media/libopus/silk/resampler_down2.c@b8a032363ba2 (annotated)
media/libopus/silk/resampler_down2.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 | #include "resampler_rom.h" |
| michael@0 | 34 | |
| michael@0 | 35 | /* Downsample by a factor 2 */ |
| michael@0 | 36 | void silk_resampler_down2( |
| michael@0 | 37 | opus_int32 *S, /* I/O State vector [ 2 ] */ |
| michael@0 | 38 | opus_int16 *out, /* O Output signal [ floor(len/2) ] */ |
| michael@0 | 39 | const opus_int16 *in, /* I Input signal [ len ] */ |
| michael@0 | 40 | opus_int32 inLen /* I Number of input samples */ |
| michael@0 | 41 | ) |
| michael@0 | 42 | { |
| michael@0 | 43 | opus_int32 k, len2 = silk_RSHIFT32( inLen, 1 ); |
| michael@0 | 44 | opus_int32 in32, out32, Y, X; |
| michael@0 | 45 | |
| michael@0 | 46 | silk_assert( silk_resampler_down2_0 > 0 ); |
| michael@0 | 47 | silk_assert( silk_resampler_down2_1 < 0 ); |
| michael@0 | 48 | |
| michael@0 | 49 | /* Internal variables and state are in Q10 format */ |
| michael@0 | 50 | for( k = 0; k < len2; k++ ) { |
| michael@0 | 51 | /* Convert to Q10 */ |
| michael@0 | 52 | in32 = silk_LSHIFT( (opus_int32)in[ 2 * k ], 10 ); |
| michael@0 | 53 | |
| michael@0 | 54 | /* All-pass section for even input sample */ |
| michael@0 | 55 | Y = silk_SUB32( in32, S[ 0 ] ); |
| michael@0 | 56 | X = silk_SMLAWB( Y, Y, silk_resampler_down2_1 ); |
| michael@0 | 57 | out32 = silk_ADD32( S[ 0 ], X ); |
| michael@0 | 58 | S[ 0 ] = silk_ADD32( in32, X ); |
| michael@0 | 59 | |
| michael@0 | 60 | /* Convert to Q10 */ |
| michael@0 | 61 | in32 = silk_LSHIFT( (opus_int32)in[ 2 * k + 1 ], 10 ); |
| michael@0 | 62 | |
| michael@0 | 63 | /* All-pass section for odd input sample, and add to output of previous section */ |
| michael@0 | 64 | Y = silk_SUB32( in32, S[ 1 ] ); |
| michael@0 | 65 | X = silk_SMULWB( Y, silk_resampler_down2_0 ); |
| michael@0 | 66 | out32 = silk_ADD32( out32, S[ 1 ] ); |
| michael@0 | 67 | out32 = silk_ADD32( out32, X ); |
| michael@0 | 68 | S[ 1 ] = silk_ADD32( in32, X ); |
| michael@0 | 69 | |
| michael@0 | 70 | /* Add, convert back to int16 and store to output */ |
| michael@0 | 71 | out[ k ] = (opus_int16)silk_SAT16( silk_RSHIFT_ROUND( out32, 11 ) ); |
| michael@0 | 72 | } |
| michael@0 | 73 | } |
| michael@0 | 74 |
