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Merge pull request #834 from TomHarte/FloatingSpeaker

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Resolves lowpass-speaker position aliasing
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Thomas Harte 2020-09-16 19:05:54 -04:00 committed by GitHub
commit 8b16da9695
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1 changed files with 6 additions and 6 deletions
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12
Outputs/Speaker/Implementation/LowpassSpeaker.hpp
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@ -10,7 +10,6 @@
#define FilteringSpeaker_h
#include "../Speaker.hpp"
#include "../../../SignalProcessing/Stepper.hpp"
#include "../../../SignalProcessing/FIRFilter.hpp"
#include "../../../ClockReceiver/ClockReceiver.hpp"
#include "../../../Concurrency/AsyncTaskQueue.hpp"
@ -198,7 +197,8 @@ template <typename SampleSource> class LowpassSpeaker: public Speaker {
std::vector<int16_t> input_buffer_;
std::vector<int16_t> output_buffer_;
std::unique_ptr<SignalProcessing::Stepper> stepper_;
float step_rate_ = 0.0f;
float position_error_ = 0.0f;
std::unique_ptr<SignalProcessing::FIRFilter> filter_;
std::mutex filter_parameters_mutex_;
@ -223,9 +223,8 @@ template <typename SampleSource> class LowpassSpeaker: public Speaker {
);
number_of_taps = (number_of_taps * 2) | 1;
stepper_ = std::make_unique<SignalProcessing::Stepper>(
uint64_t(filter_parameters.input_cycles_per_second),
uint64_t(filter_parameters.output_cycles_per_second));
step_rate_ = filter_parameters.input_cycles_per_second / filter_parameters.output_cycles_per_second;
position_error_ = 0.0f;
filter_ = std::make_unique<SignalProcessing::FIRFilter>(
unsigned(number_of_taps),
@ -304,7 +303,8 @@ template <typename SampleSource> class LowpassSpeaker: public Speaker {
// If the next loop around is going to reuse some of the samples just collected, use a memmove to
// preserve them in the correct locations (TODO: use a longer buffer to fix that?) and don't skip
// anything. Otherwise skip as required to get to the next sample batch and don't expect to reuse.
const auto steps = stepper_->step() * (SampleSource::get_is_stereo() ? 2 : 1);
const size_t steps = size_t(step_rate_ + position_error_) * (SampleSource::get_is_stereo() ? 2 : 1);
position_error_ = fmodf(step_rate_ + position_error_, 1.0f);
if(steps < input_buffer_.size()) {
auto *const input_buffer = input_buffer_.data();
std::memmove( input_buffer,