67 lines
2.5 KiB
C++
67 lines
2.5 KiB
C++
// Copyright 2022-2023 The Mumble Developers. All rights reserved.
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// Use of this source code is governed by a BSD-style license
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// that can be found in the LICENSE file at the root of the
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// Mumble source tree or at <https://www.mumble.info/LICENSE>.
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#include "VolumeAdjustment.h"
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#include <cassert>
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#include <cmath>
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constexpr float DB_THRESHOLD = 0.1f;
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VolumeAdjustment::VolumeAdjustment(float factor, int dbAdjustment) : factor(factor), dbAdjustment(dbAdjustment) {
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assert(dbAdjustment == INVALID_DB_ADJUSTMENT
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// Verify that the used dbAdjustment is a reasonable representation of the given factor. Particularly, we
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// want to make sure that the deviation of the true dB representation of the factor (usually a floating point
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// value) doesn't deviate more than dbThreshold from the passed integer dB value. For all cases, where this
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// would be the case, we expect INVALID_DB_ADJUSTMENT to be passed instead.
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//
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// If dB is the dB-representation of a loudness change factor f, we have
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// dB = log2(f) * 6 <=> f = 2^{dB/6}
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// (+6dB equals a doubling in loudness)
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|| DB_THRESHOLD >= std::abs(static_cast< float >(dbAdjustment) - VolumeAdjustment::toDBAdjustment(factor)));
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}
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// Decibel formula: +6db = *2
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float VolumeAdjustment::toFactor(int dbAdjustment) {
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return static_cast< float >(std::pow(2.0, dbAdjustment / 6.0));
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}
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float VolumeAdjustment::toDBAdjustment(float factor) {
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return static_cast< float >(std::log2(factor) * 6.0);
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}
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int VolumeAdjustment::toIntegerDBAdjustment(float factor) {
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return static_cast< int >(std::roundf(VolumeAdjustment::toDBAdjustment(factor)));
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}
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VolumeAdjustment VolumeAdjustment::fromFactor(float factor) {
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if (factor > 0) {
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float dB = VolumeAdjustment::toDBAdjustment(factor);
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if (std::abs(dB - static_cast< float >(static_cast< int >(dB))) < DB_THRESHOLD) {
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// Close-enough
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return VolumeAdjustment(factor, static_cast< int >(std::round(dB)));
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} else {
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return VolumeAdjustment(factor, INVALID_DB_ADJUSTMENT);
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}
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} else {
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return VolumeAdjustment(factor, INVALID_DB_ADJUSTMENT);
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}
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}
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VolumeAdjustment VolumeAdjustment::fromDBAdjustment(int dbAdjustment) {
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float factor = VolumeAdjustment::toFactor(dbAdjustment);
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return VolumeAdjustment(factor, dbAdjustment);
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}
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bool operator==(const VolumeAdjustment &lhs, const VolumeAdjustment &rhs) {
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return lhs.dbAdjustment == rhs.dbAdjustment && std::abs(lhs.factor - rhs.factor) < 0.1f;
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}
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bool operator!=(const VolumeAdjustment &lhs, const VolumeAdjustment &rhs) {
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return !(lhs == rhs);
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}
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