequency band of the first portion of the at least one audio channel indicates the first direction of origin close to the selected set direction of origin with respect to the second frequency band of the second portion of the frame of the at least one audio channel for which the second associated direction parameter indicates the second direction of origin further away from the selected set direction of origin.