michael@0: /* Copyright (c) 2007-2008 CSIRO
michael@0:    Copyright (c) 2007-2008 Xiph.Org Foundation
michael@0:    Written by Jean-Marc Valin */
michael@0: /*
michael@0:    Redistribution and use in source and binary forms, with or without
michael@0:    modification, are permitted provided that the following conditions
michael@0:    are met:
michael@0: 
michael@0:    - Redistributions of source code must retain the above copyright
michael@0:    notice, this list of conditions and the following disclaimer.
michael@0: 
michael@0:    - Redistributions in binary form must reproduce the above copyright
michael@0:    notice, this list of conditions and the following disclaimer in the
michael@0:    documentation and/or other materials provided with the distribution.
michael@0: 
michael@0:    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
michael@0:    ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
michael@0:    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
michael@0:    A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
michael@0:    OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
michael@0:    EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
michael@0:    PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
michael@0:    PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
michael@0:    LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
michael@0:    NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
michael@0:    SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
michael@0: */
michael@0: 
michael@0: /* This is a simple MDCT implementation that uses a N/4 complex FFT
michael@0:    to do most of the work. It should be relatively straightforward to
michael@0:    plug in pretty much and FFT here.
michael@0: 
michael@0:    This replaces the Vorbis FFT (and uses the exact same API), which
michael@0:    was a bit too messy and that was ending up duplicating code
michael@0:    (might as well use the same FFT everywhere).
michael@0: 
michael@0:    The algorithm is similar to (and inspired from) Fabrice Bellard's
michael@0:    MDCT implementation in FFMPEG, but has differences in signs, ordering
michael@0:    and scaling in many places.
michael@0: */
michael@0: 
michael@0: #ifndef MDCT_H
michael@0: #define MDCT_H
michael@0: 
michael@0: #include "opus_defines.h"
michael@0: #include "kiss_fft.h"
michael@0: #include "arch.h"
michael@0: 
michael@0: typedef struct {
michael@0:    int n;
michael@0:    int maxshift;
michael@0:    const kiss_fft_state *kfft[4];
michael@0:    const kiss_twiddle_scalar * OPUS_RESTRICT trig;
michael@0: } mdct_lookup;
michael@0: 
michael@0: int clt_mdct_init(mdct_lookup *l,int N, int maxshift);
michael@0: void clt_mdct_clear(mdct_lookup *l);
michael@0: 
michael@0: /** Compute a forward MDCT and scale by 4/N, trashes the input array */
michael@0: void clt_mdct_forward(const mdct_lookup *l, kiss_fft_scalar *in,
michael@0:       kiss_fft_scalar * OPUS_RESTRICT out,
michael@0:       const opus_val16 *window, int overlap, int shift, int stride);
michael@0: 
michael@0: /** Compute a backward MDCT (no scaling) and performs weighted overlap-add
michael@0:     (scales implicitly by 1/2) */
michael@0: void clt_mdct_backward(const mdct_lookup *l, kiss_fft_scalar *in,
michael@0:       kiss_fft_scalar * OPUS_RESTRICT out,
michael@0:       const opus_val16 * OPUS_RESTRICT window, int overlap, int shift, int stride);
michael@0: 
michael@0: #endif