EP-4740206-A1 - AN APPARATUS AND METHOD FOR SPATIAL RENDERING OF REVERBERATION

Abstract

A method for producing reverberation for rendering at least one audio signal, the method comprising: obtaining the at least one audio signal of an audio scene; obtaining at least one reverberation delay line parameter for the audio scene; configuring a digital reverberator with a number of delay lines based on the at least one reverberation delay line parameter; and generating at least one reverberated audio signal using the digital reverberator output and the at least one audio signal to achieve late reverberation during rendering the at least one audio signal within the audio scene, where the late reverberation is controlled by the at least one reverberation delay line parameter, such that the delay line parameter controls density of the at least one reverberated audio signal.

Inventors

• ERONEN, ANTTI JOHANNES
• MATE, SUJEET SHYAMSUNDAR

Assignees

• Nokia Technologies Oy

Dates

Publication Date

20260513

Application Date

20240620

Claims (20)

1. CLAIMS: 1. A method for producing reverberation for rendering at least one audio signal, the method comprising: obtaining the at least one audio signal of an audio scene; obtaining at least one reverberation delay line parameter for the audio scene; configuring a digital reverberator with a number of delay lines based on the at least one reverberation delay line parameter; and generating at least one reverberated audio signal using the digital reverberator output and the at least one audio signal to achieve late reverberation during rendering the at least one audio signal within the audio scene, where the late reverberation is controlled by the at least one reverberation delay line parameter, such that the delay line parameter controls density of the at least one reverberated audio signal.
2. 2. The method as claimed in claim 1, such that the delay line parameter furthermore controls a density or diffuseness of the at least one reverberated audio signal.
3. 3. The method as claimed in claim 1, wherein obtaining at least one reverberation delay line parameter comprises: obtaining an encoded number of delay line loops; and decoding the encoded number of delay line loops to provide the number of delay lines.
4. 4. The method as claimed in claim 3, wherein the encoded number of delay line loops is a Huffman encoded representation of the number.
5. 5. The method as claimed in any of claims 1 to 4, wherein obtaining at least one reverberation delay line parameter comprises: obtaining a diffusion and/or density parameter; and determining the number of delay lines based on the obtained diffusion and/or density parameter.
6. 6. The method as claimed in claim 5, wherein determining the number of delay lines based on the obtained diffusion and/or density parameter comprises using a look up table to obtain the number of delay lines from the obtained diffusion or density parameter.
7. 7. The method as claimed in any of claims 1 to 6, wherein obtaining at least one reverberation delay line parameter comprises: determining a processing or memory capacity associated with apparatus implementing the digital reverberator; and determining the number of delay lines based on the processing or memory capacity associated with apparatus implementing the digital reverberator.
8. 8. The method as claimed in any of claims 1 to 7, further comprising: obtaining at least one reverberation parameter, wherein the at least one reverberation parameter comprises at least one of: a delay line length parameter; a delay line length attenuation filter parameter; a reverberation ratio control filter parameter; a pre-delay line delay parameter; a feedback matrix coefficient parameter; and a directional configuration parameter.
9. 9. The method as claimed in claim 8, further comprising configuring a digital reverberator based on the number of delay lines and the at least one reverberation parameter.
10. 10. The method as claimed in any of claims 1 to 9, wherein configuring a digital reverberator with a number of delay lines based on the at least one reverberation delay line parameter comprises configuring a digital reverberator with a set of the number of delay lines comprising positive feedback gain and the remainder of the number of delay lines comprising negative feedback gain, wherein the set is defined based on the at least one reverberation delay line parameter.
11. 11. The method as claimed in claim 10, wherein the at least one reverberation delay line parameter comprises one or both of: a first feedback delay line parameter indicating indices of positive feedback delay lines; and a second feedback delay line parameter indicating indices of negative feedback delay lines.
12. 12. The method as claimed in any of claims 1 to 11, wherein configuring a digital reverberator with a number of delay lines based on the at least one reverberation delay line parameter comprises: configuring a first digital reverberator with a number of delay lines based on the at least one reverberation delay line parameter; and configuring a second digital reverberator with a second, and smaller, number of delay lines, wherein the second digital reverberator output channel positions are mapped to the output positions of the first digital reverberator.
13. 13. A method for assisting producing of reverberation for rendering at least one audio signal for an audio scene, the method comprising: obtaining a diffusion and/or density parameter; determining a number of delay lines based on the obtained diffusion and/or density parameter; and encoding the number of delay lines as at least one reverberation delay line parameter for configuring a digital reverberator with a number of delay lines based on the at least one reverberation delay line parameter.
14. 14. The method as claimed in claim 13, wherein determining the number of delay lines based on the obtained diffusion and/or density parameter comprises using a look up table to obtain the number of delay lines from the obtained diffusion or density parameter.
15. 15. The method as claimed in any of claims 13 or 14, wherein encoding the defined number of delay lines as at least one reverberation delay line parameter comprises Huffman encoding the number of delay lines.
16. 16. An apparatus comprising means for performing the method of any of claims 1 to 15.
17. 17. A computer program comprising instructions, which, when executed by an apparatus, cause the apparatus to perform the method of any of claims 1 to 15.
18. 18. An apparatus for producing reverberation for rendering at least one audio signal, the apparatus comprising means configured to: obtain the at least one audio signal of an audio scene; obtain at least one reverberation delay line parameter for the audio scene; configure a digital reverberator with a number of delay lines based on the at least one reverberation delay line parameter; and generate at least one reverberated audio signal using the digital reverberator output and the at least one audio signal to achieve late reverberation during rendering the at least one audio signal within the audio scene, where the late reverberation is controlled by the at least one reverberation delay line parameter, such that the delay line parameter controls density of the at least one reverberated audio signal.
19. 19. An apparatus for assisting producing of reverberation for rendering at least one audio signal for an audio scene, the apparatus comprising means configured to: obtain a diffusion and/or density parameter; determine a number of delay lines based on the obtained diffusion and/or density parameter; and encode the number of delay lines as at least one reverberation delay line parameter for configuring a digital reverberator with a number of delay lines based on the at least one reverberation delay line parameter.
20. 20. An apparatus for producing reverberation for rendering at least one audio signal, the apparatus comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the system at least to: obtain the at least one audio signal of an audio scene; obtain at least one reverberation delay line parameter for the audio scene; configuring a digital reverberator with a number of delay lines based on the at least one reverberation delay line parameter; and generating at least one reverberated audio signal using the digital reverberator output and the at least one audio signal to achieve late reverberation during rendering the at least one audio signal within the audio scene, where the late reverberation is controlled by the at least one reverberation delay line parameter, such that the delay line parameter controls density of the at least one reverberated audio signal.

Description

AN APPARATUS AND METHOD FOR SPATIAL RENDERING OF REVERBERATION Field The present application relates to apparatus and methods for spatial rendering of reverberation, and not exclusively configuring a number of delay line loops for reverberation for reverberation in augmented reality and/or virtual reality apparatus. Background Reverberation refers to the persistence of sound in a space after the actual sound source has stopped. Different spaces are characterized by different reverberation characteristics. For conveying spatial impression of an environment, reproducing reverberation perceptually accurately is important. Room acoustics are often modelled with individually synthesized early reflection portion and a statistical model for the diffuse late reverberation. Figure 1 depicts an example of a synthesized room impulse response where the direct sound 101 is followed by discrete early reflections 103 (or reflection echoes) which have a direction of arrival (DOA) and diffuse late reverberation 105 which can be synthesized without any specific direction of arrival. The delay ^1(^) 102 in Figure 1 can be seen to denote the direct sound arrival delay from the source to the listener and the delay ^2(^) 104 can denote the delay from the source to the listener for one of the early reflections (in this case the first arriving reflection). One method of reproducing reverberation is to utilize a set of ^ loudspeakers (or virtual loudspeakers reproduced binaurally using a set of head- related transfer functions (HRTF)). The loudspeakers are positioned around the listener somewhat evenly. Mutually incoherent reverberant signals are reproduced from these loudspeakers, producing a perception of surrounding diffuse reverberation. The reverberation produced by the different loudspeakers has to be mutually incoherent. In a simple case the reverberations can be produced using the different channels of the same reverberator, where the output channels are uncorrelated but otherwise share the same acoustic characteristics such as reverberation time and level (specifically, the diffuse-to-direct ratio or reverberant-to-direct ratio or diffuse- to-total ratio or diffuse-to-source ratio or any other suitable parameter for representing reverberation energy or level). Such uncorrelated outputs sharing the same acoustic characteristics can be obtained, for example, from the output taps of a feedback delay network (FDN) reverberator with suitable tuning of the delay line lengths and mixing matrix, or from a reverberator based on using decaying uncorrelated noise sequences by using a different uncorrelated noise sequence in each channel. In this case, the different reverberant signals effectively have the same features, and the reverberation is typically perceived to be similar in all directions. There is provided according to a first aspect a method for rendering at least one audio signal, the method comprising: obtaining the at least one audio signal of an audio scene; obtaining at least one reverberation delay line parameter for the audio scene; configuring a digital reverberator with a number of delay lines based on the at least one reverberation delay line parameter; and generating at least one reverberated audio signal using the digital reverberator output and the at least one audio signal to achieve late reverberation during rendering the at least one audio signal within the audio scene, where the late reverberation is controlled by the at least one reverberation delay line parameter, such that the delay line parameter controls density of the at least one reverberated audio signal. The delay line parameter may furthermore control a density or diffuseness of the at least one reverberated audio signal. Obtaining at least one reverberation delay line parameter may comprise: obtaining an encoded number of delay line loops; and decoding the encoded number of delay line loops to provide the number of delay lines. The encoded number of delay line loops may be a Huffman encoded representation of the number. Obtaining at least one reverberation delay line parameter may comprise: obtaining a diffusion and/or density parameter; determining the number of delay lines based on the obtained diffusion and/or density parameter. Determining the number of delay lines based on the obtained diffusion and/or density parameter may comprise using a look up table to obtain the number of delay lines from the obtained diffusion or density parameter. Obtaining at least one reverberation delay line parameter may comprise: determining a processing or memory capacity associated with apparatus implementing the digital reverberator; determining the number of delay lines based on the processing or memory capacity associated with apparatus implementing the digital reverberator. The method may further comprise: obtaining at least one reverberation parameter, wherein the at least one reverberation parameter comprises at least one of: a delay line length p