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ffmpeg / libavcodec / fft-test.c @ 727c236a

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1 983e3246 Michael Niedermayer
/**
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 * @file fft-test.c
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 * FFT and MDCT tests.
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 */
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6 bb6f5690 Fabrice Bellard
#include "dsputil.h"
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#include <math.h>
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#include <unistd.h>
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#include <sys/time.h>
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int mm_flags;
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/* reference fft */
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#define MUL16(a,b) ((a) * (b))
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#define CMAC(pre, pim, are, aim, bre, bim) \
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{\
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   pre += (MUL16(are, bre) - MUL16(aim, bim));\
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   pim += (MUL16(are, bim) + MUL16(bre, aim));\
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}
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FFTComplex *exptab;
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void fft_ref_init(int nbits, int inverse)
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{
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    int n, i;
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    float c1, s1, alpha;
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    n = 1 << nbits;
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    exptab = av_malloc((n / 2) * sizeof(FFTComplex));
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    for(i=0;i<(n/2);i++) {
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        alpha = 2 * M_PI * (float)i / (float)n;
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        c1 = cos(alpha);
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        s1 = sin(alpha);
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        if (!inverse)
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            s1 = -s1;
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        exptab[i].re = c1;
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        exptab[i].im = s1;
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    }
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}
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void fft_ref(FFTComplex *tabr, FFTComplex *tab, int nbits)
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{
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    int n, i, j, k, n2;
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    float tmp_re, tmp_im, s, c;
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    FFTComplex *q;
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    n = 1 << nbits;
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    n2 = n >> 1;
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    for(i=0;i<n;i++) {
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        tmp_re = 0;
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        tmp_im = 0;
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        q = tab;
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        for(j=0;j<n;j++) {
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            k = (i * j) & (n - 1);
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            if (k >= n2) {
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                c = -exptab[k - n2].re;
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                s = -exptab[k - n2].im;
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            } else {
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                c = exptab[k].re;
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                s = exptab[k].im;
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            }
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            CMAC(tmp_re, tmp_im, c, s, q->re, q->im);
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            q++;
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        }
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        tabr[i].re = tmp_re;
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        tabr[i].im = tmp_im;
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    }
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}
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void imdct_ref(float *out, float *in, int n)
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{
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    int k, i, a;
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    float sum, f;
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    for(i=0;i<n;i++) {
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        sum = 0;
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        for(k=0;k<n/2;k++) {
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            a = (2 * i + 1 + (n / 2)) * (2 * k + 1);
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            f = cos(M_PI * a / (double)(2 * n));
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            sum += f * in[k];
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        }
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        out[i] = -sum;
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    }
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}
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/* NOTE: no normalisation by 1 / N is done */
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void mdct_ref(float *output, float *input, int n)
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{
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    int k, i;
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    float a, s;
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    /* do it by hand */
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    for(k=0;k<n/2;k++) {
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        s = 0;
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        for(i=0;i<n;i++) {
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            a = (2*M_PI*(2*i+1+n/2)*(2*k+1) / (4 * n));
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            s += input[i] * cos(a);
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        }
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        output[k] = s;
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    }
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}
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float frandom(void)
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{
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    return (float)((random() & 0xffff) - 32768) / 32768.0;
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}
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int64_t gettime(void)
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{
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    struct timeval tv;
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    gettimeofday(&tv,NULL);
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    return (int64_t)tv.tv_sec * 1000000 + tv.tv_usec;
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}
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void check_diff(float *tab1, float *tab2, int n)
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{
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    int i;
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    for(i=0;i<n;i++) {
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        if (fabsf(tab1[i] - tab2[i]) >= 1e-3) {
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            av_log(NULL, AV_LOG_ERROR, "ERROR %d: %f %f\n",
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                   i, tab1[i], tab2[i]);
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        }
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    }
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}
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void help(void)
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{
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    av_log(NULL, AV_LOG_INFO,"usage: fft-test [-h] [-s] [-i] [-n b]\n"
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           "-h     print this help\n"
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           "-s     speed test\n"
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           "-m     (I)MDCT test\n"
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           "-i     inverse transform test\n"
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           "-n b   set the transform size to 2^b\n"
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           );
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    exit(1);
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}
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int main(int argc, char **argv)
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{
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    FFTComplex *tab, *tab1, *tab_ref;
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    FFTSample *tabtmp, *tab2;
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    int it, i, c;
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    int do_speed = 0;
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    int do_mdct = 0;
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    int do_inverse = 0;
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    FFTContext s1, *s = &s1;
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    MDCTContext m1, *m = &m1;
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    int fft_nbits, fft_size;
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    mm_flags = 0;
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    fft_nbits = 9;
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    for(;;) {
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        c = getopt(argc, argv, "hsimn:");
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        if (c == -1)
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            break;
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        switch(c) {
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        case 'h':
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            help();
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            break;
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        case 's':
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            do_speed = 1;
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            break;
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        case 'i':
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            do_inverse = 1;
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            break;
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        case 'm':
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            do_mdct = 1;
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            break;
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        case 'n':
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            fft_nbits = atoi(optarg);
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            break;
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        }
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    }
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    fft_size = 1 << fft_nbits;
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    tab = av_malloc(fft_size * sizeof(FFTComplex));
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    tab1 = av_malloc(fft_size * sizeof(FFTComplex));
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    tab_ref = av_malloc(fft_size * sizeof(FFTComplex));
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    tabtmp = av_malloc(fft_size / 2 * sizeof(FFTSample));
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    tab2 = av_malloc(fft_size * sizeof(FFTSample));
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    if (do_mdct) {
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        if (do_inverse)
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            av_log(NULL, AV_LOG_INFO,"IMDCT");
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        else
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            av_log(NULL, AV_LOG_INFO,"MDCT");
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        ff_mdct_init(m, fft_nbits, do_inverse);
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    } else {
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        if (do_inverse)
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            av_log(NULL, AV_LOG_INFO,"IFFT");
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        else
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            av_log(NULL, AV_LOG_INFO,"FFT");
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        ff_fft_init(s, fft_nbits, do_inverse);
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        fft_ref_init(fft_nbits, do_inverse);
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    }
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    av_log(NULL, AV_LOG_INFO," %d test\n", fft_size);
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    /* generate random data */
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    for(i=0;i<fft_size;i++) {
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        tab1[i].re = frandom();
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        tab1[i].im = frandom();
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    }
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    /* checking result */
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    av_log(NULL, AV_LOG_INFO,"Checking...\n");
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    if (do_mdct) {
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        if (do_inverse) {
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            imdct_ref((float *)tab_ref, (float *)tab1, fft_size);
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            ff_imdct_calc(m, tab2, (float *)tab1, tabtmp);
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            check_diff((float *)tab_ref, tab2, fft_size);
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        } else {
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            mdct_ref((float *)tab_ref, (float *)tab1, fft_size);
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            ff_mdct_calc(m, tab2, (float *)tab1, tabtmp);
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            check_diff((float *)tab_ref, tab2, fft_size / 2);
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        }
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    } else {
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        memcpy(tab, tab1, fft_size * sizeof(FFTComplex));
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        ff_fft_permute(s, tab);
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        ff_fft_calc(s, tab);
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        fft_ref(tab_ref, tab1, fft_nbits);
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        check_diff((float *)tab_ref, (float *)tab, fft_size * 2);
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    }
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    /* do a speed test */
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    if (do_speed) {
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        int64_t time_start, duration;
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        int nb_its;
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        av_log(NULL, AV_LOG_INFO,"Speed test...\n");
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        /* we measure during about 1 seconds */
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        nb_its = 1;
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        for(;;) {
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            time_start = gettime();
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            for(it=0;it<nb_its;it++) {
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                if (do_mdct) {
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                    if (do_inverse) {
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                        ff_imdct_calc(m, (float *)tab, (float *)tab1, tabtmp);
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                    } else {
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                        ff_mdct_calc(m, (float *)tab, (float *)tab1, tabtmp);
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                    }
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                } else {
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                    memcpy(tab, tab1, fft_size * sizeof(FFTComplex));
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                    ff_fft_calc(s, tab);
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                }
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            }
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            duration = gettime() - time_start;
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            if (duration >= 1000000)
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                break;
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            nb_its *= 2;
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        }
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        av_log(NULL, AV_LOG_INFO,"time: %0.1f us/transform [total time=%0.2f s its=%d]\n",
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               (double)duration / nb_its,
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               (double)duration / 1000000.0,
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               nb_its);
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    }
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    if (do_mdct) {
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        ff_mdct_end(m);
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    } else {
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        ff_fft_end(s);
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    }
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    return 0;
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}