media/libopus/silk/bwexpander.c@b8a032363ba2 (annotated)
media/libopus/silk/bwexpander.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 "SigProc_FIX.h" |
| michael@0 | 33 | |
| michael@0 | 34 | /* Chirp (bandwidth expand) LP AR filter */ |
| michael@0 | 35 | void silk_bwexpander( |
| michael@0 | 36 | opus_int16 *ar, /* I/O AR filter to be expanded (without leading 1) */ |
| michael@0 | 37 | const opus_int d, /* I Length of ar */ |
| michael@0 | 38 | opus_int32 chirp_Q16 /* I Chirp factor (typically in the range 0 to 1) */ |
| michael@0 | 39 | ) |
| michael@0 | 40 | { |
| michael@0 | 41 | opus_int i; |
| michael@0 | 42 | opus_int32 chirp_minus_one_Q16 = chirp_Q16 - 65536; |
| michael@0 | 43 | |
| michael@0 | 44 | /* NB: Dont use silk_SMULWB, instead of silk_RSHIFT_ROUND( silk_MUL(), 16 ), below. */ |
| michael@0 | 45 | /* Bias in silk_SMULWB can lead to unstable filters */ |
| michael@0 | 46 | for( i = 0; i < d - 1; i++ ) { |
| michael@0 | 47 | ar[ i ] = (opus_int16)silk_RSHIFT_ROUND( silk_MUL( chirp_Q16, ar[ i ] ), 16 ); |
| michael@0 | 48 | chirp_Q16 += silk_RSHIFT_ROUND( silk_MUL( chirp_Q16, chirp_minus_one_Q16 ), 16 ); |
| michael@0 | 49 | } |
| michael@0 | 50 | ar[ d - 1 ] = (opus_int16)silk_RSHIFT_ROUND( silk_MUL( chirp_Q16, ar[ d - 1 ] ), 16 ); |
| michael@0 | 51 | } |
