rgbx_audio_bars.h

Go to the documentation of this file.

 
#ifndef RGBX_AUDIO_BARS_H
#define RGBX_AUDIO_BARS_H
 
#include <math.h>
#include <rgbx/rgbx_api.h>
#include <stddef.h>
 
#ifdef __cplusplus
extern "C" {
#endif
 
#define RGBX_AUDIO_BAR_FLOOR_DB (-36.0f)
 
#define RGBX_AUDIO_BAR_RANGE_DB (36.0f)
 
#define RGBX_AUDIO_BAR_TILT_DB_PER_OCTAVE (3.0f)
 
#define RGBX_AUDIO_BAR_POWER_FLOOR (1e-9f)
 
static const float rgbx_audio_bar_octaves[RGBX_AUDIO_NUM_DISPLAY_BUCKETS] = {
    0.0000f, 1.0995f, 1.5850f, 1.8931f, 2.1468f, 2.3626f, 2.6521f, 2.9206f, 3.1234f, 3.3424f,
    3.5677f, 3.7318f, 3.8791f, 4.0000f, 4.0753f, 4.1584f, 4.2907f, 4.4500f, 4.5935f, 4.7240f};
 
static inline float rgbx_audio_bar_power_db(float energy) {
    /* `!(x > floor)` rather than `x <= floor`: NaN fails every comparison, so
     * this one form catches zero, negative AND non-finite input. */
    if (!(energy > RGBX_AUDIO_BAR_POWER_FLOOR)) {
        energy = RGBX_AUDIO_BAR_POWER_FLOOR;
    }
    /* 10*log10(x) = (10 / ln 10) * ln(x); logf is the allowed import. */
    return 4.3429448f * logf(energy);
}
 
static inline float rgbx_audio_bar_height(float energy, size_t bucket, float floor_db,
                                          float range_db, float tilt_db_per_octave) {
    float tilt, range, h;
    /* No signal, no bar — whatever the window. Without this the -90 dB log
     * floor plus a large tilt and a low floor would draw a bar out of nothing. */
    if (!(energy > 0.0f)) {
        return 0.0f;
    }
    tilt = (bucket < RGBX_AUDIO_NUM_DISPLAY_BUCKETS)
               ? tilt_db_per_octave * rgbx_audio_bar_octaves[bucket]
               : 0.0f;
    range = (range_db > 0.0f) ? range_db : 1.0f;
    h = (rgbx_audio_bar_power_db(energy) + tilt - floor_db) / range;
    if (!(h > 0.0f)) { /* also NaN, should any window value be non-finite */
        return 0.0f;
    }
    if (h > 1.0f) {
        return 1.0f;
    }
    return h;
}
 
#ifdef __cplusplus
} /* extern "C" */
#endif
 
#endif /* RGBX_AUDIO_BARS_H */