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comparison: media/libopus/silk/NLSF2A.c
media/libopus/silk/NLSF2A.c
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| -1:000000000000 | 0:39650275e10c |
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| 1 /*********************************************************************** | |
| 2 Copyright (c) 2006-2011, Skype Limited. All rights reserved. | |
| 3 Redistribution and use in source and binary forms, with or without | |
| 4 modification, are permitted provided that the following conditions | |
| 5 are met: | |
| 6 - Redistributions of source code must retain the above copyright notice, | |
| 7 this list of conditions and the following disclaimer. | |
| 8 - Redistributions in binary form must reproduce the above copyright | |
| 9 notice, this list of conditions and the following disclaimer in the | |
| 10 documentation and/or other materials provided with the distribution. | |
| 11 - Neither the name of Internet Society, IETF or IETF Trust, nor the | |
| 12 names of specific contributors, may be used to endorse or promote | |
| 13 products derived from this software without specific prior written | |
| 14 permission. | |
| 15 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" | |
| 16 AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
| 17 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | |
| 18 ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE | |
| 19 LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR | |
| 20 CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF | |
| 21 SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS | |
| 22 INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN | |
| 23 CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) | |
| 24 ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE | |
| 25 POSSIBILITY OF SUCH DAMAGE. | |
| 26 ***********************************************************************/ | |
| 27 | |
| 28 #ifdef HAVE_CONFIG_H | |
| 29 #include "config.h" | |
| 30 #endif | |
| 31 | |
| 32 /* conversion between prediction filter coefficients and LSFs */ | |
| 33 /* order should be even */ | |
| 34 /* a piecewise linear approximation maps LSF <-> cos(LSF) */ | |
| 35 /* therefore the result is not accurate LSFs, but the two */ | |
| 36 /* functions are accurate inverses of each other */ | |
| 37 | |
| 38 #include "SigProc_FIX.h" | |
| 39 #include "tables.h" | |
| 40 | |
| 41 #define QA 16 | |
| 42 | |
| 43 /* helper function for NLSF2A(..) */ | |
| 44 static OPUS_INLINE void silk_NLSF2A_find_poly( | |
| 45 opus_int32 *out, /* O intermediate polynomial, QA [dd+1] */ | |
| 46 const opus_int32 *cLSF, /* I vector of interleaved 2*cos(LSFs), QA [d] */ | |
| 47 opus_int dd /* I polynomial order (= 1/2 * filter order) */ | |
| 48 ) | |
| 49 { | |
| 50 opus_int k, n; | |
| 51 opus_int32 ftmp; | |
| 52 | |
| 53 out[0] = silk_LSHIFT( 1, QA ); | |
| 54 out[1] = -cLSF[0]; | |
| 55 for( k = 1; k < dd; k++ ) { | |
| 56 ftmp = cLSF[2*k]; /* QA*/ | |
| 57 out[k+1] = silk_LSHIFT( out[k-1], 1 ) - (opus_int32)silk_RSHIFT_ROUND64( silk_SMULL( ftmp, out[k] ), QA ); | |
| 58 for( n = k; n > 1; n-- ) { | |
| 59 out[n] += out[n-2] - (opus_int32)silk_RSHIFT_ROUND64( silk_SMULL( ftmp, out[n-1] ), QA ); | |
| 60 } | |
| 61 out[1] -= ftmp; | |
| 62 } | |
| 63 } | |
| 64 | |
| 65 /* compute whitening filter coefficients from normalized line spectral frequencies */ | |
| 66 void silk_NLSF2A( | |
| 67 opus_int16 *a_Q12, /* O monic whitening filter coefficients in Q12, [ d ] */ | |
| 68 const opus_int16 *NLSF, /* I normalized line spectral frequencies in Q15, [ d ] */ | |
| 69 const opus_int d /* I filter order (should be even) */ | |
| 70 ) | |
| 71 { | |
| 72 /* This ordering was found to maximize quality. It improves numerical accuracy of | |
| 73 silk_NLSF2A_find_poly() compared to "standard" ordering. */ | |
| 74 static const unsigned char ordering16[16] = { | |
| 75 0, 15, 8, 7, 4, 11, 12, 3, 2, 13, 10, 5, 6, 9, 14, 1 | |
| 76 }; | |
| 77 static const unsigned char ordering10[10] = { | |
| 78 0, 9, 6, 3, 4, 5, 8, 1, 2, 7 | |
| 79 }; | |
| 80 const unsigned char *ordering; | |
| 81 opus_int k, i, dd; | |
| 82 opus_int32 cos_LSF_QA[ SILK_MAX_ORDER_LPC ]; | |
| 83 opus_int32 P[ SILK_MAX_ORDER_LPC / 2 + 1 ], Q[ SILK_MAX_ORDER_LPC / 2 + 1 ]; | |
| 84 opus_int32 Ptmp, Qtmp, f_int, f_frac, cos_val, delta; | |
| 85 opus_int32 a32_QA1[ SILK_MAX_ORDER_LPC ]; | |
| 86 opus_int32 maxabs, absval, idx=0, sc_Q16; | |
| 87 | |
| 88 silk_assert( LSF_COS_TAB_SZ_FIX == 128 ); | |
| 89 silk_assert( d==10||d==16 ); | |
| 90 | |
| 91 /* convert LSFs to 2*cos(LSF), using piecewise linear curve from table */ | |
| 92 ordering = d == 16 ? ordering16 : ordering10; | |
| 93 for( k = 0; k < d; k++ ) { | |
| 94 silk_assert(NLSF[k] >= 0 ); | |
| 95 | |
| 96 /* f_int on a scale 0-127 (rounded down) */ | |
| 97 f_int = silk_RSHIFT( NLSF[k], 15 - 7 ); | |
| 98 | |
| 99 /* f_frac, range: 0..255 */ | |
| 100 f_frac = NLSF[k] - silk_LSHIFT( f_int, 15 - 7 ); | |
| 101 | |
| 102 silk_assert(f_int >= 0); | |
| 103 silk_assert(f_int < LSF_COS_TAB_SZ_FIX ); | |
| 104 | |
| 105 /* Read start and end value from table */ | |
| 106 cos_val = silk_LSFCosTab_FIX_Q12[ f_int ]; /* Q12 */ | |
| 107 delta = silk_LSFCosTab_FIX_Q12[ f_int + 1 ] - cos_val; /* Q12, with a range of 0..200 */ | |
| 108 | |
| 109 /* Linear interpolation */ | |
| 110 cos_LSF_QA[ordering[k]] = silk_RSHIFT_ROUND( silk_LSHIFT( cos_val, 8 ) + silk_MUL( delta, f_frac ), 20 - QA ); /* QA */ | |
| 111 } | |
| 112 | |
| 113 dd = silk_RSHIFT( d, 1 ); | |
| 114 | |
| 115 /* generate even and odd polynomials using convolution */ | |
| 116 silk_NLSF2A_find_poly( P, &cos_LSF_QA[ 0 ], dd ); | |
| 117 silk_NLSF2A_find_poly( Q, &cos_LSF_QA[ 1 ], dd ); | |
| 118 | |
| 119 /* convert even and odd polynomials to opus_int32 Q12 filter coefs */ | |
| 120 for( k = 0; k < dd; k++ ) { | |
| 121 Ptmp = P[ k+1 ] + P[ k ]; | |
| 122 Qtmp = Q[ k+1 ] - Q[ k ]; | |
| 123 | |
| 124 /* the Ptmp and Qtmp values at this stage need to fit in int32 */ | |
| 125 a32_QA1[ k ] = -Qtmp - Ptmp; /* QA+1 */ | |
| 126 a32_QA1[ d-k-1 ] = Qtmp - Ptmp; /* QA+1 */ | |
| 127 } | |
| 128 | |
| 129 /* Limit the maximum absolute value of the prediction coefficients, so that they'll fit in int16 */ | |
| 130 for( i = 0; i < 10; i++ ) { | |
| 131 /* Find maximum absolute value and its index */ | |
| 132 maxabs = 0; | |
| 133 for( k = 0; k < d; k++ ) { | |
| 134 absval = silk_abs( a32_QA1[k] ); | |
| 135 if( absval > maxabs ) { | |
| 136 maxabs = absval; | |
| 137 idx = k; | |
| 138 } | |
| 139 } | |
| 140 maxabs = silk_RSHIFT_ROUND( maxabs, QA + 1 - 12 ); /* QA+1 -> Q12 */ | |
| 141 | |
| 142 if( maxabs > silk_int16_MAX ) { | |
| 143 /* Reduce magnitude of prediction coefficients */ | |
| 144 maxabs = silk_min( maxabs, 163838 ); /* ( silk_int32_MAX >> 14 ) + silk_int16_MAX = 163838 */ | |
| 145 sc_Q16 = SILK_FIX_CONST( 0.999, 16 ) - silk_DIV32( silk_LSHIFT( maxabs - silk_int16_MAX, 14 ), | |
| 146 silk_RSHIFT32( silk_MUL( maxabs, idx + 1), 2 ) ); | |
| 147 silk_bwexpander_32( a32_QA1, d, sc_Q16 ); | |
| 148 } else { | |
| 149 break; | |
| 150 } | |
| 151 } | |
| 152 | |
| 153 if( i == 10 ) { | |
| 154 /* Reached the last iteration, clip the coefficients */ | |
| 155 for( k = 0; k < d; k++ ) { | |
| 156 a_Q12[ k ] = (opus_int16)silk_SAT16( silk_RSHIFT_ROUND( a32_QA1[ k ], QA + 1 - 12 ) ); /* QA+1 -> Q12 */ | |
| 157 a32_QA1[ k ] = silk_LSHIFT( (opus_int32)a_Q12[ k ], QA + 1 - 12 ); | |
| 158 } | |
| 159 } else { | |
| 160 for( k = 0; k < d; k++ ) { | |
| 161 a_Q12[ k ] = (opus_int16)silk_RSHIFT_ROUND( a32_QA1[ k ], QA + 1 - 12 ); /* QA+1 -> Q12 */ | |
| 162 } | |
| 163 } | |
| 164 | |
| 165 for( i = 0; i < MAX_LPC_STABILIZE_ITERATIONS; i++ ) { | |
| 166 if( silk_LPC_inverse_pred_gain( a_Q12, d ) < SILK_FIX_CONST( 1.0 / MAX_PREDICTION_POWER_GAIN, 30 ) ) { | |
| 167 /* Prediction coefficients are (too close to) unstable; apply bandwidth expansion */ | |
| 168 /* on the unscaled coefficients, convert to Q12 and measure again */ | |
| 169 silk_bwexpander_32( a32_QA1, d, 65536 - silk_LSHIFT( 2, i ) ); | |
| 170 for( k = 0; k < d; k++ ) { | |
| 171 a_Q12[ k ] = (opus_int16)silk_RSHIFT_ROUND( a32_QA1[ k ], QA + 1 - 12 ); /* QA+1 -> Q12 */ | |
| 172 } | |
| 173 } else { | |
| 174 break; | |
| 175 } | |
| 176 } | |
| 177 } | |
| 178 |
