Mario Lang:

#include <jack.hpp>

#include <boost/accumulators/accumulators.hpp>
#include <boost/accumulators/statistics.hpp>

template<typename... Features>
using AudioAccumulatorSet = boost::accumulators::accumulator_set<
float, boost::accumulators::features<Features...>
>;

using Count = boost::accumulators::tag::count;
using Max = boost::accumulators::tag::max;
using Min = boost::accumulators::tag::min;
using Mean = boost::accumulators::tag::mean;
using Variance = boost::accumulators::tag::variance;

class Statistics final : public JACK::Client {
JACK::AudioIn In;
AudioAccumulatorSet<Count, Max, Mean, Min, Variance> Accumulator;

public:
Statistics() : JACK::Client("Statistics"), In(createAudioIn("In")) {}
int process(std::uint32_t FrameCount) override {
for (auto &Value: In.buffer(FrameCount)) Accumulator(Value);
return 0;
}
auto max() const { return boost::accumulators::max(Accumulator); }
auto mean() const { return boost::accumulators::mean(Accumulator); }
auto min() const { return boost::accumulators::min(Accumulator); }
auto sampleCount() const { return boost::accumulators::count(Accumulator); }
auto variance() const { return boost::accumulators::variance(Accumulator); }
};

Nice code. But I wonder about one small thing related to C++.

Couldn't these max/mean/etc. methods in the Statististics class

be written shorter like this?:

auto max() const { return Max(Accumulator); }
auto mean() const { return Mean(Accumulator); }
auto min() const { return Min(Accumulator); }
auto sampleCount() const { return Count(Accumulator); }
auto variance() const { return Variance(Accumulator); }

Sorry if it's a stupid question, but I haven't used "using" in C++ yet. :-)

Also thanks for demonstrating these things from boost.