92 lines
2.5 KiB
C++
92 lines
2.5 KiB
C++
#pragma once
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#include "audio_buffer.h"
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#include "midi_event.h"
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#include "voice_allocator.h"
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#include <cstddef>
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#include <cstring>
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#include <vector>
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namespace trnr {
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// a generic midi synth base class with sample accurate event handling.
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// the templated type t_voice must derive from ivoice
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template <typename t_voice, typename t_sample>
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class midi_synth : public voice_allocator<t_voice, t_sample> {
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public:
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std::vector<midi_event> m_event_queue;
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int m_block_size;
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bool m_voices_active;
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midi_synth(size_t num_voices = 1)
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: m_voices_active {false}
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, voice_allocator<t_voice, t_sample>(num_voices)
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{
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}
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void set_samplerate_blocksize(double _samplerate, int _block_size)
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{
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m_block_size = _block_size;
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voice_allocator<t_voice, t_sample>::set_samplerate(_samplerate);
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}
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void process_block(t_sample** _outputs, int _n_frames, std::vector<audio_buffer<t_sample>> _modulators = {})
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{
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// clear outputs
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for (auto i = 0; i < 2; i++) { memset(_outputs[i], 0, _n_frames * sizeof(t_sample)); }
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// sample accurate event handling based on the iPlug2 synth by Oli Larkin
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if (m_voices_active || !m_event_queue.empty()) {
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int block_size = m_block_size;
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int samples_remaining = _n_frames;
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int start_index = 0;
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while (samples_remaining > 0) {
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if (samples_remaining < block_size) block_size = samples_remaining;
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while (!m_event_queue.empty()) {
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midi_event event = m_event_queue.front();
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// we assume the messages are in chronological order. If we find one later than the current block we
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// are done.
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if (event.offset > start_index + block_size) break;
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// send performance messages to the voice allocator
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// message offset is relative to the start of this process_samples() block
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event.offset -= start_index;
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voice_allocator<t_voice, t_sample>::add_event(event);
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m_event_queue.erase(m_event_queue.begin());
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}
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voice_allocator<t_voice, t_sample>::process_samples(_outputs, start_index, block_size, _modulators);
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samples_remaining -= block_size;
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start_index += block_size;
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}
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m_voices_active = voice_allocator<t_voice, t_sample>::voices_active();
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flush_event_queue(_n_frames);
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} else {
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for (int s = 0; s < _n_frames; s++) {
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_outputs[0][s] = 0.;
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_outputs[1][s] = 0.;
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}
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}
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}
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void add_event(midi_event event)
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{
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if (event.type == midi_event_type::note_on) m_voices_active = true;
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m_event_queue.push_back(event);
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}
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void flush_event_queue(int frames)
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{
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for (int i = 0; i < m_event_queue.size(); i++) { m_event_queue.at(i).offset -= frames; }
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}
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};
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} // namespace trnr
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