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comparison: media/libopus/silk/ana_filt_bank_1.c
media/libopus/silk/ana_filt_bank_1.c
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- TOR_BUG_9701
- changeset 10
- ac0c01689b40
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| -1:000000000000 | 0:693e30d329f3 |
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| 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 "SigProc_FIX.h" | |
| 33 | |
| 34 /* Coefficients for 2-band filter bank based on first-order allpass filters */ | |
| 35 static opus_int16 A_fb1_20 = 5394 << 1; | |
| 36 static opus_int16 A_fb1_21 = -24290; /* (opus_int16)(20623 << 1) */ | |
| 37 | |
| 38 /* Split signal into two decimated bands using first-order allpass filters */ | |
| 39 void silk_ana_filt_bank_1( | |
| 40 const opus_int16 *in, /* I Input signal [N] */ | |
| 41 opus_int32 *S, /* I/O State vector [2] */ | |
| 42 opus_int16 *outL, /* O Low band [N/2] */ | |
| 43 opus_int16 *outH, /* O High band [N/2] */ | |
| 44 const opus_int32 N /* I Number of input samples */ | |
| 45 ) | |
| 46 { | |
| 47 opus_int k, N2 = silk_RSHIFT( N, 1 ); | |
| 48 opus_int32 in32, X, Y, out_1, out_2; | |
| 49 | |
| 50 /* Internal variables and state are in Q10 format */ | |
| 51 for( k = 0; k < N2; k++ ) { | |
| 52 /* Convert to Q10 */ | |
| 53 in32 = silk_LSHIFT( (opus_int32)in[ 2 * k ], 10 ); | |
| 54 | |
| 55 /* All-pass section for even input sample */ | |
| 56 Y = silk_SUB32( in32, S[ 0 ] ); | |
| 57 X = silk_SMLAWB( Y, Y, A_fb1_21 ); | |
| 58 out_1 = silk_ADD32( S[ 0 ], X ); | |
| 59 S[ 0 ] = silk_ADD32( in32, X ); | |
| 60 | |
| 61 /* Convert to Q10 */ | |
| 62 in32 = silk_LSHIFT( (opus_int32)in[ 2 * k + 1 ], 10 ); | |
| 63 | |
| 64 /* All-pass section for odd input sample, and add to output of previous section */ | |
| 65 Y = silk_SUB32( in32, S[ 1 ] ); | |
| 66 X = silk_SMULWB( Y, A_fb1_20 ); | |
| 67 out_2 = silk_ADD32( S[ 1 ], X ); | |
| 68 S[ 1 ] = silk_ADD32( in32, X ); | |
| 69 | |
| 70 /* Add/subtract, convert back to int16 and store to output */ | |
| 71 outL[ k ] = (opus_int16)silk_SAT16( silk_RSHIFT_ROUND( silk_ADD32( out_2, out_1 ), 11 ) ); | |
| 72 outH[ k ] = (opus_int16)silk_SAT16( silk_RSHIFT_ROUND( silk_SUB32( out_2, out_1 ), 11 ) ); | |
| 73 } | |
| 74 } |
