Sound Spectrum
Description
This node spectrally analyse the input sound and return the spectral
intensities. The node have multiple modes of operations. All mode of operations
have a number of common inputs and options that we shall introduce in the
following sections.
- Sound - The input sound.
- Frame - The input frame to analyse the sound at.
- Attack - The Attack Time, a value that defines how fast the sound
intensity increases. A low value means the sound intensity will rapidly
increase, while a high value means the sound intensity will slowly and
gradually increase. This value only have an effect if the Smoothing Samples
in the Advancted Node Settings is not zero.
- Release - The Release Time, a value that defines how fast the sound
intensity decrease. A low value means the sound intensity will rapidly
decrease, while a high value means the sound intensity will slowly and
gradually decrease. This value only have an effect if the Smoothing Samples
in the Advancted Node Settings is not zero.
- Amplitude - The maximum value the sound intensity can reach.
- Scene - The target scene. This only affects the frame rate of the
animation.
Outputs
- Spectrum - The output spectrum intensities.
Advanced Node Settings
- Reduction Function - To compute the intensity of the sound at a
particular frequency, a range of neighbouring frequencies are sampled and
are reduced to a single value through a reduction function. The possible
reduction functions are as follows.
- Max - The maximum of the frequencies is used.
- Mean - The average of the frequencies is used.
- Smoothing Samples - The number of samples used to compute the
intensities. Multiple samples are needed to achieve attack and release times.
A high values results in a more accurate and smoother result but takes more
time to compute.
- Kaiser Beta - Beta parameter of the Kasier window function. High values
corresponds to higher main-lob leaking and lower side-lobe leaking. If you
are not sure what that means, leave the value at 6.
- Minimum Duration - The minimum duration of the sound used to compute the
spectrum. Higher values corresponds to higher spectral resolution but will
have overlapping spectrum.
Types
Full
In this mode of operation, the full spectral data is returned.
Single
In this mode of operation, the spectral data in the input range are reduced to
a single value and returned.
- Low - The lowest sound frequency to be considered. A value of zero means
the lowest possible frequency while a value of one means the highest possible
frequency.
- High - The highest sound frequency to be considered. A value of zero
means the lowest possible frequency while a value of one means the highest
possible frequency.
Custom
In this mode of operation, the spectral data between each two consecutive pins
are reduced and returned.
- Pins - A list of floats between zero and one. Each two consecutive pins
will define the frequency range of one output frequency bin. So the number of
frequency bins will be equal to the number of pins minus one. A pin value of
zero means the lowest possible frequency while a value of one means the
highest possible frequency.
Exponential
In this mode of operation, the spectral data is partitioned into a number of
frequency bins that are exponentially distributed, then each bin data is
reduced into a single value and returned.
- Count - The number of frequency bins to compute.
- Exponential Rate - The rate of the exponential distribution. Higher
values corresponds to more bins in the low frequency region. But be careful
not to set this to a very high value or else most bins will have the same
value.