FFmpeg coverage

Directory: ../../../ffmpeg/
File: src/libavcodec/aacenc_tns.c
Date: 2026-01-14 03:33:33
Exec Total Coverage
Lines: 109 113 96.5%
Functions: 5 5 100.0%
Branches: 81 94 86.2%
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1 /*
2 * AAC encoder TNS
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 temporal noise shaping
25 * @author Rostislav Pehlivanov ( atomnuker gmail com )
26 */
27
28 #include "libavutil/libm.h"
29 #include "aacenc.h"
30 #include "aacenc_tns.h"
31 #include "aactab.h"
32 #include "aacenc_utils.h"
33 #include "lpc_functions.h"
34
35 /* Could be set to 3 to save an additional bit at the cost of little quality */
36 #define TNS_Q_BITS 4
37
38 /* Coefficient resolution in short windows */
39 #define TNS_Q_BITS_IS8 4
40
41 /* We really need the bits we save here elsewhere */
42 #define TNS_ENABLE_COEF_COMPRESSION
43
44 /* TNS will only be used if the LPC gain is within these margins */
45 #define TNS_GAIN_THRESHOLD_LOW 1.4f
46 #define TNS_GAIN_THRESHOLD_HIGH 1.16f*TNS_GAIN_THRESHOLD_LOW
47
48 72 static inline int compress_coeffs(int *coef, int order, int c_bits)
49 {
50 int i;
51
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 72 const int low_idx = c_bits ? 4 : 2;
52
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 72 const int shift_val = c_bits ? 8 : 4;
53
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 72 const int high_idx = c_bits ? 11 : 5;
54 #ifndef TNS_ENABLE_COEF_COMPRESSION
55 return 0;
56 #endif /* TNS_ENABLE_COEF_COMPRESSION */
57
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 530 for (i = 0; i < order; i++)
58
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 458 if (coef[i] >= low_idx && coef[i] <= high_idx)
59 ✗ return 0;
60
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 530 for (i = 0; i < order; i++)
61
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 458 coef[i] -= (coef[i] > high_idx) ? shift_val : 0;
62 72 return 1;
63 }
64
65 /**
66 * Encode TNS data.
67 * Coefficient compression is simply not lossless as it should be
68 * on any decoder tested and as such is not active.
69 */
70 9375 void ff_aac_encode_tns_info(AACEncContext *s, SingleChannelElement *sce)
71 {
72 9375 TemporalNoiseShaping *tns = &sce->tns;
73 9375 int i, w, filt, coef_compress = 0, coef_len;
74 9375 const int is8 = sce->ics.window_sequence[0] == EIGHT_SHORT_SEQUENCE;
75 9375 const int c_bits = is8 ? TNS_Q_BITS_IS8 == 4 : TNS_Q_BITS == 4;
76
77
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 9375 if (!sce->tns.present)
78 9337 return;
79
80
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 181 for (i = 0; i < sce->ics.num_windows; i++) {
81 143 put_bits(&s->pb, 2 - is8, sce->tns.n_filt[i]);
82
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 143 if (!tns->n_filt[i])
83 94 continue;
84 49 put_bits(&s->pb, 1, c_bits);
85
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 121 for (filt = 0; filt < tns->n_filt[i]; filt++) {
86 72 put_bits(&s->pb, 6 - 2 * is8, tns->length[i][filt]);
87 72 put_bits(&s->pb, 5 - 2 * is8, tns->order[i][filt]);
88
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 72 if (!tns->order[i][filt])
89 ✗ continue;
90 72 put_bits(&s->pb, 1, tns->direction[i][filt]);
91 72 coef_compress = compress_coeffs(tns->coef_idx[i][filt],
92 tns->order[i][filt], c_bits);
93 72 put_bits(&s->pb, 1, coef_compress);
94 72 coef_len = c_bits + 3 - coef_compress;
95
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 530 for (w = 0; w < tns->order[i][filt]; w++)
96 458 put_bits(&s->pb, coef_len, tns->coef_idx[i][filt][w]);
97 }
98 }
99 }
100
101 /* Apply TNS filter */
102 1971 void ff_aac_apply_tns(AACEncContext *s, SingleChannelElement *sce)
103 {
104 1971 TemporalNoiseShaping *tns = &sce->tns;
105 1971 IndividualChannelStream *ics = &sce->ics;
106 int w, filt, m, i, top, order, bottom, start, end, size, inc;
107 1971 const int mmm = FFMIN(ics->tns_max_bands, ics->max_sfb);
108 float lpc[TNS_MAX_ORDER];
109
110
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 4257 for (w = 0; w < ics->num_windows; w++) {
111 2286 bottom = ics->num_swb;
112
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 2358 for (filt = 0; filt < tns->n_filt[w]; filt++) {
113 72 top = bottom;
114 72 bottom = FFMAX(0, top - tns->length[w][filt]);
115 72 order = tns->order[w][filt];
116
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 72 if (order == 0)
117 ✗ continue;
118
119 // tns_decode_coef
120 72 compute_lpc_coefs(tns->coef[w][filt], 0, order, lpc, 0, 0, 0, NULL);
121
122
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 72 start = ics->swb_offset[FFMIN(bottom, mmm)];
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 72 end = ics->swb_offset[FFMIN( top, mmm)];
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 72 if ((size = end - start) <= 0)
125 ✗ continue;
126
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 72 if (tns->direction[w][filt]) {
127 40 inc = -1;
128 40 start = end - 1;
129 } else {
130 32 inc = 1;
131 }
132 72 start += w * 128;
133
134 /* AR filter */
135
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 14664 for (m = 0; m < size; m++, start += inc) {
136
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 103146 for (i = 1; i <= FFMIN(m, order); i++) {
137 88554 sce->coeffs[start] += lpc[i-1]*sce->pcoeffs[start - i*inc];
138 }
139 }
140 }
141 }
142 1971 }
143
144 /*
145 * c_bits - 1 if 4 bit coefficients, 0 if 3 bit coefficients
146 */
147 72 static inline void quantize_coefs(double *coef, int *idx, float *lpc, int order,
148 int c_bits)
149 {
150 int i;
151 72 const float *quant_arr = ff_tns_tmp2_map[c_bits];
152
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 530 for (i = 0; i < order; i++) {
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 458 idx[i] = quant_array_idx(coef[i], quant_arr, c_bits ? 16 : 8);
154 458 lpc[i] = quant_arr[idx[i]];
155 }
156 72 }
157
158 /*
159 * 3 bits per coefficient with 8 short windows
160 */
161 1971 void ff_aac_search_for_tns(AACEncContext *s, SingleChannelElement *sce)
162 {
163 1971 TemporalNoiseShaping *tns = &sce->tns;
164 1971 int w, g, count = 0;
165 double gain, coefs[MAX_LPC_ORDER];
166 1971 const int mmm = FFMIN(sce->ics.tns_max_bands, sce->ics.max_sfb);
167 1971 const int is8 = sce->ics.window_sequence[0] == EIGHT_SHORT_SEQUENCE;
168 1971 const int c_bits = is8 ? TNS_Q_BITS_IS8 == 4 : TNS_Q_BITS == 4;
169 1971 const int sfb_start = av_clip(tns_min_sfb[is8][s->samplerate_index], 0, mmm);
170 1971 const int sfb_end = av_clip(sce->ics.num_swb, 0, mmm);
171
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 1971 const int order = is8 ? 7 : 12;
172
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 3929 const int slant = sce->ics.window_sequence[0] == LONG_STOP_SEQUENCE ? 1 :
173
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 1958 sce->ics.window_sequence[0] == LONG_START_SEQUENCE ? 0 : 2;
174 1971 const int sfb_len = sfb_end - sfb_start;
175 1971 const int coef_len = sce->ics.swb_offset[sfb_end] - sce->ics.swb_offset[sfb_start];
176
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 1971 const int n_filt = is8 ? 1 : order != TNS_MAX_ORDER ? 2 : 3;
177
178
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 1971 if (coef_len <= 0 || sfb_len <= 0) {
179 106 sce->tns.present = 0;
180 106 return;
181 }
182
183
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 3968 for (w = 0; w < sce->ics.num_windows; w++) {
184 2103 float en[4] = {0.0f, 0.0f, 0.0f, 0.0f};
185 2103 int oc_start = 0;
186 2103 int coef_start = sce->ics.swb_offset[sfb_start];
187
188
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 2103 if (n_filt == 2) {
189
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 49119 for (g = sfb_start; g < sce->ics.num_swb && g <= sfb_end; g++) {
190 47288 FFPsyBand *band = &s->psy.ch[s->cur_channel].psy_bands[w*16+g];
191
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 47288 if (g > sfb_start + (sfb_len/2))
192 23485 en[1] += band->energy; /* End */
193 else
194 23803 en[0] += band->energy; /* Start */
195 }
196 1831 en[2] = en[0];
197 } else {
198
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 3176 for (g = sfb_start; g < sce->ics.num_swb && g <= sfb_end; g++) {
199 2904 FFPsyBand *band = &s->psy.ch[s->cur_channel].psy_bands[w*16+g];
200
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 2904 if (g > sfb_start + (sfb_len/2) + (sfb_len/4))
201 816 en[2] += band->energy; /* End */
202
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 2088 else if (g > sfb_start + (sfb_len/2) - (sfb_len/4))
203 1088 en[1] += band->energy; /* Middle */
204 else
205 1000 en[0] += band->energy; /* Start */
206 }
207 272 en[3] = en[0];
208 }
209
210 /* LPC */
211 2103 gain = ff_lpc_calc_ref_coefs_f(&s->lpc, &sce->coeffs[w*128 + coef_start],
212 coef_len, order, coefs);
213
214
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 2103 if (!order || !isfinite(gain) || gain < TNS_GAIN_THRESHOLD_LOW || gain > TNS_GAIN_THRESHOLD_HIGH)
215 2054 continue;
216
217 49 tns->n_filt[w] = n_filt;
218
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 121 for (g = 0; g < tns->n_filt[w]; g++) {
219
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 72 tns->direction[w][g] = slant != 2 ? slant : en[g] < en[g + 1];
220 72 tns->order[w][g] = order/tns->n_filt[w];
221 72 tns->length[w][g] = sfb_len/tns->n_filt[w];
222 72 quantize_coefs(&coefs[oc_start], tns->coef_idx[w][g], tns->coef[w][g],
223 tns->order[w][g], c_bits);
224 72 oc_start += tns->order[w][g];
225 }
226 49 count++;
227 }
228 1865 sce->tns.present = !!count;
229 }
230