/**
* init MDCT or IMDCT computation.
*/
-av_cold int ff_mdct_init(MDCTContext *s, int nbits, int inverse)
+av_cold int ff_mdct_init(MDCTContext *s, int nbits, int inverse, double scale)
{
int n, n4, i;
- double alpha;
+ double alpha, theta;
memset(s, 0, sizeof(*s));
n = 1 << nbits;
if (!s->tsin)
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 + 1.0 / 8.0) / n;
- s->tcos[i] = -cos(alpha);
- s->tsin[i] = -sin(alpha);
+ alpha = 2 * M_PI * (i + theta) / n;
+ s->tcos[i] = -cos(alpha) * scale;
+ s->tsin[i] = -sin(alpha) * scale;
}
if (ff_fft_init(&s->fft, s->nbits - 2, inverse) < 0)
goto fail;