Libraries: Add LibDSP

LibDSP is a library for digital signal processing, and is primarily intended to support the future DAW version of Piano.
2025-07-27 18:27:35 +00:00 · 2021-08-27 16:18:11 +02:00 · 2021-08-27 16:18:11 +02:00 · a749b16674
commit a749b16674
parent 8f4b577405
14 changed files with 829 additions and 0 deletions
--- a/Userland/Libraries/LibDSP/Music.h
+++ b/Userland/Libraries/LibDSP/Music.h
@ -0,0 +1,146 @@
+/*
+ * Copyright (c) 2021, kleines Filmröllchen <malu.bertsch@gmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Types.h>
+#include <AK/Variant.h>
+#include <AK/Vector.h>
+#include <LibAudio/Buffer.h>
+
+namespace LibDSP {
+
+// FIXME: Audio::Frame is 64-bit float, which is quite large for long clips.
+using Sample = Audio::Frame;
+
+Sample const SAMPLE_OFF = { 0.0, 0.0 };
+
+struct RollNote {
+    u32 length() const { return (off_sample - on_sample) + 1; }
+
+    u32 on_sample;
+    u32 off_sample;
+    u8 pitch;
+    i8 velocity;
+};
+
+enum class SignalType : u8 {
+    Invalid,
+    Sample,
+    Note
+};
+
+struct Signal : public Variant<Sample, Vector<RollNote>> {
+    using Variant::Variant;
+    ALWAYS_INLINE SignalType type() const
+    {
+        return has<Sample>() ? SignalType::Sample : has<Vector<RollNote>>() ? SignalType::Note
+                                                                            : SignalType::Invalid;
+    }
+};
+
+// Equal temperament, A = 440Hz
+// We calculate note frequencies relative to A4:
+// 440.0 * pow(pow(2.0, 1.0 / 12.0), N)
+// Where N is the note distance from A.
+constexpr double note_frequencies[] = {
+    // Octave 1
+    32.703195662574764,
+    34.647828872108946,
+    36.708095989675876,
+    38.890872965260044,
+    41.203444614108669,
+    43.653528929125407,
+    46.249302838954222,
+    48.99942949771858,
+    51.913087197493056,
+    54.999999999999915,
+    58.270470189761156,
+    61.735412657015416,
+    // Octave 2
+    65.406391325149571,
+    69.295657744217934,
+    73.416191979351794,
+    77.781745930520117,
+    82.406889228217381,
+    87.307057858250872,
+    92.4986056779085,
+    97.998858995437217,
+    103.82617439498618,
+    109.99999999999989,
+    116.54094037952237,
+    123.4708253140309,
+    // Octave 3
+    130.8127826502992,
+    138.59131548843592,
+    146.83238395870364,
+    155.56349186104035,
+    164.81377845643485,
+    174.61411571650183,
+    184.99721135581709,
+    195.99771799087452,
+    207.65234878997245,
+    219.99999999999989,
+    233.08188075904488,
+    246.94165062806198,
+    // Octave 4
+    261.62556530059851,
+    277.18263097687202,
+    293.66476791740746,
+    311.12698372208081,
+    329.62755691286986,
+    349.22823143300383,
+    369.99442271163434,
+    391.99543598174927,
+    415.30469757994513,
+    440,
+    466.16376151808993,
+    493.88330125612413,
+    // Octave 5
+    523.25113060119736,
+    554.36526195374427,
+    587.32953583481526,
+    622.25396744416196,
+    659.25511382574007,
+    698.456462866008,
+    739.98884542326903,
+    783.99087196349899,
+    830.60939515989071,
+    880.00000000000034,
+    932.32752303618031,
+    987.76660251224882,
+    // Octave 6
+    1046.5022612023952,
+    1108.7305239074892,
+    1174.659071669631,
+    1244.5079348883246,
+    1318.5102276514808,
+    1396.9129257320169,
+    1479.977690846539,
+    1567.9817439269987,
+    1661.2187903197821,
+    1760.000000000002,
+    1864.6550460723618,
+    1975.5332050244986,
+    // Octave 7
+    2093.0045224047913,
+    2217.4610478149793,
+    2349.3181433392633,
+    2489.0158697766506,
+    2637.020455302963,
+    2793.8258514640347,
+    2959.9553816930793,
+    3135.9634878539991,
+    3322.437580639566,
+    3520.0000000000055,
+    3729.3100921447249,
+    3951.0664100489994,
+};
+constexpr size_t note_count = array_size(note_frequencies);
+
+constexpr double middle_c = note_frequencies[36];
+
+}