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comparison: media/libopus/silk/float/apply_sine_window_FLP.c
media/libopus/silk/float/apply_sine_window_FLP.c
- branch
- TOR_BUG_9701
- changeset 15
- b8a032363ba2
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| -1:000000000000 | 0:a11d379354db |
|---|---|
| 1 /*********************************************************************** | |
| 2 Copyright (c) 2006-2011, Skype Limited. All rights reserved. | |
| 3 Redistribution and use in source and binary forms, with or without | |
| 4 modification, are permitted provided that the following conditions | |
| 5 are met: | |
| 6 - Redistributions of source code must retain the above copyright notice, | |
| 7 this list of conditions and the following disclaimer. | |
| 8 - Redistributions in binary form must reproduce the above copyright | |
| 9 notice, this list of conditions and the following disclaimer in the | |
| 10 documentation and/or other materials provided with the distribution. | |
| 11 - Neither the name of Internet Society, IETF or IETF Trust, nor the | |
| 12 names of specific contributors, may be used to endorse or promote | |
| 13 products derived from this software without specific prior written | |
| 14 permission. | |
| 15 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" | |
| 16 AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
| 17 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | |
| 18 ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE | |
| 19 LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR | |
| 20 CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF | |
| 21 SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS | |
| 22 INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN | |
| 23 CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) | |
| 24 ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE | |
| 25 POSSIBILITY OF SUCH DAMAGE. | |
| 26 ***********************************************************************/ | |
| 27 | |
| 28 #ifdef HAVE_CONFIG_H | |
| 29 #include "config.h" | |
| 30 #endif | |
| 31 | |
| 32 #include "main_FLP.h" | |
| 33 | |
| 34 /* Apply sine window to signal vector */ | |
| 35 /* Window types: */ | |
| 36 /* 1 -> sine window from 0 to pi/2 */ | |
| 37 /* 2 -> sine window from pi/2 to pi */ | |
| 38 void silk_apply_sine_window_FLP( | |
| 39 silk_float px_win[], /* O Pointer to windowed signal */ | |
| 40 const silk_float px[], /* I Pointer to input signal */ | |
| 41 const opus_int win_type, /* I Selects a window type */ | |
| 42 const opus_int length /* I Window length, multiple of 4 */ | |
| 43 ) | |
| 44 { | |
| 45 opus_int k; | |
| 46 silk_float freq, c, S0, S1; | |
| 47 | |
| 48 silk_assert( win_type == 1 || win_type == 2 ); | |
| 49 | |
| 50 /* Length must be multiple of 4 */ | |
| 51 silk_assert( ( length & 3 ) == 0 ); | |
| 52 | |
| 53 freq = PI / ( length + 1 ); | |
| 54 | |
| 55 /* Approximation of 2 * cos(f) */ | |
| 56 c = 2.0f - freq * freq; | |
| 57 | |
| 58 /* Initialize state */ | |
| 59 if( win_type < 2 ) { | |
| 60 /* Start from 0 */ | |
| 61 S0 = 0.0f; | |
| 62 /* Approximation of sin(f) */ | |
| 63 S1 = freq; | |
| 64 } else { | |
| 65 /* Start from 1 */ | |
| 66 S0 = 1.0f; | |
| 67 /* Approximation of cos(f) */ | |
| 68 S1 = 0.5f * c; | |
| 69 } | |
| 70 | |
| 71 /* Uses the recursive equation: sin(n*f) = 2 * cos(f) * sin((n-1)*f) - sin((n-2)*f) */ | |
| 72 /* 4 samples at a time */ | |
| 73 for( k = 0; k < length; k += 4 ) { | |
| 74 px_win[ k + 0 ] = px[ k + 0 ] * 0.5f * ( S0 + S1 ); | |
| 75 px_win[ k + 1 ] = px[ k + 1 ] * S1; | |
| 76 S0 = c * S1 - S0; | |
| 77 px_win[ k + 2 ] = px[ k + 2 ] * 0.5f * ( S1 + S0 ); | |
| 78 px_win[ k + 3 ] = px[ k + 3 ] * S0; | |
| 79 S1 = c * S0 - S1; | |
| 80 } | |
| 81 } |
