pitchamdf
Files: pitchamdf.h, pitchamdf.c

Pitch detection using AMDF method. Pitchamdf tracks the pitch of signal using the AMDF (Average Magnitude Difference Function) method of Pitch following.

Functions

sp_pitchamdf_create(sp_pitchamdf **pitchamdf)
sp_pitchamdf_init(sp_data *sp, sp_pitchamdf *pitchamdf, SPFLOAT min, SPFLOAT max)
sp_pitchamdf_compute(sp_data *sp, sp_pitchamdf *pitchamdf, SPFLOAT *input, SPFLOAT *freq, SPFLOAT *rms)
sp_pitchamdf_destroy(sp_pitchamdf **pitchamdf)

Mandatory Parameters

min: Minimum expected frequency to detect
(Recommended value: 200)
max: Maximum expected frequency to detect
(Recommended value: 500)

Inputs

input: Signal input

Outputs

freq: Detected frequency.
rms: Average amplitude.

Example Code

#include <stdlib.h>
#include <stdio.h>
#include <time.h>
#include "soundpipe.h"

typedef struct {
    sp_pitchamdf *pitchamdf;
    sp_osc *osc;
    sp_ftbl *ft;
    sp_blsaw *blsaw;
    sp_randh *randh;
} UserData;

void process(sp_data *sp, void *udata) {
    UserData *ud = udata;
    SPFLOAT freq = 0, amp = 0, blsaw = 0, randh = 0, osc = 0;
    sp_randh_compute(sp, ud->randh, NULL, &randh);
    *ud->blsaw->freq = randh;
    sp_blsaw_compute(sp, ud->blsaw, NULL, &blsaw);
    sp_pitchamdf_compute(sp, ud->pitchamdf, &blsaw, &freq, &);
    ud->osc->freq = freq;
    sp_osc_compute(sp, ud->osc, NULL, &osc);
    sp->out[0] = osc;
}

int main() {
    srand(1234567);
    UserData ud;
    sp_data *sp;
    sp_create(&sp);

    sp_pitchamdf_create(&ud.pitchamdf);
    sp_osc_create(&ud.osc);
    sp_ftbl_create(sp, &ud.ft, 2048);
    sp_blsaw_create(&ud.blsaw);
    sp_randh_create(&ud.randh);

    sp_pitchamdf_init(sp, ud.pitchamdf, 200, 500);
    sp_randh_init(sp, ud.randh);
    ud.randh->max = 500;
    ud.randh->min = 200;
    ud.randh->freq = 6;

    sp_blsaw_init(sp, ud.blsaw);

    sp_gen_sine(sp, ud.ft);
    sp_osc_init(sp, ud.osc, ud.ft, 0);

    sp->len = 44100 * 5;
    sp_process(sp, &ud, process);

    sp_blsaw_destroy(&ud.blsaw);
    sp_randh_destroy(&ud.randh);
    sp_pitchamdf_destroy(&ud.pitchamdf);
    sp_ftbl_destroy(&ud.ft);
    sp_osc_destroy(&ud.osc);

    sp_destroy(&sp);
    return 0;
}