GCC Code Coverage Report
Directory: ../../../ffmpeg/ Exec Total Coverage
File: src/libavcodec/aacenc_tns.c Lines: 99 103 96.1 %
Date: 2019-11-18 18:00:01 Branches: 75 90 83.3 %

Line Branch Exec Source
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
90
static inline int compress_coeffs(int *coef, int order, int c_bits)
49
{
50
    int i;
51
90
    const int low_idx   = c_bits ?  4 : 2;
52
90
    const int shift_val = c_bits ?  8 : 4;
53
90
    const int high_idx  = c_bits ? 11 : 5;
54
#ifndef TNS_ENABLE_COEF_COMPRESSION
55
    return 0;
56
#endif /* TNS_ENABLE_COEF_COMPRESSION */
57
674
    for (i = 0; i < order; i++)
58

584
        if (coef[i] >= low_idx && coef[i] <= high_idx)
59
            return 0;
60
674
    for (i = 0; i < order; i++)
61
584
        coef[i] -= (coef[i] > high_idx) ? shift_val : 0;
62
90
    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
11739
void ff_aac_encode_tns_info(AACEncContext *s, SingleChannelElement *sce)
71
{
72
11739
    TemporalNoiseShaping *tns = &sce->tns;
73
11739
    int i, w, filt, coef_compress = 0, coef_len;
74
11739
    const int is8 = sce->ics.window_sequence[0] == EIGHT_SHORT_SEQUENCE;
75
11739
    const int c_bits = is8 ? TNS_Q_BITS_IS8 == 4 : TNS_Q_BITS == 4;
76
77
11739
    if (!sce->tns.present)
78
11693
        return;
79
80
253
    for (i = 0; i < sce->ics.num_windows; i++) {
81
207
        put_bits(&s->pb, 2 - is8, sce->tns.n_filt[i]);
82
207
        if (!tns->n_filt[i])
83
140
            continue;
84
67
        put_bits(&s->pb, 1, c_bits);
85
157
        for (filt = 0; filt < tns->n_filt[i]; filt++) {
86
90
            put_bits(&s->pb, 6 - 2 * is8, tns->length[i][filt]);
87
90
            put_bits(&s->pb, 5 - 2 * is8, tns->order[i][filt]);
88
90
            if (!tns->order[i][filt])
89
                continue;
90
90
            put_bits(&s->pb, 1, tns->direction[i][filt]);
91
90
            coef_compress = compress_coeffs(tns->coef_idx[i][filt],
92
                                            tns->order[i][filt], c_bits);
93
90
            put_bits(&s->pb, 1, coef_compress);
94
90
            coef_len = c_bits + 3 - coef_compress;
95
674
            for (w = 0; w < tns->order[i][filt]; w++)
96
584
                put_bits(&s->pb, coef_len, tns->coef_idx[i][filt][w]);
97
        }
98
    }
99
}
100
101
/* Apply TNS filter */
102
3515
void ff_aac_apply_tns(AACEncContext *s, SingleChannelElement *sce)
103
{
104
3515
    TemporalNoiseShaping *tns = &sce->tns;
105
3515
    IndividualChannelStream *ics = &sce->ics;
106
    int w, filt, m, i, top, order, bottom, start, end, size, inc;
107
3515
    const int mmm = FFMIN(ics->tns_max_bands, ics->max_sfb);
108
    float lpc[TNS_MAX_ORDER];
109
110
7471
    for (w = 0; w < ics->num_windows; w++) {
111
3956
        bottom = ics->num_swb;
112
4046
        for (filt = 0; filt < tns->n_filt[w]; filt++) {
113
90
            top    = bottom;
114
90
            bottom = FFMAX(0, top - tns->length[w][filt]);
115
90
            order  = tns->order[w][filt];
116
90
            if (order == 0)
117
                continue;
118
119
            // tns_decode_coef
120
90
            compute_lpc_coefs(tns->coef[w][filt], order, lpc, 0, 0, 0);
121
122
90
            start = ics->swb_offset[FFMIN(bottom, mmm)];
123
90
            end   = ics->swb_offset[FFMIN(   top, mmm)];
124
90
            if ((size = end - start) <= 0)
125
                continue;
126
90
            if (tns->direction[w][filt]) {
127
41
                inc = -1;
128
41
                start = end - 1;
129
            } else {
130
49
                inc = 1;
131
            }
132
90
            start += w * 128;
133
134
            /* AR filter */
135
16290
            for (m = 0; m < size; m++, start += inc) {
136
115506
                for (i = 1; i <= FFMIN(m, order); i++) {
137
99306
                    sce->coeffs[start] += lpc[i-1]*sce->pcoeffs[start - i*inc];
138
                }
139
            }
140
        }
141
    }
142
3515
}
143
144
/*
145
 * c_bits - 1 if 4 bit coefficients, 0 if 3 bit coefficients
146
 */
147
90
static inline void quantize_coefs(double *coef, int *idx, float *lpc, int order,
148
                                  int c_bits)
149
{
150
    int i;
151
90
    const float *quant_arr = tns_tmp2_map[c_bits];
152
674
    for (i = 0; i < order; i++) {
153
584
        idx[i] = quant_array_idx(coef[i], quant_arr, c_bits ? 16 : 8);
154
584
        lpc[i] = quant_arr[idx[i]];
155
    }
156
90
}
157
158
/*
159
 * 3 bits per coefficient with 8 short windows
160
 */
161
3515
void ff_aac_search_for_tns(AACEncContext *s, SingleChannelElement *sce)
162
{
163
3515
    TemporalNoiseShaping *tns = &sce->tns;
164
3515
    int w, g, count = 0;
165
    double gain, coefs[MAX_LPC_ORDER];
166
3515
    const int mmm = FFMIN(sce->ics.tns_max_bands, sce->ics.max_sfb);
167
3515
    const int is8 = sce->ics.window_sequence[0] == EIGHT_SHORT_SEQUENCE;
168
3515
    const int c_bits = is8 ? TNS_Q_BITS_IS8 == 4 : TNS_Q_BITS == 4;
169
3515
    const int sfb_start = av_clip(tns_min_sfb[is8][s->samplerate_index], 0, mmm);
170
3515
    const int sfb_end   = av_clip(sce->ics.num_swb, 0, mmm);
171

3515
    const int order = is8 ? 7 : s->profile == FF_PROFILE_AAC_LOW ? 12 : TNS_MAX_ORDER;
172
7013
    const int slant = sce->ics.window_sequence[0] == LONG_STOP_SEQUENCE  ? 1 :
173
3498
                      sce->ics.window_sequence[0] == LONG_START_SEQUENCE ? 0 : 2;
174
3515
    const int sfb_len = sfb_end - sfb_start;
175
3515
    const int coef_len = sce->ics.swb_offset[sfb_end] - sce->ics.swb_offset[sfb_start];
176
177

3515
    if (coef_len <= 0 || sfb_len <= 0) {
178
115
        sce->tns.present = 0;
179
115
        return;
180
    }
181
182
7164
    for (w = 0; w < sce->ics.num_windows; w++) {
183
3764
        float en[2] = {0.0f, 0.0f};
184
3764
        int oc_start = 0, os_start = 0;
185
3764
        int coef_start = sce->ics.swb_offset[sfb_start];
186
187

94831
        for (g = sfb_start; g < sce->ics.num_swb && g <= sfb_end; g++) {
188
91067
            FFPsyBand *band = &s->psy.ch[s->cur_channel].psy_bands[w*16+g];
189
91067
            if (g > sfb_start + (sfb_len/2))
190
45263
                en[1] += band->energy;
191
            else
192
45804
                en[0] += band->energy;
193
        }
194
195
        /* LPC */
196
3764
        gain = ff_lpc_calc_ref_coefs_f(&s->lpc, &sce->coeffs[w*128 + coef_start],
197
                                       coef_len, order, coefs);
198
199


3764
        if (!order || !isfinite(gain) || gain < TNS_GAIN_THRESHOLD_LOW || gain > TNS_GAIN_THRESHOLD_HIGH)
200
3697
            continue;
201
202

67
        tns->n_filt[w] = is8 ? 1 : order != TNS_MAX_ORDER ? 2 : 3;
203
157
        for (g = 0; g < tns->n_filt[w]; g++) {
204
90
            tns->direction[w][g] = slant != 2 ? slant : en[g] < en[!g];
205
90
            tns->order[w][g] = g < tns->n_filt[w] ? order/tns->n_filt[w] : order - oc_start;
206
90
            tns->length[w][g] = g < tns->n_filt[w] ? sfb_len/tns->n_filt[w] : sfb_len - os_start;
207
90
            quantize_coefs(&coefs[oc_start], tns->coef_idx[w][g], tns->coef[w][g],
208
                            tns->order[w][g], c_bits);
209
90
            oc_start += tns->order[w][g];
210
90
            os_start += tns->length[w][g];
211
        }
212
67
        count++;
213
    }
214
3400
    sce->tns.present = !!count;
215
}