Struct AudioMixer 

pub struct AudioMixer {
    pub sample_rate: u32,
    pub channels: u16,
    /* private fields */
}

Multi-track, constant-power-panned stereo mixer.

Combines N mono tracks into a single interleaved stereo f32 output at 48 kHz. Per-track volume and pan adjustments take effect on the next call to mix.

Pan law

For a pan position p ∈ [-1.0, +1.0]:

p_norm = (p + 1.0) * π / 4
l_gain = volume * cos(p_norm)
r_gain = volume * sin(p_norm)

At p = 0 (center): l_gain == r_gain ≈ 0.707 × volume (constant-power law — equal loudness in both ears).

Example

let mut mixer = AudioMixer::new(48_000);
let track = mixer.add_track();

// Background audio-decode thread:
track.push_samples(&mono_pcm_chunk);

// Audio-device output callback:
let stereo = mixer.mix(output_buf.len());
output_buf[..stereo.len()].copy_from_slice(&stereo);

Fields

sample_rate: u32

Output sample rate in Hz.

channels: u16

Number of output channels — always 2 (stereo).

Implementations

impl AudioMixer

pub fn new(sample_rate: u32) -> Self

Create a new mixer with no tracks.

pub fn add_track(&mut self) -> AudioTrackHandle

Add a new mono track and return a cloneable handle.

The track starts with volume = 1.0 and pan = 0.0 (center).

pub fn mix(&mut self, n_samples: usize) -> Vec<f32>

Mix n_samples interleaved stereo f32 values from all tracks.

n_samples is the total number of f32 elements to produce (L + R interleaved). Tracks with insufficient buffered data are zero-padded. The output is clipped to [-1.0, 1.0].