ESP32/components/audio-resampler/resampler.h

////////////////////////////////////////////////////////////////////////////
//                         **** RESAMPLER ****                            //
//                     Sinc-based Audio Resampling                        //
//                Copyright (c) 2006 - 2023 David Bryant.                 //
//                          All Rights Reserved.                          //
//      Distributed under the BSD Software License (see license.txt)      //
////////////////////////////////////////////////////////////////////////////

// resampler.h

#include <string.h>
#include <stdlib.h>
#include <stdint.h>
#include <stdio.h>
#define _USE_MATH_DEFINES
#include <math.h>

#ifdef ENABLE_THREADS
#include "workers.h"
#endif

#if defined(PATH_WIDTH) && (PATH_WIDTH == 64)
typedef double artsample_t;
#else
typedef float artsample_t;
#endif

#define SUBSAMPLE_INTERPOLATE   0x1
#define BLACKMAN_HARRIS         0x2
#define INCLUDE_LOWPASS         0x4
#define RESAMPLE_MULTITHREADED  0x8
#define NO_FILTER_REDUCTION     0x10
#define RESAMPLE_FIXED_RATIO    0x20 // internal use only, do not set
#define EXTRAPOLATE_ENDPOINTS   0x40
#define EXTRAPOLATE_PREFILL     0x80 // internal use only, do not set
#define EXTEND_CONVOLUTION_MATH 0x100
#define RESAMPLER_FLUSHED       0x200 // internal use only, do not set
#define RESAMPLER_SNAP_OFFSET   0x400 // internal use only, do not set

typedef struct {
  unsigned int input_used, output_generated;
} ResampleResult;

typedef struct resample {
  int numChannels, numSamples, numFilters, numTaps, inputIndex, flags;
  double *tempFilter, outputOffset, fixedRatio, lowpassRatio;
  double (*subsample)(struct resample *cxt, artsample_t *source, double offset);
  artsample_t **buffers, **filters;

#ifdef ENABLE_THREADS
  Workers *workers;
  const artsample_t *input;
  artsample_t *cbuffer, *output;
  int numInputFrames, numOutputFrames, stride;
  ResampleResult res;
  double ratio;
#endif
} Resample;

#ifdef __cplusplus
extern "C" {
#endif

Resample *resampleInit(int numChannels, int numTaps, int numFilters,
                       double lowpassRatio, int flags);
Resample *resampleFixedRatioInit(int numChannels, int numTaps, int maxFilters,
                                 double sourceRate, double destinRate,
                                 int lowpassFreq, int flags);
ResampleResult resampleProcess(Resample *cxt, const artsample_t *const *input,
                               int numInputFrames, artsample_t *const *output,
                               int numOutputFrames, double ratio);
ResampleResult resampleProcessInterleaved(Resample *cxt,
                                          const artsample_t *input,
                                          int numInputFrames,
                                          artsample_t *output,
                                          int numOutputFrames, double ratio);
ResampleResult resampleProcessAndFlush(Resample *cxt,
                                       const artsample_t *const *input,
                                       int numInputFrames,
                                       artsample_t *const *output,
                                       int numOutputFrames, double ratio);
ResampleResult
resampleProcessAndFlushInterleaved(Resample *cxt, const artsample_t *input,
                                   int numInputFrames, artsample_t *output,
                                   int numOutputFrames, double ratio);
unsigned int resampleGetRequiredSamples(Resample *cxt, int numOutputFrames,
                                        double ratio);
unsigned int resampleGetExpectedOutput(Resample *cxt, int numInputFrames,
                                       double ratio);
void resampleAdvancePosition(Resample *cxt, double delta);
double resampleGetLowpassRatio(Resample *cxt);
double resampleGetPosition(Resample *cxt);
int resampleGetNumFilters(Resample *cxt);
int resampleInterpolationUsed(Resample *cxt);
void resampleReset(Resample *cxt);
void resampleFree(Resample *cxt);

#ifdef __cplusplus
}
#endif