Method for processing data for the estimation of mixing parameters of audio signals, mixing method, devices, and associated computers programs

Patent metadata

Field	Value
Publication number	US-9769565-B2
Application number	US-201615091315-A
Country	US
Kind code	B2
Filing date	Apr 5, 2016
Priority date	Apr 10, 2015
Publication date	Sep 19, 2017
Grant date	Sep 19, 2017

Abstract

A method and apparatus are provided for processing data for estimating mixing parameters of at least one audio spot signal captured by a sound recording device, called a spot microphone, arranged in the vicinity of a source among a plurality of acoustic sources constituting a sound scene, and a primary audio signal captured by an ambisonic sound recording device, arranged to capture said plurality of acoustic sources of the sound scene.

First claim

The invention claimed is:

1. A method comprising the following acts performed by a processing device:
receiving at least one spot audio signal captured by a sound recording device, called a spot microphone, arranged in the vicinity of a source among a plurality of acoustic sources constituting a sound scene, and a primary audio signal captured by an ambisonic sound recording device, called a primary microphone, arranged to capture said plurality of acoustic sources of the sound scene, said primary audio signal being encoded in a format called “ambisonic”, comprising at least one omnidirectional component (W) and three bidirectional components (X, Y, Z) projected along orthogonal axes of a referential of the primary microphone;
processing the received at least one spot audio signal and the primary audio signal by implementing the following acts, for a frame of the primary audio signal and a frame of said at least one spot audio signal, each frame comprising at least one block of N samples:
estimating a delay between the omnidirectional component of the frame of the primary audio signal and the frame of said at least one spot audio signal, from at least one block of N samples of one of the two frames, so-called block of reference (BRef I ), associated with predetermined moment of acquisition (TI), and an observation area (ZObs i ) of the other frame, so-called observation area, including at least one block of N samples and formed in proximity of the moment of acquisition, by maximizing a measurement of similarity between the block of reference and a block of the observation area, so-called block of observation (BObs i ), temporally offset by the delay (τ) in relation to the block of reference;
estimating at least one angular position of the source captured by said spot microphone in the referential of the primary microphone by calculation of ratio between a first scalar material of a block of the at least one spot audio signal associated with the predetermined moment of acquisition and a first bidirectional component of the block of the primary audio signal temporally offset by the estimated delay (τ) and a second scalar material of the same block of said at least one spot audio signal and the block of a second bidirectional component of the primary audio signal temporally offset by the estimated delay (τ); and
performing an act comprising:
transmitting the estimated delay and the estimated at least one angular position of the captured source to a mixing device; or
modifying the at least one spot audio signal according to the estimated delay and the estimated at least one angular position of the captured source to produce at least one modified spot audio signal.

2. The method according to claim 1 , wherein, the block of reference (BRef i ) being chosen in the at least one spot audio signal, the stage of estimating the delay comprises a calculation of a similarity measurement at least for the block of reference (BRef i ), from a normalized cross-correlation function (C i ) which is expressed in the following way:

C
i

⁡

(
τ
)

=

〈

a
n

|
W

〉

-
τ

||

a
n

||

·

||
W
⁢

||

-
τ

with W(t) omnidirectional component of the ambisonic signal, a n (t) the at least one spot audio signal, x|y −τ = 0 x|y −τ , the scalar product between the two finite support signals temporally offset by −τ, in the observation area is associated with the block of reference (BRef i ), and ∥x∥ τ =√{square root over ( τ x|x τ )}, the norm of a discrete finite support signal;
and in that the delay (τ) is estimated from the maximum value of the similarity measurement calculated:
{tilde over (τ)}=Argmax τ C i (τ).

3. The method according to claim 2 wherein the act of estimating the delay also comprises a temporal smoothing of the similarity measurement calculated for the current block of reference (BRef i ) taking into account the similarity measurement calculated for at least one previous block of reference (BRef I−1 ).

4. The method according to claim 2 , comprising an act of calculating a local index of reliability associated with a mixed parameter estimated for the block of reference by analysis of the normalized cross-correlation function calculated between the omnidirectional component of the primary audio signal and the at least one spot audio signal and energy from the signal of the block of reference.

5. The method according to claim 4 , wherein the local index of reliability associated with the estimated delay parameter is based on a ratio between the values of the primary and secondary peaks, the cross-correlation function multiplied by the energy of the block of reference (BRef i ).

6. The method according to claim 4 , wherein the local index of reliability associated with the parameter of angular position is based on the maximum value of the cross-correlation associated with the delay ({tilde over (τ)} i ) estimated and on a ratio between the energy of the block of reference (BRef i ) and that of the block of observation (BObs i ).

7. The method according to claim 1 , wherein the estimation of the at least one angular position of the captured source comprises an estimation of an azimuth angle ({tilde over (θ)} n ) from a ratio between the scalar material of the signal of the block of reference associated with the predetermined moment of acquisition with the block component Y of the primary audio signal offset by the estimated delay and the scalar product of the signal of the block of reference associated with the predetermined moment of acquisition with the block component X of the primary audio signal offset by the estimated delay.

8. The method according to claim 7 , wherein the azimuth angle is estimated from the following equation:
{tilde over (θ)} n=a tan 2( a n |Y −τ , a n |X −τ ).

9. The method according to claim 1 , wherein the estimation of the at least one angular position of the captured source comprises an estimation of an elevation angle from a ratio between the scalar product of the block of reference of the at least one spot audio signal associated with the moment of acquisition with the block component Z of the primary audio signal offset by the estimated delay (τ) and the scalar material of the block of the at least one spot audio signal associated with the moment of acquisition with the block of omnidirectional component of the primary signal offset by the estimated delay (τ).

10. The method according to claim 9 , wherein the an

Assignees

• B<>Com
• Orange

Inventors

• Fedosov Andrey
• Daniel Jerome
• Pallone Gregory

Classifications

• H04S3/008

  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

• H04R2430/20

  Processing of the output signals of the acoustic transducers of an array for obtaining a desired directivity characteristic (H04R2203/12 takes precedence) · CPC title

• H04R29/005

  Microphone arrays · CPC title

• H04S2400/15

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

• G06F17/15

  Correlation function computation {including computation of convolution operations (arithmetic circuits for sum of products per se, e.g. multiply-accumulators G06F7/5443; digital filters, e.g. FIR, IIR, adaptive filters H03H17/00)} · CPC title