Improve Audio Data Processing and Spectrum Analyzer

src/libprojectM/Audio/AudioConstants.hpp

@@ -1,10 +1,16 @@
 #pragma once
 
+#include <array>
+
 namespace libprojectM {
 namespace Audio {
 
-static constexpr int WaveformSamples = 576; //!< Number of waveform data samples available for rendering a frame.
-static constexpr int SpectrumSamples = 512; //!< Number of spectrum analyzer samples.
+static constexpr int AudioBufferSamples = 576; //!< Number of waveform data samples stored in the buffer for analysis.
+static constexpr int WaveformSamples = 480;    //!< Number of waveform data samples available for rendering a frame.
+static constexpr int SpectrumSamples = 512;    //!< Number of spectrum analyzer samples.
+
+using WaveformBuffer = std::array<float, AudioBufferSamples>; //!< Buffer with waveform data. Only the first WaveformSamples number of samples are valid.
+using SpectrumBuffer = std::array<float, SpectrumSamples>;    //!< Buffer with spectrum data.
 
 } // namespace Audio
 } // namespace libprojectM

src/libprojectM/Audio/CMakeLists.txt

@@ -0,0 +1,24 @@
+
+add_library(Audio OBJECT
+        AudioConstants.hpp
+        MilkdropFFT.cpp
+        MilkdropFFT.hpp
+        FrameAudioData.cpp
+        FrameAudioData.hpp
+        PCM.cpp
+        PCM.hpp
+        Loudness.cpp
+        Loudness.hpp
+        WaveformAligner.cpp
+        WaveformAligner.hpp
+        )
+
+target_include_directories(Audio
+        PUBLIC
+        ${CMAKE_CURRENT_SOURCE_DIR}
+        )
+
+target_link_libraries(Audio
+        PUBLIC
+        libprojectM::API
+        )

src/libprojectM/Audio/Loudness.cpp

@@ -0,0 +1,62 @@
+#include "Loudness.hpp"
+
+#include <cmath>
+
+namespace libprojectM {
+namespace Audio {
+
+Loudness::Loudness(Loudness::Band band)
+    : m_band(band)
+{
+}
+
+void Loudness::Update(const std::array<float, SpectrumSamples>& spectrumSamples, double secondsSinceLastFrame, uint32_t frame)
+{
+    SumBand(spectrumSamples);
+    UpdateBandAverage(secondsSinceLastFrame, frame);
+}
+
+auto Loudness::CurrentRelative() const -> float
+{
+    return m_currentRelative;
+}
+
+auto Loudness::AverageRelative() const -> float
+{
+    return m_averageRelative;
+}
+
+void Loudness::SumBand(const std::array<float, SpectrumSamples>& spectrumSamples)
+{
+    int start = SpectrumSamples * static_cast<int>(m_band) / 6;
+    int end = SpectrumSamples * (static_cast<int>(m_band) + 1) / 6;
+
+    m_current = 0.0f;
+    for (int sample = start; sample < end; sample++)
+    {
+        m_current += spectrumSamples[sample];
+    }
+}
+
+void Loudness::UpdateBandAverage(double secondsSinceLastFrame, uint32_t frame)
+{
+    float rate = AdjustRateToFps(m_current > m_average ? 0.2f : 0.5f, secondsSinceLastFrame);
+    m_average = m_average * rate + m_current * (1.0f - rate);
+
+    rate = AdjustRateToFps(frame < 50 ? 0.9f : 0.992f, secondsSinceLastFrame);
+    m_longAverage = m_longAverage * rate + m_current * (1.0f - rate);
+
+    m_currentRelative = std::fabs(m_longAverage) < 0.001f ? 1.0f : m_current / m_longAverage;
+    m_averageRelative = std::fabs(m_longAverage) < 0.001f ? 1.0f : m_average / m_longAverage;
+}
+
+auto Loudness::AdjustRateToFps(float rate, double secondsSinceLastFrame) -> float
+{
+    float const perSecondDecayRateAtFps1 = std::pow(rate, 30.0f);
+    float const perFrameDecayRateAtFps2 = std::pow(perSecondDecayRateAtFps1, static_cast<float>(secondsSinceLastFrame));
+
+    return perFrameDecayRateAtFps2;
+}
+
+} // namespace Audio
+} // namespace libprojectM