FFmpeg coverage


Directory: ../../../ffmpeg/
File: src/libavcodec/aacenc_tns.c
Date: 2021-09-26 18:22:30
Exec Total Coverage
Lines: 99 103 96.1%
Branches: 75 90 83.3%

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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 "aacenc_quantization.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 78 static inline int compress_coeffs(int *coef, int order, int c_bits)
49 {
50 int i;
51
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78 const int low_idx = c_bits ? 4 : 2;
52
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78 const int shift_val = c_bits ? 8 : 4;
53
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78 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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578 for (i = 0; i < order; i++)
58
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500 if (coef[i] >= low_idx && coef[i] <= high_idx)
59 return 0;
60
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578 for (i = 0; i < order; i++)
61
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500 coef[i] -= (coef[i] > high_idx) ? shift_val : 0;
62 78 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 10231 void ff_aac_encode_tns_info(AACEncContext *s, SingleChannelElement *sce)
71 {
72 10231 TemporalNoiseShaping *tns = &sce->tns;
73 10231 int i, w, filt, coef_compress = 0, coef_len;
74 10231 const int is8 = sce->ics.window_sequence[0] == EIGHT_SHORT_SEQUENCE;
75 10231 const int c_bits = is8 ? TNS_Q_BITS_IS8 == 4 : TNS_Q_BITS == 4;
76
77
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10231 if (!sce->tns.present)
78 10191 return;
79
80
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199 for (i = 0; i < sce->ics.num_windows; i++) {
81 159 put_bits(&s->pb, 2 - is8, sce->tns.n_filt[i]);
82
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159 if (!tns->n_filt[i])
83 104 continue;
84 55 put_bits(&s->pb, 1, c_bits);
85
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133 for (filt = 0; filt < tns->n_filt[i]; filt++) {
86 78 put_bits(&s->pb, 6 - 2 * is8, tns->length[i][filt]);
87 78 put_bits(&s->pb, 5 - 2 * is8, tns->order[i][filt]);
88
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78 if (!tns->order[i][filt])
89 continue;
90 78 put_bits(&s->pb, 1, tns->direction[i][filt]);
91 78 coef_compress = compress_coeffs(tns->coef_idx[i][filt],
92 tns->order[i][filt], c_bits);
93 78 put_bits(&s->pb, 1, coef_compress);
94 78 coef_len = c_bits + 3 - coef_compress;
95
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578 for (w = 0; w < tns->order[i][filt]; w++)
96 500 put_bits(&s->pb, coef_len, tns->coef_idx[i][filt][w]);
97 }
98 }
99 }
100
101 /* Apply TNS filter */
102 2003 void ff_aac_apply_tns(AACEncContext *s, SingleChannelElement *sce)
103 {
104 2003 TemporalNoiseShaping *tns = &sce->tns;
105 2003 IndividualChannelStream *ics = &sce->ics;
106 int w, filt, m, i, top, order, bottom, start, end, size, inc;
107 2003 const int mmm = FFMIN(ics->tns_max_bands, ics->max_sfb);
108 float lpc[TNS_MAX_ORDER];
109
110
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4342 for (w = 0; w < ics->num_windows; w++) {
111 2339 bottom = ics->num_swb;
112
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2417 for (filt = 0; filt < tns->n_filt[w]; filt++) {
113 78 top = bottom;
114 78 bottom = FFMAX(0, top - tns->length[w][filt]);
115 78 order = tns->order[w][filt];
116
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78 if (order == 0)
117 continue;
118
119 // tns_decode_coef
120 78 compute_lpc_coefs(tns->coef[w][filt], order, lpc, 0, 0, 0);
121
122
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78 start = ics->swb_offset[FFMIN(bottom, mmm)];
123
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78 end = ics->swb_offset[FFMIN( top, mmm)];
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78 if ((size = end - start) <= 0)
125 continue;
126
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78 if (tns->direction[w][filt]) {
127 29 inc = -1;
128 29 start = end - 1;
129 } else {
130 49 inc = 1;
131 }
132 78 start += w * 128;
133
134 /* AR filter */
135
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15366 for (m = 0; m < size; m++, start += inc) {
136
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108546 for (i = 1; i <= FFMIN(m, order); i++) {
137 93258 sce->coeffs[start] += lpc[i-1]*sce->pcoeffs[start - i*inc];
138 }
139 }
140 }
141 }
142 2003 }
143
144 /*
145 * c_bits - 1 if 4 bit coefficients, 0 if 3 bit coefficients
146 */
147 78 static inline void quantize_coefs(double *coef, int *idx, float *lpc, int order,
148 int c_bits)
149 {
150 int i;
151 78 const float *quant_arr = tns_tmp2_map[c_bits];
152
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578 for (i = 0; i < order; i++) {
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500 idx[i] = quant_array_idx(coef[i], quant_arr, c_bits ? 16 : 8);
154 500 lpc[i] = quant_arr[idx[i]];
155 }
156 78 }
157
158 /*
159 * 3 bits per coefficient with 8 short windows
160 */
161 2003 void ff_aac_search_for_tns(AACEncContext *s, SingleChannelElement *sce)
162 {
163 2003 TemporalNoiseShaping *tns = &sce->tns;
164 2003 int w, g, count = 0;
165 double gain, coefs[MAX_LPC_ORDER];
166 2003 const int mmm = FFMIN(sce->ics.tns_max_bands, sce->ics.max_sfb);
167 2003 const int is8 = sce->ics.window_sequence[0] == EIGHT_SHORT_SEQUENCE;
168 2003 const int c_bits = is8 ? TNS_Q_BITS_IS8 == 4 : TNS_Q_BITS == 4;
169 2003 const int sfb_start = av_clip(tns_min_sfb[is8][s->samplerate_index], 0, mmm);
170 2003 const int sfb_end = av_clip(sce->ics.num_swb, 0, mmm);
171
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2003 const int order = is8 ? 7 : s->profile == FF_PROFILE_AAC_LOW ? 12 : TNS_MAX_ORDER;
172
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3989 const int slant = sce->ics.window_sequence[0] == LONG_STOP_SEQUENCE ? 1 :
173
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1986 sce->ics.window_sequence[0] == LONG_START_SEQUENCE ? 0 : 2;
174 2003 const int sfb_len = sfb_end - sfb_start;
175 2003 const int coef_len = sce->ics.swb_offset[sfb_end] - sce->ics.swb_offset[sfb_start];
176
177
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2003 if (coef_len <= 0 || sfb_len <= 0) {
178 115 sce->tns.present = 0;
179 115 return;
180 }
181
182
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4035 for (w = 0; w < sce->ics.num_windows; w++) {
183 2147 float en[2] = {0.0f, 0.0f};
184 2147 int oc_start = 0, os_start = 0;
185 2147 int coef_start = sce->ics.swb_offset[sfb_start];
186
187
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53100 for (g = sfb_start; g < sce->ics.num_swb && g <= sfb_end; g++) {
188 50953 FFPsyBand *band = &s->psy.ch[s->cur_channel].psy_bands[w*16+g];
189
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50953 if (g > sfb_start + (sfb_len/2))
190 25202 en[1] += band->energy;
191 else
192 25751 en[0] += band->energy;
193 }
194
195 /* LPC */
196 2147 gain = ff_lpc_calc_ref_coefs_f(&s->lpc, &sce->coeffs[w*128 + coef_start],
197 coef_len, order, coefs);
198
199
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2147 if (!order || !isfinite(gain) || gain < TNS_GAIN_THRESHOLD_LOW || gain > TNS_GAIN_THRESHOLD_HIGH)
200 2092 continue;
201
202
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55 tns->n_filt[w] = is8 ? 1 : order != TNS_MAX_ORDER ? 2 : 3;
203
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133 for (g = 0; g < tns->n_filt[w]; g++) {
204
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78 tns->direction[w][g] = slant != 2 ? slant : en[g] < en[!g];
205
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78 tns->order[w][g] = g < tns->n_filt[w] ? order/tns->n_filt[w] : order - oc_start;
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78 tns->length[w][g] = g < tns->n_filt[w] ? sfb_len/tns->n_filt[w] : sfb_len - os_start;
207 78 quantize_coefs(&coefs[oc_start], tns->coef_idx[w][g], tns->coef[w][g],
208 tns->order[w][g], c_bits);
209 78 oc_start += tns->order[w][g];
210 78 os_start += tns->length[w][g];
211 }
212 55 count++;
213 }
214 1888 sce->tns.present = !!count;
215 }
216