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/*
* Copyright (c) 2022, kleines Filmröllchen <filmroellchen@serenityos.org>.
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/Concepts.h>
#include <AK/Types.h>
#include <AK/Vector.h>
namespace Audio {
// Small helper to resample from one playback rate to another
// This isn't really "smart", in that we just insert (or drop) samples.
// Should do better...
template<typename SampleType>
class ResampleHelper {
public:
ResampleHelper(u32 source, u32 target)
: m_source(source)
, m_target(target)
{
VERIFY(source > 0);
VERIFY(target > 0);
}
// To be used as follows:
// while the resampler doesn't need a new sample, read_sample(current) and store the resulting samples.
// as long as the resampler needs a new sample, process_sample(current)
// Stores a new sample
void process_sample(SampleType sample_l, SampleType sample_r)
{
m_last_sample_l = sample_l;
m_last_sample_r = sample_r;
m_current_ratio += m_target;
}
// Assigns the given sample to its correct value and returns false if there is a new sample required
bool read_sample(SampleType& next_l, SampleType& next_r)
{
if (m_current_ratio >= m_source) {
m_current_ratio -= m_source;
next_l = m_last_sample_l;
next_r = m_last_sample_r;
return true;
}
return false;
}
template<ArrayLike<SampleType> Samples>
ErrorOr<Vector<SampleType>> try_resample(Samples&& to_resample)
{
Vector<SampleType> resampled;
TRY(resampled.try_ensure_capacity(to_resample.size() * ceil_div(m_source, m_target)));
for (auto sample : to_resample) {
process_sample(sample, sample);
while (read_sample(sample, sample))
resampled.unchecked_append(sample);
}
return resampled;
}
template<ArrayLike<SampleType> Samples>
Vector<SampleType> resample(Samples&& to_resample)
{
return MUST(try_resample(forward<Samples>(to_resample)));
}
void reset()
{
m_current_ratio = 0;
m_last_sample_l = {};
m_last_sample_r = {};
}
u32 source() const { return m_source; }
u32 target() const { return m_target; }
private:
const u32 m_source;
const u32 m_target;
u32 m_current_ratio { 0 };
SampleType m_last_sample_l {};
SampleType m_last_sample_r {};
};
}
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