#include <stdio.h>#include <string.h>#include <errno.h>#include <sys/mman.h>#include <sys/types.h>#include <sys/stat.h>#include <unistd.h>#include <fcntl.h>#include <stdlib.h>#include <math.h>#define MINIMP3_IMPLEMENTATION#include "decode.h" #define MIN(a, b) ((a) < (b) ? (a) : (b)) static void get_spectrum(decoder *dec, int numch){    int i, ch, band;    const mp3dec_t *d = &dec->mp3d.mp3d;    // Average spectrum power for 32 frequency band    for (ch = 0; ch < numch; ch++)    {        for (band = 0; band < 32; band++)        {            float band_power = 0;            for (i = 0; i < 9; i++)            {                float sample = d->mdct_overlap[ch][i + band*9];                band_power += sample*sample;            }            // with averaging            //dec->spectrum[band][ch] += (band_power/9 - spectrum[band][ch]) * 0.25;             // w/o averaging            dec->spectrum[band][ch] = band_power/9;        }    }    // Calculate dB scale from power for better visualization    for (ch = 0; ch < numch; ch++)    {        for (band = 0; band < 32; band++)        {            float power = dec->spectrum[band][ch];            float db_offset = 100;      // to shift dB values from [0..-inf] to [max..0]            float db = 10*log10f(power + 1e-15) + db_offset;            if (db < 0) db = 0;            //printf("% .5f\t", db);        }        //printf("\n");    }} void decode_samples(decoder *dec, uint8_t *buf, int bytes){    memset(buf, 0, bytes);    mp3dec_ex_read(&dec->mp3d, (mp3d_sample_t*)buf, bytes/sizeof(mp3d_sample_t));} int open_dec(decoder *dec, const char *file_name){    if (!dec || !file_name || !*file_name)        return 0;     memset(dec, 0, sizeof(*dec));     mp3dec_ex_open(&dec->mp3d, file_name, MP3D_SEEK_TO_SAMPLE);    if (!dec->mp3d.samples)        return 0;    return 1;} int close_dec(decoder *dec){    mp3dec_ex_close(&dec->mp3d);    memset(dec, 0, sizeof(*dec));}