dbFS

#include <iostream> #include <filesystem> #include <fstream> #include <cmath> #include <limits> static constexpr int SAMPLES_PER_MS_FOR_16K = 16; static constexpr int SAMPLES_60MS_FOR_16K = SAMPLES_PER_MS_FOR_16K * 60; static constexpr double MAX_SAMPLE_VALUE = 32768.0; // 2^(n - 1) = 2^(16-1) = 2^15 = 32768 double getRmsInDecibel(const double meanSquareValue, const int sampleCount) { if (sampleCount <= 0) { return std::numeric_limits<double>::quiet_NaN(); } #ifdef _DEBUG double RMS = meanSquareValue / sampleCount; const double SQRT_RMS = std::sqrt(RMS); const double LOG_10 = std::log10(SQRT_RMS / MAX_SAMPLE_VALUE); const double LOG_10_TIMES_20 = 20 * LOG_10 + 3.01; return RMS = LOG_10_TIMES_20; #else return 20 * std::log10(std::sqrt(meanSquareValue / sampleCount) / MAX_SAMPLE_VALUE) + 3.01; // FS sine wave vs. FS square wave #endif } int main(int argc, char* argv[]) { if (argc <= 1) { std::cout << "argc is less than or equal to one\n"; return -1; } std::filesystem::path pcmSource{ argv[1], std::filesystem::path::auto_format }; std::ifstream fin{ pcmSource.native(), std::ios_base::binary }; if (!fin.is_open()) { std::cerr << "Fail to open file " << pcmSource.filename() << ".\n"; return -1; } std::cout << "Read PCM data from " << pcmSource.filename() << "\n"; short min = std::numeric_limits<short>::max(); short max = std::numeric_limits<short>::min(); int count = 0; double RMS = 0; while (!fin.eof()) { short frame = 0; fin.read(reinterpret_cast<char*>(&frame), sizeof frame); min = std::min(frame, min); max = std::max(frame, max); RMS += (frame * frame); if (++count % SAMPLES_60MS_FOR_16K == 0) { RMS = getRmsInDecibel(RMS, SAMPLES_60MS_FOR_16K); std::cout << "[ " << count << " ]\n"; std::cout << "max: " << max << ", min: " << min << '\n'; std::cout << "RMS: " << RMS << "dB\n"; max = std::numeric_limits<short>::min(); min = std::numeric_limits<short>::max(); RMS = 0.0; } } std::cout << "[ " << count << " ]\n"; std::cout << "max: " << max << ", min: " << min << '\n'; std::cout << "RMS: " << getRmsInDecibel(RMS, SAMPLES_60MS_FOR_16K) << "dB\n"; return 0; }