/*
* MDCT/IMDCT transforms
- * Copyright (c) 2002 Fabrice Bellard.
+ * Copyright (c) 2002 Fabrice Bellard
*
* This file is part of FFmpeg.
*
#include "dsputil.h"
/**
- * @file mdct.c
+ * @file libavcodec/mdct.c
* MDCT/IMDCT transforms.
*/
// Generate a Kaiser-Bessel Derived Window.
#define BESSEL_I0_ITER 50 // default: 50 iterations of Bessel I0 approximation
-void ff_kbd_window_init(float *window, float alpha, int n)
+av_cold void ff_kbd_window_init(float *window, float alpha, int n)
{
int i, j;
double sum = 0.0, bessel, tmp;
window[i] = sqrt(local_window[i] / sum);
}
+#include "mdct_tablegen.h"
+
/**
* init MDCT or IMDCT computation.
*/
-int ff_mdct_init(MDCTContext *s, int nbits, int inverse)
+av_cold int ff_mdct_init(FFTContext *s, int nbits, int inverse, double scale)
{
int n, n4, i;
- float alpha;
+ double alpha, theta;
+ int tstep;
memset(s, 0, sizeof(*s));
n = 1 << nbits;
- s->nbits = nbits;
- s->n = n;
+ s->mdct_bits = nbits;
+ s->mdct_size = n;
n4 = n >> 2;
- s->tcos = av_malloc(n4 * sizeof(FFTSample));
+ s->permutation = FF_MDCT_PERM_NONE;
+
+ if (ff_fft_init(s, s->mdct_bits - 2, inverse) < 0)
+ goto fail;
+
+ s->tcos = av_malloc(n/2 * sizeof(FFTSample));
if (!s->tcos)
goto fail;
- s->tsin = av_malloc(n4 * sizeof(FFTSample));
- if (!s->tsin)
+
+ switch (s->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 + 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*tstep] = -cos(alpha) * scale;
+ s->tsin[i*tstep] = -sin(alpha) * scale;
}
- if (ff_fft_init(&s->fft, s->nbits - 2, inverse) < 0)
- goto fail;
return 0;
fail:
- av_freep(&s->tcos);
- av_freep(&s->tsin);
+ ff_mdct_end(s);
return -1;
}
/* complex multiplication: p = a * b */
#define CMUL(pre, pim, are, aim, bre, bim) \
{\
- float _are = (are);\
- float _aim = (aim);\
- float _bre = (bre);\
- float _bim = (bim);\
+ FFTSample _are = (are);\
+ FFTSample _aim = (aim);\
+ FFTSample _bre = (bre);\
+ FFTSample _bim = (bim);\
(pre) = _are * _bre - _aim * _bim;\
(pim) = _are * _bim + _aim * _bre;\
}
/**
- * Compute inverse MDCT of size N = 2^nbits
- * @param output N samples
+ * Compute the middle half of the inverse MDCT of size N = 2^nbits,
+ * thus excluding the parts that can be derived by symmetry
+ * @param output N/2 samples
* @param input N/2 samples
- * @param tmp N/2 samples
*/
-void ff_imdct_calc(MDCTContext *s, FFTSample *output,
- const FFTSample *input, FFTSample *tmp)
+void ff_imdct_half_c(FFTContext *s, FFTSample *output, const FFTSample *input)
{
int k, n8, n4, n2, n, j;
- const uint16_t *revtab = s->fft.revtab;
+ const uint16_t *revtab = s->revtab;
const FFTSample *tcos = s->tcos;
const FFTSample *tsin = s->tsin;
const FFTSample *in1, *in2;
- FFTComplex *z = (FFTComplex *)tmp;
+ FFTComplex *z = (FFTComplex *)output;
- n = 1 << s->nbits;
+ n = 1 << s->mdct_bits;
n2 = n >> 1;
n4 = n >> 2;
n8 = n >> 3;
in1 += 2;
in2 -= 2;
}
- ff_fft_calc(&s->fft, z);
+ ff_fft_calc(s, z);
/* post rotation + reordering */
- /* XXX: optimize */
- for(k = 0; k < n4; k++) {
- CMUL(z[k].re, z[k].im, z[k].re, z[k].im, tcos[k], tsin[k]);
- }
for(k = 0; k < n8; k++) {
- output[2*k] = -z[n8 + k].im;
- output[n2-1-2*k] = z[n8 + k].im;
+ FFTSample r0, i0, r1, i1;
+ CMUL(r0, i1, z[n8-k-1].im, z[n8-k-1].re, tsin[n8-k-1], tcos[n8-k-1]);
+ CMUL(r1, i0, z[n8+k ].im, z[n8+k ].re, tsin[n8+k ], tcos[n8+k ]);
+ z[n8-k-1].re = r0;
+ z[n8-k-1].im = i0;
+ z[n8+k ].re = r1;
+ z[n8+k ].im = i1;
+ }
+}
- output[2*k+1] = z[n8-1-k].re;
- output[n2-1-2*k-1] = -z[n8-1-k].re;
+/**
+ * Compute inverse MDCT of size N = 2^nbits
+ * @param output N samples
+ * @param input N/2 samples
+ */
+void ff_imdct_calc_c(FFTContext *s, FFTSample *output, const FFTSample *input)
+{
+ int k;
+ int n = 1 << s->mdct_bits;
+ int n2 = n >> 1;
+ int n4 = n >> 2;
- output[n2 + 2*k]=-z[k+n8].re;
- output[n-1- 2*k]=-z[k+n8].re;
+ ff_imdct_half_c(s, output+n4, input);
- output[n2 + 2*k+1]=z[n8-k-1].im;
- output[n-2 - 2 * k] = z[n8-k-1].im;
+ for(k = 0; k < n4; k++) {
+ output[k] = -output[n2-k-1];
+ output[n-k-1] = output[n2+k];
}
}
* Compute MDCT of size N = 2^nbits
* @param input N samples
* @param out N/2 samples
- * @param tmp temporary storage of N/2 samples
*/
-void ff_mdct_calc(MDCTContext *s, FFTSample *out,
- const FFTSample *input, FFTSample *tmp)
+void ff_mdct_calc_c(FFTContext *s, FFTSample *out, const FFTSample *input)
{
int i, j, n, n8, n4, n2, n3;
- FFTSample re, im, re1, im1;
- const uint16_t *revtab = s->fft.revtab;
+ FFTSample re, im;
+ const uint16_t *revtab = s->revtab;
const FFTSample *tcos = s->tcos;
const FFTSample *tsin = s->tsin;
- FFTComplex *x = (FFTComplex *)tmp;
+ FFTComplex *x = (FFTComplex *)out;
- n = 1 << s->nbits;
+ n = 1 << s->mdct_bits;
n2 = n >> 1;
n4 = n >> 2;
n8 = n >> 3;
CMUL(x[j].re, x[j].im, re, im, -tcos[n8 + i], tsin[n8 + i]);
}
- ff_fft_calc(&s->fft, x);
+ ff_fft_calc(s, x);
/* post rotation */
- for(i=0;i<n4;i++) {
- re = x[i].re;
- im = x[i].im;
- CMUL(re1, im1, re, im, -tsin[i], -tcos[i]);
- out[2*i] = im1;
- out[n2-1-2*i] = re1;
+ for(i=0;i<n8;i++) {
+ FFTSample r0, i0, r1, i1;
+ CMUL(i1, r0, x[n8-i-1].re, x[n8-i-1].im, -tsin[n8-i-1], -tcos[n8-i-1]);
+ CMUL(i0, r1, x[n8+i ].re, x[n8+i ].im, -tsin[n8+i ], -tcos[n8+i ]);
+ x[n8-i-1].re = r0;
+ x[n8-i-1].im = i0;
+ x[n8+i ].re = r1;
+ x[n8+i ].im = i1;
}
}
-void ff_mdct_end(MDCTContext *s)
+av_cold void ff_mdct_end(FFTContext *s)
{
av_freep(&s->tcos);
- av_freep(&s->tsin);
- ff_fft_end(&s->fft);
+ ff_fft_end(s);
}
projects / ffmpeg / blobdiff