libavcodec/fft-test.c

Go to the documentation of this file.

/*
 * (c) 2002 Fabrice Bellard
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include "libavutil/mathematics.h"
#include "libavutil/lfg.h"
#include "libavutil/log.h"
#include "fft.h"
#if CONFIG_FFT_FLOAT
#include "dct.h"
#include "rdft.h"
#endif
#include <math.h>
#include <unistd.h>
#include <sys/time.h>
#include <stdlib.h>
#include <string.h>

#undef exit

/* reference fft */

#define MUL16(a,b) ((a) * (b))

#define CMAC(pre, pim, are, aim, bre, bim) \
{\
   pre += (MUL16(are, bre) - MUL16(aim, bim));\
   pim += (MUL16(are, bim) + MUL16(bre, aim));\
}

#if CONFIG_FFT_FLOAT
#   define RANGE 1.0
#   define REF_SCALE(x, bits)  (x)
#   define FMT "%10.6f"
#else
#   define RANGE 16384
#   define REF_SCALE(x, bits) ((x) / (1<<(bits)))
#   define FMT "%6d"
#endif

struct {
    float re, im;
} *exptab;

static void fft_ref_init(int nbits, int inverse)
{
    int n, i;
    double c1, s1, alpha;

    n = 1 << nbits;
    exptab = av_malloc((n / 2) * sizeof(*exptab));

    for (i = 0; i < (n/2); i++) {
        alpha = 2 * M_PI * (float)i / (float)n;
        c1 = cos(alpha);
        s1 = sin(alpha);
        if (!inverse)
            s1 = -s1;
        exptab[i].re = c1;
        exptab[i].im = s1;
    }
}

static void fft_ref(FFTComplex *tabr, FFTComplex *tab, int nbits)
{
    int n, i, j, k, n2;
    double tmp_re, tmp_im, s, c;
    FFTComplex *q;

    n = 1 << nbits;
    n2 = n >> 1;
    for (i = 0; i < n; i++) {
        tmp_re = 0;
        tmp_im = 0;
        q = tab;
        for (j = 0; j < n; j++) {
            k = (i * j) & (n - 1);
            if (k >= n2) {
                c = -exptab[k - n2].re;
                s = -exptab[k - n2].im;
            } else {
                c = exptab[k].re;
                s = exptab[k].im;
            }
            CMAC(tmp_re, tmp_im, c, s, q->re, q->im);
            q++;
        }
        tabr[i].re = REF_SCALE(tmp_re, nbits);
        tabr[i].im = REF_SCALE(tmp_im, nbits);
    }
}

static void imdct_ref(FFTSample *out, FFTSample *in, int nbits)
{
    int n = 1<<nbits;
    int k, i, a;
    double sum, f;

    for (i = 0; i < n; i++) {
        sum = 0;
        for (k = 0; k < n/2; k++) {
            a = (2 * i + 1 + (n / 2)) * (2 * k + 1);
            f = cos(M_PI * a / (double)(2 * n));
            sum += f * in[k];
        }
        out[i] = REF_SCALE(-sum, nbits - 2);
    }
}

/* NOTE: no normalisation by 1 / N is done */
static void mdct_ref(FFTSample *output, FFTSample *input, int nbits)
{
    int n = 1<<nbits;
    int k, i;
    double a, s;

    /* do it by hand */
    for (k = 0; k < n/2; k++) {
        s = 0;
        for (i = 0; i < n; i++) {
            a = (2*M_PI*(2*i+1+n/2)*(2*k+1) / (4 * n));
            s += input[i] * cos(a);
        }
        output[k] = REF_SCALE(s, nbits - 1);
    }
}

#if CONFIG_FFT_FLOAT
static void idct_ref(float *output, float *input, int nbits)
{
    int n = 1<<nbits;
    int k, i;
    double a, s;

    /* do it by hand */
    for (i = 0; i < n; i++) {
        s = 0.5 * input[0];
        for (k = 1; k < n; k++) {
            a = M_PI*k*(i+0.5) / n;
            s += input[k] * cos(a);
        }
        output[i] = 2 * s / n;
    }
}
static void dct_ref(float *output, float *input, int nbits)
{
    int n = 1<<nbits;
    int k, i;
    double a, s;

    /* do it by hand */
    for (k = 0; k < n; k++) {
        s = 0;
        for (i = 0; i < n; i++) {
            a = M_PI*k*(i+0.5) / n;
            s += input[i] * cos(a);
        }
        output[k] = s;
    }
}
#endif


static FFTSample frandom(AVLFG *prng)
{
    return (int16_t)av_lfg_get(prng) / 32768.0 * RANGE;
}

static int64_t gettime(void)
{
    struct timeval tv;
    gettimeofday(&tv,NULL);
    return (int64_t)tv.tv_sec * 1000000 + tv.tv_usec;
}

static int check_diff(FFTSample *tab1, FFTSample *tab2, int n, double scale)
{
    int i;
    double max= 0;
    double error= 0;
    int err = 0;

    for (i = 0; i < n; i++) {
        double e = fabsf(tab1[i] - (tab2[i] / scale)) / RANGE;
        if (e >= 1e-3) {
            av_log(NULL, AV_LOG_ERROR, "ERROR %5d: "FMT" "FMT"\n",
                   i, tab1[i], tab2[i]);
            err = 1;
        }
        error+= e*e;
        if(e>max) max= e;
    }
    av_log(NULL, AV_LOG_INFO, "max:%f e:%g\n", max, sqrt(error)/n);
    return err;
}


static void help(void)
{
    av_log(NULL, AV_LOG_INFO,"usage: fft-test [-h] [-s] [-i] [-n b]\n"
           "-h     print this help\n"
           "-s     speed test\n"
           "-m     (I)MDCT test\n"
           "-d     (I)DCT test\n"
           "-r     (I)RDFT test\n"
           "-i     inverse transform test\n"
           "-n b   set the transform size to 2^b\n"
           "-f x   set scale factor for output data of (I)MDCT to x\n"
           );
    exit(1);
}

enum tf_transform {
    TRANSFORM_FFT,
    TRANSFORM_MDCT,
    TRANSFORM_RDFT,
    TRANSFORM_DCT,
};

int main(int argc, char **argv)
{
    FFTComplex *tab, *tab1, *tab_ref;
    FFTSample *tab2;
    int it, i, c;
    int do_speed = 0;
    int err = 1;
    enum tf_transform transform = TRANSFORM_FFT;
    int do_inverse = 0;
    FFTContext s1, *s = &s1;
    FFTContext m1, *m = &m1;
#if CONFIG_FFT_FLOAT
    RDFTContext r1, *r = &r1;
    DCTContext d1, *d = &d1;
#endif
    int fft_nbits, fft_size, fft_size_2;
    double scale = 1.0;
    AVLFG prng;
    av_lfg_init(&prng, 1);

    fft_nbits = 9;
    for(;;) {
        c = getopt(argc, argv, "hsimrdn:f:");
        if (c == -1)
            break;
        switch(c) {
        case 'h':
            help();
            break;
        case 's':
            do_speed = 1;
            break;
        case 'i':
            do_inverse = 1;
            break;
        case 'm':
            transform = TRANSFORM_MDCT;
            break;
        case 'r':
            transform = TRANSFORM_RDFT;
            break;
        case 'd':
            transform = TRANSFORM_DCT;
            break;
        case 'n':
            fft_nbits = atoi(optarg);
            break;
        case 'f':
            scale = atof(optarg);
            break;
        }
    }

    fft_size = 1 << fft_nbits;
    fft_size_2 = fft_size >> 1;
    tab = av_malloc(fft_size * sizeof(FFTComplex));
    tab1 = av_malloc(fft_size * sizeof(FFTComplex));
    tab_ref = av_malloc(fft_size * sizeof(FFTComplex));
    tab2 = av_malloc(fft_size * sizeof(FFTSample));

    switch (transform) {
    case TRANSFORM_MDCT:
        av_log(NULL, AV_LOG_INFO,"Scale factor is set to %f\n", scale);
        if (do_inverse)
            av_log(NULL, AV_LOG_INFO,"IMDCT");
        else
            av_log(NULL, AV_LOG_INFO,"MDCT");
        ff_mdct_init(m, fft_nbits, do_inverse, scale);
        break;
    case TRANSFORM_FFT:
        if (do_inverse)
            av_log(NULL, AV_LOG_INFO,"IFFT");
        else
            av_log(NULL, AV_LOG_INFO,"FFT");
        ff_fft_init(s, fft_nbits, do_inverse);
        fft_ref_init(fft_nbits, do_inverse);
        break;
#if CONFIG_FFT_FLOAT
    case TRANSFORM_RDFT:
        if (do_inverse)
            av_log(NULL, AV_LOG_INFO,"IDFT_C2R");
        else
            av_log(NULL, AV_LOG_INFO,"DFT_R2C");
        ff_rdft_init(r, fft_nbits, do_inverse ? IDFT_C2R : DFT_R2C);
        fft_ref_init(fft_nbits, do_inverse);
        break;
    case TRANSFORM_DCT:
        if (do_inverse)
            av_log(NULL, AV_LOG_INFO,"DCT_III");
        else
            av_log(NULL, AV_LOG_INFO,"DCT_II");
        ff_dct_init(d, fft_nbits, do_inverse ? DCT_III : DCT_II);
        break;
#endif
    default:
        av_log(NULL, AV_LOG_ERROR, "Requested transform not supported\n");
        return 1;
    }
    av_log(NULL, AV_LOG_INFO," %d test\n", fft_size);

    /* generate random data */

    for (i = 0; i < fft_size; i++) {
        tab1[i].re = frandom(&prng);
        tab1[i].im = frandom(&prng);
    }

    /* checking result */
    av_log(NULL, AV_LOG_INFO,"Checking...\n");

    switch (transform) {
    case TRANSFORM_MDCT:
        if (do_inverse) {
            imdct_ref((FFTSample *)tab_ref, (FFTSample *)tab1, fft_nbits);
            m->imdct_calc(m, tab2, (FFTSample *)tab1);
            err = check_diff((FFTSample *)tab_ref, tab2, fft_size, scale);
        } else {
            mdct_ref((FFTSample *)tab_ref, (FFTSample *)tab1, fft_nbits);

            m->mdct_calc(m, tab2, (FFTSample *)tab1);

            err = check_diff((FFTSample *)tab_ref, tab2, fft_size / 2, scale);
        }
        break;
    case TRANSFORM_FFT:
        memcpy(tab, tab1, fft_size * sizeof(FFTComplex));
        s->fft_permute(s, tab);
        s->fft_calc(s, tab);

        fft_ref(tab_ref, tab1, fft_nbits);
        err = check_diff((FFTSample *)tab_ref, (FFTSample *)tab, fft_size * 2, 1.0);
        break;
#if CONFIG_FFT_FLOAT
    case TRANSFORM_RDFT:
        if (do_inverse) {
            tab1[         0].im = 0;
            tab1[fft_size_2].im = 0;
            for (i = 1; i < fft_size_2; i++) {
                tab1[fft_size_2+i].re =  tab1[fft_size_2-i].re;
                tab1[fft_size_2+i].im = -tab1[fft_size_2-i].im;
            }

            memcpy(tab2, tab1, fft_size * sizeof(FFTSample));
            tab2[1] = tab1[fft_size_2].re;

            r->rdft_calc(r, tab2);
            fft_ref(tab_ref, tab1, fft_nbits);
            for (i = 0; i < fft_size; i++) {
                tab[i].re = tab2[i];
                tab[i].im = 0;
            }
            err = check_diff((float *)tab_ref, (float *)tab, fft_size * 2, 0.5);
        } else {
            for (i = 0; i < fft_size; i++) {
                tab2[i]    = tab1[i].re;
                tab1[i].im = 0;
            }
            r->rdft_calc(r, tab2);
            fft_ref(tab_ref, tab1, fft_nbits);
            tab_ref[0].im = tab_ref[fft_size_2].re;
            err = check_diff((float *)tab_ref, (float *)tab2, fft_size, 1.0);
        }
        break;
    case TRANSFORM_DCT:
        memcpy(tab, tab1, fft_size * sizeof(FFTComplex));
        d->dct_calc(d, tab);
        if (do_inverse) {
            idct_ref(tab_ref, tab1, fft_nbits);
        } else {
            dct_ref(tab_ref, tab1, fft_nbits);
        }
        err = check_diff((float *)tab_ref, (float *)tab, fft_size, 1.0);
        break;
#endif
    }

    /* do a speed test */

    if (do_speed) {
        int64_t time_start, duration;
        int nb_its;

        av_log(NULL, AV_LOG_INFO,"Speed test...\n");
        /* we measure during about 1 seconds */
        nb_its = 1;
        for(;;) {
            time_start = gettime();
            for (it = 0; it < nb_its; it++) {
                switch (transform) {
                case TRANSFORM_MDCT:
                    if (do_inverse) {
                        m->imdct_calc(m, (FFTSample *)tab, (FFTSample *)tab1);
                    } else {
                        m->mdct_calc(m, (FFTSample *)tab, (FFTSample *)tab1);
                    }
                    break;
                case TRANSFORM_FFT:
                    memcpy(tab, tab1, fft_size * sizeof(FFTComplex));
                    s->fft_calc(s, tab);
                    break;
#if CONFIG_FFT_FLOAT
                case TRANSFORM_RDFT:
                    memcpy(tab2, tab1, fft_size * sizeof(FFTSample));
                    r->rdft_calc(r, tab2);
                    break;
                case TRANSFORM_DCT:
                    memcpy(tab2, tab1, fft_size * sizeof(FFTSample));
                    d->dct_calc(d, tab2);
                    break;
#endif
                }
            }
            duration = gettime() - time_start;
            if (duration >= 1000000)
                break;
            nb_its *= 2;
        }
        av_log(NULL, AV_LOG_INFO,"time: %0.1f us/transform [total time=%0.2f s its=%d]\n",
               (double)duration / nb_its,
               (double)duration / 1000000.0,
               nb_its);
    }

    switch (transform) {
    case TRANSFORM_MDCT:
        ff_mdct_end(m);
        break;
    case TRANSFORM_FFT:
        ff_fft_end(s);
        break;
#if CONFIG_FFT_FLOAT
    case TRANSFORM_RDFT:
        ff_rdft_end(r);
        break;
    case TRANSFORM_DCT:
        ff_dct_end(d);
        break;
#endif
    }

    av_free(tab);
    av_free(tab1);
    av_free(tab2);
    av_free(tab_ref);
    av_free(exptab);

    return err;
}

---