1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/media/libopus/silk/resampler_down2.c Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,74 @@
1.4 +/***********************************************************************
1.5 +Copyright (c) 2006-2011, Skype Limited. All rights reserved.
1.6 +Redistribution and use in source and binary forms, with or without
1.7 +modification, are permitted provided that the following conditions
1.8 +are met:
1.9 +- Redistributions of source code must retain the above copyright notice,
1.10 +this list of conditions and the following disclaimer.
1.11 +- Redistributions in binary form must reproduce the above copyright
1.12 +notice, this list of conditions and the following disclaimer in the
1.13 +documentation and/or other materials provided with the distribution.
1.14 +- Neither the name of Internet Society, IETF or IETF Trust, nor the
1.15 +names of specific contributors, may be used to endorse or promote
1.16 +products derived from this software without specific prior written
1.17 +permission.
1.18 +THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
1.19 +AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
1.20 +IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
1.21 +ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
1.22 +LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
1.23 +CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
1.24 +SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
1.25 +INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
1.26 +CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
1.27 +ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
1.28 +POSSIBILITY OF SUCH DAMAGE.
1.29 +***********************************************************************/
1.30 +
1.31 +#ifdef HAVE_CONFIG_H
1.32 +#include "config.h"
1.33 +#endif
1.34 +
1.35 +#include "SigProc_FIX.h"
1.36 +#include "resampler_rom.h"
1.37 +
1.38 +/* Downsample by a factor 2 */
1.39 +void silk_resampler_down2(
1.40 + opus_int32 *S, /* I/O State vector [ 2 ] */
1.41 + opus_int16 *out, /* O Output signal [ floor(len/2) ] */
1.42 + const opus_int16 *in, /* I Input signal [ len ] */
1.43 + opus_int32 inLen /* I Number of input samples */
1.44 +)
1.45 +{
1.46 + opus_int32 k, len2 = silk_RSHIFT32( inLen, 1 );
1.47 + opus_int32 in32, out32, Y, X;
1.48 +
1.49 + silk_assert( silk_resampler_down2_0 > 0 );
1.50 + silk_assert( silk_resampler_down2_1 < 0 );
1.51 +
1.52 + /* Internal variables and state are in Q10 format */
1.53 + for( k = 0; k < len2; k++ ) {
1.54 + /* Convert to Q10 */
1.55 + in32 = silk_LSHIFT( (opus_int32)in[ 2 * k ], 10 );
1.56 +
1.57 + /* All-pass section for even input sample */
1.58 + Y = silk_SUB32( in32, S[ 0 ] );
1.59 + X = silk_SMLAWB( Y, Y, silk_resampler_down2_1 );
1.60 + out32 = silk_ADD32( S[ 0 ], X );
1.61 + S[ 0 ] = silk_ADD32( in32, X );
1.62 +
1.63 + /* Convert to Q10 */
1.64 + in32 = silk_LSHIFT( (opus_int32)in[ 2 * k + 1 ], 10 );
1.65 +
1.66 + /* All-pass section for odd input sample, and add to output of previous section */
1.67 + Y = silk_SUB32( in32, S[ 1 ] );
1.68 + X = silk_SMULWB( Y, silk_resampler_down2_0 );
1.69 + out32 = silk_ADD32( out32, S[ 1 ] );
1.70 + out32 = silk_ADD32( out32, X );
1.71 + S[ 1 ] = silk_ADD32( in32, X );
1.72 +
1.73 + /* Add, convert back to int16 and store to output */
1.74 + out[ k ] = (opus_int16)silk_SAT16( silk_RSHIFT_ROUND( out32, 11 ) );
1.75 + }
1.76 +}
1.77 +
