dsps_resampler_mr.c File Reference

#include "dsps_resampler.h"
#include <math.h>

Include dependency graph for dsps_resampler_mr.c:

Go to the source code of this file.

Functions
esp_err_t	dsps_resampler_mr_init (dsps_resample_mr_t *resampler, void *coeffs, int16_t length, int16_t interp, float samplerate_factor, int32_t fixed_point, int16_t shift)
	Initialize the multi-rate resampler.
int32_t	dsps_resampler_mr_exec (dsps_resample_mr_t *resampler, void *input, void *output, int32_t length, int32_t length_correction)
	Execute the multi-rate resampler.
void	dsps_resampler_mr_free (dsps_resample_mr_t *resampler)
	Free the multi-rate resampler.

Variables
static const float	decim_avg_coeff = 0.9999

Function Documentation

dsps_resampler_mr_exec()

int32_t dsps_resampler_mr_exec	(	dsps_resample_mr_t *	resampler,
		void *	input,
		void *	output,
		int32_t	length,
		int32_t	length_correction )

Execute the multi-rate resampler.

This function executes the multi-rate resampler. The input and output buffers can be the same. The function based on multi-rate FIR filter. The decimation factor is updated for each execution. The current decimation factor calculated as division of average input and average output sample rate. To correct the output sample rate, the length_correction parameter is used. To increase the output sample rate, the length_correction parameter should be positive. To decrease the output sample rate, the length_correction parameter should be negative. This parameter is used when the input and output sample rates are comes from different sources.

Parameters

resampler	Pointer to the resampler structure
input	Pointer to the input buffer
output	Pointer to the output buffer
length	Length of the input buffers
length_correction	Length correction for the current execution. Positive value increases the output sample rate, negative value decreases the output sample rate.

Returns

Length of the output buffer

Definition at line 47 of file dsps_resampler_mr.c.

{
    int32_t result = 0;
 
    if (resampler->fixed_point == 0) {
        ((fir_f32_t *)resampler->filter)->decim = resampler->active_decim;
    } else {
        ((fir_s16_t *)resampler->filter)->decim = resampler->active_decim;
    }
 
    result = resampler->dsps_firmr(resampler->filter, input, output, length);
 
    resampler->decim_avg_in = resampler->decim_avg_in * decim_avg_coeff + (float)length * (1 - decim_avg_coeff);
    resampler->decim_avg_out = resampler->decim_avg_out * decim_avg_coeff + (float)(result - length_correction) * (1 - decim_avg_coeff);
 
    if ((resampler->decim_avg_in * resampler->samplerate_factor) > (resampler->decim_avg_out)) {
        resampler->active_decim = resampler->decim_f;
    } else {
        resampler->active_decim = resampler->decim_c;
    }
    return result;
}

References dsps_resample_mr_s::active_decim, decim_avg_coeff, dsps_resample_mr_s::decim_avg_in, dsps_resample_mr_s::decim_avg_out, dsps_resample_mr_s::decim_c, dsps_resample_mr_s::decim_f, dsps_resample_mr_s::dsps_firmr, dsps_resample_mr_s::filter, dsps_resample_mr_s::fixed_point, and dsps_resample_mr_s::samplerate_factor.

dsps_resampler_mr_free()

void dsps_resampler_mr_free

(

dsps_resample_mr_t *

resampler

)

Free the multi-rate resampler.

Parameters

resampler

Pointer to the resampler structure

Definition at line 70 of file dsps_resampler_mr.c.

{
    if (resampler->fixed_point == 0) {
        dsps_fir_f32_free((fir_f32_t *)(resampler->filter));
    } else {
        dsps_fird_s16_aexx_free((fir_s16_t *)(resampler->filter));
    }
    free(resampler->filter);
}

References dsps_fir_f32_free(), dsps_fird_s16_aexx_free(), dsps_resample_mr_s::filter, and dsps_resample_mr_s::fixed_point.

Here is the call graph for this function:

dsps_resampler_mr_init()

esp_err_t dsps_resampler_mr_init	(	dsps_resample_mr_t *	resampler,
		void *	coeffs,
		int16_t	length,
		int16_t	interp,
		float	samplerate_factor,
		int32_t	fixed_point,
		int16_t	shift )

Initialize the multi-rate resampler.

Parameters

resampler	Pointer to the resampler structure
coeffs	Pointer to the filter coefficients (float or int16_t for fixed point)
length	Length of the filter coefficients
interp	Interpolation factor for the filter
samplerate_factor	Sample rate factor
fixed_point	Fixed point flag, 0 for float, 1 for fixed point
shift	Shift value for fixed point

Returns

ESP_OK on success, ESP_ERR_INVALID_ARG if the parameters are invalid

Definition at line 12 of file dsps_resampler_mr.c.

{
    esp_err_t ret = ESP_OK;
 
    if (samplerate_factor < 1) {
        return ESP_ERR_DSP_INVALID_PARAM;
    }
 
    resampler->fixed_point = fixed_point;
    resampler->samplerate_factor = samplerate_factor;
    float decimation = (float)interp / samplerate_factor;
    resampler->decim_f = floor(decimation);
    resampler->decim_c = ceil(decimation);
    resampler->active_decim = resampler->decim_c;
    resampler->decim_avg_in = 1;
    resampler->decim_avg_out = resampler->samplerate_factor;
 
    if (fixed_point == 0) {
        resampler->dsps_firmr = (int32_t (*)(void *, void *, void *, int32_t))dsps_firmr_f32;
        resampler->filter = (void *)malloc(sizeof(fir_f32_t));
 
        ret = dsps_firmr_init_f32((fir_f32_t *)resampler->filter, coeffs, NULL, length, interp, resampler->decim_c, 0);
    } else {
        resampler->dsps_firmr = (int32_t (*)(void *, void *, void *, int32_t))dsps_firmr_s16;
        resampler->filter = (void *)malloc(sizeof(fir_s16_t));
        ret = dsps_firmr_init_s16((fir_s16_t *)resampler->filter, coeffs, NULL, length, interp, resampler->decim_c, 0, shift);
    }
 
    if (ret != ESP_OK) {
        return ret;
    }
 
    return ret;
}

References dsps_resample_mr_s::active_decim, coeffs, dsps_resample_mr_s::decim_avg_in, dsps_resample_mr_s::decim_avg_out, dsps_resample_mr_s::decim_c, dsps_resample_mr_s::decim_f, dsps_resample_mr_s::dsps_firmr, dsps_firmr_f32, dsps_firmr_init_f32(), dsps_firmr_init_s16(), dsps_firmr_s16, ESP_ERR_DSP_INVALID_PARAM, ESP_OK, dsps_resample_mr_s::filter, dsps_resample_mr_s::fixed_point, and dsps_resample_mr_s::samplerate_factor.

Here is the call graph for this function:

Variable Documentation

decim_avg_coeff

const float decim_avg_coeff = 0.9999

static

Definition at line 10 of file dsps_resampler_mr.c.

Referenced by dsps_resampler_mr_exec().