Struct AuxiliaryBuffers 

pub struct AuxiliaryBuffers<'a, S: Sample = f32> { /* private fields */ }

Auxiliary audio buffers for sidechain and multi-bus processing.

Contains all non-main audio buses. Most plugins don’t need this - they only use the main Buffer.

Type Parameter

S is the sample type, defaulting to f32. Use AuxiliaryBuffers<f64> for 64-bit double precision processing.

Bus Indexing

Auxiliary buses are indexed starting from 0:

• Bus 0: Sidechain (most common aux use case)
• Bus 1+: Additional auxiliary I/O

Real-Time Safety

This struct uses fixed-size stack storage. No heap allocations occur during construction or use.

Example: Sidechain Access

if let Some(sidechain) = aux.sidechain() {
    let key_signal = sidechain.input(0);
    // Use for compression keying, ducking, etc.
}

Implementations

impl<'a, S: Sample> AuxiliaryBuffers<'a, S>

pub fn new( inputs: impl IntoIterator<Item = impl IntoIterator<Item = &'a [S]>>, outputs: impl IntoIterator<Item = impl IntoIterator<Item = &'a mut [S]>>, num_samples: usize, ) -> Self

Create new auxiliary buffers.

This is called by the VST3 wrapper, not by plugin code. Buses/channels beyond the limits are silently ignored.

pub fn empty() -> Self

Create empty auxiliary buffers (no aux buses).

pub fn num_samples(&self) -> usize

Number of samples in this processing block.

pub fn num_input_buses(&self) -> usize

Number of auxiliary input buses.

pub fn num_output_buses(&self) -> usize

Number of auxiliary output buses.

pub fn is_empty(&self) -> bool

Returns true if there are no auxiliary buses.

pub fn sidechain(&self) -> Option<AuxInput<'_, S>>

Get the sidechain input bus (auxiliary input bus 0).

This is the most common aux use case. Returns None if no sidechain is connected.

Example

let key_level = aux.sidechain()
    .map(|sc| sc.rms(0))
    .unwrap_or(0.0);

pub fn input(&self, bus: usize) -> Option<AuxInput<'_, S>>

Get an auxiliary input bus by index.

Returns None if the bus doesn’t exist or has no channels.

pub fn output(&mut self, bus: usize) -> Option<AuxOutput<'_, 'a, S>>

Get a mutable auxiliary output bus by index.

Returns None if the bus doesn’t exist or has no channels.

pub fn iter_inputs(&self) -> impl Iterator<Item = AuxInput<'_, S>> + '_

Iterate over all auxiliary input buses.

pub fn iter_outputs( &mut self, ) -> impl Iterator<Item = AuxOutput<'_, 'a, S>> + '_

Iterate over all auxiliary output buses mutably.