/**
* init MDCT or IMDCT computation.
*/
av_cold int ff_mdct_init(FFTContext *s, int nbits, int inverse, double scale)
{
int n, n4, i;
double alpha, theta;
int tstep;
memset(s, 0, sizeof(*s));
n = 1 << nbits;
s->mdct_bits = nbits;
s->mdct_size = n;
n4 = n >> 2;
s->mdct_permutation = FF_MDCT_PERM_NONE;
if (ff_fft_init(s, s->mdct_bits - 2, inverse) < 0)
goto fail;
s->tcos = av_malloc_array(n/2, sizeof(FFTSample));
if (!s->tcos)
goto fail;
switch (s->mdct_permutation) {
case FF_MDCT_PERM_NONE:
s->tsin = s->tcos + n4;
tstep = 1;
break;
case FF_MDCT_PERM_INTERLEAVE:
s->tsin = s->tcos + 1;
tstep = 2;
break;
default:
goto fail;
}
theta = 1.0 / 8.0 + (scale < 0 ? n4 : 0);
scale = sqrt(fabs(scale));
for(i=0;i<n4;i++) {
alpha = 2 * M_PI * (i + theta) / n;
#if FFT_FIXED_32
s->tcos[i*tstep] = lrint(-cos(alpha) * 2147483648.0);
s->tsin[i*tstep] = lrint(-sin(alpha) * 2147483648.0);
#else
s->tcos[i*tstep] = FIX15(-cos(alpha) * scale);
s->tsin[i*tstep] = FIX15(-sin(alpha) * scale);
#endif
}
return 0;
fail:
ff_mdct_end(s);
return -1;
}
/**
* init MDCT or IMDCT computation.
*/
av_cold int ff_mdct_init(FFTContext *s, int nbits, int inverse, double scale)
{
int n, n4, i;
double alpha, theta;
int tstep;
memset(s, 0, sizeof(*s));
n = 1 << nbits;
s->mdct_bits = nbits;
s->mdct_size = n;
n4 = n >> 2;
s->mdct_permutation = FF_MDCT_PERM_NONE;
if (ff_fft_init(s, s->mdct_bits - 2, inverse) < 0)
goto fail;
s->imdct_calc = ff_imdct_calc_c;
s->imdct_half = ff_imdct_half_c;
s->mdct_calc = ff_mdct_calc_c;
#if FFT_FLOAT
if (ARCH_AARCH64)
ff_mdct_init_aarch64(s);
if (ARCH_ARM)
ff_mdct_init_arm(s);
if (ARCH_PPC)
ff_mdct_init_ppc(s);
if (ARCH_X86)
ff_mdct_init_x86(s);
s->mdct_calcw = s->mdct_calc;
#else
s->mdct_calcw = ff_mdct_calcw_c;
if (ARCH_ARM)
ff_mdct_fixed_init_arm(s);
#endif
s->tcos = av_malloc(n/2 * sizeof(FFTSample));
if (!s->tcos)
goto fail;
switch (s->mdct_permutation) {
case FF_MDCT_PERM_NONE:
s->tsin = s->tcos + n4;
tstep = 1;
break;
case FF_MDCT_PERM_INTERLEAVE:
s->tsin = s->tcos + 1;
tstep = 2;
break;
default:
goto fail;
}
theta = 1.0 / 8.0 + (scale < 0 ? n4 : 0);
scale = sqrt(fabs(scale));
for(i=0;i<n4;i++) {
alpha = 2 * M_PI * (i + theta) / n;
s->tcos[i*tstep] = FIX15(-cos(alpha) * scale);
s->tsin[i*tstep] = FIX15(-sin(alpha) * scale);
}
return 0;
fail:
ff_mdct_end(s);
return -1;
}
