101 lines
4.8 KiB
C
101 lines
4.8 KiB
C
/***********************************************************************
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Copyright (c) 2006-2011, Skype Limited. All rights reserved.
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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 notice,
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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 Internet Society, IETF or IETF Trust, nor the
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names of specific contributors, may be used to endorse or promote
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products derived from this software without specific prior written
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permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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POSSIBILITY OF SUCH DAMAGE.
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***********************************************************************/
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#ifdef OPUS_ENABLED
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#include "opus/opus_config.h"
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#endif
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#include "opus/silk/SigProc_FIX.h"
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/* Apply sine window to signal vector. */
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/* Window types: */
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/* 1 -> sine window from 0 to pi/2 */
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/* 2 -> sine window from pi/2 to pi */
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/* Every other sample is linearly interpolated, for speed. */
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/* Window length must be between 16 and 120 (incl) and a multiple of 4. */
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/* Matlab code for table:
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for k=16:9*4:16+2*9*4, fprintf(' %7.d,', -round(65536*pi ./ (k:4:k+8*4))); fprintf('\n'); end
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*/
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static const opus_int16 freq_table_Q16[ 27 ] = {
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12111, 9804, 8235, 7100, 6239, 5565, 5022, 4575, 4202,
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3885, 3612, 3375, 3167, 2984, 2820, 2674, 2542, 2422,
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2313, 2214, 2123, 2038, 1961, 1889, 1822, 1760, 1702,
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};
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void silk_apply_sine_window(
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opus_int16 px_win[], /* O Pointer to windowed signal */
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const opus_int16 px[], /* I Pointer to input signal */
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const opus_int win_type, /* I Selects a window type */
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const opus_int length /* I Window length, multiple of 4 */
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)
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{
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opus_int k, f_Q16, c_Q16;
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opus_int32 S0_Q16, S1_Q16;
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silk_assert( win_type == 1 || win_type == 2 );
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/* Length must be in a range from 16 to 120 and a multiple of 4 */
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silk_assert( length >= 16 && length <= 120 );
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silk_assert( ( length & 3 ) == 0 );
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/* Frequency */
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k = ( length >> 2 ) - 4;
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silk_assert( k >= 0 && k <= 26 );
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f_Q16 = (opus_int)freq_table_Q16[ k ];
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/* Factor used for cosine approximation */
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c_Q16 = silk_SMULWB( (opus_int32)f_Q16, -f_Q16 );
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silk_assert( c_Q16 >= -32768 );
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/* initialize state */
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if( win_type == 1 ) {
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/* start from 0 */
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S0_Q16 = 0;
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/* approximation of sin(f) */
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S1_Q16 = f_Q16 + silk_RSHIFT( length, 3 );
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} else {
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/* start from 1 */
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S0_Q16 = ( (opus_int32)1 << 16 );
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/* approximation of cos(f) */
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S1_Q16 = ( (opus_int32)1 << 16 ) + silk_RSHIFT( c_Q16, 1 ) + silk_RSHIFT( length, 4 );
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}
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/* Uses the recursive equation: sin(n*f) = 2 * cos(f) * sin((n-1)*f) - sin((n-2)*f) */
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/* 4 samples at a time */
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for( k = 0; k < length; k += 4 ) {
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px_win[ k ] = (opus_int16)silk_SMULWB( silk_RSHIFT( S0_Q16 + S1_Q16, 1 ), px[ k ] );
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px_win[ k + 1 ] = (opus_int16)silk_SMULWB( S1_Q16, px[ k + 1] );
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S0_Q16 = silk_SMULWB( S1_Q16, c_Q16 ) + silk_LSHIFT( S1_Q16, 1 ) - S0_Q16 + 1;
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S0_Q16 = silk_min( S0_Q16, ( (opus_int32)1 << 16 ) );
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px_win[ k + 2 ] = (opus_int16)silk_SMULWB( silk_RSHIFT( S0_Q16 + S1_Q16, 1 ), px[ k + 2] );
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px_win[ k + 3 ] = (opus_int16)silk_SMULWB( S0_Q16, px[ k + 3 ] );
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S1_Q16 = silk_SMULWB( S0_Q16, c_Q16 ) + silk_LSHIFT( S0_Q16, 1 ) - S1_Q16;
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S1_Q16 = silk_min( S1_Q16, ( (opus_int32)1 << 16 ) );
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}
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}
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