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path: root/libavcodec/aacenc_ltp.c (plain)
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1/*
2 * AAC encoder long term prediction extension
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 long term prediction extension
25 * @author Rostislav Pehlivanov ( atomnuker gmail com )
26 */
27
28#include "aacenc_ltp.h"
29#include "aacenc_quantization.h"
30#include "aacenc_utils.h"
31
32/**
33 * Encode LTP data.
34 */
35void ff_aac_encode_ltp_info(AACEncContext *s, SingleChannelElement *sce,
36 int common_window)
37{
38 int i;
39 IndividualChannelStream *ics = &sce->ics;
40 if (s->profile != FF_PROFILE_AAC_LTP || !ics->predictor_present)
41 return;
42 if (common_window)
43 put_bits(&s->pb, 1, 0);
44 put_bits(&s->pb, 1, ics->ltp.present);
45 if (!ics->ltp.present)
46 return;
47 put_bits(&s->pb, 11, ics->ltp.lag);
48 put_bits(&s->pb, 3, ics->ltp.coef_idx);
49 for (i = 0; i < FFMIN(ics->max_sfb, MAX_LTP_LONG_SFB); i++)
50 put_bits(&s->pb, 1, ics->ltp.used[i]);
51}
52
53void ff_aac_ltp_insert_new_frame(AACEncContext *s)
54{
55 int i, ch, tag, chans, cur_channel, start_ch = 0;
56 ChannelElement *cpe;
57 SingleChannelElement *sce;
58 for (i = 0; i < s->chan_map[0]; i++) {
59 cpe = &s->cpe[i];
60 tag = s->chan_map[i+1];
61 chans = tag == TYPE_CPE ? 2 : 1;
62 for (ch = 0; ch < chans; ch++) {
63 sce = &cpe->ch[ch];
64 cur_channel = start_ch + ch;
65 /* New sample + overlap */
66 memcpy(&sce->ltp_state[0], &sce->ltp_state[1024], 1024*sizeof(sce->ltp_state[0]));
67 memcpy(&sce->ltp_state[1024], &s->planar_samples[cur_channel][2048], 1024*sizeof(sce->ltp_state[0]));
68 memcpy(&sce->ltp_state[2048], &sce->ret_buf[0], 1024*sizeof(sce->ltp_state[0]));
69 sce->ics.ltp.lag = 0;
70 }
71 start_ch += chans;
72 }
73}
74
75static void get_lag(float *buf, const float *new, LongTermPrediction *ltp)
76{
77 int i, j, lag, max_corr = 0;
78 float max_ratio;
79 for (i = 0; i < 2048; i++) {
80 float corr, s0 = 0.0f, s1 = 0.0f;
81 const int start = FFMAX(0, i - 1024);
82 for (j = start; j < 2048; j++) {
83 const int idx = j - i + 1024;
84 s0 += new[j]*buf[idx];
85 s1 += buf[idx]*buf[idx];
86 }
87 corr = s1 > 0.0f ? s0/sqrt(s1) : 0.0f;
88 if (corr > max_corr) {
89 max_corr = corr;
90 lag = i;
91 max_ratio = corr/(2048-start);
92 }
93 }
94 ltp->lag = FFMAX(av_clip_uintp2(lag, 11), 0);
95 ltp->coef_idx = quant_array_idx(max_ratio, ltp_coef, 8);
96 ltp->coef = ltp_coef[ltp->coef_idx];
97}
98
99static void generate_samples(float *buf, LongTermPrediction *ltp)
100{
101 int i, samples_num = 2048;
102 if (!ltp->lag) {
103 ltp->present = 0;
104 return;
105 } else if (ltp->lag < 1024) {
106 samples_num = ltp->lag + 1024;
107 }
108 for (i = 0; i < samples_num; i++)
109 buf[i] = ltp->coef*buf[i + 2048 - ltp->lag];
110 memset(&buf[i], 0, (2048 - i)*sizeof(float));
111}
112
113/**
114 * Process LTP parameters
115 * @see Patent WO2006070265A1
116 */
117void ff_aac_update_ltp(AACEncContext *s, SingleChannelElement *sce)
118{
119 float *pred_signal = &sce->ltp_state[0];
120 const float *samples = &s->planar_samples[s->cur_channel][1024];
121
122 if (s->profile != FF_PROFILE_AAC_LTP)
123 return;
124
125 /* Calculate lag */
126 get_lag(pred_signal, samples, &sce->ics.ltp);
127 generate_samples(pred_signal, &sce->ics.ltp);
128}
129
130void ff_aac_adjust_common_ltp(AACEncContext *s, ChannelElement *cpe)
131{
132 int sfb, count = 0;
133 SingleChannelElement *sce0 = &cpe->ch[0];
134 SingleChannelElement *sce1 = &cpe->ch[1];
135
136 if (!cpe->common_window ||
137 sce0->ics.window_sequence[0] == EIGHT_SHORT_SEQUENCE ||
138 sce1->ics.window_sequence[0] == EIGHT_SHORT_SEQUENCE) {
139 sce0->ics.ltp.present = 0;
140 return;
141 }
142
143 for (sfb = 0; sfb < FFMIN(sce0->ics.max_sfb, MAX_LTP_LONG_SFB); sfb++) {
144 int sum = sce0->ics.ltp.used[sfb] + sce1->ics.ltp.used[sfb];
145 if (sum != 2) {
146 sce0->ics.ltp.used[sfb] = 0;
147 } else if (sum == 2) {
148 count++;
149 }
150 }
151
152 sce0->ics.ltp.present = !!count;
153 sce0->ics.predictor_present = !!count;
154}
155
156/**
157 * Mark LTP sfb's
158 */
159void ff_aac_search_for_ltp(AACEncContext *s, SingleChannelElement *sce,
160 int common_window)
161{
162 int w, g, w2, i, start = 0, count = 0;
163 int saved_bits = -(15 + FFMIN(sce->ics.max_sfb, MAX_LTP_LONG_SFB));
164 float *C34 = &s->scoefs[128*0], *PCD = &s->scoefs[128*1];
165 float *PCD34 = &s->scoefs[128*2];
166 const int max_ltp = FFMIN(sce->ics.max_sfb, MAX_LTP_LONG_SFB);
167
168 if (sce->ics.window_sequence[0] == EIGHT_SHORT_SEQUENCE) {
169 if (sce->ics.ltp.lag) {
170 memset(&sce->ltp_state[0], 0, 3072*sizeof(sce->ltp_state[0]));
171 memset(&sce->ics.ltp, 0, sizeof(LongTermPrediction));
172 }
173 return;
174 }
175
176 if (!sce->ics.ltp.lag || s->lambda > 120.0f)
177 return;
178
179 for (w = 0; w < sce->ics.num_windows; w += sce->ics.group_len[w]) {
180 start = 0;
181 for (g = 0; g < sce->ics.num_swb; g++) {
182 int bits1 = 0, bits2 = 0;
183 float dist1 = 0.0f, dist2 = 0.0f;
184 if (w*16+g > max_ltp) {
185 start += sce->ics.swb_sizes[g];
186 continue;
187 }
188 for (w2 = 0; w2 < sce->ics.group_len[w]; w2++) {
189 int bits_tmp1, bits_tmp2;
190 FFPsyBand *band = &s->psy.ch[s->cur_channel].psy_bands[(w+w2)*16+g];
191 for (i = 0; i < sce->ics.swb_sizes[g]; i++)
192 PCD[i] = sce->coeffs[start+(w+w2)*128+i] - sce->lcoeffs[start+(w+w2)*128+i];
193 s->abs_pow34(C34, &sce->coeffs[start+(w+w2)*128], sce->ics.swb_sizes[g]);
194 s->abs_pow34(PCD34, PCD, sce->ics.swb_sizes[g]);
195 dist1 += quantize_band_cost(s, &sce->coeffs[start+(w+w2)*128], C34, sce->ics.swb_sizes[g],
196 sce->sf_idx[(w+w2)*16+g], sce->band_type[(w+w2)*16+g],
197 s->lambda/band->threshold, INFINITY, &bits_tmp1, NULL, 0);
198 dist2 += quantize_band_cost(s, PCD, PCD34, sce->ics.swb_sizes[g],
199 sce->sf_idx[(w+w2)*16+g],
200 sce->band_type[(w+w2)*16+g],
201 s->lambda/band->threshold, INFINITY, &bits_tmp2, NULL, 0);
202 bits1 += bits_tmp1;
203 bits2 += bits_tmp2;
204 }
205 if (dist2 < dist1 && bits2 < bits1) {
206 for (w2 = 0; w2 < sce->ics.group_len[w]; w2++)
207 for (i = 0; i < sce->ics.swb_sizes[g]; i++)
208 sce->coeffs[start+(w+w2)*128+i] -= sce->lcoeffs[start+(w+w2)*128+i];
209 sce->ics.ltp.used[w*16+g] = 1;
210 saved_bits += bits1 - bits2;
211 count++;
212 }
213 start += sce->ics.swb_sizes[g];
214 }
215 }
216
217 sce->ics.ltp.present = !!count && (saved_bits >= 0);
218 sce->ics.predictor_present = !!sce->ics.ltp.present;
219
220 /* Reset any marked sfbs */
221 if (!sce->ics.ltp.present && !!count) {
222 for (w = 0; w < sce->ics.num_windows; w += sce->ics.group_len[w]) {
223 start = 0;
224 for (g = 0; g < sce->ics.num_swb; g++) {
225 if (sce->ics.ltp.used[w*16+g]) {
226 for (w2 = 0; w2 < sce->ics.group_len[w]; w2++) {
227 for (i = 0; i < sce->ics.swb_sizes[g]; i++) {
228 sce->coeffs[start+(w+w2)*128+i] += sce->lcoeffs[start+(w+w2)*128+i];
229 }
230 }
231 }
232 start += sce->ics.swb_sizes[g];
233 }
234 }
235 }
236}
237
generated by cgit at 2024-05-17 15:55:38 (GMT)