diff options
Diffstat (limited to 'libavcodec/aacenc_ltp.c')
| -rw-r--r-- | libavcodec/aacenc_ltp.c | 236 |
1 files changed, 236 insertions, 0 deletions
diff --git a/libavcodec/aacenc_ltp.c b/libavcodec/aacenc_ltp.c new file mode 100644 index 0000000..674a2a0 --- /dev/null +++ b/libavcodec/aacenc_ltp.c @@ -0,0 +1,236 @@ +/* + * 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 != FF_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, ltp_coef, 8); + ltp->coef = 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 != FF_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 if (sum == 2) { + 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->abs_pow34(C34, &sce->coeffs[start+(w+w2)*128], sce->ics.swb_sizes[g]); + s->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, 0); + 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, 0); + 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]; + } + } + } +} |
