1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/media/libopus/silk/NLSF2A.c Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,178 @@
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 +/* conversion between prediction filter coefficients and LSFs */
1.36 +/* order should be even */
1.37 +/* a piecewise linear approximation maps LSF <-> cos(LSF) */
1.38 +/* therefore the result is not accurate LSFs, but the two */
1.39 +/* functions are accurate inverses of each other */
1.40 +
1.41 +#include "SigProc_FIX.h"
1.42 +#include "tables.h"
1.43 +
1.44 +#define QA 16
1.45 +
1.46 +/* helper function for NLSF2A(..) */
1.47 +static OPUS_INLINE void silk_NLSF2A_find_poly(
1.48 + opus_int32 *out, /* O intermediate polynomial, QA [dd+1] */
1.49 + const opus_int32 *cLSF, /* I vector of interleaved 2*cos(LSFs), QA [d] */
1.50 + opus_int dd /* I polynomial order (= 1/2 * filter order) */
1.51 +)
1.52 +{
1.53 + opus_int k, n;
1.54 + opus_int32 ftmp;
1.55 +
1.56 + out[0] = silk_LSHIFT( 1, QA );
1.57 + out[1] = -cLSF[0];
1.58 + for( k = 1; k < dd; k++ ) {
1.59 + ftmp = cLSF[2*k]; /* QA*/
1.60 + out[k+1] = silk_LSHIFT( out[k-1], 1 ) - (opus_int32)silk_RSHIFT_ROUND64( silk_SMULL( ftmp, out[k] ), QA );
1.61 + for( n = k; n > 1; n-- ) {
1.62 + out[n] += out[n-2] - (opus_int32)silk_RSHIFT_ROUND64( silk_SMULL( ftmp, out[n-1] ), QA );
1.63 + }
1.64 + out[1] -= ftmp;
1.65 + }
1.66 +}
1.67 +
1.68 +/* compute whitening filter coefficients from normalized line spectral frequencies */
1.69 +void silk_NLSF2A(
1.70 + opus_int16 *a_Q12, /* O monic whitening filter coefficients in Q12, [ d ] */
1.71 + const opus_int16 *NLSF, /* I normalized line spectral frequencies in Q15, [ d ] */
1.72 + const opus_int d /* I filter order (should be even) */
1.73 +)
1.74 +{
1.75 + /* This ordering was found to maximize quality. It improves numerical accuracy of
1.76 + silk_NLSF2A_find_poly() compared to "standard" ordering. */
1.77 + static const unsigned char ordering16[16] = {
1.78 + 0, 15, 8, 7, 4, 11, 12, 3, 2, 13, 10, 5, 6, 9, 14, 1
1.79 + };
1.80 + static const unsigned char ordering10[10] = {
1.81 + 0, 9, 6, 3, 4, 5, 8, 1, 2, 7
1.82 + };
1.83 + const unsigned char *ordering;
1.84 + opus_int k, i, dd;
1.85 + opus_int32 cos_LSF_QA[ SILK_MAX_ORDER_LPC ];
1.86 + opus_int32 P[ SILK_MAX_ORDER_LPC / 2 + 1 ], Q[ SILK_MAX_ORDER_LPC / 2 + 1 ];
1.87 + opus_int32 Ptmp, Qtmp, f_int, f_frac, cos_val, delta;
1.88 + opus_int32 a32_QA1[ SILK_MAX_ORDER_LPC ];
1.89 + opus_int32 maxabs, absval, idx=0, sc_Q16;
1.90 +
1.91 + silk_assert( LSF_COS_TAB_SZ_FIX == 128 );
1.92 + silk_assert( d==10||d==16 );
1.93 +
1.94 + /* convert LSFs to 2*cos(LSF), using piecewise linear curve from table */
1.95 + ordering = d == 16 ? ordering16 : ordering10;
1.96 + for( k = 0; k < d; k++ ) {
1.97 + silk_assert(NLSF[k] >= 0 );
1.98 +
1.99 + /* f_int on a scale 0-127 (rounded down) */
1.100 + f_int = silk_RSHIFT( NLSF[k], 15 - 7 );
1.101 +
1.102 + /* f_frac, range: 0..255 */
1.103 + f_frac = NLSF[k] - silk_LSHIFT( f_int, 15 - 7 );
1.104 +
1.105 + silk_assert(f_int >= 0);
1.106 + silk_assert(f_int < LSF_COS_TAB_SZ_FIX );
1.107 +
1.108 + /* Read start and end value from table */
1.109 + cos_val = silk_LSFCosTab_FIX_Q12[ f_int ]; /* Q12 */
1.110 + delta = silk_LSFCosTab_FIX_Q12[ f_int + 1 ] - cos_val; /* Q12, with a range of 0..200 */
1.111 +
1.112 + /* Linear interpolation */
1.113 + cos_LSF_QA[ordering[k]] = silk_RSHIFT_ROUND( silk_LSHIFT( cos_val, 8 ) + silk_MUL( delta, f_frac ), 20 - QA ); /* QA */
1.114 + }
1.115 +
1.116 + dd = silk_RSHIFT( d, 1 );
1.117 +
1.118 + /* generate even and odd polynomials using convolution */
1.119 + silk_NLSF2A_find_poly( P, &cos_LSF_QA[ 0 ], dd );
1.120 + silk_NLSF2A_find_poly( Q, &cos_LSF_QA[ 1 ], dd );
1.121 +
1.122 + /* convert even and odd polynomials to opus_int32 Q12 filter coefs */
1.123 + for( k = 0; k < dd; k++ ) {
1.124 + Ptmp = P[ k+1 ] + P[ k ];
1.125 + Qtmp = Q[ k+1 ] - Q[ k ];
1.126 +
1.127 + /* the Ptmp and Qtmp values at this stage need to fit in int32 */
1.128 + a32_QA1[ k ] = -Qtmp - Ptmp; /* QA+1 */
1.129 + a32_QA1[ d-k-1 ] = Qtmp - Ptmp; /* QA+1 */
1.130 + }
1.131 +
1.132 + /* Limit the maximum absolute value of the prediction coefficients, so that they'll fit in int16 */
1.133 + for( i = 0; i < 10; i++ ) {
1.134 + /* Find maximum absolute value and its index */
1.135 + maxabs = 0;
1.136 + for( k = 0; k < d; k++ ) {
1.137 + absval = silk_abs( a32_QA1[k] );
1.138 + if( absval > maxabs ) {
1.139 + maxabs = absval;
1.140 + idx = k;
1.141 + }
1.142 + }
1.143 + maxabs = silk_RSHIFT_ROUND( maxabs, QA + 1 - 12 ); /* QA+1 -> Q12 */
1.144 +
1.145 + if( maxabs > silk_int16_MAX ) {
1.146 + /* Reduce magnitude of prediction coefficients */
1.147 + maxabs = silk_min( maxabs, 163838 ); /* ( silk_int32_MAX >> 14 ) + silk_int16_MAX = 163838 */
1.148 + sc_Q16 = SILK_FIX_CONST( 0.999, 16 ) - silk_DIV32( silk_LSHIFT( maxabs - silk_int16_MAX, 14 ),
1.149 + silk_RSHIFT32( silk_MUL( maxabs, idx + 1), 2 ) );
1.150 + silk_bwexpander_32( a32_QA1, d, sc_Q16 );
1.151 + } else {
1.152 + break;
1.153 + }
1.154 + }
1.155 +
1.156 + if( i == 10 ) {
1.157 + /* Reached the last iteration, clip the coefficients */
1.158 + for( k = 0; k < d; k++ ) {
1.159 + a_Q12[ k ] = (opus_int16)silk_SAT16( silk_RSHIFT_ROUND( a32_QA1[ k ], QA + 1 - 12 ) ); /* QA+1 -> Q12 */
1.160 + a32_QA1[ k ] = silk_LSHIFT( (opus_int32)a_Q12[ k ], QA + 1 - 12 );
1.161 + }
1.162 + } else {
1.163 + for( k = 0; k < d; k++ ) {
1.164 + a_Q12[ k ] = (opus_int16)silk_RSHIFT_ROUND( a32_QA1[ k ], QA + 1 - 12 ); /* QA+1 -> Q12 */
1.165 + }
1.166 + }
1.167 +
1.168 + for( i = 0; i < MAX_LPC_STABILIZE_ITERATIONS; i++ ) {
1.169 + if( silk_LPC_inverse_pred_gain( a_Q12, d ) < SILK_FIX_CONST( 1.0 / MAX_PREDICTION_POWER_GAIN, 30 ) ) {
1.170 + /* Prediction coefficients are (too close to) unstable; apply bandwidth expansion */
1.171 + /* on the unscaled coefficients, convert to Q12 and measure again */
1.172 + silk_bwexpander_32( a32_QA1, d, 65536 - silk_LSHIFT( 2, i ) );
1.173 + for( k = 0; k < d; k++ ) {
1.174 + a_Q12[ k ] = (opus_int16)silk_RSHIFT_ROUND( a32_QA1[ k ], QA + 1 - 12 ); /* QA+1 -> Q12 */
1.175 + }
1.176 + } else {
1.177 + break;
1.178 + }
1.179 + }
1.180 +}
1.181 +
