dsp.h

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// SPDX-License-Identifier: Apache-2.0
#pragma once
 
#include "audio_player/audio.h"
 
#ifdef __cplusplus
extern "C" {
#endif
 
#define DSP_MAX_BANDS 10
#define DSP_PRESET_NAME_MAX 48
 
typedef enum { PEQ_PEAK = 0, PEQ_LOW_SHELF, PEQ_HIGH_SHELF, PEQ_LOW_PASS, PEQ_HIGH_PASS } peq_type_t;
 
typedef struct {
    peq_type_t type;
    float freq_hz;
    float gain_db;  
    float q;
    bool enabled;
} peq_band_t;
 
typedef struct {
    char name[DSP_PRESET_NAME_MAX];
    float preamp_db;           
    uint8_t band_count;
    peq_band_t bands[DSP_MAX_BANDS];
} eq_preset_t;
 
int eq_preset_parse_autoeq(const char *text, eq_preset_t *out);
int eq_preset_format_autoeq(const eq_preset_t *p, char *out, size_t out_size);
uint32_t eq_builtin_count(void);
const eq_preset_t *eq_builtin_get(uint32_t index);
 
typedef enum { RG_OFF = 0, RG_TRACK, RG_ALBUM, RG_AUTO /* album gain when playing an album in order */ } rg_mode_t;
 
typedef struct {
    bool eq_enabled;
    eq_preset_t eq;
    rg_mode_t rg_mode;
    float rg_preamp_db;        
    float rg_fallback_db;      
    bool rg_prevent_clip;      
    bool crossfeed_enabled;
    uint16_t crossfeed_fcut_hz;  
    float crossfeed_level_db;    
    bool sw_volume;            
    float volume_db;           
    bool limiter_enabled;      
    uint8_t out_bits;          
} dsp_config_t;
 
void dsp_config_defaults(dsp_config_t *c);
 
enum {
    DSP_FLAG_RG = 1u << 0,
    DSP_FLAG_EQ = 1u << 1,
    DSP_FLAG_CROSSFEED = 1u << 2,
    DSP_FLAG_SW_VOLUME = 1u << 3,
    DSP_FLAG_LIMITER = 1u << 4,
    DSP_FLAG_DITHER = 1u << 5,
    DSP_FLAG_RESAMPLE = 1u << 6,  
};
 
typedef struct dsp dsp_t;
dsp_t *dsp_create(void);
void dsp_destroy(dsp_t *d);
void dsp_configure(dsp_t *d, const dsp_config_t *cfg, uint32_t sample_rate, uint8_t channels);
void dsp_set_replaygain(dsp_t *d, float track_gain_db, float track_peak, float album_gain_db, float album_peak,
                        bool album_context);
void dsp_process(dsp_t *d, int32_t *pcm, uint32_t frames);  
#define DSP_DRAIN_MAX 128u
uint32_t dsp_process_out(dsp_t *d, int32_t *pcm, uint32_t frames, uint32_t cap_frames);
void dsp_reset(dsp_t *d);                                   
bool dsp_is_bypass(const dsp_t *d);
uint32_t dsp_active_flags(const dsp_t *d);
 
// ---------------------------------------------------------------------------
// ---------------------------------------------------------------------------
typedef struct {
    float b0, b1, b2, a1, a2;  
} biquad_coef_t;
 
void biquad_design(biquad_coef_t *c, peq_type_t type, float fs, float f0, float gain_db, float q);
float biquad_response_db(const biquad_coef_t *c, float fs, float f);
 
void pcm_q31_to_f32(const int32_t *in, float *out, size_t samples);
void pcm_f32_to_q31(const float *in, int32_t *out, size_t samples);  
 
void pcm_q31_to_s16_dither(const int32_t *in, int16_t *out, size_t samples, uint32_t *state);
void pcm_mono_to_stereo(const int32_t *in, int32_t *out, size_t frames);
 
float db_to_lin(float db);
float lin_to_db(float lin);
 
#ifdef __cplusplus
}
#endif