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358 lines
12 KiB
C
358 lines
12 KiB
C
/* ***** BEGIN LICENSE BLOCK *****
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* Source last modified: $Id: pns.c,v 1.2 2005/03/10 17:01:56 jrecker Exp $
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*
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* Portions Copyright (c) 1995-2005 RealNetworks, Inc. All Rights Reserved.
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*
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* The contents of this file, and the files included with this file,
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* are subject to the current version of the RealNetworks Public
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* Source License (the "RPSL") available at
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* http://www.helixcommunity.org/content/rpsl unless you have licensed
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* the file under the current version of the RealNetworks Community
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* Source License (the "RCSL") available at
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* http://www.helixcommunity.org/content/rcsl, in which case the RCSL
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* will apply. You may also obtain the license terms directly from
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* RealNetworks. You may not use this file except in compliance with
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* the RPSL or, if you have a valid RCSL with RealNetworks applicable
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* to this file, the RCSL. Please see the applicable RPSL or RCSL for
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* the rights, obligations and limitations governing use of the
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* contents of the file.
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*
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* This file is part of the Helix DNA Technology. RealNetworks is the
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* developer of the Original Code and owns the copyrights in the
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* portions it created.
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*
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* This file, and the files included with this file, is distributed
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* and made available on an 'AS IS' basis, WITHOUT WARRANTY OF ANY
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* KIND, EITHER EXPRESS OR IMPLIED, AND REALNETWORKS HEREBY DISCLAIMS
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* ALL SUCH WARRANTIES, INCLUDING WITHOUT LIMITATION, ANY WARRANTIES
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* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, QUIET
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* ENJOYMENT OR NON-INFRINGEMENT.
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*
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* Technology Compatibility Kit Test Suite(s) Location:
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* http://www.helixcommunity.org/content/tck
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*
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* Contributor(s):
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*
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* ***** END LICENSE BLOCK ***** */
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/**************************************************************************************
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* Fixed-point HE-AAC decoder
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* Jon Recker (jrecker@real.com)
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* February 2005
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*
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* pns.c - perceptual noise substitution
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**************************************************************************************/
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#include "coder.h"
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#include "assembly.h"
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/**************************************************************************************
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* Function: Get32BitVal
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*
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* Description: generate 32-bit unsigned random number
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*
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* Inputs: last number calculated (seed, first time through)
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*
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* Outputs: new number, saved in *last
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*
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* Return: 32-bit number, uniformly distributed between [0, 2^32)
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*
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* Notes: uses simple linear congruential generator
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**************************************************************************************/
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static unsigned int Get32BitVal(unsigned int *last)
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{
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unsigned int r = *last;
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/* use same coefs as MPEG reference code (classic LCG)
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* use unsigned multiply to force reliable wraparound behavior in C (mod 2^32)
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*/
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r = (1664525U * r) + 1013904223U;
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*last = r;
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return r;
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}
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#define NUM_ITER_INVSQRT 4
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#define X0_COEF_2 0xc0000000 /* Q29: -2.0 */
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#define X0_OFF_2 0x60000000 /* Q29: 3.0 */
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#define Q26_3 0x0c000000 /* Q26: 3.0 */
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/**************************************************************************************
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* Function: InvRootR
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*
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* Description: use Newton's method to solve for x = 1/sqrt(r)
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*
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* Inputs: r in Q30 format, range = [0.25, 1] (normalize inputs to this range)
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*
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* Outputs: none
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*
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* Return: x = Q29, range = (1, 2)
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*
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* Notes: guaranteed to converge and not overflow for any r in this range
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*
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* xn+1 = xn - f(xn)/f'(xn)
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* f(x) = 1/sqrt(r) - x = 0 (find root)
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* = 1/x^2 - r
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* f'(x) = -2/x^3
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*
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* so xn+1 = xn/2 * (3 - r*xn^2)
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*
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* NUM_ITER_INVSQRT = 3, maxDiff = 1.3747e-02
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* NUM_ITER_INVSQRT = 4, maxDiff = 3.9832e-04
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**************************************************************************************/
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static int InvRootR(int r)
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{
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int i, xn, t;
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/* use linear equation for initial guess
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* x0 = -2*r + 3 (so x0 always >= correct answer in range [0.25, 1))
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* xn = Q29 (at every step)
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*/
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xn = (MULSHIFT32(r, X0_COEF_2) << 2) + X0_OFF_2;
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for (i = 0; i < NUM_ITER_INVSQRT; i++) {
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t = MULSHIFT32(xn, xn); /* Q26 = Q29*Q29 */
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t = Q26_3 - (MULSHIFT32(r, t) << 2); /* Q26 = Q26 - (Q31*Q26 << 1) */
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xn = MULSHIFT32(xn, t) << (6 - 1); /* Q29 = (Q29*Q26 << 6), and -1 for division by 2 */
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}
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/* clip to range (1.0, 2.0)
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* (because of rounding, this can converge to xn slightly > 2.0 when r is near 0.25)
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*/
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if (xn >> 30)
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xn = (1 << 30) - 1;
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return xn;
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}
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/**************************************************************************************
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* Function: ScaleNoiseVector
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*
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* Description: apply scaling to vector of noise coefficients for one scalefactor band
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*
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* Inputs: unscaled coefficients
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* number of coefficients in vector (one scalefactor band of coefs)
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* scalefactor for this band (i.e. noise energy)
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*
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* Outputs: nVals coefficients in Q(FBITS_OUT_DQ_OFF)
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*
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* Return: guard bit mask (OR of abs value of all noise coefs)
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**************************************************************************************/
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static int ScaleNoiseVector(int *coef, int nVals, int sf)
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{
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/* pow(2, i/4.0) for i = [0,1,2,3], format = Q30 */
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static const int pow14[4] PROGMEM = {
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0x40000000, 0x4c1bf829, 0x5a82799a, 0x6ba27e65
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};
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int i, c, spec, energy, sq, scalef, scalei, invSqrtEnergy, z, gbMask;
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energy = 0;
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for (i = 0; i < nVals; i++) {
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spec = coef[i];
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/* max nVals = max SFB width = 96, so energy can gain < 2^7 bits in accumulation */
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sq = (spec * spec) >> 8; /* spec*spec range = (-2^30, 2^30) */
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energy += sq;
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}
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/* unless nVals == 1 (or the number generator is broken...), this should not happen */
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if (energy == 0)
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return 0; /* coef[i] must = 0 for i = [0, nVals-1], so gbMask = 0 */
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/* pow(2, sf/4) * pow(2, FBITS_OUT_DQ_OFF) */
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scalef = pow14[sf & 0x3];
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scalei = (sf >> 2) + FBITS_OUT_DQ_OFF;
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/* energy has implied factor of 2^-8 since we shifted the accumulator
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* normalize energy to range [0.25, 1.0), calculate 1/sqrt(1), and denormalize
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* i.e. divide input by 2^(30-z) and convert to Q30
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* output of 1/sqrt(i) now has extra factor of 2^((30-z)/2)
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* for energy > 0, z is an even number between 0 and 28
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* final scaling of invSqrtEnergy:
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* 2^(15 - z/2) to compensate for implicit 2^(30-z) factor in input
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* +4 to compensate for implicit 2^-8 factor in input
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*/
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z = CLZ(energy) - 2; /* energy has at least 2 leading zeros (see acc loop) */
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z &= 0xfffffffe; /* force even */
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invSqrtEnergy = InvRootR(energy << z); /* energy << z must be in range [0x10000000, 0x40000000] */
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scalei -= (15 - z/2 + 4); /* nInt = 1/sqrt(energy) in Q29 */
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/* normalize for final scaling */
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z = CLZ(invSqrtEnergy) - 1;
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invSqrtEnergy <<= z;
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scalei -= (z - 3 - 2); /* -2 for scalef, z-3 for invSqrtEnergy */
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scalef = MULSHIFT32(scalef, invSqrtEnergy); /* scalef (input) = Q30, invSqrtEnergy = Q29 * 2^z */
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gbMask = 0;
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if (scalei < 0) {
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scalei = -scalei;
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if (scalei > 31)
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scalei = 31;
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for (i = 0; i < nVals; i++) {
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c = MULSHIFT32(coef[i], scalef) >> scalei;
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gbMask |= FASTABS(c);
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coef[i] = c;
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}
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} else {
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/* for scalei <= 16, no clipping possible (coef[i] is < 2^15 before scaling)
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* for scalei > 16, just saturate exponent (rare)
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* scalef is close to full-scale (since we normalized invSqrtEnergy)
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* remember, we are just producing noise here
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*/
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if (scalei > 16)
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scalei = 16;
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for (i = 0; i < nVals; i++) {
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c = MULSHIFT32(coef[i] << scalei, scalef);
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coef[i] = c;
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gbMask |= FASTABS(c);
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}
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}
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return gbMask;
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}
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/**************************************************************************************
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* Function: GenerateNoiseVector
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*
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* Description: create vector of noise coefficients for one scalefactor band
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*
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* Inputs: seed for number generator
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* number of coefficients to generate
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*
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* Outputs: buffer of nVals coefficients, range = [-2^15, 2^15)
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* updated seed for number generator
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*
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* Return: none
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**************************************************************************************/
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static void GenerateNoiseVector(int *coef, int *last, int nVals)
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{
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int i;
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for (i = 0; i < nVals; i++)
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coef[i] = ((signed int)Get32BitVal((unsigned int *)last)) >> 16;
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}
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/**************************************************************************************
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* Function: CopyNoiseVector
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*
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* Description: copy vector of noise coefficients for one scalefactor band from L to R
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*
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* Inputs: buffer of left coefficients
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* number of coefficients to copy
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*
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* Outputs: buffer of right coefficients
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*
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* Return: none
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**************************************************************************************/
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static void CopyNoiseVector(int *coefL, int *coefR, int nVals)
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{
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int i;
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for (i = 0; i < nVals; i++)
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coefR[i] = coefL[i];
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}
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/**************************************************************************************
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* Function: PNS
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*
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* Description: apply perceptual noise substitution, if enabled (MPEG-4 only)
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*
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* Inputs: valid AACDecInfo struct
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* index of current channel
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*
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* Outputs: shaped noise in scalefactor bands where PNS is active
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* updated minimum guard bit count for this channel
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*
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* Return: 0 if successful, -1 if error
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**************************************************************************************/
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int PNS(AACDecInfo *aacDecInfo, int ch)
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{
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int gp, sfb, win, width, nSamps, gb, gbMask;
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int *coef;
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const /*short*/ int *sfbTab;
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unsigned char *sfbCodeBook;
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short *scaleFactors;
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int msMaskOffset, checkCorr, genNew;
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unsigned char msMask;
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unsigned char *msMaskPtr;
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PSInfoBase *psi;
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ICSInfo *icsInfo;
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/* validate pointers */
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if (!aacDecInfo || !aacDecInfo->psInfoBase)
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return -1;
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psi = (PSInfoBase *)(aacDecInfo->psInfoBase);
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icsInfo = (ch == 1 && psi->commonWin == 1) ? &(psi->icsInfo[0]) : &(psi->icsInfo[ch]);
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if (!psi->pnsUsed[ch])
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return 0;
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if (icsInfo->winSequence == 2) {
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sfbTab = sfBandTabShort + sfBandTabShortOffset[psi->sampRateIdx];
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nSamps = NSAMPS_SHORT;
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} else {
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sfbTab = sfBandTabLong + sfBandTabLongOffset[psi->sampRateIdx];
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nSamps = NSAMPS_LONG;
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}
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coef = psi->coef[ch];
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sfbCodeBook = psi->sfbCodeBook[ch];
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scaleFactors = psi->scaleFactors[ch];
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checkCorr = (aacDecInfo->currBlockID == AAC_ID_CPE && psi->commonWin == 1 ? 1 : 0);
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gbMask = 0;
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for (gp = 0; gp < icsInfo->numWinGroup; gp++) {
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for (win = 0; win < icsInfo->winGroupLen[gp]; win++) {
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msMaskPtr = psi->msMaskBits + ((gp*icsInfo->maxSFB) >> 3);
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msMaskOffset = ((gp*icsInfo->maxSFB) & 0x07);
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msMask = (*msMaskPtr++) >> msMaskOffset;
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for (sfb = 0; sfb < icsInfo->maxSFB; sfb++) {
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width = sfbTab[sfb+1] - sfbTab[sfb];
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if (sfbCodeBook[sfb] == 13) {
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if (ch == 0) {
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/* generate new vector, copy into ch 1 if it's possible that the channels will be correlated
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* if ch 1 has PNS enabled for this SFB but it's uncorrelated (i.e. ms_used == 0),
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* the copied values will be overwritten when we process ch 1
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*/
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GenerateNoiseVector(coef, &psi->pnsLastVal, width);
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if (checkCorr && psi->sfbCodeBook[1][gp*icsInfo->maxSFB + sfb] == 13)
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CopyNoiseVector(coef, psi->coef[1] + (coef - psi->coef[0]), width);
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} else {
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/* generate new vector if no correlation between channels */
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genNew = 1;
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if (checkCorr && psi->sfbCodeBook[0][gp*icsInfo->maxSFB + sfb] == 13) {
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if ( (psi->msMaskPresent == 1 && (msMask & 0x01)) || psi->msMaskPresent == 2 )
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genNew = 0;
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}
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if (genNew)
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GenerateNoiseVector(coef, &psi->pnsLastVal, width);
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}
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gbMask |= ScaleNoiseVector(coef, width, psi->scaleFactors[ch][gp*icsInfo->maxSFB + sfb]);
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}
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coef += width;
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/* get next mask bit (should be branchless on ARM) */
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msMask >>= 1;
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if (++msMaskOffset == 8) {
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msMask = *msMaskPtr++;
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msMaskOffset = 0;
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}
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}
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coef += (nSamps - sfbTab[icsInfo->maxSFB]);
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}
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sfbCodeBook += icsInfo->maxSFB;
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scaleFactors += icsInfo->maxSFB;
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}
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/* update guard bit count if necessary */
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gb = CLZ(gbMask) - 1;
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if (psi->gbCurrent[ch] > gb)
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psi->gbCurrent[ch] = gb;
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return 0;
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}
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