media/libopus/silk/float/apply_sine_window_FLP.c@b8a032363ba2 (annotated)
media/libopus/silk/float/apply_sine_window_FLP.c
Thu, 22 Jan 2015 13:21:57 +0100
- author
- Michael Schloh von Bennewitz <michael@schloh.com>
- date
- Thu, 22 Jan 2015 13:21:57 +0100
- branch
- TOR_BUG_9701
- changeset 15
- b8a032363ba2
- permissions
- -rw-r--r--
Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6
| michael@0 | 1 | /*********************************************************************** |
| michael@0 | 2 | Copyright (c) 2006-2011, Skype Limited. All rights reserved. |
| michael@0 | 3 | Redistribution and use in source and binary forms, with or without |
| michael@0 | 4 | modification, are permitted provided that the following conditions |
| michael@0 | 5 | are met: |
| michael@0 | 6 | - Redistributions of source code must retain the above copyright notice, |
| michael@0 | 7 | this list of conditions and the following disclaimer. |
| michael@0 | 8 | - Redistributions in binary form must reproduce the above copyright |
| michael@0 | 9 | notice, this list of conditions and the following disclaimer in the |
| michael@0 | 10 | documentation and/or other materials provided with the distribution. |
| michael@0 | 11 | - Neither the name of Internet Society, IETF or IETF Trust, nor the |
| michael@0 | 12 | names of specific contributors, may be used to endorse or promote |
| michael@0 | 13 | products derived from this software without specific prior written |
| michael@0 | 14 | permission. |
| michael@0 | 15 | THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
| michael@0 | 16 | AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| michael@0 | 17 | IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| michael@0 | 18 | ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE |
| michael@0 | 19 | LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
| michael@0 | 20 | CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
| michael@0 | 21 | SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
| michael@0 | 22 | INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
| michael@0 | 23 | CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
| michael@0 | 24 | ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
| michael@0 | 25 | POSSIBILITY OF SUCH DAMAGE. |
| michael@0 | 26 | ***********************************************************************/ |
| michael@0 | 27 | |
| michael@0 | 28 | #ifdef HAVE_CONFIG_H |
| michael@0 | 29 | #include "config.h" |
| michael@0 | 30 | #endif |
| michael@0 | 31 | |
| michael@0 | 32 | #include "main_FLP.h" |
| michael@0 | 33 | |
| michael@0 | 34 | /* Apply sine window to signal vector */ |
| michael@0 | 35 | /* Window types: */ |
| michael@0 | 36 | /* 1 -> sine window from 0 to pi/2 */ |
| michael@0 | 37 | /* 2 -> sine window from pi/2 to pi */ |
| michael@0 | 38 | void silk_apply_sine_window_FLP( |
| michael@0 | 39 | silk_float px_win[], /* O Pointer to windowed signal */ |
| michael@0 | 40 | const silk_float px[], /* I Pointer to input signal */ |
| michael@0 | 41 | const opus_int win_type, /* I Selects a window type */ |
| michael@0 | 42 | const opus_int length /* I Window length, multiple of 4 */ |
| michael@0 | 43 | ) |
| michael@0 | 44 | { |
| michael@0 | 45 | opus_int k; |
| michael@0 | 46 | silk_float freq, c, S0, S1; |
| michael@0 | 47 | |
| michael@0 | 48 | silk_assert( win_type == 1 || win_type == 2 ); |
| michael@0 | 49 | |
| michael@0 | 50 | /* Length must be multiple of 4 */ |
| michael@0 | 51 | silk_assert( ( length & 3 ) == 0 ); |
| michael@0 | 52 | |
| michael@0 | 53 | freq = PI / ( length + 1 ); |
| michael@0 | 54 | |
| michael@0 | 55 | /* Approximation of 2 * cos(f) */ |
| michael@0 | 56 | c = 2.0f - freq * freq; |
| michael@0 | 57 | |
| michael@0 | 58 | /* Initialize state */ |
| michael@0 | 59 | if( win_type < 2 ) { |
| michael@0 | 60 | /* Start from 0 */ |
| michael@0 | 61 | S0 = 0.0f; |
| michael@0 | 62 | /* Approximation of sin(f) */ |
| michael@0 | 63 | S1 = freq; |
| michael@0 | 64 | } else { |
| michael@0 | 65 | /* Start from 1 */ |
| michael@0 | 66 | S0 = 1.0f; |
| michael@0 | 67 | /* Approximation of cos(f) */ |
| michael@0 | 68 | S1 = 0.5f * c; |
| michael@0 | 69 | } |
| michael@0 | 70 | |
| michael@0 | 71 | /* Uses the recursive equation: sin(n*f) = 2 * cos(f) * sin((n-1)*f) - sin((n-2)*f) */ |
| michael@0 | 72 | /* 4 samples at a time */ |
| michael@0 | 73 | for( k = 0; k < length; k += 4 ) { |
| michael@0 | 74 | px_win[ k + 0 ] = px[ k + 0 ] * 0.5f * ( S0 + S1 ); |
| michael@0 | 75 | px_win[ k + 1 ] = px[ k + 1 ] * S1; |
| michael@0 | 76 | S0 = c * S1 - S0; |
| michael@0 | 77 | px_win[ k + 2 ] = px[ k + 2 ] * 0.5f * ( S1 + S0 ); |
| michael@0 | 78 | px_win[ k + 3 ] = px[ k + 3 ] * S0; |
| michael@0 | 79 | S1 = c * S0 - S1; |
| michael@0 | 80 | } |
| michael@0 | 81 | } |
