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Diffstat (limited to 'ffmpeg/libavcodec/aacpsy.c')
| -rw-r--r-- | ffmpeg/libavcodec/aacpsy.c | 940 |
1 files changed, 940 insertions, 0 deletions
diff --git a/ffmpeg/libavcodec/aacpsy.c b/ffmpeg/libavcodec/aacpsy.c new file mode 100644 index 0000000..e399be5 --- /dev/null +++ b/ffmpeg/libavcodec/aacpsy.c @@ -0,0 +1,940 @@ +/* + * AAC encoder psychoacoustic model + * Copyright (C) 2008 Konstantin Shishkov + * + * 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 psychoacoustic model + */ + +#include "libavutil/libm.h" + +#include "avcodec.h" +#include "aactab.h" +#include "psymodel.h" + +/*********************************** + * TODOs: + * try other bitrate controlling mechanism (maybe use ratecontrol.c?) + * control quality for quality-based output + **********************************/ + +/** + * constants for 3GPP AAC psychoacoustic model + * @{ + */ +#define PSY_3GPP_THR_SPREAD_HI 1.5f // spreading factor for low-to-hi threshold spreading (15 dB/Bark) +#define PSY_3GPP_THR_SPREAD_LOW 3.0f // spreading factor for hi-to-low threshold spreading (30 dB/Bark) +/* spreading factor for low-to-hi energy spreading, long block, > 22kbps/channel (20dB/Bark) */ +#define PSY_3GPP_EN_SPREAD_HI_L1 2.0f +/* spreading factor for low-to-hi energy spreading, long block, <= 22kbps/channel (15dB/Bark) */ +#define PSY_3GPP_EN_SPREAD_HI_L2 1.5f +/* spreading factor for low-to-hi energy spreading, short block (15 dB/Bark) */ +#define PSY_3GPP_EN_SPREAD_HI_S 1.5f +/* spreading factor for hi-to-low energy spreading, long block (30dB/Bark) */ +#define PSY_3GPP_EN_SPREAD_LOW_L 3.0f +/* spreading factor for hi-to-low energy spreading, short block (20dB/Bark) */ +#define PSY_3GPP_EN_SPREAD_LOW_S 2.0f + +#define PSY_3GPP_RPEMIN 0.01f +#define PSY_3GPP_RPELEV 2.0f + +#define PSY_3GPP_C1 3.0f /* log2(8) */ +#define PSY_3GPP_C2 1.3219281f /* log2(2.5) */ +#define PSY_3GPP_C3 0.55935729f /* 1 - C2 / C1 */ + +#define PSY_SNR_1DB 7.9432821e-1f /* -1dB */ +#define PSY_SNR_25DB 3.1622776e-3f /* -25dB */ + +#define PSY_3GPP_SAVE_SLOPE_L -0.46666667f +#define PSY_3GPP_SAVE_SLOPE_S -0.36363637f +#define PSY_3GPP_SAVE_ADD_L -0.84285712f +#define PSY_3GPP_SAVE_ADD_S -0.75f +#define PSY_3GPP_SPEND_SLOPE_L 0.66666669f +#define PSY_3GPP_SPEND_SLOPE_S 0.81818181f +#define PSY_3GPP_SPEND_ADD_L -0.35f +#define PSY_3GPP_SPEND_ADD_S -0.26111111f +#define PSY_3GPP_CLIP_LO_L 0.2f +#define PSY_3GPP_CLIP_LO_S 0.2f +#define PSY_3GPP_CLIP_HI_L 0.95f +#define PSY_3GPP_CLIP_HI_S 0.75f + +#define PSY_3GPP_AH_THR_LONG 0.5f +#define PSY_3GPP_AH_THR_SHORT 0.63f + +enum { + PSY_3GPP_AH_NONE, + PSY_3GPP_AH_INACTIVE, + PSY_3GPP_AH_ACTIVE +}; + +#define PSY_3GPP_BITS_TO_PE(bits) ((bits) * 1.18f) + +/* LAME psy model constants */ +#define PSY_LAME_FIR_LEN 21 ///< LAME psy model FIR order +#define AAC_BLOCK_SIZE_LONG 1024 ///< long block size +#define AAC_BLOCK_SIZE_SHORT 128 ///< short block size +#define AAC_NUM_BLOCKS_SHORT 8 ///< number of blocks in a short sequence +#define PSY_LAME_NUM_SUBBLOCKS 3 ///< Number of sub-blocks in each short block + +/** + * @} + */ + +/** + * information for single band used by 3GPP TS26.403-inspired psychoacoustic model + */ +typedef struct AacPsyBand{ + float energy; ///< band energy + float thr; ///< energy threshold + float thr_quiet; ///< threshold in quiet + float nz_lines; ///< number of non-zero spectral lines + float active_lines; ///< number of active spectral lines + float pe; ///< perceptual entropy + float pe_const; ///< constant part of the PE calculation + float norm_fac; ///< normalization factor for linearization + int avoid_holes; ///< hole avoidance flag +}AacPsyBand; + +/** + * single/pair channel context for psychoacoustic model + */ +typedef struct AacPsyChannel{ + AacPsyBand band[128]; ///< bands information + AacPsyBand prev_band[128]; ///< bands information from the previous frame + + float win_energy; ///< sliding average of channel energy + float iir_state[2]; ///< hi-pass IIR filter state + uint8_t next_grouping; ///< stored grouping scheme for the next frame (in case of 8 short window sequence) + enum WindowSequence next_window_seq; ///< window sequence to be used in the next frame + /* LAME psy model specific members */ + float attack_threshold; ///< attack threshold for this channel + float prev_energy_subshort[AAC_NUM_BLOCKS_SHORT * PSY_LAME_NUM_SUBBLOCKS]; + int prev_attack; ///< attack value for the last short block in the previous sequence +}AacPsyChannel; + +/** + * psychoacoustic model frame type-dependent coefficients + */ +typedef struct AacPsyCoeffs{ + float ath; ///< absolute threshold of hearing per bands + float barks; ///< Bark value for each spectral band in long frame + float spread_low[2]; ///< spreading factor for low-to-high threshold spreading in long frame + float spread_hi [2]; ///< spreading factor for high-to-low threshold spreading in long frame + float min_snr; ///< minimal SNR +}AacPsyCoeffs; + +/** + * 3GPP TS26.403-inspired psychoacoustic model specific data + */ +typedef struct AacPsyContext{ + int chan_bitrate; ///< bitrate per channel + int frame_bits; ///< average bits per frame + int fill_level; ///< bit reservoir fill level + struct { + float min; ///< minimum allowed PE for bit factor calculation + float max; ///< maximum allowed PE for bit factor calculation + float previous; ///< allowed PE of the previous frame + float correction; ///< PE correction factor + } pe; + AacPsyCoeffs psy_coef[2][64]; + AacPsyChannel *ch; +}AacPsyContext; + +/** + * LAME psy model preset struct + */ +typedef struct { + int quality; ///< Quality to map the rest of the vaules to. + /* This is overloaded to be both kbps per channel in ABR mode, and + * requested quality in constant quality mode. + */ + float st_lrm; ///< short threshold for L, R, and M channels +} PsyLamePreset; + +/** + * LAME psy model preset table for ABR + */ +static const PsyLamePreset psy_abr_map[] = { +/* TODO: Tuning. These were taken from LAME. */ +/* kbps/ch st_lrm */ + { 8, 6.60}, + { 16, 6.60}, + { 24, 6.60}, + { 32, 6.60}, + { 40, 6.60}, + { 48, 6.60}, + { 56, 6.60}, + { 64, 6.40}, + { 80, 6.00}, + { 96, 5.60}, + {112, 5.20}, + {128, 5.20}, + {160, 5.20} +}; + +/** +* LAME psy model preset table for constant quality +*/ +static const PsyLamePreset psy_vbr_map[] = { +/* vbr_q st_lrm */ + { 0, 4.20}, + { 1, 4.20}, + { 2, 4.20}, + { 3, 4.20}, + { 4, 4.20}, + { 5, 4.20}, + { 6, 4.20}, + { 7, 4.20}, + { 8, 4.20}, + { 9, 4.20}, + {10, 4.20} +}; + +/** + * LAME psy model FIR coefficient table + */ +static const float psy_fir_coeffs[] = { + -8.65163e-18 * 2, -0.00851586 * 2, -6.74764e-18 * 2, 0.0209036 * 2, + -3.36639e-17 * 2, -0.0438162 * 2, -1.54175e-17 * 2, 0.0931738 * 2, + -5.52212e-17 * 2, -0.313819 * 2 +}; + +/** + * Calculate the ABR attack threshold from the above LAME psymodel table. + */ +static float lame_calc_attack_threshold(int bitrate) +{ + /* Assume max bitrate to start with */ + int lower_range = 12, upper_range = 12; + int lower_range_kbps = psy_abr_map[12].quality; + int upper_range_kbps = psy_abr_map[12].quality; + int i; + + /* Determine which bitrates the value specified falls between. + * If the loop ends without breaking our above assumption of 320kbps was correct. + */ + for (i = 1; i < 13; i++) { + if (FFMAX(bitrate, psy_abr_map[i].quality) != bitrate) { + upper_range = i; + upper_range_kbps = psy_abr_map[i ].quality; + lower_range = i - 1; + lower_range_kbps = psy_abr_map[i - 1].quality; + break; /* Upper range found */ + } + } + + /* Determine which range the value specified is closer to */ + if ((upper_range_kbps - bitrate) > (bitrate - lower_range_kbps)) + return psy_abr_map[lower_range].st_lrm; + return psy_abr_map[upper_range].st_lrm; +} + +/** + * LAME psy model specific initialization + */ +static void lame_window_init(AacPsyContext *ctx, AVCodecContext *avctx) { + int i, j; + + for (i = 0; i < avctx->channels; i++) { + AacPsyChannel *pch = &ctx->ch[i]; + + if (avctx->flags & CODEC_FLAG_QSCALE) + pch->attack_threshold = psy_vbr_map[avctx->global_quality / FF_QP2LAMBDA].st_lrm; + else + pch->attack_threshold = lame_calc_attack_threshold(avctx->bit_rate / avctx->channels / 1000); + + for (j = 0; j < AAC_NUM_BLOCKS_SHORT * PSY_LAME_NUM_SUBBLOCKS; j++) + pch->prev_energy_subshort[j] = 10.0f; + } +} + +/** + * Calculate Bark value for given line. + */ +static av_cold float calc_bark(float f) +{ + return 13.3f * atanf(0.00076f * f) + 3.5f * atanf((f / 7500.0f) * (f / 7500.0f)); +} + +#define ATH_ADD 4 +/** + * Calculate ATH value for given frequency. + * Borrowed from Lame. + */ +static av_cold float ath(float f, float add) +{ + f /= 1000.0f; + return 3.64 * pow(f, -0.8) + - 6.8 * exp(-0.6 * (f - 3.4) * (f - 3.4)) + + 6.0 * exp(-0.15 * (f - 8.7) * (f - 8.7)) + + (0.6 + 0.04 * add) * 0.001 * f * f * f * f; +} + +static av_cold int psy_3gpp_init(FFPsyContext *ctx) { + AacPsyContext *pctx; + float bark; + int i, j, g, start; + float prev, minscale, minath, minsnr, pe_min; + const int chan_bitrate = ctx->avctx->bit_rate / ctx->avctx->channels; + const int bandwidth = ctx->avctx->cutoff ? ctx->avctx->cutoff : AAC_CUTOFF(ctx->avctx); + const float num_bark = calc_bark((float)bandwidth); + + ctx->model_priv_data = av_mallocz(sizeof(AacPsyContext)); + pctx = (AacPsyContext*) ctx->model_priv_data; + + pctx->chan_bitrate = chan_bitrate; + pctx->frame_bits = chan_bitrate * AAC_BLOCK_SIZE_LONG / ctx->avctx->sample_rate; + pctx->pe.min = 8.0f * AAC_BLOCK_SIZE_LONG * bandwidth / (ctx->avctx->sample_rate * 2.0f); + pctx->pe.max = 12.0f * AAC_BLOCK_SIZE_LONG * bandwidth / (ctx->avctx->sample_rate * 2.0f); + ctx->bitres.size = 6144 - pctx->frame_bits; + ctx->bitres.size -= ctx->bitres.size % 8; + pctx->fill_level = ctx->bitres.size; + minath = ath(3410, ATH_ADD); + for (j = 0; j < 2; j++) { + AacPsyCoeffs *coeffs = pctx->psy_coef[j]; + const uint8_t *band_sizes = ctx->bands[j]; + float line_to_frequency = ctx->avctx->sample_rate / (j ? 256.f : 2048.0f); + float avg_chan_bits = chan_bitrate / ctx->avctx->sample_rate * (j ? 128.0f : 1024.0f); + /* reference encoder uses 2.4% here instead of 60% like the spec says */ + float bark_pe = 0.024f * PSY_3GPP_BITS_TO_PE(avg_chan_bits) / num_bark; + float en_spread_low = j ? PSY_3GPP_EN_SPREAD_LOW_S : PSY_3GPP_EN_SPREAD_LOW_L; + /* High energy spreading for long blocks <= 22kbps/channel and short blocks are the same. */ + float en_spread_hi = (j || (chan_bitrate <= 22.0f)) ? PSY_3GPP_EN_SPREAD_HI_S : PSY_3GPP_EN_SPREAD_HI_L1; + + i = 0; + prev = 0.0; + for (g = 0; g < ctx->num_bands[j]; g++) { + i += band_sizes[g]; + bark = calc_bark((i-1) * line_to_frequency); + coeffs[g].barks = (bark + prev) / 2.0; + prev = bark; + } + for (g = 0; g < ctx->num_bands[j] - 1; g++) { + AacPsyCoeffs *coeff = &coeffs[g]; + float bark_width = coeffs[g+1].barks - coeffs->barks; + coeff->spread_low[0] = pow(10.0, -bark_width * PSY_3GPP_THR_SPREAD_LOW); + coeff->spread_hi [0] = pow(10.0, -bark_width * PSY_3GPP_THR_SPREAD_HI); + coeff->spread_low[1] = pow(10.0, -bark_width * en_spread_low); + coeff->spread_hi [1] = pow(10.0, -bark_width * en_spread_hi); + pe_min = bark_pe * bark_width; + minsnr = exp2(pe_min / band_sizes[g]) - 1.5f; + coeff->min_snr = av_clipf(1.0f / minsnr, PSY_SNR_25DB, PSY_SNR_1DB); + } + start = 0; + for (g = 0; g < ctx->num_bands[j]; g++) { + minscale = ath(start * line_to_frequency, ATH_ADD); + for (i = 1; i < band_sizes[g]; i++) + minscale = FFMIN(minscale, ath((start + i) * line_to_frequency, ATH_ADD)); + coeffs[g].ath = minscale - minath; + start += band_sizes[g]; + } + } + + pctx->ch = av_mallocz(sizeof(AacPsyChannel) * ctx->avctx->channels); + + lame_window_init(pctx, ctx->avctx); + + return 0; +} + +/** + * IIR filter used in block switching decision + */ +static float iir_filter(int in, float state[2]) +{ + float ret; + + ret = 0.7548f * (in - state[0]) + 0.5095f * state[1]; + state[0] = in; + state[1] = ret; + return ret; +} + +/** + * window grouping information stored as bits (0 - new group, 1 - group continues) + */ +static const uint8_t window_grouping[9] = { + 0xB6, 0x6C, 0xD8, 0xB2, 0x66, 0xC6, 0x96, 0x36, 0x36 +}; + +/** + * Tell encoder which window types to use. + * @see 3GPP TS26.403 5.4.1 "Blockswitching" + */ +static av_unused FFPsyWindowInfo psy_3gpp_window(FFPsyContext *ctx, + const int16_t *audio, + const int16_t *la, + int channel, int prev_type) +{ + int i, j; + int br = ctx->avctx->bit_rate / ctx->avctx->channels; + int attack_ratio = br <= 16000 ? 18 : 10; + AacPsyContext *pctx = (AacPsyContext*) ctx->model_priv_data; + AacPsyChannel *pch = &pctx->ch[channel]; + uint8_t grouping = 0; + int next_type = pch->next_window_seq; + FFPsyWindowInfo wi = { { 0 } }; + + if (la) { + float s[8], v; + int switch_to_eight = 0; + float sum = 0.0, sum2 = 0.0; + int attack_n = 0; + int stay_short = 0; + for (i = 0; i < 8; i++) { + for (j = 0; j < 128; j++) { + v = iir_filter(la[i*128+j], pch->iir_state); + sum += v*v; + } + s[i] = sum; + sum2 += sum; + } + for (i = 0; i < 8; i++) { + if (s[i] > pch->win_energy * attack_ratio) { + attack_n = i + 1; + switch_to_eight = 1; + break; + } + } + pch->win_energy = pch->win_energy*7/8 + sum2/64; + + wi.window_type[1] = prev_type; + switch (prev_type) { + case ONLY_LONG_SEQUENCE: + wi.window_type[0] = switch_to_eight ? LONG_START_SEQUENCE : ONLY_LONG_SEQUENCE; + next_type = switch_to_eight ? EIGHT_SHORT_SEQUENCE : ONLY_LONG_SEQUENCE; + break; + case LONG_START_SEQUENCE: + wi.window_type[0] = EIGHT_SHORT_SEQUENCE; + grouping = pch->next_grouping; + next_type = switch_to_eight ? EIGHT_SHORT_SEQUENCE : LONG_STOP_SEQUENCE; + break; + case LONG_STOP_SEQUENCE: + wi.window_type[0] = switch_to_eight ? LONG_START_SEQUENCE : ONLY_LONG_SEQUENCE; + next_type = switch_to_eight ? EIGHT_SHORT_SEQUENCE : ONLY_LONG_SEQUENCE; + break; + case EIGHT_SHORT_SEQUENCE: + stay_short = next_type == EIGHT_SHORT_SEQUENCE || switch_to_eight; + wi.window_type[0] = stay_short ? EIGHT_SHORT_SEQUENCE : LONG_STOP_SEQUENCE; + grouping = next_type == EIGHT_SHORT_SEQUENCE ? pch->next_grouping : 0; + next_type = switch_to_eight ? EIGHT_SHORT_SEQUENCE : LONG_STOP_SEQUENCE; + break; + } + + pch->next_grouping = window_grouping[attack_n]; + pch->next_window_seq = next_type; + } else { + for (i = 0; i < 3; i++) + wi.window_type[i] = prev_type; + grouping = (prev_type == EIGHT_SHORT_SEQUENCE) ? window_grouping[0] : 0; + } + + wi.window_shape = 1; + if (wi.window_type[0] != EIGHT_SHORT_SEQUENCE) { + wi.num_windows = 1; + wi.grouping[0] = 1; + } else { + int lastgrp = 0; + wi.num_windows = 8; + for (i = 0; i < 8; i++) { + if (!((grouping >> i) & 1)) + lastgrp = i; + wi.grouping[lastgrp]++; + } + } + + return wi; +} + +/* 5.6.1.2 "Calculation of Bit Demand" */ +static int calc_bit_demand(AacPsyContext *ctx, float pe, int bits, int size, + int short_window) +{ + const float bitsave_slope = short_window ? PSY_3GPP_SAVE_SLOPE_S : PSY_3GPP_SAVE_SLOPE_L; + const float bitsave_add = short_window ? PSY_3GPP_SAVE_ADD_S : PSY_3GPP_SAVE_ADD_L; + const float bitspend_slope = short_window ? PSY_3GPP_SPEND_SLOPE_S : PSY_3GPP_SPEND_SLOPE_L; + const float bitspend_add = short_window ? PSY_3GPP_SPEND_ADD_S : PSY_3GPP_SPEND_ADD_L; + const float clip_low = short_window ? PSY_3GPP_CLIP_LO_S : PSY_3GPP_CLIP_LO_L; + const float clip_high = short_window ? PSY_3GPP_CLIP_HI_S : PSY_3GPP_CLIP_HI_L; + float clipped_pe, bit_save, bit_spend, bit_factor, fill_level; + + ctx->fill_level += ctx->frame_bits - bits; + ctx->fill_level = av_clip(ctx->fill_level, 0, size); + fill_level = av_clipf((float)ctx->fill_level / size, clip_low, clip_high); + clipped_pe = av_clipf(pe, ctx->pe.min, ctx->pe.max); + bit_save = (fill_level + bitsave_add) * bitsave_slope; + assert(bit_save <= 0.3f && bit_save >= -0.05000001f); + bit_spend = (fill_level + bitspend_add) * bitspend_slope; + assert(bit_spend <= 0.5f && bit_spend >= -0.1f); + /* The bit factor graph in the spec is obviously incorrect. + * bit_spend + ((bit_spend - bit_spend))... + * The reference encoder subtracts everything from 1, but also seems incorrect. + * 1 - bit_save + ((bit_spend + bit_save))... + * Hopefully below is correct. + */ + bit_factor = 1.0f - bit_save + ((bit_spend - bit_save) / (ctx->pe.max - ctx->pe.min)) * (clipped_pe - ctx->pe.min); + /* NOTE: The reference encoder attempts to center pe max/min around the current pe. */ + ctx->pe.max = FFMAX(pe, ctx->pe.max); + ctx->pe.min = FFMIN(pe, ctx->pe.min); + + return FFMIN(ctx->frame_bits * bit_factor, ctx->frame_bits + size - bits); +} + +static float calc_pe_3gpp(AacPsyBand *band) +{ + float pe, a; + + band->pe = 0.0f; + band->pe_const = 0.0f; + band->active_lines = 0.0f; + if (band->energy > band->thr) { + a = log2f(band->energy); + pe = a - log2f(band->thr); + band->active_lines = band->nz_lines; + if (pe < PSY_3GPP_C1) { + pe = pe * PSY_3GPP_C3 + PSY_3GPP_C2; + a = a * PSY_3GPP_C3 + PSY_3GPP_C2; + band->active_lines *= PSY_3GPP_C3; + } + band->pe = pe * band->nz_lines; + band->pe_const = a * band->nz_lines; + } + + return band->pe; +} + +static float calc_reduction_3gpp(float a, float desired_pe, float pe, + float active_lines) +{ + float thr_avg, reduction; + + if(active_lines == 0.0) + return 0; + + thr_avg = exp2f((a - pe) / (4.0f * active_lines)); + reduction = exp2f((a - desired_pe) / (4.0f * active_lines)) - thr_avg; + + return FFMAX(reduction, 0.0f); +} + +static float calc_reduced_thr_3gpp(AacPsyBand *band, float min_snr, + float reduction) +{ + float thr = band->thr; + + if (band->energy > thr) { + thr = sqrtf(thr); + thr = sqrtf(thr) + reduction; + thr *= thr; + thr *= thr; + + /* This deviates from the 3GPP spec to match the reference encoder. + * It performs min(thr_reduced, max(thr, energy/min_snr)) only for bands + * that have hole avoidance on (active or inactive). It always reduces the + * threshold of bands with hole avoidance off. + */ + if (thr > band->energy * min_snr && band->avoid_holes != PSY_3GPP_AH_NONE) { + thr = FFMAX(band->thr, band->energy * min_snr); + band->avoid_holes = PSY_3GPP_AH_ACTIVE; + } + } + + return thr; +} + +/** + * Calculate band thresholds as suggested in 3GPP TS26.403 + */ +static void psy_3gpp_analyze_channel(FFPsyContext *ctx, int channel, + const float *coefs, const FFPsyWindowInfo *wi) +{ + AacPsyContext *pctx = (AacPsyContext*) ctx->model_priv_data; + AacPsyChannel *pch = &pctx->ch[channel]; + int start = 0; + int i, w, g; + float desired_bits, desired_pe, delta_pe, reduction= NAN, spread_en[128] = {0}; + float a = 0.0f, active_lines = 0.0f, norm_fac = 0.0f; + float pe = pctx->chan_bitrate > 32000 ? 0.0f : FFMAX(50.0f, 100.0f - pctx->chan_bitrate * 100.0f / 32000.0f); + const int num_bands = ctx->num_bands[wi->num_windows == 8]; + const uint8_t *band_sizes = ctx->bands[wi->num_windows == 8]; + AacPsyCoeffs *coeffs = pctx->psy_coef[wi->num_windows == 8]; + const float avoid_hole_thr = wi->num_windows == 8 ? PSY_3GPP_AH_THR_SHORT : PSY_3GPP_AH_THR_LONG; + + //calculate energies, initial thresholds and related values - 5.4.2 "Threshold Calculation" + for (w = 0; w < wi->num_windows*16; w += 16) { + for (g = 0; g < num_bands; g++) { + AacPsyBand *band = &pch->band[w+g]; + + float form_factor = 0.0f; + float Temp; + band->energy = 0.0f; + for (i = 0; i < band_sizes[g]; i++) { + band->energy += coefs[start+i] * coefs[start+i]; + form_factor += sqrtf(fabs(coefs[start+i])); + } + Temp = band->energy > 0 ? sqrtf((float)band_sizes[g] / band->energy) : 0; + band->thr = band->energy * 0.001258925f; + band->nz_lines = form_factor * sqrtf(Temp); + + start += band_sizes[g]; + } + } + //modify thresholds and energies - spread, threshold in quiet, pre-echo control + for (w = 0; w < wi->num_windows*16; w += 16) { + AacPsyBand *bands = &pch->band[w]; + + /* 5.4.2.3 "Spreading" & 5.4.3 "Spread Energy Calculation" */ + spread_en[0] = bands[0].energy; + for (g = 1; g < num_bands; g++) { + bands[g].thr = FFMAX(bands[g].thr, bands[g-1].thr * coeffs[g].spread_hi[0]); + spread_en[w+g] = FFMAX(bands[g].energy, spread_en[w+g-1] * coeffs[g].spread_hi[1]); + } + for (g = num_bands - 2; g >= 0; g--) { + bands[g].thr = FFMAX(bands[g].thr, bands[g+1].thr * coeffs[g].spread_low[0]); + spread_en[w+g] = FFMAX(spread_en[w+g], spread_en[w+g+1] * coeffs[g].spread_low[1]); + } + //5.4.2.4 "Threshold in quiet" + for (g = 0; g < num_bands; g++) { + AacPsyBand *band = &bands[g]; + + band->thr_quiet = band->thr = FFMAX(band->thr, coeffs[g].ath); + //5.4.2.5 "Pre-echo control" + if (!(wi->window_type[0] == LONG_STOP_SEQUENCE || (wi->window_type[1] == LONG_START_SEQUENCE && !w))) + band->thr = FFMAX(PSY_3GPP_RPEMIN*band->thr, FFMIN(band->thr, + PSY_3GPP_RPELEV*pch->prev_band[w+g].thr_quiet)); + + /* 5.6.1.3.1 "Preparatory steps of the perceptual entropy calculation" */ + pe += calc_pe_3gpp(band); + a += band->pe_const; + active_lines += band->active_lines; + + /* 5.6.1.3.3 "Selection of the bands for avoidance of holes" */ + if (spread_en[w+g] * avoid_hole_thr > band->energy || coeffs[g].min_snr > 1.0f) + band->avoid_holes = PSY_3GPP_AH_NONE; + else + band->avoid_holes = PSY_3GPP_AH_INACTIVE; + } + } + + /* 5.6.1.3.2 "Calculation of the desired perceptual entropy" */ + ctx->ch[channel].entropy = pe; + desired_bits = calc_bit_demand(pctx, pe, ctx->bitres.bits, ctx->bitres.size, wi->num_windows == 8); + desired_pe = PSY_3GPP_BITS_TO_PE(desired_bits); + /* NOTE: PE correction is kept simple. During initial testing it had very + * little effect on the final bitrate. Probably a good idea to come + * back and do more testing later. + */ + if (ctx->bitres.bits > 0) + desired_pe *= av_clipf(pctx->pe.previous / PSY_3GPP_BITS_TO_PE(ctx->bitres.bits), + 0.85f, 1.15f); + pctx->pe.previous = PSY_3GPP_BITS_TO_PE(desired_bits); + + if (desired_pe < pe) { + /* 5.6.1.3.4 "First Estimation of the reduction value" */ + for (w = 0; w < wi->num_windows*16; w += 16) { + reduction = calc_reduction_3gpp(a, desired_pe, pe, active_lines); + pe = 0.0f; + a = 0.0f; + active_lines = 0.0f; + for (g = 0; g < num_bands; g++) { + AacPsyBand *band = &pch->band[w+g]; + + band->thr = calc_reduced_thr_3gpp(band, coeffs[g].min_snr, reduction); + /* recalculate PE */ + pe += calc_pe_3gpp(band); + a += band->pe_const; + active_lines += band->active_lines; + } + } + + /* 5.6.1.3.5 "Second Estimation of the reduction value" */ + for (i = 0; i < 2; i++) { + float pe_no_ah = 0.0f, desired_pe_no_ah; + active_lines = a = 0.0f; + for (w = 0; w < wi->num_windows*16; w += 16) { + for (g = 0; g < num_bands; g++) { + AacPsyBand *band = &pch->band[w+g]; + + if (band->avoid_holes != PSY_3GPP_AH_ACTIVE) { + pe_no_ah += band->pe; + a += band->pe_const; + active_lines += band->active_lines; + } + } + } + desired_pe_no_ah = FFMAX(desired_pe - (pe - pe_no_ah), 0.0f); + if (active_lines > 0.0f) + reduction += calc_reduction_3gpp(a, desired_pe_no_ah, pe_no_ah, active_lines); + + pe = 0.0f; + for (w = 0; w < wi->num_windows*16; w += 16) { + for (g = 0; g < num_bands; g++) { + AacPsyBand *band = &pch->band[w+g]; + + if (active_lines > 0.0f) + band->thr = calc_reduced_thr_3gpp(band, coeffs[g].min_snr, reduction); + pe += calc_pe_3gpp(band); + band->norm_fac = band->active_lines / band->thr; + norm_fac += band->norm_fac; + } + } + delta_pe = desired_pe - pe; + if (fabs(delta_pe) > 0.05f * desired_pe) + break; + } + + if (pe < 1.15f * desired_pe) { + /* 6.6.1.3.6 "Final threshold modification by linearization" */ + norm_fac = 1.0f / norm_fac; + for (w = 0; w < wi->num_windows*16; w += 16) { + for (g = 0; g < num_bands; g++) { + AacPsyBand *band = &pch->band[w+g]; + + if (band->active_lines > 0.5f) { + float delta_sfb_pe = band->norm_fac * norm_fac * delta_pe; + float thr = band->thr; + + thr *= exp2f(delta_sfb_pe / band->active_lines); + if (thr > coeffs[g].min_snr * band->energy && band->avoid_holes == PSY_3GPP_AH_INACTIVE) + thr = FFMAX(band->thr, coeffs[g].min_snr * band->energy); + band->thr = thr; + } + } + } + } else { + /* 5.6.1.3.7 "Further perceptual entropy reduction" */ + g = num_bands; + while (pe > desired_pe && g--) { + for (w = 0; w < wi->num_windows*16; w+= 16) { + AacPsyBand *band = &pch->band[w+g]; + if (band->avoid_holes != PSY_3GPP_AH_NONE && coeffs[g].min_snr < PSY_SNR_1DB) { + coeffs[g].min_snr = PSY_SNR_1DB; + band->thr = band->energy * PSY_SNR_1DB; + pe += band->active_lines * 1.5f - band->pe; + } + } + } + /* TODO: allow more holes (unused without mid/side) */ + } + } + + for (w = 0; w < wi->num_windows*16; w += 16) { + for (g = 0; g < num_bands; g++) { + AacPsyBand *band = &pch->band[w+g]; + FFPsyBand *psy_band = &ctx->ch[channel].psy_bands[w+g]; + + psy_band->threshold = band->thr; + psy_band->energy = band->energy; + } + } + + memcpy(pch->prev_band, pch->band, sizeof(pch->band)); +} + +static void psy_3gpp_analyze(FFPsyContext *ctx, int channel, + const float **coeffs, const FFPsyWindowInfo *wi) +{ + int ch; + FFPsyChannelGroup *group = ff_psy_find_group(ctx, channel); + + for (ch = 0; ch < group->num_ch; ch++) + psy_3gpp_analyze_channel(ctx, channel + ch, coeffs[ch], &wi[ch]); +} + +static av_cold void psy_3gpp_end(FFPsyContext *apc) +{ + AacPsyContext *pctx = (AacPsyContext*) apc->model_priv_data; + av_freep(&pctx->ch); + av_freep(&apc->model_priv_data); +} + +static void lame_apply_block_type(AacPsyChannel *ctx, FFPsyWindowInfo *wi, int uselongblock) +{ + int blocktype = ONLY_LONG_SEQUENCE; + if (uselongblock) { + if (ctx->next_window_seq == EIGHT_SHORT_SEQUENCE) + blocktype = LONG_STOP_SEQUENCE; + } else { + blocktype = EIGHT_SHORT_SEQUENCE; + if (ctx->next_window_seq == ONLY_LONG_SEQUENCE) + ctx->next_window_seq = LONG_START_SEQUENCE; + if (ctx->next_window_seq == LONG_STOP_SEQUENCE) + ctx->next_window_seq = EIGHT_SHORT_SEQUENCE; + } + + wi->window_type[0] = ctx->next_window_seq; + ctx->next_window_seq = blocktype; +} + +static FFPsyWindowInfo psy_lame_window(FFPsyContext *ctx, const float *audio, + const float *la, int channel, int prev_type) +{ + AacPsyContext *pctx = (AacPsyContext*) ctx->model_priv_data; + AacPsyChannel *pch = &pctx->ch[channel]; + int grouping = 0; + int uselongblock = 1; + int attacks[AAC_NUM_BLOCKS_SHORT + 1] = { 0 }; + int i; + FFPsyWindowInfo wi = { { 0 } }; + + if (la) { + float hpfsmpl[AAC_BLOCK_SIZE_LONG]; + float const *pf = hpfsmpl; + float attack_intensity[(AAC_NUM_BLOCKS_SHORT + 1) * PSY_LAME_NUM_SUBBLOCKS]; + float energy_subshort[(AAC_NUM_BLOCKS_SHORT + 1) * PSY_LAME_NUM_SUBBLOCKS]; + float energy_short[AAC_NUM_BLOCKS_SHORT + 1] = { 0 }; + const float *firbuf = la + (AAC_BLOCK_SIZE_SHORT/4 - PSY_LAME_FIR_LEN); + int j, att_sum = 0; + + /* LAME comment: apply high pass filter of fs/4 */ + for (i = 0; i < AAC_BLOCK_SIZE_LONG; i++) { + float sum1, sum2; + sum1 = firbuf[i + (PSY_LAME_FIR_LEN - 1) / 2]; + sum2 = 0.0; + for (j = 0; j < ((PSY_LAME_FIR_LEN - 1) / 2) - 1; j += 2) { + sum1 += psy_fir_coeffs[j] * (firbuf[i + j] + firbuf[i + PSY_LAME_FIR_LEN - j]); + sum2 += psy_fir_coeffs[j + 1] * (firbuf[i + j + 1] + firbuf[i + PSY_LAME_FIR_LEN - j - 1]); + } + /* NOTE: The LAME psymodel expects it's input in the range -32768 to 32768. Tuning this for normalized floats would be difficult. */ + hpfsmpl[i] = (sum1 + sum2) * 32768.0f; + } + + /* Calculate the energies of each sub-shortblock */ + for (i = 0; i < PSY_LAME_NUM_SUBBLOCKS; i++) { + energy_subshort[i] = pch->prev_energy_subshort[i + ((AAC_NUM_BLOCKS_SHORT - 1) * PSY_LAME_NUM_SUBBLOCKS)]; + assert(pch->prev_energy_subshort[i + ((AAC_NUM_BLOCKS_SHORT - 2) * PSY_LAME_NUM_SUBBLOCKS + 1)] > 0); + attack_intensity[i] = energy_subshort[i] / pch->prev_energy_subshort[i + ((AAC_NUM_BLOCKS_SHORT - 2) * PSY_LAME_NUM_SUBBLOCKS + 1)]; + energy_short[0] += energy_subshort[i]; + } + + for (i = 0; i < AAC_NUM_BLOCKS_SHORT * PSY_LAME_NUM_SUBBLOCKS; i++) { + float const *const pfe = pf + AAC_BLOCK_SIZE_LONG / (AAC_NUM_BLOCKS_SHORT * PSY_LAME_NUM_SUBBLOCKS); + float p = 1.0f; + for (; pf < pfe; pf++) + p = FFMAX(p, fabsf(*pf)); + pch->prev_energy_subshort[i] = energy_subshort[i + PSY_LAME_NUM_SUBBLOCKS] = p; + energy_short[1 + i / PSY_LAME_NUM_SUBBLOCKS] += p; + /* NOTE: The indexes below are [i + 3 - 2] in the LAME source. + * Obviously the 3 and 2 have some significance, or this would be just [i + 1] + * (which is what we use here). What the 3 stands for is ambiguous, as it is both + * number of short blocks, and the number of sub-short blocks. + * It seems that LAME is comparing each sub-block to sub-block + 1 in the + * previous block. + */ + if (p > energy_subshort[i + 1]) + p = p / energy_subshort[i + 1]; + else if (energy_subshort[i + 1] > p * 10.0f) + p = energy_subshort[i + 1] / (p * 10.0f); + else + p = 0.0; + attack_intensity[i + PSY_LAME_NUM_SUBBLOCKS] = p; + } + + /* compare energy between sub-short blocks */ + for (i = 0; i < (AAC_NUM_BLOCKS_SHORT + 1) * PSY_LAME_NUM_SUBBLOCKS; i++) + if (!attacks[i / PSY_LAME_NUM_SUBBLOCKS]) + if (attack_intensity[i] > pch->attack_threshold) + attacks[i / PSY_LAME_NUM_SUBBLOCKS] = (i % PSY_LAME_NUM_SUBBLOCKS) + 1; + + /* should have energy change between short blocks, in order to avoid periodic signals */ + /* Good samples to show the effect are Trumpet test songs */ + /* GB: tuned (1) to avoid too many short blocks for test sample TRUMPET */ + /* RH: tuned (2) to let enough short blocks through for test sample FSOL and SNAPS */ + for (i = 1; i < AAC_NUM_BLOCKS_SHORT + 1; i++) { + float const u = energy_short[i - 1]; + float const v = energy_short[i]; + float const m = FFMAX(u, v); + if (m < 40000) { /* (2) */ + if (u < 1.7f * v && v < 1.7f * u) { /* (1) */ + if (i == 1 && attacks[0] < attacks[i]) + attacks[0] = 0; + attacks[i] = 0; + } + } + att_sum += attacks[i]; + } + + if (attacks[0] <= pch->prev_attack) + attacks[0] = 0; + + att_sum += attacks[0]; + /* 3 below indicates the previous attack happened in the last sub-block of the previous sequence */ + if (pch->prev_attack == 3 || att_sum) { + uselongblock = 0; + + for (i = 1; i < AAC_NUM_BLOCKS_SHORT + 1; i++) + if (attacks[i] && attacks[i-1]) + attacks[i] = 0; + } + } else { + /* We have no lookahead info, so just use same type as the previous sequence. */ + uselongblock = !(prev_type == EIGHT_SHORT_SEQUENCE); + } + + lame_apply_block_type(pch, &wi, uselongblock); + + wi.window_type[1] = prev_type; + if (wi.window_type[0] != EIGHT_SHORT_SEQUENCE) { + wi.num_windows = 1; + wi.grouping[0] = 1; + if (wi.window_type[0] == LONG_START_SEQUENCE) + wi.window_shape = 0; + else + wi.window_shape = 1; + } else { + int lastgrp = 0; + + wi.num_windows = 8; + wi.window_shape = 0; + for (i = 0; i < 8; i++) { + if (!((pch->next_grouping >> i) & 1)) + lastgrp = i; + wi.grouping[lastgrp]++; + } + } + + /* Determine grouping, based on the location of the first attack, and save for + * the next frame. + * FIXME: Move this to analysis. + * TODO: Tune groupings depending on attack location + * TODO: Handle more than one attack in a group + */ + for (i = 0; i < 9; i++) { + if (attacks[i]) { + grouping = i; + break; + } + } + pch->next_grouping = window_grouping[grouping]; + + pch->prev_attack = attacks[8]; + + return wi; +} + +const FFPsyModel ff_aac_psy_model = +{ + .name = "3GPP TS 26.403-inspired model", + .init = psy_3gpp_init, + .window = psy_lame_window, + .analyze = psy_3gpp_analyze, + .end = psy_3gpp_end, +}; |