Use cubic mapping for volume control (#6020)

* Use cubic mapping for volume control

* Update comment for hardware volume slider
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scribblemaniac 2022-05-20 11:17:37 -06:00 committed by GitHub
parent 46c6e5c4c0
commit a6e7a81de9
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@ -84,11 +84,11 @@ void DspInterface::OutputCallback(s16* buffer, std::size_t num_frames) {
std::memcpy(buffer + 2 * i, &last_frame[0], 2 * sizeof(s16));
}
// Implementation of the hardware volume slider with a dynamic range of 60 dB
// Implementation of the hardware volume slider
// A cubic curve is used to approximate a linear change in human-perceived loudness
const float linear_volume = std::clamp(Settings::values.volume, 0.0f, 1.0f);
if (linear_volume != 1.0) {
const float volume_scale_factor =
linear_volume == 0 ? 0 : std::exp(6.90775f * linear_volume) * 0.001f;
const float volume_scale_factor = linear_volume * linear_volume * linear_volume;
for (std::size_t i = 0; i < num_frames; i++) {
buffer[i * 2 + 0] = static_cast<s16>(buffer[i * 2 + 0] * volume_scale_factor);
buffer[i * 2 + 1] = static_cast<s16>(buffer[i * 2 + 1] * volume_scale_factor);