add time variant EMA for #58

Author: phandasm

data/locale/en-US.ini

@@ -79,9 +79,10 @@ slope="Slope"
 rolloff_q="Roll-off Bandwidth (Octaves)"
 rolloff_rate="Roll-off Rate (dB/Octave)"
 
-gravity="Gravity"
+gravity="Inertia"
 temporal_smoothing="Temporal Smoothing"
-exp_moving_avg="Exponential Moving Average"
+exp_moving_avg="Simple EMA"
+tv_exp_moving_avg="Time Variant EMA"
 fast_peaks="Fast Peaks"
 
 color_base="Base Color"

src/settings.hpp

@@ -105,6 +105,7 @@ static inline bool p_equ(const char *s1, const char *s2) { return std::strcmp(s1
 #define P_GRAVITY           "gravity"
 #define P_TSMOOTHING        "temporal_smoothing"
 #define P_EXPAVG            "exp_moving_avg"
+#define P_TVEXPAVG          "tv_exp_moving_avg"
 #define P_FAST_PEAKS        "fast_peaks"
 
 #define P_COLOR_BASE        "color_base"

src/source.cpp

@@ -376,6 +376,7 @@ namespace callbacks {
         auto tsmoothlist = obs_properties_add_list(props, P_TSMOOTHING, T(P_TSMOOTHING), OBS_COMBO_TYPE_LIST, OBS_COMBO_FORMAT_STRING);
         obs_property_list_add_string(tsmoothlist, T(P_NONE), P_NONE);
         obs_property_list_add_string(tsmoothlist, T(P_EXPAVG), P_EXPAVG);
+        obs_property_list_add_string(tsmoothlist, T(P_TVEXPAVG), P_TVEXPAVG);
         auto grav = obs_properties_add_float_slider(props, P_GRAVITY, T(P_GRAVITY), 0.0, 1.0, 0.01);
         auto peaks = obs_properties_add_bool(props, P_FAST_PEAKS, T(P_FAST_PEAKS));
         obs_property_set_long_description(tsmoothlist, T(P_TEMPORAL_DESC));
@@ -603,6 +604,8 @@ void WAVSource::get_settings(obs_data_t *settings)
 
     if(p_equ(tsmoothing, P_EXPAVG))
         m_tsmoothing = TSmoothingMode::EXPONENTIAL;
+    else if(p_equ(tsmoothing, P_TVEXPAVG))
+        m_tsmoothing = TSmoothingMode::TVEXPONENTIAL;
     else
         m_tsmoothing = TSmoothingMode::NONE;
 

src/source.hpp

@@ -56,7 +56,8 @@ enum class FilterMode
 enum class TSmoothingMode
 {
     NONE,
-    EXPONENTIAL
+    EXPONENTIAL,
+    TVEXPONENTIAL
 };
 
 enum class RenderMode
@@ -288,6 +289,16 @@ class WAVSource
             return DB_MIN;
     }
 
+    inline float get_gravity(float seconds)
+    {
+        constexpr float denom = 0.03868924705242879469662125316986f;
+        constexpr float hi = denom * 5.0f;
+        constexpr float lo = 0.0f;
+        if((m_tsmoothing == TSmoothingMode::NONE) || (m_gravity <= 0.0f))
+            return 0.0f;
+        return (m_tsmoothing == TSmoothingMode::TVEXPONENTIAL) ? std::exp(-seconds / lerp(lo, hi, m_gravity)) : m_gravity;
+    }
+
 public:
     WAVSource(obs_source_t *source);
     virtual ~WAVSource();

src/source_avx.cpp

@@ -24,6 +24,8 @@
 
 // adaptation of WAVSourceAVX2 to support CPUs without AVX2
 // see comments of WAVSourceAVX2
+// FIXME: this specialization should be removed.
+// The only CPUs with FMA3 but not AVX2 are ancient AMD chips that prefer SSE code anyway.
 void WAVSourceAVX::tick_spectrum([[maybe_unused]] float seconds)
 {
     //std::lock_guard lock(m_mtx); // now locked in tick()
@@ -114,7 +116,7 @@ void WAVSourceAVX::tick_spectrum([[maybe_unused]] float seconds)
         constexpr auto shuffle_mask_r = 0 | (2 << 2) | (0 << 4) | (2 << 6);
         constexpr auto shuffle_mask_i = 1 | (3 << 2) | (1 << 4) | (3 << 6);
         const auto mag_coefficient = _mm256_set1_ps(2.0f / m_window_sum);
-        const auto g = _mm256_set1_ps(m_gravity);
+        const auto g = _mm256_set1_ps(get_gravity(seconds));
         const auto g2 = _mm256_sub_ps(_mm256_set1_ps(1.0), g);
         const bool slope = m_slope > 0.0f;
         for(size_t i = 0; i < outsz; i += step)
@@ -138,7 +140,7 @@ void WAVSourceAVX::tick_spectrum([[maybe_unused]] float seconds)
             if(slope)
                 mag = _mm256_mul_ps(mag, _mm256_load_ps(&m_slope_modifiers[i]));
 
-            if(m_tsmoothing == TSmoothingMode::EXPONENTIAL)
+            if(m_tsmoothing != TSmoothingMode::NONE)
             {
                 auto oldval = _mm256_load_ps(&m_tsmooth_buf[channel][i]);
                 if(m_fast_peaks)
@@ -280,9 +282,9 @@ void WAVSourceAVX::tick_meter([[maybe_unused]] float seconds)
             out = horizontal_max(_mm256_max_ps(max1, max2));
         }
 
-        if(m_tsmoothing == TSmoothingMode::EXPONENTIAL)
+        if(m_tsmoothing != TSmoothingMode::NONE)
         {
-            const auto g = m_gravity;
+            const auto g = get_gravity(seconds);
             const auto g2 = 1.0f - g;
             if(!m_fast_peaks || (out <= m_meter_buf[channel]))
                 out = (g * m_meter_buf[channel]) + (g2 * out);

src/source_avx2.cpp

@@ -118,7 +118,7 @@ void WAVSourceAVX2::tick_spectrum([[maybe_unused]] float seconds)
         // normalize FFT output and convert to dBFS
         const auto shuffle_mask = _mm256_setr_epi32(0, 2, 4, 6, 1, 3, 5, 7);
         const auto mag_coefficient = _mm256_set1_ps(2.0f / m_window_sum);
-        const auto g = _mm256_set1_ps(m_gravity);
+        const auto g = _mm256_set1_ps(get_gravity(seconds));
         const auto g2 = _mm256_sub_ps(_mm256_set1_ps(1.0), g); // 1 - gravity
         const bool slope = m_slope > 0.0f;
         for(size_t i = 0; i < outsz; i += step)
@@ -143,7 +143,7 @@ void WAVSourceAVX2::tick_spectrum([[maybe_unused]] float seconds)
                 mag = _mm256_mul_ps(mag, _mm256_load_ps(&m_slope_modifiers[i]));
 
             // time domain smoothing
-            if(m_tsmoothing == TSmoothingMode::EXPONENTIAL)
+            if(m_tsmoothing != TSmoothingMode::NONE)
             {
                 auto oldval = _mm256_load_ps(&m_tsmooth_buf[channel][i]);
                 // take new values immediately if larger

src/source_generic.cpp

@@ -108,20 +108,20 @@ void WAVSourceGeneric::tick_spectrum([[maybe_unused]] float seconds)
             continue;
 
         const auto mag_coefficient = 2.0f / m_window_sum;
-        const auto g = m_gravity;
+        const auto g = get_gravity(seconds);
         const auto g2 = 1.0f - g;
         const bool slope = m_slope > 0.0f;
         for(size_t i = 0; i < outsz; i += step)
         {
             auto real = m_fft_output[i][0];
             auto imag = m_fft_output[i][1];
 
-            auto mag = std::sqrt((real * real) + (imag * imag)) * mag_coefficient;
+            auto mag = std::hypot(real, imag) * mag_coefficient;
 
             if(slope)
                 mag *= m_slope_modifiers[i];
 
-            if(m_tsmoothing == TSmoothingMode::EXPONENTIAL)
+            if(m_tsmoothing != TSmoothingMode::NONE)
             {
                 auto oldval = m_tsmooth_buf[channel][i];
                 if(m_fast_peaks)
@@ -249,9 +249,9 @@ void WAVSourceGeneric::tick_meter([[maybe_unused]] float seconds)
                 out = std::max(out, std::abs(m_decibels[channel][i]));
         }
 
-        if(m_tsmoothing == TSmoothingMode::EXPONENTIAL)
+        if(m_tsmoothing != TSmoothingMode::NONE)
         {
-            const auto g = m_gravity;
+            const auto g = get_gravity(seconds);
             const auto g2 = 1.0f - g;
             if(!m_fast_peaks || (out <= m_meter_buf[channel]))
                 out = (g * m_meter_buf[channel]) + (g2 * out);