267 lines
10 KiB
C
267 lines
10 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.
|
|
***********************************************************************/
|
|
|
|
/* Conversion between prediction filter coefficients and NLSFs */
|
|
/* Requires the order to be an even number */
|
|
/* A piecewise linear approximation maps LSF <-> cos(LSF) */
|
|
/* Therefore the result is not accurate NLSFs, but the two */
|
|
/* functions are accurate inverses of each other */
|
|
|
|
#ifdef HAVE_CONFIG_H
|
|
#include "config.h"
|
|
#endif
|
|
|
|
#include "SigProc_FIX.h"
|
|
#include "tables.h"
|
|
|
|
/* Number of binary divisions, when not in low complexity mode */
|
|
#define BIN_DIV_STEPS_A2NLSF_FIX 3 /* must be no higher than 16 - log2( LSF_COS_TAB_SZ_FIX ) */
|
|
#define MAX_ITERATIONS_A2NLSF_FIX 16
|
|
|
|
/* Helper function for A2NLSF(..) */
|
|
/* Transforms polynomials from cos(n*f) to cos(f)^n */
|
|
static OPUS_INLINE void silk_A2NLSF_trans_poly(
|
|
opus_int32 *p, /* I/O Polynomial */
|
|
const opus_int dd /* I Polynomial order (= filter order / 2 ) */
|
|
)
|
|
{
|
|
opus_int k, n;
|
|
|
|
for( k = 2; k <= dd; k++ ) {
|
|
for( n = dd; n > k; n-- ) {
|
|
p[ n - 2 ] -= p[ n ];
|
|
}
|
|
p[ k - 2 ] -= silk_LSHIFT( p[ k ], 1 );
|
|
}
|
|
}
|
|
/* Helper function for A2NLSF(..) */
|
|
/* Polynomial evaluation */
|
|
static OPUS_INLINE opus_int32 silk_A2NLSF_eval_poly( /* return the polynomial evaluation, in Q16 */
|
|
opus_int32 *p, /* I Polynomial, Q16 */
|
|
const opus_int32 x, /* I Evaluation point, Q12 */
|
|
const opus_int dd /* I Order */
|
|
)
|
|
{
|
|
opus_int n;
|
|
opus_int32 x_Q16, y32;
|
|
|
|
y32 = p[ dd ]; /* Q16 */
|
|
x_Q16 = silk_LSHIFT( x, 4 );
|
|
|
|
if ( opus_likely( 8 == dd ) )
|
|
{
|
|
y32 = silk_SMLAWW( p[ 7 ], y32, x_Q16 );
|
|
y32 = silk_SMLAWW( p[ 6 ], y32, x_Q16 );
|
|
y32 = silk_SMLAWW( p[ 5 ], y32, x_Q16 );
|
|
y32 = silk_SMLAWW( p[ 4 ], y32, x_Q16 );
|
|
y32 = silk_SMLAWW( p[ 3 ], y32, x_Q16 );
|
|
y32 = silk_SMLAWW( p[ 2 ], y32, x_Q16 );
|
|
y32 = silk_SMLAWW( p[ 1 ], y32, x_Q16 );
|
|
y32 = silk_SMLAWW( p[ 0 ], y32, x_Q16 );
|
|
}
|
|
else
|
|
{
|
|
for( n = dd - 1; n >= 0; n-- ) {
|
|
y32 = silk_SMLAWW( p[ n ], y32, x_Q16 ); /* Q16 */
|
|
}
|
|
}
|
|
return y32;
|
|
}
|
|
|
|
static OPUS_INLINE void silk_A2NLSF_init(
|
|
const opus_int32 *a_Q16,
|
|
opus_int32 *P,
|
|
opus_int32 *Q,
|
|
const opus_int dd
|
|
)
|
|
{
|
|
opus_int k;
|
|
|
|
/* Convert filter coefs to even and odd polynomials */
|
|
P[dd] = silk_LSHIFT( 1, 16 );
|
|
Q[dd] = silk_LSHIFT( 1, 16 );
|
|
for( k = 0; k < dd; k++ ) {
|
|
P[ k ] = -a_Q16[ dd - k - 1 ] - a_Q16[ dd + k ]; /* Q16 */
|
|
Q[ k ] = -a_Q16[ dd - k - 1 ] + a_Q16[ dd + k ]; /* Q16 */
|
|
}
|
|
|
|
/* Divide out zeros as we have that for even filter orders, */
|
|
/* z = 1 is always a root in Q, and */
|
|
/* z = -1 is always a root in P */
|
|
for( k = dd; k > 0; k-- ) {
|
|
P[ k - 1 ] -= P[ k ];
|
|
Q[ k - 1 ] += Q[ k ];
|
|
}
|
|
|
|
/* Transform polynomials from cos(n*f) to cos(f)^n */
|
|
silk_A2NLSF_trans_poly( P, dd );
|
|
silk_A2NLSF_trans_poly( Q, dd );
|
|
}
|
|
|
|
/* Compute Normalized Line Spectral Frequencies (NLSFs) from whitening filter coefficients */
|
|
/* If not all roots are found, the a_Q16 coefficients are bandwidth expanded until convergence. */
|
|
void silk_A2NLSF(
|
|
opus_int16 *NLSF, /* O Normalized Line Spectral Frequencies in Q15 (0..2^15-1) [d] */
|
|
opus_int32 *a_Q16, /* I/O Monic whitening filter coefficients in Q16 [d] */
|
|
const opus_int d /* I Filter order (must be even) */
|
|
)
|
|
{
|
|
opus_int i, k, m, dd, root_ix, ffrac;
|
|
opus_int32 xlo, xhi, xmid;
|
|
opus_int32 ylo, yhi, ymid, thr;
|
|
opus_int32 nom, den;
|
|
opus_int32 P[ SILK_MAX_ORDER_LPC / 2 + 1 ];
|
|
opus_int32 Q[ SILK_MAX_ORDER_LPC / 2 + 1 ];
|
|
opus_int32 *PQ[ 2 ];
|
|
opus_int32 *p;
|
|
|
|
/* Store pointers to array */
|
|
PQ[ 0 ] = P;
|
|
PQ[ 1 ] = Q;
|
|
|
|
dd = silk_RSHIFT( d, 1 );
|
|
|
|
silk_A2NLSF_init( a_Q16, P, Q, dd );
|
|
|
|
/* Find roots, alternating between P and Q */
|
|
p = P; /* Pointer to polynomial */
|
|
|
|
xlo = silk_LSFCosTab_FIX_Q12[ 0 ]; /* Q12*/
|
|
ylo = silk_A2NLSF_eval_poly( p, xlo, dd );
|
|
|
|
if( ylo < 0 ) {
|
|
/* Set the first NLSF to zero and move on to the next */
|
|
NLSF[ 0 ] = 0;
|
|
p = Q; /* Pointer to polynomial */
|
|
ylo = silk_A2NLSF_eval_poly( p, xlo, dd );
|
|
root_ix = 1; /* Index of current root */
|
|
} else {
|
|
root_ix = 0; /* Index of current root */
|
|
}
|
|
k = 1; /* Loop counter */
|
|
i = 0; /* Counter for bandwidth expansions applied */
|
|
thr = 0;
|
|
while( 1 ) {
|
|
/* Evaluate polynomial */
|
|
xhi = silk_LSFCosTab_FIX_Q12[ k ]; /* Q12 */
|
|
yhi = silk_A2NLSF_eval_poly( p, xhi, dd );
|
|
|
|
/* Detect zero crossing */
|
|
if( ( ylo <= 0 && yhi >= thr ) || ( ylo >= 0 && yhi <= -thr ) ) {
|
|
if( yhi == 0 ) {
|
|
/* If the root lies exactly at the end of the current */
|
|
/* interval, look for the next root in the next interval */
|
|
thr = 1;
|
|
} else {
|
|
thr = 0;
|
|
}
|
|
/* Binary division */
|
|
ffrac = -256;
|
|
for( m = 0; m < BIN_DIV_STEPS_A2NLSF_FIX; m++ ) {
|
|
/* Evaluate polynomial */
|
|
xmid = silk_RSHIFT_ROUND( xlo + xhi, 1 );
|
|
ymid = silk_A2NLSF_eval_poly( p, xmid, dd );
|
|
|
|
/* Detect zero crossing */
|
|
if( ( ylo <= 0 && ymid >= 0 ) || ( ylo >= 0 && ymid <= 0 ) ) {
|
|
/* Reduce frequency */
|
|
xhi = xmid;
|
|
yhi = ymid;
|
|
} else {
|
|
/* Increase frequency */
|
|
xlo = xmid;
|
|
ylo = ymid;
|
|
ffrac = silk_ADD_RSHIFT( ffrac, 128, m );
|
|
}
|
|
}
|
|
|
|
/* Interpolate */
|
|
if( silk_abs( ylo ) < 65536 ) {
|
|
/* Avoid dividing by zero */
|
|
den = ylo - yhi;
|
|
nom = silk_LSHIFT( ylo, 8 - BIN_DIV_STEPS_A2NLSF_FIX ) + silk_RSHIFT( den, 1 );
|
|
if( den != 0 ) {
|
|
ffrac += silk_DIV32( nom, den );
|
|
}
|
|
} else {
|
|
/* No risk of dividing by zero because abs(ylo - yhi) >= abs(ylo) >= 65536 */
|
|
ffrac += silk_DIV32( ylo, silk_RSHIFT( ylo - yhi, 8 - BIN_DIV_STEPS_A2NLSF_FIX ) );
|
|
}
|
|
NLSF[ root_ix ] = (opus_int16)silk_min_32( silk_LSHIFT( (opus_int32)k, 8 ) + ffrac, silk_int16_MAX );
|
|
|
|
silk_assert( NLSF[ root_ix ] >= 0 );
|
|
|
|
root_ix++; /* Next root */
|
|
if( root_ix >= d ) {
|
|
/* Found all roots */
|
|
break;
|
|
}
|
|
/* Alternate pointer to polynomial */
|
|
p = PQ[ root_ix & 1 ];
|
|
|
|
/* Evaluate polynomial */
|
|
xlo = silk_LSFCosTab_FIX_Q12[ k - 1 ]; /* Q12*/
|
|
ylo = silk_LSHIFT( 1 - ( root_ix & 2 ), 12 );
|
|
} else {
|
|
/* Increment loop counter */
|
|
k++;
|
|
xlo = xhi;
|
|
ylo = yhi;
|
|
thr = 0;
|
|
|
|
if( k > LSF_COS_TAB_SZ_FIX ) {
|
|
i++;
|
|
if( i > MAX_ITERATIONS_A2NLSF_FIX ) {
|
|
/* Set NLSFs to white spectrum and exit */
|
|
NLSF[ 0 ] = (opus_int16)silk_DIV32_16( 1 << 15, d + 1 );
|
|
for( k = 1; k < d; k++ ) {
|
|
NLSF[ k ] = (opus_int16)silk_ADD16( NLSF[ k-1 ], NLSF[ 0 ] );
|
|
}
|
|
return;
|
|
}
|
|
|
|
/* Error: Apply progressively more bandwidth expansion and run again */
|
|
silk_bwexpander_32( a_Q16, d, 65536 - silk_LSHIFT( 1, i ) );
|
|
|
|
silk_A2NLSF_init( a_Q16, P, Q, dd );
|
|
p = P; /* Pointer to polynomial */
|
|
xlo = silk_LSFCosTab_FIX_Q12[ 0 ]; /* Q12*/
|
|
ylo = silk_A2NLSF_eval_poly( p, xlo, dd );
|
|
if( ylo < 0 ) {
|
|
/* Set the first NLSF to zero and move on to the next */
|
|
NLSF[ 0 ] = 0;
|
|
p = Q; /* Pointer to polynomial */
|
|
ylo = silk_A2NLSF_eval_poly( p, xlo, dd );
|
|
root_ix = 1; /* Index of current root */
|
|
} else {
|
|
root_ix = 0; /* Index of current root */
|
|
}
|
|
k = 1; /* Reset loop counter */
|
|
}
|
|
}
|
|
}
|
|
}
|