AudioResampler.h

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/*
 * AudioResampler.h
 *
 * Copyright (c) 2025 saker <sakertooth@gmail.com>
 *
 * This file is part of LMMS - https://lmms.io
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public
 * License along with this program (see COPYING); if not, write to the
 * Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301 USA.
 *
 */
 
#ifndef LMMS_AUDIO_RESAMPLER_H
#define LMMS_AUDIO_RESAMPLER_H
 
#include <memory>
#include "AudioBufferView.h"
#include "lmms_export.h"
 
namespace lmms {

class LMMS_EXPORT AudioResampler
{
public:
        enum class Mode
        {
                ZOH,             
                Linear,          
                SincFastest, 
                SincMedium,      
                SincBest         
        };

        struct Result
        {
                f_cnt_t inputFramesUsed;           
                f_cnt_t outputFramesGenerated; 
        };

        AudioResampler(Mode mode, ch_cnt_t channels = 2);

        [[nodiscard]] auto process(InterleavedBufferView<const float> input, InterleavedBufferView<float> output) -> Result;

        void reset();

        void setRatio(double ratio) { m_ratio = ratio; }

        void setRatio(sample_rate_t input, sample_rate_t output) { m_ratio = static_cast<double>(output) / input; }

        auto ratio() const -> double { return m_ratio; }

        auto channels() const -> ch_cnt_t { return m_channels; }

        auto mode() const -> Mode { return m_mode; }
 
private:
        struct LMMS_EXPORT StateDeleter { void operator()(void* state); };
        std::unique_ptr<void, StateDeleter> m_state;
        Mode m_mode;
        ch_cnt_t m_channels = 0;
        double m_ratio = 1.0;
        int m_error = 0;
};
 
} // namespace lmms
 
#endif // LMMS_AUDIO_RESAMPLER_H