The CoefficientBiquad audio object accepts biquad filter coefficients via its tuning interface and then filters signals accordingly. This audio object also adjusts the input audio buffers based on the bi-quadratic filter coefficients provided into it via tuning and stores the resulting audio in the output buffers.
Use Case: This object can be deployed whenever a user wants to filter a signal based on user specified coefficients.
CoefficientBiquad Properties
Below table describes about the CoefficientBiquad audio object properties and functionality.
| Properties | Description |
| # of Channels | The object has a configurable number of channels. The number of audio inputs is always equal to the number of audio outputs.
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| Number of biquads | The number of elements generally describes the number of filters requested by the user. This value is configurable between 1 and a 100 and is by default set to 1. |
| Display Name | Display the name of the Adder audio object in signal flow design. It can be changed based on the intended usage of the object. |
Mode
There are no mode available for CoefficientBiquad audio object.
Additional Parameters
| Parameters | Description | |
| Biquad Topology | Allows to choose the filter topology at design time.
By default, it is configured for DFII. |
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| Coefficient Type | Allows to configurable object variable that indicates whether the filter coefficients are shared across all channels or not.
In this layout, the filter coefficients are unique per channel. The number of filters selected above would apply per channel in this layout. If the number of filters above is selected to be two, then two unique biquad sets of coefficients will be applied across each channel.
This layout will share a set of filter coefficients across all channels. If the number of filters above is selected to be two, then the same two biquad sets of coefficients will be applied across all channels. By default, it is configured for Coefficient. |
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Tuning Parameters
This object does not support state and control interfaces; it only supports a tuning interface.
The five values below represent filter coefficients per biquad. Coefficient Layout exposes five values per biquad per channel, whereas Coefficient One Layout exposes one set of coefficients per biquad, and these are shared across all channels.
| Parameter | Description | Type | Unit | Range | Default Value | Memory Offset |
| b0 | Biquad coefficient | float | None | 1 | f * 5 * 4 + 0 | |
| b1 | Biquad coefficient | float | None | 0 | f * 5 * 4 + 4 | |
| b2 | Biquad coefficient | float | None | 0 | f * 5 * 4 + 8 | |
| – a2 | Biquad coefficient | float | None | 0 | f * 5 * 4 + 12 | |
| – a2 | Biquad coefficient | float | None | 0 | f * 5 * 4 + 16 |
b are numerator coefficients and a is denominator. The coefficients are expected to be normalized (*1/a0). And a1 and a2 are expected to be negated before being passed in.
Control Interface
There are no control parameters available for CoefficientBiquad audio object.