diff options
Diffstat (limited to 'libavcodec/rdft.c')
| -rw-r--r-- | libavcodec/rdft.c | 87 |
1 files changed, 35 insertions, 52 deletions
diff --git a/libavcodec/rdft.c b/libavcodec/rdft.c index 19652537f8..6ba7484238 100644 --- a/libavcodec/rdft.c +++ b/libavcodec/rdft.c @@ -2,20 +2,20 @@ * (I)RDFT transforms * Copyright (c) 2009 Alex Converse <alex dot converse at gmail dot com> * - * This file is part of Libav. + * This file is part of FFmpeg. * - * Libav is free software; you can redistribute it and/or + * FFmpeg is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * - * Libav is distributed in the hope that it will be useful, + * FFmpeg is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public - * License along with Libav; if not, write to the Free Software + * License along with FFmpeg; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ #include <stdlib.h> @@ -28,28 +28,6 @@ * (Inverse) Real Discrete Fourier Transforms. */ -/* sin(2*pi*x/n) for 0<=x<n/4, followed by n/2<=x<3n/4 */ -#if !CONFIG_HARDCODED_TABLES -SINTABLE(16); -SINTABLE(32); -SINTABLE(64); -SINTABLE(128); -SINTABLE(256); -SINTABLE(512); -SINTABLE(1024); -SINTABLE(2048); -SINTABLE(4096); -SINTABLE(8192); -SINTABLE(16384); -SINTABLE(32768); -SINTABLE(65536); -#endif -static SINTABLE_CONST FFTSample * const ff_sin_tabs[] = { - NULL, NULL, NULL, NULL, - ff_sin_16, ff_sin_32, ff_sin_64, ff_sin_128, ff_sin_256, ff_sin_512, ff_sin_1024, - ff_sin_2048, ff_sin_4096, ff_sin_8192, ff_sin_16384, ff_sin_32768, ff_sin_65536, -}; - /** Map one real FFT into two parallel real even and odd FFTs. Then interleave * the two real FFTs into one complex FFT. Unmangle the results. * ref: http://www.engineeringproductivitytools.com/stuff/T0001/PT10.HTM @@ -57,7 +35,7 @@ static SINTABLE_CONST FFTSample * const ff_sin_tabs[] = { static void rdft_calc_c(RDFTContext *s, FFTSample *data) { int i, i1, i2; - FFTComplex ev, od; + FFTComplex ev, od, odsum; const int n = 1 << s->nbits; const float k1 = 0.5; const float k2 = 0.5 - s->inverse; @@ -73,20 +51,31 @@ static void rdft_calc_c(RDFTContext *s, FFTSample *data) ev.re = data[0]; data[0] = ev.re+data[1]; data[1] = ev.re-data[1]; - for (i = 1; i < (n>>2); i++) { - i1 = 2*i; - i2 = n-i1; - /* Separate even and odd FFTs */ - ev.re = k1*(data[i1 ]+data[i2 ]); - od.im = -k2*(data[i1 ]-data[i2 ]); - ev.im = k1*(data[i1+1]-data[i2+1]); - od.re = k2*(data[i1+1]+data[i2+1]); - /* Apply twiddle factors to the odd FFT and add to the even FFT */ - data[i1 ] = ev.re + od.re*tcos[i] - od.im*tsin[i]; - data[i1+1] = ev.im + od.im*tcos[i] + od.re*tsin[i]; - data[i2 ] = ev.re - od.re*tcos[i] + od.im*tsin[i]; - data[i2+1] = -ev.im + od.im*tcos[i] + od.re*tsin[i]; + +#define RDFT_UNMANGLE(sign0, sign1) \ + for (i = 1; i < (n>>2); i++) { \ + i1 = 2*i; \ + i2 = n-i1; \ + /* Separate even and odd FFTs */ \ + ev.re = k1*(data[i1 ]+data[i2 ]); \ + od.im = k2*(data[i2 ]-data[i1 ]); \ + ev.im = k1*(data[i1+1]-data[i2+1]); \ + od.re = k2*(data[i1+1]+data[i2+1]); \ + /* Apply twiddle factors to the odd FFT and add to the even FFT */ \ + odsum.re = od.re*tcos[i] sign0 od.im*tsin[i]; \ + odsum.im = od.im*tcos[i] sign1 od.re*tsin[i]; \ + data[i1 ] = ev.re + odsum.re; \ + data[i1+1] = ev.im + odsum.im; \ + data[i2 ] = ev.re - odsum.re; \ + data[i2+1] = odsum.im - ev.im; \ + } + + if (s->negative_sin) { + RDFT_UNMANGLE(+,-) + } else { + RDFT_UNMANGLE(-,+) } + data[2*i+1]=s->sign_convention*data[2*i+1]; if (s->inverse) { data[0] *= k1; @@ -99,28 +88,22 @@ static void rdft_calc_c(RDFTContext *s, FFTSample *data) av_cold int ff_rdft_init(RDFTContext *s, int nbits, enum RDFTransformType trans) { int n = 1 << nbits; + int ret; s->nbits = nbits; s->inverse = trans == IDFT_C2R || trans == DFT_C2R; s->sign_convention = trans == IDFT_R2C || trans == DFT_C2R ? 1 : -1; + s->negative_sin = trans == DFT_C2R || trans == DFT_R2C; if (nbits < 4 || nbits > 16) - return -1; + return AVERROR(EINVAL); - if (ff_fft_init(&s->fft, nbits-1, trans == IDFT_C2R || trans == IDFT_R2C) < 0) - return -1; + if ((ret = ff_fft_init(&s->fft, nbits-1, trans == IDFT_C2R || trans == IDFT_R2C)) < 0) + return ret; ff_init_ff_cos_tabs(nbits); s->tcos = ff_cos_tabs[nbits]; - s->tsin = ff_sin_tabs[nbits]+(trans == DFT_R2C || trans == DFT_C2R)*(n>>2); -#if !CONFIG_HARDCODED_TABLES - { - int i; - const double theta = (trans == DFT_R2C || trans == DFT_C2R ? -1 : 1) * 2 * M_PI / n; - for (i = 0; i < (n >> 2); i++) - s->tsin[i] = sin(i * theta); - } -#endif + s->tsin = ff_cos_tabs[nbits] + (n >> 2); s->rdft_calc = rdft_calc_c; if (ARCH_ARM) ff_rdft_init_arm(s); |