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-rw-r--r--Userland/Libraries/LibDSP/CMakeLists.txt1
-rw-r--r--Userland/Libraries/LibDSP/Envelope.h3
-rw-r--r--Userland/Libraries/LibDSP/Synthesizers.cpp146
-rw-r--r--Userland/Libraries/LibDSP/Synthesizers.h72
4 files changed, 221 insertions, 1 deletions
diff --git a/Userland/Libraries/LibDSP/CMakeLists.txt b/Userland/Libraries/LibDSP/CMakeLists.txt
index baa422c63d..a5de6f120e 100644
--- a/Userland/Libraries/LibDSP/CMakeLists.txt
+++ b/Userland/Libraries/LibDSP/CMakeLists.txt
@@ -2,6 +2,7 @@ set(SOURCES
Clip.cpp
Track.cpp
Effects.cpp
+ Synthesizers.cpp
)
serenity_lib(LibDSP dsp)
diff --git a/Userland/Libraries/LibDSP/Envelope.h b/Userland/Libraries/LibDSP/Envelope.h
index a47543b008..85a2716b59 100644
--- a/Userland/Libraries/LibDSP/Envelope.h
+++ b/Userland/Libraries/LibDSP/Envelope.h
@@ -10,7 +10,8 @@
namespace LibDSP {
-enum class EnvelopeState : u8 {
+// For now, this cannot be optimal as clang doesn't know underlying type specifications.
+enum EnvelopeState {
Off,
Attack,
Decay,
diff --git a/Userland/Libraries/LibDSP/Synthesizers.cpp b/Userland/Libraries/LibDSP/Synthesizers.cpp
new file mode 100644
index 0000000000..98e97402a1
--- /dev/null
+++ b/Userland/Libraries/LibDSP/Synthesizers.cpp
@@ -0,0 +1,146 @@
+/*
+ * Copyright (c) 2021, kleines Filmröllchen <malu.bertsch@gmail.com>.
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <AK/HashMap.h>
+#include <AK/Math.h>
+#include <AK/Random.h>
+#include <LibDSP/Envelope.h>
+#include <LibDSP/Processor.h>
+#include <LibDSP/Synthesizers.h>
+#include <math.h>
+
+namespace LibDSP::Synthesizers {
+
+Classic::Classic(NonnullRefPtr<Transport> transport)
+ : LibDSP::SynthesizerProcessor(transport)
+ , m_waveform("Waveform"sv, Waveform::Saw)
+ , m_attack("Attack"sv, 0, 2000, 5)
+ , m_decay("Decay"sv, 0, 20'000, 80)
+ , m_sustain("Sustain"sv, 0, 1, 0.725)
+ , m_release("Release", 0, 6'000, 120)
+{
+ m_parameters.append(m_waveform);
+ m_parameters.append(m_attack);
+ m_parameters.append(m_decay);
+ m_parameters.append(m_sustain);
+ m_parameters.append(m_release);
+}
+
+Signal Classic::process_impl(Signal const& input_signal)
+{
+ auto& in = input_signal.get<RollNotes>();
+
+ Sample out;
+
+ SinglyLinkedList<PitchedEnvelope> playing_envelopes;
+
+ // "Press" the necessary notes in the internal representation,
+ // and "release" all of the others
+ for (u8 i = 0; i < note_count; ++i) {
+ if (auto maybe_note = in.get(i); maybe_note.has_value())
+ m_playing_notes.set(i, maybe_note.value());
+
+ if (m_playing_notes.contains(i)) {
+ Envelope note_envelope = m_playing_notes.get(i)->to_envelope(m_transport->time(), m_attack * m_transport->ms_sample_rate(), m_decay * m_transport->ms_sample_rate(), m_release * m_transport->ms_sample_rate());
+ if (!note_envelope.is_active()) {
+ m_playing_notes.remove(i);
+ continue;
+ }
+
+ playing_envelopes.append(PitchedEnvelope { note_envelope, i });
+ }
+ }
+
+ for (auto envelope : playing_envelopes) {
+ double volume = volume_from_envelope(envelope);
+ double wave = wave_position(envelope.note);
+ out += volume * wave;
+ }
+
+ return out;
+}
+
+double Classic::volume_from_envelope(Envelope envelope)
+{
+ switch (static_cast<EnvelopeState>(envelope)) {
+ case EnvelopeState::Off:
+ return 0;
+ case EnvelopeState::Attack:
+ return envelope.attack();
+ case EnvelopeState::Decay:
+ return (1. - envelope.decay()) * m_sustain + m_sustain;
+ case EnvelopeState::Sustain:
+ return m_sustain;
+ case EnvelopeState::Release:
+ return (1. - envelope.release()) * m_sustain;
+ }
+ VERIFY_NOT_REACHED();
+}
+
+double Classic::wave_position(u8 note)
+{
+ switch (m_waveform) {
+ case Sine:
+ return sin_position(note);
+ case Triangle:
+ return triangle_position(note);
+ case Square:
+ return square_position(note);
+ case Saw:
+ return saw_position(note);
+ case Noise:
+ return noise_position(note);
+ }
+ VERIFY_NOT_REACHED();
+}
+
+double Classic::samples_per_cycle(u8 note)
+{
+ return m_transport->sample_rate() / note_frequencies[note];
+}
+
+double Classic::sin_position(u8 note)
+{
+ double spc = samples_per_cycle(note);
+ double cycle_pos = m_transport->time() / spc;
+ return AK::sin(cycle_pos * 2 * AK::Pi<double>);
+}
+
+// Absolute value of the saw wave "flips" the negative portion into the positive, creating a ramp up and down.
+double Classic::triangle_position(u8 note)
+{
+ double saw = saw_position(note);
+ return AK::fabs(saw) * 2 - 1;
+}
+
+// The first half of the cycle period is 1, the other half -1.
+double Classic::square_position(u8 note)
+{
+ double spc = samples_per_cycle(note);
+ double progress = AK::fmod(static_cast<double>(m_transport->time()), spc) / spc;
+ return progress >= 0.5 ? -1 : 1;
+}
+
+// Modulus creates inverse saw, which we need to flip and scale.
+double Classic::saw_position(u8 note)
+{
+ double spc = samples_per_cycle(note);
+ double unscaled = spc - AK::fmod(static_cast<double>(m_transport->time()), spc);
+ return unscaled / (samples_per_cycle(note) / 2.) - 1;
+}
+
+// We resample the noise twenty times per cycle.
+double Classic::noise_position(u8 note)
+{
+ double spc = samples_per_cycle(note);
+ u32 getrandom_interval = max(static_cast<u32>(spc / 2), 1);
+ // Note that this code only works well if the processor is called for every increment of time.
+ if (m_transport->time() % getrandom_interval == 0)
+ last_random[note] = (get_random<u16>() / static_cast<double>(NumericLimits<u16>::max()) - .5) * 2;
+ return last_random[note];
+}
+
+}
diff --git a/Userland/Libraries/LibDSP/Synthesizers.h b/Userland/Libraries/LibDSP/Synthesizers.h
new file mode 100644
index 0000000000..3d89e014a6
--- /dev/null
+++ b/Userland/Libraries/LibDSP/Synthesizers.h
@@ -0,0 +1,72 @@
+/*
+ * Copyright (c) 2021, kleines Filmröllchen <malu.bertsch@gmail.com>.
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include "LibDSP/Music.h"
+#include <AK/SinglyLinkedList.h>
+#include <LibDSP/Processor.h>
+#include <LibDSP/ProcessorParameter.h>
+#include <LibDSP/Transport.h>
+
+namespace LibDSP::Synthesizers {
+
+enum Waveform : u8 {
+ Sine,
+ Triangle,
+ Square,
+ Saw,
+ Noise,
+};
+
+struct PitchedEnvelope : Envelope {
+ constexpr PitchedEnvelope() = default;
+ constexpr PitchedEnvelope(double envelope, u8 note)
+ : Envelope(envelope)
+ , note(note)
+ {
+ }
+ constexpr PitchedEnvelope(Envelope envelope, u8 note)
+ : Envelope(envelope)
+ , note(note)
+ {
+ }
+
+ u8 note;
+};
+
+class Classic : public SynthesizerProcessor {
+public:
+ Classic(NonnullRefPtr<Transport>);
+
+ static Envelope compute_envelope(RollNote&);
+
+ Waveform wave() const { return m_waveform.value(); }
+
+private:
+ virtual Signal process_impl(Signal const&) override;
+
+ double volume_from_envelope(Envelope);
+ double wave_position(u8 note);
+ double samples_per_cycle(u8 note);
+ double sin_position(u8 note);
+ double triangle_position(u8 note);
+ double square_position(u8 note);
+ double saw_position(u8 note);
+ double noise_position(u8 note);
+ double get_random_from_seed(u64 note);
+
+ ProcessorEnumParameter<Waveform> m_waveform;
+ ProcessorRangeParameter m_attack;
+ ProcessorRangeParameter m_decay;
+ ProcessorRangeParameter m_sustain;
+ ProcessorRangeParameter m_release;
+
+ RollNotes m_playing_notes;
+ Array<double, note_count> last_random;
+};
+
+}
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