1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/media/libopus/silk/float/apply_sine_window_FLP.c Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,81 @@
1.4 +/***********************************************************************
1.5 +Copyright (c) 2006-2011, Skype Limited. All rights reserved.
1.6 +Redistribution and use in source and binary forms, with or without
1.7 +modification, are permitted provided that the following conditions
1.8 +are met:
1.9 +- Redistributions of source code must retain the above copyright notice,
1.10 +this list of conditions and the following disclaimer.
1.11 +- Redistributions in binary form must reproduce the above copyright
1.12 +notice, this list of conditions and the following disclaimer in the
1.13 +documentation and/or other materials provided with the distribution.
1.14 +- Neither the name of Internet Society, IETF or IETF Trust, nor the
1.15 +names of specific contributors, may be used to endorse or promote
1.16 +products derived from this software without specific prior written
1.17 +permission.
1.18 +THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
1.19 +AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
1.20 +IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
1.21 +ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
1.22 +LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
1.23 +CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
1.24 +SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
1.25 +INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
1.26 +CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
1.27 +ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
1.28 +POSSIBILITY OF SUCH DAMAGE.
1.29 +***********************************************************************/
1.30 +
1.31 +#ifdef HAVE_CONFIG_H
1.32 +#include "config.h"
1.33 +#endif
1.34 +
1.35 +#include "main_FLP.h"
1.36 +
1.37 +/* Apply sine window to signal vector */
1.38 +/* Window types: */
1.39 +/* 1 -> sine window from 0 to pi/2 */
1.40 +/* 2 -> sine window from pi/2 to pi */
1.41 +void silk_apply_sine_window_FLP(
1.42 + silk_float px_win[], /* O Pointer to windowed signal */
1.43 + const silk_float px[], /* I Pointer to input signal */
1.44 + const opus_int win_type, /* I Selects a window type */
1.45 + const opus_int length /* I Window length, multiple of 4 */
1.46 +)
1.47 +{
1.48 + opus_int k;
1.49 + silk_float freq, c, S0, S1;
1.50 +
1.51 + silk_assert( win_type == 1 || win_type == 2 );
1.52 +
1.53 + /* Length must be multiple of 4 */
1.54 + silk_assert( ( length & 3 ) == 0 );
1.55 +
1.56 + freq = PI / ( length + 1 );
1.57 +
1.58 + /* Approximation of 2 * cos(f) */
1.59 + c = 2.0f - freq * freq;
1.60 +
1.61 + /* Initialize state */
1.62 + if( win_type < 2 ) {
1.63 + /* Start from 0 */
1.64 + S0 = 0.0f;
1.65 + /* Approximation of sin(f) */
1.66 + S1 = freq;
1.67 + } else {
1.68 + /* Start from 1 */
1.69 + S0 = 1.0f;
1.70 + /* Approximation of cos(f) */
1.71 + S1 = 0.5f * c;
1.72 + }
1.73 +
1.74 + /* Uses the recursive equation: sin(n*f) = 2 * cos(f) * sin((n-1)*f) - sin((n-2)*f) */
1.75 + /* 4 samples at a time */
1.76 + for( k = 0; k < length; k += 4 ) {
1.77 + px_win[ k + 0 ] = px[ k + 0 ] * 0.5f * ( S0 + S1 );
1.78 + px_win[ k + 1 ] = px[ k + 1 ] * S1;
1.79 + S0 = c * S1 - S0;
1.80 + px_win[ k + 2 ] = px[ k + 2 ] * 0.5f * ( S1 + S0 );
1.81 + px_win[ k + 3 ] = px[ k + 3 ] * S0;
1.82 + S1 = c * S0 - S1;
1.83 + }
1.84 +}
