Chris@69: /***********************************************************************
Chris@69: Copyright (c) 2006-2011, Skype Limited. All rights reserved.
Chris@69: Redistribution and use in source and binary forms, with or without
Chris@69: modification, are permitted provided that the following conditions
Chris@69: are met:
Chris@69: - Redistributions of source code must retain the above copyright notice,
Chris@69: this list of conditions and the following disclaimer.
Chris@69: - Redistributions in binary form must reproduce the above copyright
Chris@69: notice, this list of conditions and the following disclaimer in the
Chris@69: documentation and/or other materials provided with the distribution.
Chris@69: - Neither the name of Internet Society, IETF or IETF Trust, nor the
Chris@69: names of specific contributors, may be used to endorse or promote
Chris@69: products derived from this software without specific prior written
Chris@69: permission.
Chris@69: THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
Chris@69: AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
Chris@69: IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
Chris@69: ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
Chris@69: LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
Chris@69: CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
Chris@69: SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
Chris@69: INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
Chris@69: CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
Chris@69: ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
Chris@69: POSSIBILITY OF SUCH DAMAGE.
Chris@69: ***********************************************************************/
Chris@69: 
Chris@69: #ifdef HAVE_CONFIG_H
Chris@69: #include "config.h"
Chris@69: #endif
Chris@69: 
Chris@69: #include "SigProc_FIX.h"
Chris@69: #include "resampler_private.h"
Chris@69: #include "stack_alloc.h"
Chris@69: 
Chris@69: #define ORDER_FIR                   4
Chris@69: 
Chris@69: /* Downsample by a factor 2/3, low quality */
Chris@69: void silk_resampler_down2_3(
Chris@69:     opus_int32                  *S,                 /* I/O  State vector [ 6 ]                                          */
Chris@69:     opus_int16                  *out,               /* O    Output signal [ floor(2*inLen/3) ]                          */
Chris@69:     const opus_int16            *in,                /* I    Input signal [ inLen ]                                      */
Chris@69:     opus_int32                  inLen               /* I    Number of input samples                                     */
Chris@69: )
Chris@69: {
Chris@69:     opus_int32 nSamplesIn, counter, res_Q6;
Chris@69:     VARDECL( opus_int32, buf );
Chris@69:     opus_int32 *buf_ptr;
Chris@69:     SAVE_STACK;
Chris@69: 
Chris@69:     ALLOC( buf, RESAMPLER_MAX_BATCH_SIZE_IN + ORDER_FIR, opus_int32 );
Chris@69: 
Chris@69:     /* Copy buffered samples to start of buffer */
Chris@69:     silk_memcpy( buf, S, ORDER_FIR * sizeof( opus_int32 ) );
Chris@69: 
Chris@69:     /* Iterate over blocks of frameSizeIn input samples */
Chris@69:     while( 1 ) {
Chris@69:         nSamplesIn = silk_min( inLen, RESAMPLER_MAX_BATCH_SIZE_IN );
Chris@69: 
Chris@69:         /* Second-order AR filter (output in Q8) */
Chris@69:         silk_resampler_private_AR2( &S[ ORDER_FIR ], &buf[ ORDER_FIR ], in,
Chris@69:             silk_Resampler_2_3_COEFS_LQ, nSamplesIn );
Chris@69: 
Chris@69:         /* Interpolate filtered signal */
Chris@69:         buf_ptr = buf;
Chris@69:         counter = nSamplesIn;
Chris@69:         while( counter > 2 ) {
Chris@69:             /* Inner product */
Chris@69:             res_Q6 = silk_SMULWB(         buf_ptr[ 0 ], silk_Resampler_2_3_COEFS_LQ[ 2 ] );
Chris@69:             res_Q6 = silk_SMLAWB( res_Q6, buf_ptr[ 1 ], silk_Resampler_2_3_COEFS_LQ[ 3 ] );
Chris@69:             res_Q6 = silk_SMLAWB( res_Q6, buf_ptr[ 2 ], silk_Resampler_2_3_COEFS_LQ[ 5 ] );
Chris@69:             res_Q6 = silk_SMLAWB( res_Q6, buf_ptr[ 3 ], silk_Resampler_2_3_COEFS_LQ[ 4 ] );
Chris@69: 
Chris@69:             /* Scale down, saturate and store in output array */
Chris@69:             *out++ = (opus_int16)silk_SAT16( silk_RSHIFT_ROUND( res_Q6, 6 ) );
Chris@69: 
Chris@69:             res_Q6 = silk_SMULWB(         buf_ptr[ 1 ], silk_Resampler_2_3_COEFS_LQ[ 4 ] );
Chris@69:             res_Q6 = silk_SMLAWB( res_Q6, buf_ptr[ 2 ], silk_Resampler_2_3_COEFS_LQ[ 5 ] );
Chris@69:             res_Q6 = silk_SMLAWB( res_Q6, buf_ptr[ 3 ], silk_Resampler_2_3_COEFS_LQ[ 3 ] );
Chris@69:             res_Q6 = silk_SMLAWB( res_Q6, buf_ptr[ 4 ], silk_Resampler_2_3_COEFS_LQ[ 2 ] );
Chris@69: 
Chris@69:             /* Scale down, saturate and store in output array */
Chris@69:             *out++ = (opus_int16)silk_SAT16( silk_RSHIFT_ROUND( res_Q6, 6 ) );
Chris@69: 
Chris@69:             buf_ptr += 3;
Chris@69:             counter -= 3;
Chris@69:         }
Chris@69: 
Chris@69:         in += nSamplesIn;
Chris@69:         inLen -= nSamplesIn;
Chris@69: 
Chris@69:         if( inLen > 0 ) {
Chris@69:             /* More iterations to do; copy last part of filtered signal to beginning of buffer */
Chris@69:             silk_memcpy( buf, &buf[ nSamplesIn ], ORDER_FIR * sizeof( opus_int32 ) );
Chris@69:         } else {
Chris@69:             break;
Chris@69:         }
Chris@69:     }
Chris@69: 
Chris@69:     /* Copy last part of filtered signal to the state for the next call */
Chris@69:     silk_memcpy( S, &buf[ nSamplesIn ], ORDER_FIR * sizeof( opus_int32 ) );
Chris@69:     RESTORE_STACK;
Chris@69: }