pub fn bandwidth_extend(
signal: &[f32],
sample_rate: u32,
target_rate: u32,
) -> Vec<f32>Expand description
Restore high-frequency content lost to compression or low sample rates.
Uses spectral band replication: the spectral envelope from the upper octave of the source signal is transposed into the missing high band, shaped, and mixed back. No ML — pure DSP, zero weights.