HoaOrder
Extension
ExtensionDescription
Higher Order Ambisonic (HOA) component indexing, coefficients and performance, by order.
Class Methods
.new
Create a new instance.
Arguments:
| order |
Ambisonic order. Def: |
Instance Methods
.order
Return higher order ambisonic order.
(ℓ, m) & HOA indices
.lm
Return an array of Associated Legendre degrees (ℓ) and indices (m).
.l
Return an array of Associated Legendre degrees (ℓ).
.m
Return an array of Associated Legendre indices (m).
.indices
Return Higher Order Ambisonic (HOA) indices.
Arguments:
| ordering |
Component ordering scheme:
| ||||||||||
| subset |
|
Coefficients
.size
Return number of ambisonic components.
.sph
Return N3D normalized angular encoding coefficients.
Arguments:
| theta |
Azimuth, in radians. |
| phi |
Elevation, in radians. |
.normalisation
Return component normalisation coefficients.
Arguments:
| scheme |
Component normalisation schemes:
|
.reflection
Return component reflection coefficients.
Arguments:
| mirror |
|
Radial & NFE
.radiusAtFreq
Return the effective decoding radius, in meters.
Arguments:
| freq |
Frequency, in Hz. |
| speedOfSound |
Speed of sound, in meters per second. Def: |
.freqAtRadius
Return the effective decoding frequency, in Hz.
Arguments:
| radius |
Radius, in meters. Def: |
| speedOfSound |
Speed of sound, in meters per second. Def: |
.proxWeights
Return complex near-field effect proximity radial filtering coefficients, collected by Associated Legendre degree (ℓ).
Arguments:
| freq |
Frequency, in Hz. |
| radius |
Radius, in meters. Def: |
| speedOfSound |
Speed of sound, in meters per second. Def: |
Discussion:
These complex weights represent the magnitude and phase change of each degree when encoding an otherwise far-field source at a distance of radius.
See further discussion on The Near-Field Effect (NFE).
.distWeights
Return complex near-field effect distance radial filtering coefficients, collected by Associated Legendre degree (ℓ).
Arguments:
| freq |
Frequency, in Hz. |
| radius |
Radius, in meters. Def: |
| speedOfSound |
Speed of sound, in meters per second. Def: |
Discussion:
These complex weights are the reciprocal of -proxWeights.
See further discussion on The Near-Field Effect (NFE).
.ctrlWeights
Return complex near-field effect control radial filtering coefficients, collected by Associated Legendre degree (ℓ).
Arguments:
| freq |
Frequency, in Hz. |
| encRadius |
Encoding radius, in meters. Def: |
| decRadius |
Decoding radius, in meters. Def: |
| speedOfSound |
Speed of sound, in meters per second. Def: |
Discussion:
These complex weights represent a ratio of the -proxWeights of the encoding radius to the decoding radius, i.e. proxWeights(encRadius) / proxWeights(decRadius).
See further discussion on The Near-Field Effect (NFE).
.foclWeights
Return real near-field effect focalisation radial filtering coefficients, collected by Associated Legendre degree (ℓ).
Arguments:
| freq |
Frequency, in Hz. | ||||||||
| radius |
Radius, in meters. Def: | ||||||||
| window |
Angular weighting window.
| ||||||||
| speedOfSound |
Speed of sound, in meters per second. Def: |
Beaming & Decoder matching
Three standard beam shapes are offered:
| keyword | beam shape | localisation vector | virtual microphone |
\basic | strict soundfield | maximum velocity rV | Hyper-cardioid |
\energy | energy optimised | maximum energy rE | Super-cardioid |
\controlled | controlled opposites | minimum diametric energy | Cardioid |
.beamWeights
Return beamforming coefficients, collected by Associated Legendre degree (ℓ).
Arguments:
| beamShape |
Keyword argument for beam shape. See above. |
| dim |
The number of dimensions: 2D or 3D. |
.matchWeight
Return matching weight for an ambisonic decoder.
Arguments:
| beamShape |
Keyword argument for beam shape. See above. | ||||||
| dim |
The number of dimensions: 2D or 3D. | ||||||
| match |
Matching criteria:
| ||||||
| numChans |
Number of loudspeakers. NOTE: Must be set when choosing match: \energy. |
Decoder performance
.spreadE
Return the half angle of the maximum average energy spread for an ambisonic decoder.
Arguments:
| beamShape |
Keyword argument for beam shape. See above. |
| dim |
The number of dimensions: 2D or 3D. |
Returns:
An IdentityDictionary of values:
\cos | roll-off to ~-3dB, in radians |
\hvc | roll-off to ~-6dB, in radians |
.meanE
Return reduced energy for an ambisonic decoder.
Arguments:
| beamShape |
Keyword argument for beam shape. See above. |
| dim |
The number of dimensions: 2D or 3D. |
.rV
Return maximum average magnitude of the velocity localisation vector (rV) for an ambisonic decoder.
Arguments:
| beamShape |
Keyword argument for beam shape. See above. |
| dim |
The number of dimensions: 2D or 3D. |
.rE
Return maximum average magnitude of the energy localisation vector (rE) for an ambisonic decoder.
Arguments:
| beamShape |
Keyword argument for beam shape. See above. |
| dim |
The number of dimensions: 2D or 3D. |
Examples
TBD