You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
142 lines
6.2 KiB
142 lines
6.2 KiB
/***********************************************************************
|
|
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
|
|
|
|
/* conversion between prediction filter coefficients and LSFs */
|
|
/* order should be even */
|
|
/* a piecewise linear approximation maps LSF <-> cos(LSF) */
|
|
/* therefore the result is not accurate LSFs, but the two */
|
|
/* functions are accurate inverses of each other */
|
|
|
|
#include "SigProc_FIX.h"
|
|
#include "tables.h"
|
|
|
|
#define QA 16
|
|
|
|
/* helper function for NLSF2A(..) */
|
|
static OPUS_INLINE void silk_NLSF2A_find_poly(
|
|
opus_int32 *out, /* O intermediate polynomial, QA [dd+1] */
|
|
const opus_int32 *cLSF, /* I vector of interleaved 2*cos(LSFs), QA [d] */
|
|
opus_int dd /* I polynomial order (= 1/2 * filter order) */
|
|
)
|
|
{
|
|
opus_int k, n;
|
|
opus_int32 ftmp;
|
|
|
|
out[0] = silk_LSHIFT( 1, QA );
|
|
out[1] = -cLSF[0];
|
|
for( k = 1; k < dd; k++ ) {
|
|
ftmp = cLSF[2*k]; /* QA*/
|
|
out[k+1] = silk_LSHIFT( out[k-1], 1 ) - (opus_int32)silk_RSHIFT_ROUND64( silk_SMULL( ftmp, out[k] ), QA );
|
|
for( n = k; n > 1; n-- ) {
|
|
out[n] += out[n-2] - (opus_int32)silk_RSHIFT_ROUND64( silk_SMULL( ftmp, out[n-1] ), QA );
|
|
}
|
|
out[1] -= ftmp;
|
|
}
|
|
}
|
|
|
|
/* compute whitening filter coefficients from normalized line spectral frequencies */
|
|
void silk_NLSF2A(
|
|
opus_int16 *a_Q12, /* O monic whitening filter coefficients in Q12, [ d ] */
|
|
const opus_int16 *NLSF, /* I normalized line spectral frequencies in Q15, [ d ] */
|
|
const opus_int d, /* I filter order (should be even) */
|
|
int arch /* I Run-time architecture */
|
|
)
|
|
{
|
|
/* This ordering was found to maximize quality. It improves numerical accuracy of
|
|
silk_NLSF2A_find_poly() compared to "standard" ordering. */
|
|
static const unsigned char ordering16[16] = {
|
|
0, 15, 8, 7, 4, 11, 12, 3, 2, 13, 10, 5, 6, 9, 14, 1
|
|
};
|
|
static const unsigned char ordering10[10] = {
|
|
0, 9, 6, 3, 4, 5, 8, 1, 2, 7
|
|
};
|
|
const unsigned char *ordering;
|
|
opus_int k, i, dd;
|
|
opus_int32 cos_LSF_QA[ SILK_MAX_ORDER_LPC ];
|
|
opus_int32 P[ SILK_MAX_ORDER_LPC / 2 + 1 ], Q[ SILK_MAX_ORDER_LPC / 2 + 1 ];
|
|
opus_int32 Ptmp, Qtmp, f_int, f_frac, cos_val, delta;
|
|
opus_int32 a32_QA1[ SILK_MAX_ORDER_LPC ];
|
|
|
|
silk_assert( LSF_COS_TAB_SZ_FIX == 128 );
|
|
celt_assert( d==10 || d==16 );
|
|
|
|
/* convert LSFs to 2*cos(LSF), using piecewise linear curve from table */
|
|
ordering = d == 16 ? ordering16 : ordering10;
|
|
for( k = 0; k < d; k++ ) {
|
|
silk_assert( NLSF[k] >= 0 );
|
|
|
|
/* f_int on a scale 0-127 (rounded down) */
|
|
f_int = silk_RSHIFT( NLSF[k], 15 - 7 );
|
|
|
|
/* f_frac, range: 0..255 */
|
|
f_frac = NLSF[k] - silk_LSHIFT( f_int, 15 - 7 );
|
|
|
|
silk_assert(f_int >= 0);
|
|
silk_assert(f_int < LSF_COS_TAB_SZ_FIX );
|
|
|
|
/* Read start and end value from table */
|
|
cos_val = silk_LSFCosTab_FIX_Q12[ f_int ]; /* Q12 */
|
|
delta = silk_LSFCosTab_FIX_Q12[ f_int + 1 ] - cos_val; /* Q12, with a range of 0..200 */
|
|
|
|
/* Linear interpolation */
|
|
cos_LSF_QA[ordering[k]] = silk_RSHIFT_ROUND( silk_LSHIFT( cos_val, 8 ) + silk_MUL( delta, f_frac ), 20 - QA ); /* QA */
|
|
}
|
|
|
|
dd = silk_RSHIFT( d, 1 );
|
|
|
|
/* generate even and odd polynomials using convolution */
|
|
silk_NLSF2A_find_poly( P, &cos_LSF_QA[ 0 ], dd );
|
|
silk_NLSF2A_find_poly( Q, &cos_LSF_QA[ 1 ], dd );
|
|
|
|
/* convert even and odd polynomials to opus_int32 Q12 filter coefs */
|
|
for( k = 0; k < dd; k++ ) {
|
|
Ptmp = P[ k+1 ] + P[ k ];
|
|
Qtmp = Q[ k+1 ] - Q[ k ];
|
|
|
|
/* the Ptmp and Qtmp values at this stage need to fit in int32 */
|
|
a32_QA1[ k ] = -Qtmp - Ptmp; /* QA+1 */
|
|
a32_QA1[ d-k-1 ] = Qtmp - Ptmp; /* QA+1 */
|
|
}
|
|
|
|
/* Convert int32 coefficients to Q12 int16 coefs */
|
|
silk_LPC_fit( a_Q12, a32_QA1, 12, QA + 1, d );
|
|
|
|
for( i = 0; silk_LPC_inverse_pred_gain( a_Q12, d, arch ) == 0 && i < MAX_LPC_STABILIZE_ITERATIONS; i++ ) {
|
|
/* Prediction coefficients are (too close to) unstable; apply bandwidth expansion */
|
|
/* on the unscaled coefficients, convert to Q12 and measure again */
|
|
silk_bwexpander_32( a32_QA1, d, 65536 - silk_LSHIFT( 2, i ) );
|
|
for( k = 0; k < d; k++ ) {
|
|
a_Q12[ k ] = (opus_int16)silk_RSHIFT_ROUND( a32_QA1[ k ], QA + 1 - 12 ); /* QA+1 -> Q12 */
|
|
}
|
|
}
|
|
}
|
|
|