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Express follower AR in seconds

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This commit is contained in:
Jean Pierre Cimalando 2020-08-27 09:39:41 +02:00
parent b1f1fc4042
commit 298befa753
2 changed files with 8 additions and 10 deletions
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4
src/sfizz/Config.h
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@ -58,8 +58,8 @@ namespace config {
constexpr float A440 { 440.0 };
constexpr size_t powerHistoryLength { 16 };
constexpr size_t powerFollowerStep { 512 };
constexpr float powerFollowerAttackFactor { 100 };
constexpr float powerFollowerReleaseFactor { 10 };
constexpr float powerFollowerAttackTime { 5e-3f };
constexpr float powerFollowerReleaseTime { 200e-3f };
constexpr uint16_t numCCs { 512 };
constexpr int maxCurves { 256 };
constexpr int chunkSize { 1024 };

14
src/sfizz/PowerFollower.cpp
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@ -32,7 +32,6 @@ void PowerFollower::setSamplesPerBlock(unsigned samplesPerBlock)
if (samplesPerBlock_ != samplesPerBlock) {
tempBuffer_.reset(new float[samplesPerBlock]);
samplesPerBlock_ = samplesPerBlock;
updateTrackingFactor();
}
}
@ -48,8 +47,8 @@ void PowerFollower::process(AudioSpan<float> buffer) noexcept
float currentSum = currentSum_;
size_t currentCount = currentCount_;
const float attackFactor = static_cast<float>(numFrames) * attackTrackingFactor_;
const float releaseFactor = static_cast<float>(numFrames) * releaseTrackingFactor_;
const float attackFactor = attackTrackingFactor_;
const float releaseFactor = releaseTrackingFactor_;
///
size_t index = 0;
@ -67,8 +66,8 @@ void PowerFollower::process(AudioSpan<float> buffer) noexcept
if (currentCount == step) {
const float meanPower = currentSum / step;
currentPower = max(
currentPower * (1 - attackFactor) + meanPower * attackFactor,
currentPower * (1 - releaseFactor) + meanPower * releaseFactor);
currentPower * attackFactor + meanPower * (1 - attackFactor),
currentPower * releaseFactor + meanPower * (1 - releaseFactor));
currentSum = 0;
currentCount = 0;
}
@ -92,9 +91,8 @@ void PowerFollower::clear() noexcept
void PowerFollower::updateTrackingFactor() noexcept
{
// Protect the envelope follower against blowups
const auto maxTrackingFactor = sampleRate_ / samplesPerBlock_;
attackTrackingFactor_ = min(config::powerFollowerAttackFactor, maxTrackingFactor) / sampleRate_;
releaseTrackingFactor_ = min(config::powerFollowerReleaseFactor, maxTrackingFactor) / sampleRate_;
attackTrackingFactor_ = std::exp(-1.0f / ((config::powerFollowerAttackTime / config::powerFollowerStep) * sampleRate_));
releaseTrackingFactor_ = std::exp(-1.0f / ((config::powerFollowerReleaseTime / config::powerFollowerStep) * sampleRate_));
}
} // namespace sfz