/*

 * AAC encoder long term prediction extension

 * Copyright (C) 2015 Rostislav Pehlivanov

 *

 * This file is part of FFmpeg.

 *

 * FFmpeg is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2.1 of the License, or (at your option) any later version.

 *

 * FFmpeg is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with FFmpeg; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

 */

/**

 * @file

 * AAC encoder long term prediction extension

 * @author Rostislav Pehlivanov ( atomnuker gmail com )

 */

#include "aacenc_ltp.h"

#include "aacenc_quantization.h"

#include "aacenc_utils.h"

/**

 * Encode LTP data.

 */

void ff_aac_encode_ltp_info(AACEncContext *s, SingleChannelElement *sce,

                            int common_window)

{

    int i;

    IndividualChannelStream *ics = &sce->ics;

    if (s->profile != AV_PROFILE_AAC_LTP || !ics->predictor_present)

        return;

    if (common_window)

        put_bits(&s->pb, 1, 0);

    put_bits(&s->pb, 1, ics->ltp.present);

    if (!ics->ltp.present)

        return;

    put_bits(&s->pb, 11, ics->ltp.lag);

    put_bits(&s->pb, 3,  ics->ltp.coef_idx);

    for (i = 0; i < FFMIN(ics->max_sfb, MAX_LTP_LONG_SFB); i++)

        put_bits(&s->pb, 1, ics->ltp.used[i]);

}

void ff_aac_ltp_insert_new_frame(AACEncContext *s)

{

    int i, ch, tag, chans, cur_channel, start_ch = 0;

    ChannelElement *cpe;

    SingleChannelElement *sce;

    for (i = 0; i < s->chan_map[0]; i++) {

        cpe = &s->cpe[i];

        tag      = s->chan_map[i+1];

        chans    = tag == TYPE_CPE ? 2 : 1;

        for (ch = 0; ch < chans; ch++) {

            sce = &cpe->ch[ch];

            cur_channel = start_ch + ch;

            /* New sample + overlap */

            memcpy(&sce->ltp_state[0],    &sce->ltp_state[1024], 1024*sizeof(sce->ltp_state[0]));

            memcpy(&sce->ltp_state[1024], &s->planar_samples[cur_channel][2048], 1024*sizeof(sce->ltp_state[0]));

            memcpy(&sce->ltp_state[2048], &sce->ret_buf[0], 1024*sizeof(sce->ltp_state[0]));

            sce->ics.ltp.lag = 0;

        }

        start_ch += chans;

    }

}

static void get_lag(float *buf, const float *new, LongTermPrediction *ltp)

{

    int i, j, lag = 0, max_corr = 0;

    float max_ratio = 0.0f;

    for (i = 0; i < 2048; i++) {

        float corr, s0 = 0.0f, s1 = 0.0f;

        const int start = FFMAX(0, i - 1024);

        for (j = start; j < 2048; j++) {

            const int idx = j - i + 1024;

            s0 += new[j]*buf[idx];

            s1 += buf[idx]*buf[idx];

        }

        corr = s1 > 0.0f ? s0/sqrt(s1) : 0.0f;

        if (corr > max_corr) {

            max_corr = corr;

            lag = i;

            max_ratio = corr/(2048-start);

        }

    }

    ltp->lag = FFMAX(av_clip_uintp2(lag, 11), 0);

    ltp->coef_idx = quant_array_idx(max_ratio, ff_ltp_coef, 8);

    ltp->coef     = ff_ltp_coef[ltp->coef_idx];

}

static void generate_samples(float *buf, LongTermPrediction *ltp)

{

    int i, samples_num = 2048;

    if (!ltp->lag) {

        ltp->present = 0;

        return;

    } else if (ltp->lag < 1024) {

        samples_num = ltp->lag + 1024;

    }

    for (i = 0; i < samples_num; i++)

        buf[i] = ltp->coef*buf[i + 2048 - ltp->lag];

    memset(&buf[i], 0, (2048 - i)*sizeof(float));

}

/**

 * Process LTP parameters

 * @see Patent WO2006070265A1

 */

void ff_aac_update_ltp(AACEncContext *s, SingleChannelElement *sce)

{

    float *pred_signal = &sce->ltp_state[0];

    const float *samples = &s->planar_samples[s->cur_channel][1024];

    if (s->profile != AV_PROFILE_AAC_LTP)

        return;

    /* Calculate lag */

    get_lag(pred_signal, samples, &sce->ics.ltp);

    generate_samples(pred_signal, &sce->ics.ltp);

}

void ff_aac_adjust_common_ltp(AACEncContext *s, ChannelElement *cpe)

{

    int sfb, count = 0;

    SingleChannelElement *sce0 = &cpe->ch[0];

    SingleChannelElement *sce1 = &cpe->ch[1];

    if (!cpe->common_window ||

        sce0->ics.window_sequence[0] == EIGHT_SHORT_SEQUENCE ||

        sce1->ics.window_sequence[0] == EIGHT_SHORT_SEQUENCE) {

        sce0->ics.ltp.present = 0;

        return;

    }

    for (sfb = 0; sfb < FFMIN(sce0->ics.max_sfb, MAX_LTP_LONG_SFB); sfb++) {

        int sum = sce0->ics.ltp.used[sfb] + sce1->ics.ltp.used[sfb];

        if (sum != 2) {

            sce0->ics.ltp.used[sfb] = 0;

        } else {

            count++;

        }

    }

    sce0->ics.ltp.present = !!count;

    sce0->ics.predictor_present = !!count;

}

/**

 * Mark LTP sfb's

 */

void ff_aac_search_for_ltp(AACEncContext *s, SingleChannelElement *sce,

                           int common_window)

{

    int w, g, w2, i, start = 0, count = 0;

    int saved_bits = -(15 + FFMIN(sce->ics.max_sfb, MAX_LTP_LONG_SFB));

    float *C34 = &s->scoefs[128*0], *PCD = &s->scoefs[128*1];

    float *PCD34 = &s->scoefs[128*2];

    const int max_ltp = FFMIN(sce->ics.max_sfb, MAX_LTP_LONG_SFB);

    if (sce->ics.window_sequence[0] == EIGHT_SHORT_SEQUENCE) {

        if (sce->ics.ltp.lag) {

            memset(&sce->ltp_state[0], 0, 3072*sizeof(sce->ltp_state[0]));

            memset(&sce->ics.ltp, 0, sizeof(LongTermPrediction));

        }

        return;

    }

    if (!sce->ics.ltp.lag || s->lambda > 120.0f)

        return;

    for (w = 0; w < sce->ics.num_windows; w += sce->ics.group_len[w]) {

        start = 0;

        for (g = 0;  g < sce->ics.num_swb; g++) {

            int bits1 = 0, bits2 = 0;

            float dist1 = 0.0f, dist2 = 0.0f;

            if (w*16+g > max_ltp) {

                start += sce->ics.swb_sizes[g];

                continue;

            }

            for (w2 = 0; w2 < sce->ics.group_len[w]; w2++) {

                int bits_tmp1, bits_tmp2;

                FFPsyBand *band = &s->psy.ch[s->cur_channel].psy_bands[(w+w2)*16+g];

                for (i = 0; i < sce->ics.swb_sizes[g]; i++)

                    PCD[i] = sce->coeffs[start+(w+w2)*128+i] - sce->lcoeffs[start+(w+w2)*128+i];

                s->aacdsp.abs_pow34(C34,  &sce->coeffs[start+(w+w2)*128],  sce->ics.swb_sizes[g]);

                s->aacdsp.abs_pow34(PCD34, PCD, sce->ics.swb_sizes[g]);

                dist1 += quantize_band_cost(s, &sce->coeffs[start+(w+w2)*128], C34, sce->ics.swb_sizes[g],

                                            sce->sf_idx[(w+w2)*16+g], sce->band_type[(w+w2)*16+g],

                                            s->lambda/band->threshold, INFINITY, &bits_tmp1, NULL);

                dist2 += quantize_band_cost(s, PCD, PCD34, sce->ics.swb_sizes[g],

                                            sce->sf_idx[(w+w2)*16+g],

                                            sce->band_type[(w+w2)*16+g],

                                            s->lambda/band->threshold, INFINITY, &bits_tmp2, NULL);

                bits1 += bits_tmp1;

                bits2 += bits_tmp2;

            }

            if (dist2 < dist1 && bits2 < bits1) {

                for (w2 = 0; w2 < sce->ics.group_len[w]; w2++)

                    for (i = 0; i < sce->ics.swb_sizes[g]; i++)

                        sce->coeffs[start+(w+w2)*128+i] -= sce->lcoeffs[start+(w+w2)*128+i];

                sce->ics.ltp.used[w*16+g] = 1;

                saved_bits += bits1 - bits2;

                count++;

            }

            start += sce->ics.swb_sizes[g];

        }

    }

    sce->ics.ltp.present = !!count && (saved_bits >= 0);

    sce->ics.predictor_present = !!sce->ics.ltp.present;

    /* Reset any marked sfbs */

    if (!sce->ics.ltp.present && !!count) {

        for (w = 0; w < sce->ics.num_windows; w += sce->ics.group_len[w]) {

            start = 0;

            for (g = 0;  g < sce->ics.num_swb; g++) {

                if (sce->ics.ltp.used[w*16+g]) {

                    for (w2 = 0; w2 < sce->ics.group_len[w]; w2++) {

                        for (i = 0; i < sce->ics.swb_sizes[g]; i++) {

                            sce->coeffs[start+(w+w2)*128+i] += sce->lcoeffs[start+(w+w2)*128+i];

                        }

                    }

                }

                start += sce->ics.swb_sizes[g];

            }

        }

    }

}