2x half-band upsampler. More...

#include <halfband_iir.hpp>

Public Member Functions
	HalfBandUpsampler2xT () noexcept
	HalfBandUpsampler2xT (std::span< const SampleType > coeffs_a, std::span< const SampleType > coeffs_b) noexcept
std::size_t	sections_a () const noexcept
	Number of allpass sections in path A.
std::size_t	sections_b () const noexcept
	Number of allpass sections in path B.
bool	configured () const noexcept
void	reset () noexcept
void	process (SampleType x, SampleType &out_lo, SampleType &out_hi) noexcept
	Produce two output samples for one input sample.
void	process_block (std::span< const SampleType > input, std::span< SampleType > output) noexcept
	Block helper.

Detailed Description

template<typename SampleType = float>
class pulp::signal::HalfBandUpsampler2xT< SampleType >

2x half-band upsampler.

Each call to process(x, out_lo, out_hi) consumes one input sample and produces two output samples at twice the rate. The two polyphase outputs are interleaved as (out_lo, out_hi) — out_lo is time-aligned with x (after the filter's group delay), out_hi is the new sample inserted between successive inputs. Each path is individually allpass; the half-band response emerges when the two outputs are interleaved into a single 2x-rate stream — the path phase difference is 0 in the passband (samples reinforce) and pi in the stopband (samples cancel).

A thin wrapper over HalfBandIirStageT, so silence decays to exact zero (see that class). Custom coefficients must give path A the same number of sections as path B or one more, at most eight each; any other shape leaves the upsampler silent and configured() false.

RT contract: no member allocates, including the constructors.