---
title: Multichannel biquadratic filters
framework: accelerate
role: collectionGroup
role_heading: API Collection
path: accelerate/multichannel-biquadratic-filters
---

# Multichannel biquadratic filters

Filter a multichannel signal with a cascade of biquadratic sections.

## Overview

Overview The vDSP library implements biquadratic filtering as a cascade of individual infinite impulse response (IIR) filters called sections. Each section has its own set of feedback and feedforward coefficients, and implements a direct-form 2 filter. When the biquadratic filter function executes, the sections execute in sequence. Each section processes the entire input signal and passes its output to the next section for further processing. note: The vDSP biquadratic filters work in place. That is, the source and destination pointers may point to the same memory. note: Although you can use vDSP_biquadm to process a single channel of data, it’s optimized for processing multiple channels of data independently. When processing only a single channel, the single-channel API vDSP_biquad may provide better performance and energy efficiency. When processing a single channel in isolation, it’s best practice to use vDSP_biquad whenever possible.

## Topics

### Equalizing audio with biquadratic filters

- [Equalizing audio with discrete cosine transforms (DCTs)](accelerate/equalizing-audio-with-discrete-cosine-transforms-dcts.md)

### Creating a multichannel biquadratic filter setup

- [vDSP_biquadm_Setup](accelerate/vdsp_biquadm_setup.md)
- [vDSP_biquadm_SetupD](accelerate/vdsp_biquadm_setupd.md)

## See Also

### Vector filtering

- [Biquadratic IIR filters](accelerate/biquadratic-iir-filters.md)
- [Single-channel biquadratic filters](accelerate/single-channel-biquadratic-filters.md)
- [Finite impulse response filters](accelerate/finite-impulse-response-filters.md)
- [Recursive filters](accelerate/recursive-filters.md)