296 lines
9.0 KiB
C
Executable File
296 lines
9.0 KiB
C
Executable File
/* (C) 2008 Jean-Marc Valin, CSIRO
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*/
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/*
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions
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are met:
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- Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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- Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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- Neither the name of the Xiph.org Foundation nor the names of its
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contributors may be used to endorse or promote products derived from
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this software without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR
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CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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/* This is a simple MDCT implementation that uses a N/4 complex FFT
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to do most of the work. It should be relatively straightforward to
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plug in pretty much and FFT here.
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This replaces the Vorbis FFT (and uses the exact same API), which
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was a bit too messy and that was ending up duplicating code
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(might as well use the same FFT everywhere).
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The algorithm is similar to (and inspired from) Fabrice Bellard's
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MDCT implementation in FFMPEG, but has differences in signs, ordering
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and scaling in many places.
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*/
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#include "mdct.h"
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#include "kfft_double.h"
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#include <math.h>
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#include "os_support.h"
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#include "mathops.h"
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#include "stack_alloc.h"
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#ifndef M_PI
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#define M_PI 3.141592653
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#endif
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void mdct_init(mdct_lookup *l,int N)
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{
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int i;
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int N2;
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l->n = N;
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N2 = N>>1;
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l->kfft = cpx32_fft_alloc(N>>2);
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if (l->kfft==NULL)
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return;
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l->trig = (kiss_twiddle_scalar*)celt_alloc(N2*sizeof(kiss_twiddle_scalar));
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if (l->trig==NULL)
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return;
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/* We have enough points that sine isn't necessary */
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#if defined(FIXED_POINT)
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#if defined(DOUBLE_PRECISION) & !defined(MIXED_PRECISION)
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for (i=0;i<N2;i++)
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l->trig[i] = SAMP_MAX*cos(2*M_PI*(i+1./8.)/N);
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#else
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for (i=0;i<N2;i++)
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l->trig[i] = TRIG_UPSCALE*celt_cos_norm(DIV32(ADD32(SHL32(EXTEND32(i),17),16386),N));
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#endif
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#else
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for (i=0;i<N2;i++)
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l->trig[i] = cos(2*M_PI*(i+1./8.)/N);
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#endif
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}
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void mdct_clear(mdct_lookup *l)
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{
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cpx32_fft_free(l->kfft);
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celt_free(l->trig);
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}
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void mdct_forward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar * __restrict out, const celt_word16_t *window, int overlap)
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{
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int i;
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int N, N2, N4;
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VARDECL(kiss_fft_scalar, f);
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SAVE_STACK;
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N = l->n;
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N2 = N>>1;
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N4 = N>>2;
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ALLOC(f, N2, kiss_fft_scalar);
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/* Consider the input to be compused of four blocks: [a, b, c, d] */
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/* Window, shuffle, fold */
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{
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/* Temp pointers to make it really clear to the compiler what we're doing */
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const kiss_fft_scalar * __restrict xp1 = in+(overlap>>1);
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const kiss_fft_scalar * __restrict xp2 = in+N2-1+(overlap>>1);
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kiss_fft_scalar * __restrict yp = out;
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const celt_word16_t * __restrict wp1 = window+(overlap>>1);
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const celt_word16_t * __restrict wp2 = window+(overlap>>1)-1;
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for(i=0;i<(overlap>>2);i++)
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{
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/* Real part arranged as -d-cR, Imag part arranged as -b+aR*/
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*yp++ = MULT16_32_Q15(*wp2, xp1[N2]) + MULT16_32_Q15(*wp1,*xp2);
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*yp++ = MULT16_32_Q15(*wp1, *xp1) - MULT16_32_Q15(*wp2, xp2[-N2]);
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xp1+=2;
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xp2-=2;
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wp1+=2;
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wp2-=2;
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}
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wp1 = window;
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wp2 = window+overlap-1;
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for(;i<N4-(overlap>>2);i++)
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{
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/* Real part arranged as a-bR, Imag part arranged as -c-dR */
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*yp++ = *xp2;
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*yp++ = *xp1;
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xp1+=2;
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xp2-=2;
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}
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for(;i<N4;i++)
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{
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/* Real part arranged as a-bR, Imag part arranged as -c-dR */
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*yp++ = -MULT16_32_Q15(*wp1, xp1[-N2]) + MULT16_32_Q15(*wp2, *xp2);
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*yp++ = MULT16_32_Q15(*wp2, *xp1) + MULT16_32_Q15(*wp1, xp2[N2]);
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xp1+=2;
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xp2-=2;
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wp1+=2;
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wp2-=2;
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}
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}
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/* Pre-rotation */
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{
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kiss_fft_scalar * __restrict yp = out;
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kiss_fft_scalar *t = &l->trig[0];
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for(i=0;i<N4;i++)
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{
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kiss_fft_scalar re, im;
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re = yp[0];
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im = yp[1];
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*yp++ = -S_MUL(re,t[0]) + S_MUL(im,t[N4]);
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*yp++ = -S_MUL(im,t[0]) - S_MUL(re,t[N4]);
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t++;
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}
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}
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/* N/4 complex FFT, down-scales by 4/N */
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cpx32_fft(l->kfft, out, f, N4);
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/* Post-rotate */
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{
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/* Temp pointers to make it really clear to the compiler what we're doing */
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const kiss_fft_scalar * __restrict fp = f;
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kiss_fft_scalar * __restrict yp1 = out;
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kiss_fft_scalar * __restrict yp2 = out+N2-1;
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kiss_fft_scalar *t = &l->trig[0];
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/* Temp pointers to make it really clear to the compiler what we're doing */
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for(i=0;i<N4;i++)
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{
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*yp1 = -S_MUL(fp[1],t[N4]) + S_MUL(fp[0],t[0]);
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*yp2 = -S_MUL(fp[0],t[N4]) - S_MUL(fp[1],t[0]);
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fp += 2;
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yp1 += 2;
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yp2 -= 2;
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t++;
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}
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}
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RESTORE_STACK;
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}
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void mdct_backward(const mdct_lookup *l, kiss_fft_scalar *in, kiss_fft_scalar * __restrict out, const celt_word16_t * __restrict window, int overlap)
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{
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int i;
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int N, N2, N4;
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VARDECL(kiss_fft_scalar, f);
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VARDECL(kiss_fft_scalar, f2);
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SAVE_STACK;
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N = l->n;
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N2 = N>>1;
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N4 = N>>2;
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ALLOC(f, N2, kiss_fft_scalar);
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ALLOC(f2, N2, kiss_fft_scalar);
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/* Pre-rotate */
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{
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/* Temp pointers to make it really clear to the compiler what we're doing */
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const kiss_fft_scalar * __restrict xp1 = in;
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const kiss_fft_scalar * __restrict xp2 = in+N2-1;
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kiss_fft_scalar * __restrict yp = f2;
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kiss_fft_scalar *t = &l->trig[0];
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for(i=0;i<N4;i++)
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{
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*yp++ = -S_MUL(*xp2, t[0]) - S_MUL(*xp1,t[N4]);
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*yp++ = S_MUL(*xp2, t[N4]) - S_MUL(*xp1,t[0]);
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xp1+=2;
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xp2-=2;
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t++;
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}
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}
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/* Inverse N/4 complex FFT. This one should *not* downscale even in fixed-point */
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cpx32_ifft(l->kfft, f2, f, N4);
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/* Post-rotate */
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{
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kiss_fft_scalar * __restrict fp = f;
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kiss_fft_scalar *t = &l->trig[0];
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for(i=0;i<N4;i++)
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{
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kiss_fft_scalar re, im;
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re = fp[0];
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im = fp[1];
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/* We'd scale up by 2 here, but instead it's done when mixing the windows */
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*fp++ = S_MUL(re,*t) + S_MUL(im,t[N4]);
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*fp++ = S_MUL(im,*t) - S_MUL(re,t[N4]);
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t++;
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}
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}
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/* De-shuffle the components for the middle of the window only */
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{
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const kiss_fft_scalar * __restrict fp1 = f;
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const kiss_fft_scalar * __restrict fp2 = f+N2-1;
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kiss_fft_scalar * __restrict yp = f2;
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for(i = 0; i < N4; i++)
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{
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*yp++ =-*fp1;
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*yp++ = *fp2;
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fp1 += 2;
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fp2 -= 2;
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}
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}
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/* Mirror on both sides for TDAC */
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{
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kiss_fft_scalar * __restrict fp1 = f2+N4-1;
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kiss_fft_scalar * __restrict xp1 = out+N2-1;
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kiss_fft_scalar * __restrict yp1 = out+N4-overlap/2;
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const celt_word16_t * __restrict wp1 = window;
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const celt_word16_t * __restrict wp2 = window+overlap-1;
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for(i = 0; i< N4-overlap/2; i++)
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{
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*xp1 = *fp1;
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xp1--;
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fp1--;
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}
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for(; i < N4; i++)
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{
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kiss_fft_scalar x1;
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x1 = *fp1--;
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*yp1++ +=-MULT16_32_Q15(*wp1, x1);
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*xp1-- += MULT16_32_Q15(*wp2, x1);
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wp1++;
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wp2--;
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}
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}
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{
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kiss_fft_scalar * __restrict fp2 = f2+N4;
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kiss_fft_scalar * __restrict xp2 = out+N2;
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kiss_fft_scalar * __restrict yp2 = out+N-1-(N4-overlap/2);
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const celt_word16_t * __restrict wp1 = window;
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const celt_word16_t * __restrict wp2 = window+overlap-1;
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for(i = 0; i< N4-overlap/2; i++)
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{
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*xp2 = *fp2;
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xp2++;
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fp2++;
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}
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for(; i < N4; i++)
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{
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kiss_fft_scalar x2;
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x2 = *fp2++;
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*yp2-- = MULT16_32_Q15(*wp1, x2);
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*xp2++ = MULT16_32_Q15(*wp2, x2);
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wp1++;
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wp2--;
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}
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}
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RESTORE_STACK;
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}
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