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1/* ***** BEGIN LICENSE BLOCK *****
2 * Source last modified: $Id: pns.c,v 1.2 2005/03/10 17:01:56 jrecker Exp $
3 *
4 * Portions Copyright (c) 1995-2005 RealNetworks, Inc. All Rights Reserved.
5 *
6 * The contents of this file, and the files included with this file,
7 * are subject to the current version of the RealNetworks Public
8 * Source License (the "RPSL") available at
9 * http://www.helixcommunity.org/content/rpsl unless you have licensed
10 * the file under the current version of the RealNetworks Community
11 * Source License (the "RCSL") available at
12 * http://www.helixcommunity.org/content/rcsl, in which case the RCSL
13 * will apply. You may also obtain the license terms directly from
14 * RealNetworks. You may not use this file except in compliance with
15 * the RPSL or, if you have a valid RCSL with RealNetworks applicable
16 * to this file, the RCSL. Please see the applicable RPSL or RCSL for
17 * the rights, obligations and limitations governing use of the
18 * contents of the file.
19 *
20 * This file is part of the Helix DNA Technology. RealNetworks is the
21 * developer of the Original Code and owns the copyrights in the
22 * portions it created.
23 *
24 * This file, and the files included with this file, is distributed
25 * and made available on an 'AS IS' basis, WITHOUT WARRANTY OF ANY
26 * KIND, EITHER EXPRESS OR IMPLIED, AND REALNETWORKS HEREBY DISCLAIMS
27 * ALL SUCH WARRANTIES, INCLUDING WITHOUT LIMITATION, ANY WARRANTIES
28 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, QUIET
29 * ENJOYMENT OR NON-INFRINGEMENT.
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31 * Technology Compatibility Kit Test Suite(s) Location:
32 * http://www.helixcommunity.org/content/tck
33 *
34 * Contributor(s):
35 *
36 * ***** END LICENSE BLOCK ***** */
37
38/**************************************************************************************
39 * Fixed-point HE-AAC decoder
40 * Jon Recker (jrecker@real.com)
41 * February 2005
42 *
43 * pns.c - perceptual noise substitution
44 **************************************************************************************/
45
46#include "coder.h"
47#ifndef __MW__
48#include "assembly.h"
49#else
50#include "assembly_mw.h"
51#endif /* __MW__ */
52
53/**************************************************************************************
54 * Function: Get32BitVal
55 *
56 * Description: generate 32-bit unsigned random number
57 *
58 * Inputs: last number calculated (seed, first time through)
59 *
60 * Outputs: new number, saved in *last
61 *
62 * Return: 32-bit number, uniformly distributed between [0, 2^32)
63 *
64 * Notes: uses simple linear congruential generator
65 **************************************************************************************/
66static unsigned int Get32BitVal(unsigned int *last)
67{
68 unsigned int r = *last;
69
70 /* use same coefs as MPEG reference code (classic LCG)
71 * use unsigned multiply to force reliable wraparound behavior in C (mod 2^32)
72 */
73 r = (1664525U * r) + 1013904223U;
74 *last = r;
75
76 return r;
77}
78
79/* pow(2, i/4.0) for i = [0,1,2,3], format = Q30 */
80static const int pow14[4] = {
81 0x40000000, 0x4c1bf829, 0x5a82799a, 0x6ba27e65
82};
83
84#define NUM_ITER_INVSQRT 4
85
86#define X0_COEF_2 0xc0000000 /* Q29: -2.0 */
87#define X0_OFF_2 0x60000000 /* Q29: 3.0 */
88#define Q26_3 0x0c000000 /* Q26: 3.0 */
89
90/**************************************************************************************
91 * Function: InvRootR
92 *
93 * Description: use Newton's method to solve for x = 1/sqrt(r)
94 *
95 * Inputs: r in Q30 format, range = [0.25, 1] (normalize inputs to this range)
96 *
97 * Outputs: none
98 *
99 * Return: x = Q29, range = (1, 2)
100 *
101 * Notes: guaranteed to converge and not overflow for any r in this range
102 *
103 * xn+1 = xn - f(xn)/f'(xn)
104 * f(x) = 1/sqrt(r) - x = 0 (find root)
105 * = 1/x^2 - r
106 * f'(x) = -2/x^3
107 *
108 * so xn+1 = xn/2 * (3 - r*xn^2)
109 *
110 * NUM_ITER_INVSQRT = 3, maxDiff = 1.3747e-02
111 * NUM_ITER_INVSQRT = 4, maxDiff = 3.9832e-04
112 **************************************************************************************/
113static int InvRootR(int r)
114{
115 int i, xn, t;
116
117 /* use linear equation for initial guess
118 * x0 = -2*r + 3 (so x0 always >= correct answer in range [0.25, 1))
119 * xn = Q29 (at every step)
120 */
121 xn = (MULSHIFT32(r, X0_COEF_2) << 2) + X0_OFF_2;
122
123 for (i = 0; i < NUM_ITER_INVSQRT; i++) {
124 t = MULSHIFT32(xn, xn); /* Q26 = Q29*Q29 */
125 t = Q26_3 - (MULSHIFT32(r, t) << 2); /* Q26 = Q26 - (Q31*Q26 << 1) */
126 xn = MULSHIFT32(xn, t) << (6 - 1); /* Q29 = (Q29*Q26 << 6), and -1 for division by 2 */
127 }
128
129 /* clip to range (1.0, 2.0)
130 * (because of rounding, this can converge to xn slightly > 2.0 when r is near 0.25)
131 */
132 if (xn >> 30) {
133 xn = (1 << 30) - 1;
134 }
135
136 return xn;
137}
138
139/**************************************************************************************
140 * Function: ScaleNoiseVector
141 *
142 * Description: apply scaling to vector of noise coefficients for one scalefactor band
143 *
144 * Inputs: unscaled coefficients
145 * number of coefficients in vector (one scalefactor band of coefs)
146 * scalefactor for this band (i.e. noise energy)
147 *
148 * Outputs: nVals coefficients in Q(FBITS_OUT_DQ_OFF)
149 *
150 * Return: guard bit mask (OR of abs value of all noise coefs)
151 **************************************************************************************/
152static int ScaleNoiseVector(int *coef, int nVals, int sf)
153{
154 int i, c, spec, energy, sq, scalef, scalei, invSqrtEnergy, z, gbMask;
155
156 energy = 0;
157 for (i = 0; i < nVals; i++) {
158 spec = coef[i];
159
160 /* max nVals = max SFB width = 96, so energy can gain < 2^7 bits in accumulation */
161 sq = (spec * spec) >> 8; /* spec*spec range = (-2^30, 2^30) */
162 energy += sq;
163 }
164
165 /* unless nVals == 1 (or the number generator is broken...), this should not happen */
166 if (energy == 0) {
167 return 0; /* coef[i] must = 0 for i = [0, nVals-1], so gbMask = 0 */
168 }
169
170 /* pow(2, sf/4) * pow(2, FBITS_OUT_DQ_OFF) */
171 scalef = pow14[sf & 0x3];
172 scalei = (sf >> 2) + FBITS_OUT_DQ_OFF;
173
174 /* energy has implied factor of 2^-8 since we shifted the accumulator
175 * normalize energy to range [0.25, 1.0), calculate 1/sqrt(1), and denormalize
176 * i.e. divide input by 2^(30-z) and convert to Q30
177 * output of 1/sqrt(i) now has extra factor of 2^((30-z)/2)
178 * for energy > 0, z is an even number between 0 and 28
179 * final scaling of invSqrtEnergy:
180 * 2^(15 - z/2) to compensate for implicit 2^(30-z) factor in input
181 * +4 to compensate for implicit 2^-8 factor in input
182 */
183 z = CLZ(energy) - 2; /* energy has at least 2 leading zeros (see acc loop) */
184 z &= 0xfffffffe; /* force even */
185 invSqrtEnergy = InvRootR(energy << z); /* energy << z must be in range [0x10000000, 0x40000000] */
186 scalei -= (15 - z / 2 + 4); /* nInt = 1/sqrt(energy) in Q29 */
187
188 /* normalize for final scaling */
189 z = CLZ(invSqrtEnergy) - 1;
190 invSqrtEnergy <<= z;
191 scalei -= (z - 3 - 2); /* -2 for scalef, z-3 for invSqrtEnergy */
192 scalef = MULSHIFT32(scalef, invSqrtEnergy); /* scalef (input) = Q30, invSqrtEnergy = Q29 * 2^z */
193 gbMask = 0;
194
195 if (scalei < 0) {
196 scalei = -scalei;
197 if (scalei > 31) {
198 scalei = 31;
199 }
200 for (i = 0; i < nVals; i++) {
201 c = MULSHIFT32(coef[i], scalef) >> scalei;
202 gbMask |= FASTABS(c);
203 coef[i] = c;
204 }
205 } else {
206 /* for scalei <= 16, no clipping possible (coef[i] is < 2^15 before scaling)
207 * for scalei > 16, just saturate exponent (rare)
208 * scalef is close to full-scale (since we normalized invSqrtEnergy)
209 * remember, we are just producing noise here
210 */
211 if (scalei > 16) {
212 scalei = 16;
213 }
214 for (i = 0; i < nVals; i++) {
215 c = MULSHIFT32(coef[i] << scalei, scalef);
216 coef[i] = c;
217 gbMask |= FASTABS(c);
218 }
219 }
220
221 return gbMask;
222}
223
224/**************************************************************************************
225 * Function: GenerateNoiseVector
226 *
227 * Description: create vector of noise coefficients for one scalefactor band
228 *
229 * Inputs: seed for number generator
230 * number of coefficients to generate
231 *
232 * Outputs: buffer of nVals coefficients, range = [-2^15, 2^15)
233 * updated seed for number generator
234 *
235 * Return: none
236 **************************************************************************************/
237static void GenerateNoiseVector(int *coef, int *last, int nVals)
238{
239 int i;
240
241 for (i = 0; i < nVals; i++) {
242 coef[i] = ((signed int)Get32BitVal((unsigned int *)last)) >> 16;
243 }
244}
245
246/**************************************************************************************
247 * Function: CopyNoiseVector
248 *
249 * Description: copy vector of noise coefficients for one scalefactor band from L to R
250 *
251 * Inputs: buffer of left coefficients
252 * number of coefficients to copy
253 *
254 * Outputs: buffer of right coefficients
255 *
256 * Return: none
257 **************************************************************************************/
258static void CopyNoiseVector(int *coefL, int *coefR, int nVals)
259{
260 int i;
261
262 for (i = 0; i < nVals; i++) {
263 coefR[i] = coefL[i];
264 }
265}
266
267/**************************************************************************************
268 * Function: PNS
269 *
270 * Description: apply perceptual noise substitution, if enabled (MPEG-4 only)
271 *
272 * Inputs: valid AACDecInfo struct
273 * index of current channel
274 *
275 * Outputs: shaped noise in scalefactor bands where PNS is active
276 * updated minimum guard bit count for this channel
277 *
278 * Return: 0 if successful, -1 if error
279 **************************************************************************************/
280int PNS(AACDecInfo *aacDecInfo, int ch)
281{
282 int gp, sfb, win, width, nSamps, gb, gbMask;
283 int *coef;
284 const short *sfbTab;
285 unsigned char *sfbCodeBook;
286 short *scaleFactors;
287 int msMaskOffset, checkCorr, genNew;
288 unsigned char msMask;
289 unsigned char *msMaskPtr;
290 PSInfoBase *psi;
291 ICSInfo *icsInfo;
292
293 /* validate pointers */
294 if (!aacDecInfo || !aacDecInfo->psInfoBase) {
295 return -1;
296 }
297 psi = (PSInfoBase *)(aacDecInfo->psInfoBase);
298 icsInfo = (ch == 1 && psi->commonWin == 1) ? &(psi->icsInfo[0]) : &(psi->icsInfo[ch]);
299
300 if (!psi->pnsUsed[ch]) {
301 return 0;
302 }
303
304 if (icsInfo->winSequence == 2) {
305 sfbTab = sfBandTabShort + sfBandTabShortOffset[psi->sampRateIdx];
306 nSamps = NSAMPS_SHORT;
307 } else {
308 sfbTab = sfBandTabLong + sfBandTabLongOffset[psi->sampRateIdx];
309 nSamps = NSAMPS_LONG;
310 }
311 coef = psi->coef[ch];
312 sfbCodeBook = psi->sfbCodeBook[ch];
313 scaleFactors = psi->scaleFactors[ch];
314 checkCorr = (aacDecInfo->currBlockID == AAC_ID_CPE && psi->commonWin == 1 ? 1 : 0);
315
316 gbMask = 0;
317 for (gp = 0; gp < icsInfo->numWinGroup; gp++) {
318 for (win = 0; win < icsInfo->winGroupLen[gp]; win++) {
319 msMaskPtr = psi->msMaskBits + ((gp * icsInfo->maxSFB) >> 3);
320 msMaskOffset = ((gp * icsInfo->maxSFB) & 0x07);
321 msMask = (*msMaskPtr++) >> msMaskOffset;
322
323 for (sfb = 0; sfb < icsInfo->maxSFB; sfb++) {
324 width = sfbTab[sfb + 1] - sfbTab[sfb];
325 if (sfbCodeBook[sfb] == 13) {
326 if (ch == 0) {
327 /* generate new vector, copy into ch 1 if it's possible that the channels will be correlated
328 * if ch 1 has PNS enabled for this SFB but it's uncorrelated (i.e. ms_used == 0),
329 * the copied values will be overwritten when we process ch 1
330 */
331 GenerateNoiseVector(coef, &psi->pnsLastVal, width);
332 if (checkCorr && psi->sfbCodeBook[1][gp * icsInfo->maxSFB + sfb] == 13) {
333 CopyNoiseVector(coef, psi->coef[1] + (coef - psi->coef[0]), width);
334 }
335 } else {
336 /* generate new vector if no correlation between channels */
337 genNew = 1;
338 if (checkCorr && psi->sfbCodeBook[0][gp * icsInfo->maxSFB + sfb] == 13) {
339 if ((psi->msMaskPresent == 1 && (msMask & 0x01)) || psi->msMaskPresent == 2) {
340 genNew = 0;
341 }
342 }
343 if (genNew) {
344 GenerateNoiseVector(coef, &psi->pnsLastVal, width);
345 }
346 }
347 gbMask |= ScaleNoiseVector(coef, width, psi->scaleFactors[ch][gp * icsInfo->maxSFB + sfb]);
348 }
349 coef += width;
350
351 /* get next mask bit (should be branchless on ARM) */
352 msMask >>= 1;
353 if (++msMaskOffset == 8) {
354 msMask = *msMaskPtr++;
355 msMaskOffset = 0;
356 }
357 }
358 coef += (nSamps - sfbTab[icsInfo->maxSFB]);
359 }
360 sfbCodeBook += icsInfo->maxSFB;
361 scaleFactors += icsInfo->maxSFB;
362 }
363
364 /* update guard bit count if necessary */
365 gb = CLZ(gbMask) - 1;
366 if (psi->gbCurrent[ch] > gb) {
367 psi->gbCurrent[ch] = gb;
368 }
369
370 return 0;
371}
372
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