FFmpeg coverage

Directory: ../../../ffmpeg/
File: src/libavcodec/aacenc_utils.h
Date: 2025-11-10 16:28:23
Exec Total Coverage
Lines: 83 83 100.0%
Functions: 12 12 100.0%
Branches: 52 56 92.9%
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1 /*
2 * AAC encoder utilities
3 * Copyright (C) 2015 Rostislav Pehlivanov
4 *
5 * This file is part of FFmpeg.
6 *
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22 /**
23 * @file
24 * AAC encoder utilities
25 * @author Rostislav Pehlivanov ( atomnuker gmail com )
26 */
27
28 #ifndef AVCODEC_AACENC_UTILS_H
29 #define AVCODEC_AACENC_UTILS_H
30
31 #include "libavutil/ffmath.h"
32 #include "aacenc.h"
33 #include "aacenctab.h"
34 #include "aactab.h"
35
36 #define ROUND_STANDARD 0.4054f
37 #define ROUND_TO_ZERO 0.1054f
38 #define C_QUANT 0.4054f
39
40 17289 static inline float pos_pow34(float a)
41 {
42 17289 return sqrtf(a * sqrtf(a));
43 }
44
45 /**
46 * Quantize one coefficient.
47 * @return absolute value of the quantized coefficient
48 * @see 3GPP TS26.403 5.6.2 "Scalefactor determination"
49 */
50 1722676 static inline int quant(float coef, const float Q, const float rounding)
51 {
52 1722676 float a = coef * Q;
53 1722676 return sqrtf(a * sqrtf(a)) + rounding;
54 }
55
56 470159 static inline float find_max_val(int group_len, int swb_size, const float *scaled)
57 {
58 470159 float maxval = 0.0f;
59 int w2, i;
60
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 947794 for (w2 = 0; w2 < group_len; w2++) {
61
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 10522003 for (i = 0; i < swb_size; i++) {
62
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 10044368 maxval = FFMAX(maxval, scaled[w2*128+i]);
63 }
64 }
65 470159 return maxval;
66 }
67
68 15006185 static inline int find_min_book(float maxval, int sf)
69 {
70 15006185 float Q34 = ff_aac_pow34sf_tab[POW_SF2_ZERO - sf + SCALE_ONE_POS - SCALE_DIV_512];
71 int qmaxval, cb;
72 15006185 qmaxval = maxval * Q34 + C_QUANT;
73
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 15006185 if (qmaxval >= (FF_ARRAY_ELEMS(aac_maxval_cb)))
74 1336820 cb = 11;
75 else
76 13669365 cb = aac_maxval_cb[qmaxval];
77 15006185 return cb;
78 }
79
80 60354 static inline float find_form_factor(int group_len, int swb_size, float thresh,
81 const float *scaled, float nzslope) {
82 60354 const float iswb_size = 1.0f / swb_size;
83 60354 const float iswb_sizem1 = 1.0f / (swb_size - 1);
84 60354 const float ethresh = thresh;
85 60354 float form = 0.0f, weight = 0.0f;
86 int w2, i;
87
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 121924 for (w2 = 0; w2 < group_len; w2++) {
88 61570 float e = 0.0f, e2 = 0.0f, var = 0.0f, maxval = 0.0f;
89 61570 float nzl = 0;
90
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 1219218 for (i = 0; i < swb_size; i++) {
91 1157648 float s = fabsf(scaled[w2*128+i]);
92
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 1157648 maxval = FFMAX(maxval, s);
93 1157648 e += s;
94 1157648 e2 += s *= s;
95 /* We really don't want a hard non-zero-line count, since
96 * even below-threshold lines do add up towards band spectral power.
97 * So, fall steeply towards zero, but smoothly
98 */
99
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 1157648 if (s >= ethresh) {
100 350370 nzl += 1.0f;
101 } else {
102
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 807278 if (nzslope == 2.f)
103 362928 nzl += (s / ethresh) * (s / ethresh);
104 else
105 444350 nzl += ff_fast_powf(s / ethresh, nzslope);
106 }
107 }
108
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 61570 if (e2 > thresh) {
109 float frm;
110 61360 e *= iswb_size;
111
112 /** compute variance */
113
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 1217400 for (i = 0; i < swb_size; i++) {
114 1156040 float d = fabsf(scaled[w2*128+i]) - e;
115 1156040 var += d*d;
116 }
117 61360 var = sqrtf(var * iswb_sizem1);
118
119 61360 e2 *= iswb_size;
120
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 61360 frm = e / FFMIN(e+4*var,maxval);
121
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 61360 form += e2 * sqrtf(frm) / FFMAX(0.5f,nzl);
122 61360 weight += e2;
123 }
124 }
125
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 60354 if (weight > 0) {
126 60306 return form / weight;
127 } else {
128 48 return 1.0f;
129 }
130 }
131
132 /** Return the minimum scalefactor where the quantized coef does not clip. */
133 36141 static inline uint8_t coef2minsf(float coef)
134 {
135 36141 return av_clip_uint8(log2f(coef)*4 - 69 + SCALE_ONE_POS - SCALE_DIV_512);
136 }
137
138 /** Return the maximum scalefactor where the quantized coef is not zero. */
139 static inline uint8_t coef2maxsf(float coef)
140 {
141 return av_clip_uint8(log2f(coef)*4 + 6 + SCALE_ONE_POS - SCALE_DIV_512);
142 }
143
144 /*
145 * Returns the closest possible index to an array of float values, given a value.
146 */
147 458 static inline int quant_array_idx(const float val, const float *arr, const int num)
148 {
149 458 int i, index = 0;
150 458 float quant_min_err = INFINITY;
151
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 7786 for (i = 0; i < num; i++) {
152 7328 float error = (val - arr[i])*(val - arr[i]);
153
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 7328 if (error < quant_min_err) {
154 907 quant_min_err = error;
155 907 index = i;
156 }
157 }
158 458 return index;
159 }
160
161 /**
162 * approximates exp10f(-3.0f*(0.5f + 0.5f * cosf(FFMIN(b,15.5f) / 15.5f)))
163 */
164 5313 static av_always_inline float bval2bmax(float b)
165 {
166 5313 return 0.001f + 0.0035f * (b*b*b) / (15.5f*15.5f*15.5f);
167 }
168
169 /*
170 * Compute a nextband map to be used with SF delta constraint utilities.
171 * The nextband array should contain 128 elements, and positions that don't
172 * map to valid, nonzero bands of the form w*16+g (with w being the initial
173 * window of the window group, only) are left indetermined.
174 */
175 3551 static inline void ff_init_nextband_map(const SingleChannelElement *sce, uint8_t *nextband)
176 {
177 3551 unsigned char prevband = 0;
178 int w, g;
179 /** Just a safe default */
180
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 458079 for (g = 0; g < 128; g++)
181 454528 nextband[g] = g;
182
183 /** Now really navigate the nonzero band chain */
184
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 7315 for (w = 0; w < sce->ics.num_windows; w += sce->ics.group_len[w]) {
185
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 174828 for (g = 0; g < sce->ics.num_swb; g++) {
186
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 171064 if (!sce->zeroes[w*16+g] && sce->band_type[w*16+g] < RESERVED_BT)
187 141231 prevband = nextband[prevband] = w*16+g;
188 }
189 }
190 3551 nextband[prevband] = prevband; /* terminate */
191 3551 }
192
193 /*
194 * Updates nextband to reflect a removed band (equivalent to
195 * calling ff_init_nextband_map after marking a band as zero)
196 */
197 static inline void ff_nextband_remove(uint8_t *nextband, int prevband, int band)
198 {
199 nextband[prevband] = nextband[band];
200 }
201
202 /*
203 * Checks whether the specified band could be removed without inducing
204 * scalefactor delta that violates SF delta encoding constraints.
205 * prev_sf has to be the scalefactor of the previous nonzero, nonspecial
206 * band, in encoding order, or negative if there was no such band.
207 */
208 47417 static inline int ff_sfdelta_can_remove_band(const SingleChannelElement *sce,
209 const uint8_t *nextband, int prev_sf, int band)
210 {
211 return prev_sf >= 0
212
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 47243 && sce->sf_idx[nextband[band]] >= (prev_sf - SCALE_MAX_DIFF)
213
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 94660 && sce->sf_idx[nextband[band]] <= (prev_sf + SCALE_MAX_DIFF);
214 }
215
216 /*
217 * Checks whether the specified band's scalefactor could be replaced
218 * with another one without violating SF delta encoding constraints.
219 * prev_sf has to be the scalefactor of the previous nonzero, nonsepcial
220 * band, in encoding order, or negative if there was no such band.
221 */
222 6054 static inline int ff_sfdelta_can_replace(const SingleChannelElement *sce,
223 const uint8_t *nextband, int prev_sf, int new_sf, int band)
224 {
225 6054 return new_sf >= (prev_sf - SCALE_MAX_DIFF)
226
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 6054 && new_sf <= (prev_sf + SCALE_MAX_DIFF)
227
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 6054 && sce->sf_idx[nextband[band]] >= (new_sf - SCALE_MAX_DIFF)
228
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 12108 && sce->sf_idx[nextband[band]] <= (new_sf + SCALE_MAX_DIFF);
229 }
230
231 /**
232 * linear congruential pseudorandom number generator
233 *
234 * @param previous_val pointer to the current state of the generator
235 *
236 * @return Returns a 32-bit pseudorandom integer
237 */
238 904920 static av_always_inline int lcg_random(unsigned previous_val)
239 {
240 904920 union { unsigned u; int s; } v = { previous_val * 1664525u + 1013904223 };
241 904920 return v.s;
242 }
243
244 #define ERROR_IF(cond, ...) \
245 if (cond) { \
246 av_log(avctx, AV_LOG_ERROR, __VA_ARGS__); \
247 return AVERROR(EINVAL); \
248 }
249
250 #define WARN_IF(cond, ...) \
251 if (cond) { \
252 av_log(avctx, AV_LOG_WARNING, __VA_ARGS__); \
253 }
254
255 #endif /* AVCODEC_AACENC_UTILS_H */
256