vgmstream/src/base/mixing_fades.h

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2023-07-30 23:47:50 +02:00
#ifndef _MIXING_FADE_H_
#define _MIXING_FADE_H_
#include "mixing_priv.h"
#include <math.h>
#include <limits.h>
#define MIXING_PI 3.14159265358979323846f
static inline int is_fade_active(mixing_data *data, int32_t current_start, int32_t current_end) {
int i;
for (i = 0; i < data->mixing_count; i++) {
mix_command_data *mix = &data->mixing_chain[i];
int32_t fade_start, fade_end;
float vol_start = mix->vol_start;
if (mix->command != MIX_FADE)
continue;
/* check is current range falls within a fade
* (assuming fades were already optimized on add) */
if (mix->time_pre < 0 && vol_start == 1.0) {
fade_start = mix->time_start; /* ignore unused */
}
else {
fade_start = mix->time_pre < 0 ? 0 : mix->time_pre;
}
fade_end = mix->time_post < 0 ? INT_MAX : mix->time_post;
//;VGM_LOG("MIX: fade test, tp=%i, te=%i, cs=%i, ce=%i\n", mix->time_pre, mix->time_post, current_start, current_end);
if (current_start < fade_end && current_end > fade_start) {
//;VGM_LOG("MIX: fade active, cs=%i < fe=%i and ce=%i > fs=%i\n", current_start, fade_end, current_end, fade_start);
return 1;
}
}
return 0;
}
static inline int32_t get_current_pos(VGMSTREAM* vgmstream, int32_t sample_count) {
int32_t current_pos;
if (vgmstream->config_enabled) {
return vgmstream->pstate.play_position;
}
if (vgmstream->loop_flag && vgmstream->loop_count > 0) {
int loop_pre = vgmstream->loop_start_sample; /* samples before looping */
int loop_into = (vgmstream->current_sample - vgmstream->loop_start_sample); /* samples after loop */
int loop_samples = (vgmstream->loop_end_sample - vgmstream->loop_start_sample); /* looped section */
current_pos = loop_pre + (loop_samples * vgmstream->loop_count) + loop_into - sample_count;
}
else {
current_pos = (vgmstream->current_sample - sample_count);
}
return current_pos;
}
static inline float get_fade_gain_curve(char shape, float index) {
float gain;
/* don't bother doing calcs near 0.0/1.0 */
if (index <= 0.0001f || index >= 0.9999f) {
return index;
}
//todo optimizations: interleave calcs, maybe use cosf, powf, etc? (with extra defines)
/* (curve math mostly from SoX/FFmpeg) */
switch(shape) {
/* 2.5f in L/E 'pow' is the attenuation factor, where 5.0 (100db) is common but a bit fast
* (alt calculations with 'exp' from FFmpeg use (factor)*ln(0.1) = -NN.N... */
case 'E': /* exponential (for fade-outs, closer to natural decay of sound) */
//gain = pow(0.1f, (1.0f - index) * 2.5f);
gain = exp(-5.75646273248511f * (1.0f - index));
break;
case 'L': /* logarithmic (inverse of the above, maybe for crossfades) */
//gain = 1 - pow(0.1f, (index) * 2.5f);
gain = 1 - exp(-5.75646273248511f * (index));
break;
case 'H': /* raised sine wave or cosine wave (for more musical crossfades) */
gain = (1.0f - cos(index * MIXING_PI)) / 2.0f;
break;
case 'Q': /* quarter of sine wave (for musical fades) */
gain = sin(index * MIXING_PI / 2.0f);
break;
case 'p': /* parabola (maybe for crossfades) */
gain = 1.0f - sqrt(1.0f - index);
break;
case 'P': /* inverted parabola (maybe for fades) */
gain = (1.0f - (1.0f - index) * (1.0f - index));
break;
case 'T': /* triangular/linear (simpler/sharper fades) */
default:
gain = index;
break;
}
return gain;
}
static int get_fade_gain(mix_command_data *mix, float *out_cur_vol, int32_t current_subpos) {
float cur_vol = 0.0f;
if ((current_subpos >= mix->time_pre || mix->time_pre < 0) && current_subpos < mix->time_start) {
cur_vol = mix->vol_start; /* before */
}
else if (current_subpos >= mix->time_end && (current_subpos < mix->time_post || mix->time_post < 0)) {
cur_vol = mix->vol_end; /* after */
}
else if (current_subpos >= mix->time_start && current_subpos < mix->time_end) {
/* in between */
float range_vol, range_dur, range_idx, index, gain;
if (mix->vol_start < mix->vol_end) { /* fade in */
range_vol = mix->vol_end - mix->vol_start;
range_dur = mix->time_end - mix->time_start;
range_idx = current_subpos - mix->time_start;
index = range_idx / range_dur;
} else { /* fade out */
range_vol = mix->vol_end - mix->vol_start;
range_dur = mix->time_end - mix->time_start;
range_idx = mix->time_end - current_subpos;
index = range_idx / range_dur;
}
/* Fading is done like this:
* - find current position within fade duration
* - get linear % (or rather, index from 0.0 .. 1.0) of duration
* - apply shape to % (from linear fade to curved fade)
* - get final volume for that point
*
* Roughly speaking some curve shapes are better for fades (decay rate is more natural
* sounding in that highest to mid/low happens faster but low to lowest takes more time,
* kinda like a gunshot or bell), and others for crossfades (decay of fade-in + fade-out
* is adjusted so that added volume level stays constant-ish).
*
* As curves can fade in two ways ('normal' and curving 'the other way'), they are adjusted
* to get 'normal' shape on both fades (by reversing index and making 1 - gain), thus some
* curves are complementary (exponential fade-in ~= logarithmic fade-out); the following
* are described taking fade-in = normal.
*/
gain = get_fade_gain_curve(mix->shape, index);
if (mix->vol_start < mix->vol_end) { /* fade in */
cur_vol = mix->vol_start + range_vol * gain;
} else { /* fade out */
cur_vol = mix->vol_end - range_vol * gain; //mix->vol_start - range_vol * (1 - gain);
}
}
else {
/* fade is outside reach */
goto fail;
}
*out_cur_vol = cur_vol;
return 1;
fail:
return 0;
}
#endif