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b6d075bb01
"Frame" is an MPEG term, which is not only unintuitive but also overloaded with different meaning by other codecs (e.g. FLAC). Therefore, use the standard term Sample for the central audio structure. The class is also extracted to its own file, because it's becoming quite large. Bundling these two changes means not distributing similar modifications (changing names and paths) across commits. Co-authored-by: kleines Filmröllchen <malu.bertsch@gmail.com>
146 lines
3.3 KiB
C++
146 lines
3.3 KiB
C++
/*
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* Copyright (c) 2021, kleines Filmröllchen <malu.bertsch@gmail.com>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#pragma once
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#include <AK/Types.h>
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#include <AK/Variant.h>
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#include <AK/Vector.h>
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#include <LibAudio/Buffer.h>
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namespace LibDSP {
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// FIXME: Audio::Frame is 64-bit float, which is quite large for long clips.
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using Sample = Audio::Sample;
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Sample const SAMPLE_OFF = { 0.0, 0.0 };
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struct RollNote {
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u32 length() const { return (off_sample - on_sample) + 1; }
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u32 on_sample;
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u32 off_sample;
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u8 pitch;
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i8 velocity;
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};
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enum class SignalType : u8 {
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Invalid,
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Sample,
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Note
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};
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struct Signal : public Variant<Sample, Vector<RollNote>> {
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using Variant::Variant;
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ALWAYS_INLINE SignalType type() const
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{
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return has<Sample>() ? SignalType::Sample : has<Vector<RollNote>>() ? SignalType::Note
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: SignalType::Invalid;
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}
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};
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// Equal temperament, A = 440Hz
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// We calculate note frequencies relative to A4:
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// 440.0 * pow(pow(2.0, 1.0 / 12.0), N)
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// Where N is the note distance from A.
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constexpr double note_frequencies[] = {
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// Octave 1
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32.703195662574764,
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34.647828872108946,
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36.708095989675876,
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38.890872965260044,
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41.203444614108669,
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43.653528929125407,
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46.249302838954222,
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48.99942949771858,
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51.913087197493056,
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54.999999999999915,
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58.270470189761156,
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61.735412657015416,
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// Octave 2
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65.406391325149571,
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69.295657744217934,
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73.416191979351794,
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77.781745930520117,
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82.406889228217381,
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87.307057858250872,
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92.4986056779085,
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97.998858995437217,
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103.82617439498618,
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109.99999999999989,
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116.54094037952237,
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123.4708253140309,
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// Octave 3
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130.8127826502992,
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138.59131548843592,
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146.83238395870364,
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155.56349186104035,
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164.81377845643485,
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174.61411571650183,
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184.99721135581709,
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195.99771799087452,
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207.65234878997245,
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219.99999999999989,
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233.08188075904488,
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246.94165062806198,
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// Octave 4
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261.62556530059851,
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277.18263097687202,
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293.66476791740746,
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311.12698372208081,
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329.62755691286986,
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349.22823143300383,
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369.99442271163434,
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391.99543598174927,
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415.30469757994513,
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440,
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466.16376151808993,
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493.88330125612413,
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// Octave 5
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523.25113060119736,
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554.36526195374427,
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587.32953583481526,
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622.25396744416196,
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659.25511382574007,
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698.456462866008,
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739.98884542326903,
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783.99087196349899,
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830.60939515989071,
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880.00000000000034,
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932.32752303618031,
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987.76660251224882,
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// Octave 6
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1046.5022612023952,
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1108.7305239074892,
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1174.659071669631,
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1244.5079348883246,
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1318.5102276514808,
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1396.9129257320169,
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1479.977690846539,
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1567.9817439269987,
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1661.2187903197821,
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1760.000000000002,
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1864.6550460723618,
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1975.5332050244986,
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// Octave 7
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2093.0045224047913,
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2217.4610478149793,
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2349.3181433392633,
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2489.0158697766506,
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2637.020455302963,
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2793.8258514640347,
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2959.9553816930793,
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3135.9634878539991,
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3322.437580639566,
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3520.0000000000055,
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3729.3100921447249,
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3951.0664100489994,
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};
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constexpr size_t note_count = array_size(note_frequencies);
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constexpr double middle_c = note_frequencies[36];
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}
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