realtime_pitch_time_processor.hpp File Reference

Realtime pitch shifting and time-scale modification for coherent channel groups, built on SpectralFrameEngine (STFT/WOLA), MultichannelPhaseCoordinator (Laroche-Dolson phase propagation with identity peak locking) and SpectralEnvelopeShifter (formant preservation / shifting). More...

#include <pulp/signal/detail/fractional_synthesis_hop_accumulator.hpp>
#include <pulp/signal/realtime_pitch_time_geometry.hpp>
#include <pulp/signal/freeze_hold.hpp>
#include <pulp/signal/latency_aware_control_smoother.hpp>
#include <pulp/signal/multichannel_phase_coordinator.hpp>
#include <pulp/signal/noise_morpher.hpp>
#include <pulp/signal/sinc_resampler.hpp>
#include <pulp/signal/spectral_envelope_shifter.hpp>
#include <pulp/signal/spectral_frame_engine.hpp>
#include <pulp/signal/stn_decomposer.hpp>
#include <pulp/signal/transient_phase_policy.hpp>
#include <algorithm>
#include <cassert>
#include <cmath>
#include <complex>
#include <cstdint>
#include <limits>
#include <vector>

Go to the source code of this file.

Classes
class	pulp::signal::RealtimePitchTimeProcessorT< SampleType >

Namespaces
namespace	pulp
namespace	pulp::signal

Typedefs
using	pulp::signal::RealtimePitchTimeProcessor = RealtimePitchTimeProcessorT<float>
using	pulp::signal::RealtimePitchTimeProcessor64 = RealtimePitchTimeProcessorT<double>

Detailed Description

Realtime pitch shifting and time-scale modification for coherent channel groups, built on SpectralFrameEngine (STFT/WOLA), MultichannelPhaseCoordinator (Laroche-Dolson phase propagation with identity peak locking) and SpectralEnvelopeShifter (formant preservation / shifting).

Pitch shifting is realized as time-scale modification followed by resampling (Laroche & Dolson, "New Phase-Vocoder Techniques for Pitch-Shifting, Harmonizing and Other Exotic Effects," WASPAA 1999): the synthesis hop tracks pitch_ratio * analysis_hop through a fractional accumulator, and an internal Catmull-Rom reader maps each output sample to its stretched-stream position through the producer's own frame map (input frame position -> synthesized start), so process() emits exactly as many samples as it consumes with a fixed, exactly-reported latency at every ratio — the reader cannot drift against the synthesis hops by construction.

Two modes, chosen at prepare():

• realtime_pitch: equal-length process(); pitch in semitones, duration preserved. Latency = fft_size + analysis_hop, exact and block-size independent.
• time_stretch: pull-style feed()/read_stretched(); time ratio independent of pitch (pitch fixed at 0 in this mode). Output availability is tracked exactly; achieved_time_ratio() reports the hop-quantized ratio actually applied for test assertions.

Geometry is derived from the quality mode and the COLA conditions of the Hann window only (quality: 4096/512 at a 96 ms latency budget; low_latency: 1024/256 at 26.7 ms @ 48 kHz) — constants come from the algorithm's own geometry, not from any reference product.

No allocation or locks after prepare().