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Add quantized envelopes

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This commit is contained in:
Paul Ferrand 2020-03-30 22:42:43 +02:00
parent 088da9df65
commit bebb166469
1 changed files with 82 additions and 6 deletions
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88
src/sfizz/SfzHelpers.h
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@ -352,15 +352,49 @@ void linearEnvelope(const EventVector& events, absl::Span<float> envelope, F&& l
auto lastValue = lambda(events[0].value);
auto lastDelay = events[0].delay;
for (unsigned i = 1; i < events.size(); ++ i) {
const auto event = events[i];
const auto length = event.delay - lastDelay;
const auto step = (lambda(event.value) - lastValue)/ length;
const auto length = events[i].delay - lastDelay;
const auto step = (lambda(events[i].value) - lastValue)/ length;
lastValue = linearRamp<float>(envelope.subspan(lastDelay, length), lastValue, step);
lastDelay += length;
}
fill<float>(envelope.subspan(lastDelay), lastValue);
}
template<class F>
void linearEnvelope(const EventVector& events, absl::Span<float> envelope, F&& lambda, float step)
{
ASSERT(events.size() > 0);
ASSERT(events[0].delay == 0);
ASSERT(step != 0.0);
auto quantize = [step](float value) -> float {
return std::round(value / step) * step;
};
auto lastValue = quantize(lambda(events[0].value));
auto lastDelay = events[0].delay;
for (unsigned i = 1; i < events.size(); ++ i) {
const auto nextValue = quantize(lambda(events[i].value));
const auto difference = std::abs(nextValue - lastValue);
const auto length = events[i].delay - lastDelay;
if (difference < step) {
fill<float>(envelope.subspan(lastDelay, length), lastValue);
lastValue = nextValue;
lastDelay += length;
continue;
}
const auto numSteps = static_cast<int>(difference / step);
const auto stepLength = static_cast<int>(length / numSteps);
for (int i = 0; i < numSteps; ++i) {
fill<float>(envelope.subspan(lastDelay, stepLength), lastValue);
lastValue += lastValue <= nextValue ? step : -step;
lastDelay += stepLength;
}
}
fill<float>(envelope.subspan(lastDelay), lastValue);
}
template<class F>
void multiplicativeEnvelope(const EventVector& events, absl::Span<float> envelope, F&& lambda)
{
@ -370,9 +404,8 @@ void multiplicativeEnvelope(const EventVector& events, absl::Span<float> envelop
auto lastValue = lambda(events[0].value);
auto lastDelay = events[0].delay;
for (unsigned i = 1; i < events.size(); ++ i) {
const auto event = events[i];
const auto length = event.delay - lastDelay;
const auto nextValue = lambda(event.value);
const auto length = events[i].delay - lastDelay;
const auto nextValue = lambda(events[i].value);
const auto step = std::exp((std::log(nextValue) - std::log(lastValue)) / length);
multiplicativeRamp<float>(envelope.subspan(lastDelay, length), lastValue, step);
lastValue = nextValue;
@ -381,5 +414,48 @@ void multiplicativeEnvelope(const EventVector& events, absl::Span<float> envelop
fill<float>(envelope.subspan(lastDelay), lastValue);
}
template<class F>
void multiplicativeEnvelope(const EventVector& events, absl::Span<float> envelope, F&& lambda, float step)
{
ASSERT(events.size() > 0);
ASSERT(events[0].delay == 0);
ASSERT(step != 0.0f);
DBG("Called the quantized version with step " << step);
const auto logStep = std::log(step);
// If we assume that a = b.q^r for b in (1, q) then
// log a log b
// ----- = ----- + r
// log q log q
// and log(b)\log(q) is between 0 and 1.
auto quantize = [logStep](float value) -> float {
return std::exp(logStep * std::round(std::log(value)/logStep));
};
auto lastValue = quantize(lambda(events[0].value));
auto lastDelay = events[0].delay;
for (unsigned i = 1; i < events.size(); ++ i) {
const auto length = events[i].delay - lastDelay;
const auto nextValue = quantize(lambda(events[i].value));
const auto difference = nextValue > lastValue ? nextValue / lastValue : lastValue / nextValue;
if (difference < step) {
fill<float>(envelope.subspan(lastDelay, length), lastValue);
lastValue = nextValue;
lastDelay += length;
continue;
}
const auto numSteps = static_cast<int>(std::log(difference) / logStep);
const auto stepLength = static_cast<int>(length / numSteps);
for (int i = 0; i < numSteps; ++i) {
fill<float>(envelope.subspan(lastDelay, stepLength), lastValue);
lastValue = nextValue > lastValue ? lastValue * step : lastValue / step;
lastDelay += stepLength;
}
}
fill<float>(envelope.subspan(lastDelay), lastValue);
}
} // namespace sfz