75 lines
3.4 KiB
C
75 lines
3.4 KiB
C
|
/***********************************************************************
|
||
|
|
Copyright (c) 2006-2011, Skype Limited. All rights reserved.
|
||
|
|
Redistribution and use in source and binary forms, with or without
|
||
|
|
modification, are permitted provided that the following conditions
|
||
|
|
are met:
|
||
|
|
- Redistributions of source code must retain the above copyright notice,
|
||
|
|
this list of conditions and the following disclaimer.
|
||
|
|
- Redistributions in binary form must reproduce the above copyright
|
||
|
|
notice, this list of conditions and the following disclaimer in the
|
||
|
|
documentation and/or other materials provided with the distribution.
|
||
|
|
- Neither the name of Internet Society, IETF or IETF Trust, nor the
|
||
|
|
names of specific contributors, may be used to endorse or promote
|
||
|
|
products derived from this software without specific prior written
|
||
|
|
permission.
|
||
|
|
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
|
||
|
|
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
||
|
|
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
||
|
|
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
|
||
|
|
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
|
||
|
|
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
|
||
|
|
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
|
||
|
|
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
|
||
|
|
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
|
||
|
|
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
|
||
|
|
POSSIBILITY OF SUCH DAMAGE.
|
||
|
|
***********************************************************************/
|
||
|
|
|
||
|
|
#ifdef HAVE_CONFIG_H
|
||
|
|
#include "config.h"
|
||
|
|
#endif
|
||
|
|
|
||
|
|
#include "SigProc_FIX.h"
|
||
|
|
#include "resampler_rom.h"
|
||
|
|
|
||
|
|
/* Downsample by a factor 2 */
|
||
|
|
void silk_resampler_down2(
|
||
|
|
opus_int32 *S, /* I/O State vector [ 2 ] */
|
||
|
|
opus_int16 *out, /* O Output signal [ floor(len/2) ] */
|
||
|
|
const opus_int16 *in, /* I Input signal [ len ] */
|
||
|
|
opus_int32 inLen /* I Number of input samples */
|
||
|
|
)
|
||
|
|
{
|
||
|
|
opus_int32 k, len2 = silk_RSHIFT32( inLen, 1 );
|
||
|
|
opus_int32 in32, out32, Y, X;
|
||
|
|
|
||
|
|
celt_assert( silk_resampler_down2_0 > 0 );
|
||
|
|
celt_assert( silk_resampler_down2_1 < 0 );
|
||
|
|
|
||
|
|
/* Internal variables and state are in Q10 format */
|
||
|
|
for( k = 0; k < len2; k++ ) {
|
||
|
|
/* Convert to Q10 */
|
||
|
|
in32 = silk_LSHIFT( (opus_int32)in[ 2 * k ], 10 );
|
||
|
|
|
||
|
|
/* All-pass section for even input sample */
|
||
|
|
Y = silk_SUB32( in32, S[ 0 ] );
|
||
|
|
X = silk_SMLAWB( Y, Y, silk_resampler_down2_1 );
|
||
|
|
out32 = silk_ADD32( S[ 0 ], X );
|
||
|
|
S[ 0 ] = silk_ADD32( in32, X );
|
||
|
|
|
||
|
|
/* Convert to Q10 */
|
||
|
|
in32 = silk_LSHIFT( (opus_int32)in[ 2 * k + 1 ], 10 );
|
||
|
|
|
||
|
|
/* All-pass section for odd input sample, and add to output of previous section */
|
||
|
|
Y = silk_SUB32( in32, S[ 1 ] );
|
||
|
|
X = silk_SMULWB( Y, silk_resampler_down2_0 );
|
||
|
|
out32 = silk_ADD32( out32, S[ 1 ] );
|
||
|
|
out32 = silk_ADD32( out32, X );
|
||
|
|
S[ 1 ] = silk_ADD32( in32, X );
|
||
|
|
|
||
|
|
/* Add, convert back to int16 and store to output */
|
||
|
|
out[ k ] = (opus_int16)silk_SAT16( silk_RSHIFT_ROUND( out32, 11 ) );
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|