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Fixed-point MDCT with 32-bit unscaled output
Signed-off-by: Mans Rullgard <mans@mansr.com>
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@ -39,6 +39,8 @@
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#include "libavutil/intmath.h"
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#include "mathops.h"
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void ff_mdct_calcw_c(FFTContext *s, FFTDouble *output, const FFTSample *input);
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#define SCALE_FLOAT(a, bits) lrint((a) * (double)(1 << (bits)))
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#define FIX15(a) av_clip(SCALE_FLOAT(a, 15), -32767, 32767)
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@ -49,11 +51,17 @@
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y = (a + b) >> 1; \
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} while (0)
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#define CMUL(dre, dim, are, aim, bre, bim) do { \
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(dre) = (MUL16(are, bre) - MUL16(aim, bim)) >> 15; \
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(dim) = (MUL16(are, bim) + MUL16(aim, bre)) >> 15; \
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#define CMULS(dre, dim, are, aim, bre, bim, sh) do { \
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(dre) = (MUL16(are, bre) - MUL16(aim, bim)) >> sh; \
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(dim) = (MUL16(are, bim) + MUL16(aim, bre)) >> sh; \
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} while (0)
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#define CMUL(dre, dim, are, aim, bre, bim) \
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CMULS(dre, dim, are, aim, bre, bim, 15)
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#define CMULL(dre, dim, are, aim, bre, bim) \
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CMULS(dre, dim, are, aim, bre, bim, 0)
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#endif /* CONFIG_FFT_FLOAT */
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#define ff_imdct_calc_c FFT_NAME(ff_imdct_calc_c)
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@ -123,6 +123,9 @@ av_cold int ff_fft_init(FFTContext *s, int nbits, int inverse)
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if (ARCH_ARM) ff_fft_init_arm(s);
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if (HAVE_ALTIVEC) ff_fft_init_altivec(s);
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if (HAVE_MMX) ff_fft_init_mmx(s);
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if (CONFIG_MDCT) s->mdct_calcw = s->mdct_calc;
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#else
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if (CONFIG_MDCT) s->mdct_calcw = ff_mdct_calcw_c;
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#endif
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for(j=4; j<=nbits; j++) {
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@ -53,6 +53,10 @@ typedef struct FFTContext FFTContext;
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#endif /* CONFIG_FFT_FLOAT */
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typedef struct FFTDComplex {
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FFTDouble re, im;
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} FFTDComplex;
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/* FFT computation */
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struct FFTContext {
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@ -77,6 +81,7 @@ struct FFTContext {
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void (*imdct_calc)(struct FFTContext *s, FFTSample *output, const FFTSample *input);
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void (*imdct_half)(struct FFTContext *s, FFTSample *output, const FFTSample *input);
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void (*mdct_calc)(struct FFTContext *s, FFTSample *output, const FFTSample *input);
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void (*mdct_calcw)(struct FFTContext *s, FFTDouble *output, const FFTSample *input);
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int fft_permutation;
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#define FF_FFT_PERM_DEFAULT 0
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#define FF_FFT_PERM_SWAP_LSBS 1
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@ -18,3 +18,47 @@
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#define CONFIG_FFT_FLOAT 0
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#include "mdct.c"
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/* same as ff_mdct_calcw_c with double-width unscaled output */
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void ff_mdct_calcw_c(FFTContext *s, FFTDouble *out, const FFTSample *input)
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{
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int i, j, n, n8, n4, n2, n3;
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FFTDouble re, im;
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const uint16_t *revtab = s->revtab;
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const FFTSample *tcos = s->tcos;
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const FFTSample *tsin = s->tsin;
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FFTComplex *x = s->tmp_buf;
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FFTDComplex *o = (FFTDComplex *)out;
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n = 1 << s->mdct_bits;
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n2 = n >> 1;
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n4 = n >> 2;
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n8 = n >> 3;
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n3 = 3 * n4;
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/* pre rotation */
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for(i=0;i<n8;i++) {
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re = RSCALE(-input[2*i+n3] - input[n3-1-2*i]);
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im = RSCALE(-input[n4+2*i] + input[n4-1-2*i]);
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j = revtab[i];
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CMUL(x[j].re, x[j].im, re, im, -tcos[i], tsin[i]);
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re = RSCALE( input[2*i] - input[n2-1-2*i]);
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im = RSCALE(-input[n2+2*i] - input[ n-1-2*i]);
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j = revtab[n8 + i];
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CMUL(x[j].re, x[j].im, re, im, -tcos[n8 + i], tsin[n8 + i]);
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}
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s->fft_calc(s, x);
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/* post rotation */
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for(i=0;i<n8;i++) {
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FFTDouble r0, i0, r1, i1;
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CMULL(i1, r0, x[n8-i-1].re, x[n8-i-1].im, -tsin[n8-i-1], -tcos[n8-i-1]);
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CMULL(i0, r1, x[n8+i ].re, x[n8+i ].im, -tsin[n8+i ], -tcos[n8+i ]);
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o[n8-i-1].re = r0;
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o[n8-i-1].im = i0;
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o[n8+i ].re = r1;
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o[n8+i ].im = i1;
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}
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}
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