diff options
Diffstat (limited to 'libavcodec/adx.c')
-rw-r--r-- | libavcodec/adx.c | 34 |
1 files changed, 34 insertions, 0 deletions
diff --git a/libavcodec/adx.c b/libavcodec/adx.c new file mode 100644 index 0000000000..bc3e8825ca --- /dev/null +++ b/libavcodec/adx.c @@ -0,0 +1,34 @@ +/* + * Copyright (c) 2011 Justin Ruggles + * + * This file is part of Libav. + * + * Libav 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, + * 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 + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA + */ + +#include "libavutil/mathematics.h" +#include "adx.h" + +void ff_adx_calculate_coeffs(int cutoff, int sample_rate, int bits, int *coeff) +{ + double a, b, c; + + a = M_SQRT2 - cos(2.0 * M_PI * cutoff / sample_rate); + b = M_SQRT2 - 1.0; + c = (a - sqrt((a + b) * (a - b))) / b; + + coeff[0] = lrintf(c * 2.0 * (1 << bits)); + coeff[1] = lrintf(-(c * c) * (1 << bits)); +} |