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 = 0, max_corr = 0;
78    float max_ratio = 0.0f;
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 {
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