Libav 0.7.1
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00001 /* 00002 * AAC encoder psychoacoustic model 00003 * Copyright (C) 2008 Konstantin Shishkov 00004 * 00005 * This file is part of Libav. 00006 * 00007 * Libav is free software; you can redistribute it and/or 00008 * modify it under the terms of the GNU Lesser General Public 00009 * License as published by the Free Software Foundation; either 00010 * version 2.1 of the License, or (at your option) any later version. 00011 * 00012 * Libav is distributed in the hope that it will be useful, 00013 * but WITHOUT ANY WARRANTY; without even the implied warranty of 00014 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 00015 * Lesser General Public License for more details. 00016 * 00017 * You should have received a copy of the GNU Lesser General Public 00018 * License along with Libav; if not, write to the Free Software 00019 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA 00020 */ 00021 00027 #include "avcodec.h" 00028 #include "aactab.h" 00029 #include "psymodel.h" 00030 00031 /*********************************** 00032 * TODOs: 00033 * try other bitrate controlling mechanism (maybe use ratecontrol.c?) 00034 * control quality for quality-based output 00035 **********************************/ 00036 00041 #define PSY_3GPP_THR_SPREAD_HI 1.5f // spreading factor for low-to-hi threshold spreading (15 dB/Bark) 00042 #define PSY_3GPP_THR_SPREAD_LOW 3.0f // spreading factor for hi-to-low threshold spreading (30 dB/Bark) 00043 /* spreading factor for low-to-hi energy spreading, long block, > 22kbps/channel (20dB/Bark) */ 00044 #define PSY_3GPP_EN_SPREAD_HI_L1 2.0f 00045 /* spreading factor for low-to-hi energy spreading, long block, <= 22kbps/channel (15dB/Bark) */ 00046 #define PSY_3GPP_EN_SPREAD_HI_L2 1.5f 00047 /* spreading factor for low-to-hi energy spreading, short block (15 dB/Bark) */ 00048 #define PSY_3GPP_EN_SPREAD_HI_S 1.5f 00049 /* spreading factor for hi-to-low energy spreading, long block (30dB/Bark) */ 00050 #define PSY_3GPP_EN_SPREAD_LOW_L 3.0f 00051 /* spreading factor for hi-to-low energy spreading, short block (20dB/Bark) */ 00052 #define PSY_3GPP_EN_SPREAD_LOW_S 2.0f 00053 00054 #define PSY_3GPP_RPEMIN 0.01f 00055 #define PSY_3GPP_RPELEV 2.0f 00056 00057 #define PSY_3GPP_C1 3.0f /* log2(8) */ 00058 #define PSY_3GPP_C2 1.3219281f /* log2(2.5) */ 00059 #define PSY_3GPP_C3 0.55935729f /* 1 - C2 / C1 */ 00060 00061 #define PSY_SNR_1DB 7.9432821e-1f /* -1dB */ 00062 #define PSY_SNR_25DB 3.1622776e-3f /* -25dB */ 00063 00064 #define PSY_3GPP_SAVE_SLOPE_L -0.46666667f 00065 #define PSY_3GPP_SAVE_SLOPE_S -0.36363637f 00066 #define PSY_3GPP_SAVE_ADD_L -0.84285712f 00067 #define PSY_3GPP_SAVE_ADD_S -0.75f 00068 #define PSY_3GPP_SPEND_SLOPE_L 0.66666669f 00069 #define PSY_3GPP_SPEND_SLOPE_S 0.81818181f 00070 #define PSY_3GPP_SPEND_ADD_L -0.35f 00071 #define PSY_3GPP_SPEND_ADD_S -0.26111111f 00072 #define PSY_3GPP_CLIP_LO_L 0.2f 00073 #define PSY_3GPP_CLIP_LO_S 0.2f 00074 #define PSY_3GPP_CLIP_HI_L 0.95f 00075 #define PSY_3GPP_CLIP_HI_S 0.75f 00076 00077 #define PSY_3GPP_AH_THR_LONG 0.5f 00078 #define PSY_3GPP_AH_THR_SHORT 0.63f 00079 00080 enum { 00081 PSY_3GPP_AH_NONE, 00082 PSY_3GPP_AH_INACTIVE, 00083 PSY_3GPP_AH_ACTIVE 00084 }; 00085 00086 #define PSY_3GPP_BITS_TO_PE(bits) ((bits) * 1.18f) 00087 00088 /* LAME psy model constants */ 00089 #define PSY_LAME_FIR_LEN 21 ///< LAME psy model FIR order 00090 #define AAC_BLOCK_SIZE_LONG 1024 ///< long block size 00091 #define AAC_BLOCK_SIZE_SHORT 128 ///< short block size 00092 #define AAC_NUM_BLOCKS_SHORT 8 ///< number of blocks in a short sequence 00093 #define PSY_LAME_NUM_SUBBLOCKS 3 ///< Number of sub-blocks in each short block 00094 00102 typedef struct AacPsyBand{ 00103 float energy; 00104 float thr; 00105 float thr_quiet; 00106 float nz_lines; 00107 float active_lines; 00108 float pe; 00109 float pe_const; 00110 float norm_fac; 00111 int avoid_holes; 00112 }AacPsyBand; 00113 00117 typedef struct AacPsyChannel{ 00118 AacPsyBand band[128]; 00119 AacPsyBand prev_band[128]; 00120 00121 float win_energy; 00122 float iir_state[2]; 00123 uint8_t next_grouping; 00124 enum WindowSequence next_window_seq; 00125 /* LAME psy model specific members */ 00126 float attack_threshold; 00127 float prev_energy_subshort[AAC_NUM_BLOCKS_SHORT * PSY_LAME_NUM_SUBBLOCKS]; 00128 int prev_attack; 00129 }AacPsyChannel; 00130 00134 typedef struct AacPsyCoeffs{ 00135 float ath; 00136 float barks; 00137 float spread_low[2]; 00138 float spread_hi [2]; 00139 float min_snr; 00140 }AacPsyCoeffs; 00141 00145 typedef struct AacPsyContext{ 00146 int chan_bitrate; 00147 int frame_bits; 00148 int fill_level; 00149 struct { 00150 float min; 00151 float max; 00152 float previous; 00153 float correction; 00154 } pe; 00155 AacPsyCoeffs psy_coef[2][64]; 00156 AacPsyChannel *ch; 00157 }AacPsyContext; 00158 00162 typedef struct { 00163 int quality; 00164 /* This is overloaded to be both kbps per channel in ABR mode, and 00165 * requested quality in constant quality mode. 00166 */ 00167 float st_lrm; 00168 } PsyLamePreset; 00169 00173 static const PsyLamePreset psy_abr_map[] = { 00174 /* TODO: Tuning. These were taken from LAME. */ 00175 /* kbps/ch st_lrm */ 00176 { 8, 6.60}, 00177 { 16, 6.60}, 00178 { 24, 6.60}, 00179 { 32, 6.60}, 00180 { 40, 6.60}, 00181 { 48, 6.60}, 00182 { 56, 6.60}, 00183 { 64, 6.40}, 00184 { 80, 6.00}, 00185 { 96, 5.60}, 00186 {112, 5.20}, 00187 {128, 5.20}, 00188 {160, 5.20} 00189 }; 00190 00194 static const PsyLamePreset psy_vbr_map[] = { 00195 /* vbr_q st_lrm */ 00196 { 0, 4.20}, 00197 { 1, 4.20}, 00198 { 2, 4.20}, 00199 { 3, 4.20}, 00200 { 4, 4.20}, 00201 { 5, 4.20}, 00202 { 6, 4.20}, 00203 { 7, 4.20}, 00204 { 8, 4.20}, 00205 { 9, 4.20}, 00206 {10, 4.20} 00207 }; 00208 00212 static const float psy_fir_coeffs[] = { 00213 -8.65163e-18 * 2, -0.00851586 * 2, -6.74764e-18 * 2, 0.0209036 * 2, 00214 -3.36639e-17 * 2, -0.0438162 * 2, -1.54175e-17 * 2, 0.0931738 * 2, 00215 -5.52212e-17 * 2, -0.313819 * 2 00216 }; 00217 00221 static float lame_calc_attack_threshold(int bitrate) 00222 { 00223 /* Assume max bitrate to start with */ 00224 int lower_range = 12, upper_range = 12; 00225 int lower_range_kbps = psy_abr_map[12].quality; 00226 int upper_range_kbps = psy_abr_map[12].quality; 00227 int i; 00228 00229 /* Determine which bitrates the value specified falls between. 00230 * If the loop ends without breaking our above assumption of 320kbps was correct. 00231 */ 00232 for (i = 1; i < 13; i++) { 00233 if (FFMAX(bitrate, psy_abr_map[i].quality) != bitrate) { 00234 upper_range = i; 00235 upper_range_kbps = psy_abr_map[i ].quality; 00236 lower_range = i - 1; 00237 lower_range_kbps = psy_abr_map[i - 1].quality; 00238 break; /* Upper range found */ 00239 } 00240 } 00241 00242 /* Determine which range the value specified is closer to */ 00243 if ((upper_range_kbps - bitrate) > (bitrate - lower_range_kbps)) 00244 return psy_abr_map[lower_range].st_lrm; 00245 return psy_abr_map[upper_range].st_lrm; 00246 } 00247 00251 static void lame_window_init(AacPsyContext *ctx, AVCodecContext *avctx) { 00252 int i, j; 00253 00254 for (i = 0; i < avctx->channels; i++) { 00255 AacPsyChannel *pch = &ctx->ch[i]; 00256 00257 if (avctx->flags & CODEC_FLAG_QSCALE) 00258 pch->attack_threshold = psy_vbr_map[avctx->global_quality / FF_QP2LAMBDA].st_lrm; 00259 else 00260 pch->attack_threshold = lame_calc_attack_threshold(avctx->bit_rate / avctx->channels / 1000); 00261 00262 for (j = 0; j < AAC_NUM_BLOCKS_SHORT * PSY_LAME_NUM_SUBBLOCKS; j++) 00263 pch->prev_energy_subshort[j] = 10.0f; 00264 } 00265 } 00266 00270 static av_cold float calc_bark(float f) 00271 { 00272 return 13.3f * atanf(0.00076f * f) + 3.5f * atanf((f / 7500.0f) * (f / 7500.0f)); 00273 } 00274 00275 #define ATH_ADD 4 00276 00280 static av_cold float ath(float f, float add) 00281 { 00282 f /= 1000.0f; 00283 return 3.64 * pow(f, -0.8) 00284 - 6.8 * exp(-0.6 * (f - 3.4) * (f - 3.4)) 00285 + 6.0 * exp(-0.15 * (f - 8.7) * (f - 8.7)) 00286 + (0.6 + 0.04 * add) * 0.001 * f * f * f * f; 00287 } 00288 00289 static av_cold int psy_3gpp_init(FFPsyContext *ctx) { 00290 AacPsyContext *pctx; 00291 float bark; 00292 int i, j, g, start; 00293 float prev, minscale, minath, minsnr, pe_min; 00294 const int chan_bitrate = ctx->avctx->bit_rate / ctx->avctx->channels; 00295 const int bandwidth = ctx->avctx->cutoff ? ctx->avctx->cutoff : ctx->avctx->sample_rate / 2; 00296 const float num_bark = calc_bark((float)bandwidth); 00297 00298 ctx->model_priv_data = av_mallocz(sizeof(AacPsyContext)); 00299 pctx = (AacPsyContext*) ctx->model_priv_data; 00300 00301 pctx->chan_bitrate = chan_bitrate; 00302 pctx->frame_bits = chan_bitrate * AAC_BLOCK_SIZE_LONG / ctx->avctx->sample_rate; 00303 pctx->pe.min = 8.0f * AAC_BLOCK_SIZE_LONG * bandwidth / (ctx->avctx->sample_rate * 2.0f); 00304 pctx->pe.max = 12.0f * AAC_BLOCK_SIZE_LONG * bandwidth / (ctx->avctx->sample_rate * 2.0f); 00305 ctx->bitres.size = 6144 - pctx->frame_bits; 00306 ctx->bitres.size -= ctx->bitres.size % 8; 00307 pctx->fill_level = ctx->bitres.size; 00308 minath = ath(3410, ATH_ADD); 00309 for (j = 0; j < 2; j++) { 00310 AacPsyCoeffs *coeffs = pctx->psy_coef[j]; 00311 const uint8_t *band_sizes = ctx->bands[j]; 00312 float line_to_frequency = ctx->avctx->sample_rate / (j ? 256.f : 2048.0f); 00313 float avg_chan_bits = chan_bitrate / ctx->avctx->sample_rate * (j ? 128.0f : 1024.0f); 00314 /* reference encoder uses 2.4% here instead of 60% like the spec says */ 00315 float bark_pe = 0.024f * PSY_3GPP_BITS_TO_PE(avg_chan_bits) / num_bark; 00316 float en_spread_low = j ? PSY_3GPP_EN_SPREAD_LOW_S : PSY_3GPP_EN_SPREAD_LOW_L; 00317 /* High energy spreading for long blocks <= 22kbps/channel and short blocks are the same. */ 00318 float en_spread_hi = (j || (chan_bitrate <= 22.0f)) ? PSY_3GPP_EN_SPREAD_HI_S : PSY_3GPP_EN_SPREAD_HI_L1; 00319 00320 i = 0; 00321 prev = 0.0; 00322 for (g = 0; g < ctx->num_bands[j]; g++) { 00323 i += band_sizes[g]; 00324 bark = calc_bark((i-1) * line_to_frequency); 00325 coeffs[g].barks = (bark + prev) / 2.0; 00326 prev = bark; 00327 } 00328 for (g = 0; g < ctx->num_bands[j] - 1; g++) { 00329 AacPsyCoeffs *coeff = &coeffs[g]; 00330 float bark_width = coeffs[g+1].barks - coeffs->barks; 00331 coeff->spread_low[0] = pow(10.0, -bark_width * PSY_3GPP_THR_SPREAD_LOW); 00332 coeff->spread_hi [0] = pow(10.0, -bark_width * PSY_3GPP_THR_SPREAD_HI); 00333 coeff->spread_low[1] = pow(10.0, -bark_width * en_spread_low); 00334 coeff->spread_hi [1] = pow(10.0, -bark_width * en_spread_hi); 00335 pe_min = bark_pe * bark_width; 00336 minsnr = pow(2.0f, pe_min / band_sizes[g]) - 1.5f; 00337 coeff->min_snr = av_clipf(1.0f / minsnr, PSY_SNR_25DB, PSY_SNR_1DB); 00338 } 00339 start = 0; 00340 for (g = 0; g < ctx->num_bands[j]; g++) { 00341 minscale = ath(start * line_to_frequency, ATH_ADD); 00342 for (i = 1; i < band_sizes[g]; i++) 00343 minscale = FFMIN(minscale, ath((start + i) * line_to_frequency, ATH_ADD)); 00344 coeffs[g].ath = minscale - minath; 00345 start += band_sizes[g]; 00346 } 00347 } 00348 00349 pctx->ch = av_mallocz(sizeof(AacPsyChannel) * ctx->avctx->channels); 00350 00351 lame_window_init(pctx, ctx->avctx); 00352 00353 return 0; 00354 } 00355 00359 static float iir_filter(int in, float state[2]) 00360 { 00361 float ret; 00362 00363 ret = 0.7548f * (in - state[0]) + 0.5095f * state[1]; 00364 state[0] = in; 00365 state[1] = ret; 00366 return ret; 00367 } 00368 00372 static const uint8_t window_grouping[9] = { 00373 0xB6, 0x6C, 0xD8, 0xB2, 0x66, 0xC6, 0x96, 0x36, 0x36 00374 }; 00375 00380 static FFPsyWindowInfo psy_3gpp_window(FFPsyContext *ctx, 00381 const int16_t *audio, const int16_t *la, 00382 int channel, int prev_type) 00383 { 00384 int i, j; 00385 int br = ctx->avctx->bit_rate / ctx->avctx->channels; 00386 int attack_ratio = br <= 16000 ? 18 : 10; 00387 AacPsyContext *pctx = (AacPsyContext*) ctx->model_priv_data; 00388 AacPsyChannel *pch = &pctx->ch[channel]; 00389 uint8_t grouping = 0; 00390 int next_type = pch->next_window_seq; 00391 FFPsyWindowInfo wi; 00392 00393 memset(&wi, 0, sizeof(wi)); 00394 if (la) { 00395 float s[8], v; 00396 int switch_to_eight = 0; 00397 float sum = 0.0, sum2 = 0.0; 00398 int attack_n = 0; 00399 int stay_short = 0; 00400 for (i = 0; i < 8; i++) { 00401 for (j = 0; j < 128; j++) { 00402 v = iir_filter(la[(i*128+j)*ctx->avctx->channels], pch->iir_state); 00403 sum += v*v; 00404 } 00405 s[i] = sum; 00406 sum2 += sum; 00407 } 00408 for (i = 0; i < 8; i++) { 00409 if (s[i] > pch->win_energy * attack_ratio) { 00410 attack_n = i + 1; 00411 switch_to_eight = 1; 00412 break; 00413 } 00414 } 00415 pch->win_energy = pch->win_energy*7/8 + sum2/64; 00416 00417 wi.window_type[1] = prev_type; 00418 switch (prev_type) { 00419 case ONLY_LONG_SEQUENCE: 00420 wi.window_type[0] = switch_to_eight ? LONG_START_SEQUENCE : ONLY_LONG_SEQUENCE; 00421 next_type = switch_to_eight ? EIGHT_SHORT_SEQUENCE : ONLY_LONG_SEQUENCE; 00422 break; 00423 case LONG_START_SEQUENCE: 00424 wi.window_type[0] = EIGHT_SHORT_SEQUENCE; 00425 grouping = pch->next_grouping; 00426 next_type = switch_to_eight ? EIGHT_SHORT_SEQUENCE : LONG_STOP_SEQUENCE; 00427 break; 00428 case LONG_STOP_SEQUENCE: 00429 wi.window_type[0] = switch_to_eight ? LONG_START_SEQUENCE : ONLY_LONG_SEQUENCE; 00430 next_type = switch_to_eight ? EIGHT_SHORT_SEQUENCE : ONLY_LONG_SEQUENCE; 00431 break; 00432 case EIGHT_SHORT_SEQUENCE: 00433 stay_short = next_type == EIGHT_SHORT_SEQUENCE || switch_to_eight; 00434 wi.window_type[0] = stay_short ? EIGHT_SHORT_SEQUENCE : LONG_STOP_SEQUENCE; 00435 grouping = next_type == EIGHT_SHORT_SEQUENCE ? pch->next_grouping : 0; 00436 next_type = switch_to_eight ? EIGHT_SHORT_SEQUENCE : LONG_STOP_SEQUENCE; 00437 break; 00438 } 00439 00440 pch->next_grouping = window_grouping[attack_n]; 00441 pch->next_window_seq = next_type; 00442 } else { 00443 for (i = 0; i < 3; i++) 00444 wi.window_type[i] = prev_type; 00445 grouping = (prev_type == EIGHT_SHORT_SEQUENCE) ? window_grouping[0] : 0; 00446 } 00447 00448 wi.window_shape = 1; 00449 if (wi.window_type[0] != EIGHT_SHORT_SEQUENCE) { 00450 wi.num_windows = 1; 00451 wi.grouping[0] = 1; 00452 } else { 00453 int lastgrp = 0; 00454 wi.num_windows = 8; 00455 for (i = 0; i < 8; i++) { 00456 if (!((grouping >> i) & 1)) 00457 lastgrp = i; 00458 wi.grouping[lastgrp]++; 00459 } 00460 } 00461 00462 return wi; 00463 } 00464 00465 /* 5.6.1.2 "Calculation of Bit Demand" */ 00466 static int calc_bit_demand(AacPsyContext *ctx, float pe, int bits, int size, 00467 int short_window) 00468 { 00469 const float bitsave_slope = short_window ? PSY_3GPP_SAVE_SLOPE_S : PSY_3GPP_SAVE_SLOPE_L; 00470 const float bitsave_add = short_window ? PSY_3GPP_SAVE_ADD_S : PSY_3GPP_SAVE_ADD_L; 00471 const float bitspend_slope = short_window ? PSY_3GPP_SPEND_SLOPE_S : PSY_3GPP_SPEND_SLOPE_L; 00472 const float bitspend_add = short_window ? PSY_3GPP_SPEND_ADD_S : PSY_3GPP_SPEND_ADD_L; 00473 const float clip_low = short_window ? PSY_3GPP_CLIP_LO_S : PSY_3GPP_CLIP_LO_L; 00474 const float clip_high = short_window ? PSY_3GPP_CLIP_HI_S : PSY_3GPP_CLIP_HI_L; 00475 float clipped_pe, bit_save, bit_spend, bit_factor, fill_level; 00476 00477 ctx->fill_level += ctx->frame_bits - bits; 00478 ctx->fill_level = av_clip(ctx->fill_level, 0, size); 00479 fill_level = av_clipf((float)ctx->fill_level / size, clip_low, clip_high); 00480 clipped_pe = av_clipf(pe, ctx->pe.min, ctx->pe.max); 00481 bit_save = (fill_level + bitsave_add) * bitsave_slope; 00482 assert(bit_save <= 0.3f && bit_save >= -0.05000001f); 00483 bit_spend = (fill_level + bitspend_add) * bitspend_slope; 00484 assert(bit_spend <= 0.5f && bit_spend >= -0.1f); 00485 /* The bit factor graph in the spec is obviously incorrect. 00486 * bit_spend + ((bit_spend - bit_spend))... 00487 * The reference encoder subtracts everything from 1, but also seems incorrect. 00488 * 1 - bit_save + ((bit_spend + bit_save))... 00489 * Hopefully below is correct. 00490 */ 00491 bit_factor = 1.0f - bit_save + ((bit_spend - bit_save) / (ctx->pe.max - ctx->pe.min)) * (clipped_pe - ctx->pe.min); 00492 /* NOTE: The reference encoder attempts to center pe max/min around the current pe. */ 00493 ctx->pe.max = FFMAX(pe, ctx->pe.max); 00494 ctx->pe.min = FFMIN(pe, ctx->pe.min); 00495 00496 return FFMIN(ctx->frame_bits * bit_factor, ctx->frame_bits + size - bits); 00497 } 00498 00499 static float calc_pe_3gpp(AacPsyBand *band) 00500 { 00501 float pe, a; 00502 00503 band->pe = 0.0f; 00504 band->pe_const = 0.0f; 00505 band->active_lines = 0.0f; 00506 if (band->energy > band->thr) { 00507 a = log2f(band->energy); 00508 pe = a - log2f(band->thr); 00509 band->active_lines = band->nz_lines; 00510 if (pe < PSY_3GPP_C1) { 00511 pe = pe * PSY_3GPP_C3 + PSY_3GPP_C2; 00512 a = a * PSY_3GPP_C3 + PSY_3GPP_C2; 00513 band->active_lines *= PSY_3GPP_C3; 00514 } 00515 band->pe = pe * band->nz_lines; 00516 band->pe_const = a * band->nz_lines; 00517 } 00518 00519 return band->pe; 00520 } 00521 00522 static float calc_reduction_3gpp(float a, float desired_pe, float pe, 00523 float active_lines) 00524 { 00525 float thr_avg, reduction; 00526 00527 thr_avg = powf(2.0f, (a - pe) / (4.0f * active_lines)); 00528 reduction = powf(2.0f, (a - desired_pe) / (4.0f * active_lines)) - thr_avg; 00529 00530 return FFMAX(reduction, 0.0f); 00531 } 00532 00533 static float calc_reduced_thr_3gpp(AacPsyBand *band, float min_snr, 00534 float reduction) 00535 { 00536 float thr = band->thr; 00537 00538 if (band->energy > thr) { 00539 thr = powf(thr, 0.25f) + reduction; 00540 thr = powf(thr, 4.0f); 00541 00542 /* This deviates from the 3GPP spec to match the reference encoder. 00543 * It performs min(thr_reduced, max(thr, energy/min_snr)) only for bands 00544 * that have hole avoidance on (active or inactive). It always reduces the 00545 * threshold of bands with hole avoidance off. 00546 */ 00547 if (thr > band->energy * min_snr && band->avoid_holes != PSY_3GPP_AH_NONE) { 00548 thr = FFMAX(band->thr, band->energy * min_snr); 00549 band->avoid_holes = PSY_3GPP_AH_ACTIVE; 00550 } 00551 } 00552 00553 return thr; 00554 } 00555 00559 static void psy_3gpp_analyze(FFPsyContext *ctx, int channel, 00560 const float *coefs, const FFPsyWindowInfo *wi) 00561 { 00562 AacPsyContext *pctx = (AacPsyContext*) ctx->model_priv_data; 00563 AacPsyChannel *pch = &pctx->ch[channel]; 00564 int start = 0; 00565 int i, w, g; 00566 float desired_bits, desired_pe, delta_pe, reduction, spread_en[128] = {0}; 00567 float a = 0.0f, active_lines = 0.0f, norm_fac = 0.0f; 00568 float pe = pctx->chan_bitrate > 32000 ? 0.0f : FFMAX(50.0f, 100.0f - pctx->chan_bitrate * 100.0f / 32000.0f); 00569 const int num_bands = ctx->num_bands[wi->num_windows == 8]; 00570 const uint8_t *band_sizes = ctx->bands[wi->num_windows == 8]; 00571 AacPsyCoeffs *coeffs = pctx->psy_coef[wi->num_windows == 8]; 00572 const float avoid_hole_thr = wi->num_windows == 8 ? PSY_3GPP_AH_THR_SHORT : PSY_3GPP_AH_THR_LONG; 00573 00574 //calculate energies, initial thresholds and related values - 5.4.2 "Threshold Calculation" 00575 for (w = 0; w < wi->num_windows*16; w += 16) { 00576 for (g = 0; g < num_bands; g++) { 00577 AacPsyBand *band = &pch->band[w+g]; 00578 00579 float form_factor = 0.0f; 00580 band->energy = 0.0f; 00581 for (i = 0; i < band_sizes[g]; i++) { 00582 band->energy += coefs[start+i] * coefs[start+i]; 00583 form_factor += sqrtf(fabs(coefs[start+i])); 00584 } 00585 band->thr = band->energy * 0.001258925f; 00586 band->nz_lines = form_factor / powf(band->energy / band_sizes[g], 0.25f); 00587 00588 start += band_sizes[g]; 00589 } 00590 } 00591 //modify thresholds and energies - spread, threshold in quiet, pre-echo control 00592 for (w = 0; w < wi->num_windows*16; w += 16) { 00593 AacPsyBand *bands = &pch->band[w]; 00594 00595 //5.4.2.3 "Spreading" & 5.4.3 "Spreaded Energy Calculation" 00596 spread_en[0] = bands[0].energy; 00597 for (g = 1; g < num_bands; g++) { 00598 bands[g].thr = FFMAX(bands[g].thr, bands[g-1].thr * coeffs[g].spread_hi[0]); 00599 spread_en[w+g] = FFMAX(bands[g].energy, spread_en[w+g-1] * coeffs[g].spread_hi[1]); 00600 } 00601 for (g = num_bands - 2; g >= 0; g--) { 00602 bands[g].thr = FFMAX(bands[g].thr, bands[g+1].thr * coeffs[g].spread_low[0]); 00603 spread_en[w+g] = FFMAX(spread_en[w+g], spread_en[w+g+1] * coeffs[g].spread_low[1]); 00604 } 00605 //5.4.2.4 "Threshold in quiet" 00606 for (g = 0; g < num_bands; g++) { 00607 AacPsyBand *band = &bands[g]; 00608 00609 band->thr_quiet = band->thr = FFMAX(band->thr, coeffs[g].ath); 00610 //5.4.2.5 "Pre-echo control" 00611 if (!(wi->window_type[0] == LONG_STOP_SEQUENCE || (wi->window_type[1] == LONG_START_SEQUENCE && !w))) 00612 band->thr = FFMAX(PSY_3GPP_RPEMIN*band->thr, FFMIN(band->thr, 00613 PSY_3GPP_RPELEV*pch->prev_band[w+g].thr_quiet)); 00614 00615 /* 5.6.1.3.1 "Prepatory steps of the perceptual entropy calculation" */ 00616 pe += calc_pe_3gpp(band); 00617 a += band->pe_const; 00618 active_lines += band->active_lines; 00619 00620 /* 5.6.1.3.3 "Selection of the bands for avoidance of holes" */ 00621 if (spread_en[w+g] * avoid_hole_thr > band->energy || coeffs[g].min_snr > 1.0f) 00622 band->avoid_holes = PSY_3GPP_AH_NONE; 00623 else 00624 band->avoid_holes = PSY_3GPP_AH_INACTIVE; 00625 } 00626 } 00627 00628 /* 5.6.1.3.2 "Calculation of the desired perceptual entropy" */ 00629 ctx->pe[channel] = pe; 00630 desired_bits = calc_bit_demand(pctx, pe, ctx->bitres.bits, ctx->bitres.size, wi->num_windows == 8); 00631 desired_pe = PSY_3GPP_BITS_TO_PE(desired_bits); 00632 /* NOTE: PE correction is kept simple. During initial testing it had very 00633 * little effect on the final bitrate. Probably a good idea to come 00634 * back and do more testing later. 00635 */ 00636 if (ctx->bitres.bits > 0) 00637 desired_pe *= av_clipf(pctx->pe.previous / PSY_3GPP_BITS_TO_PE(ctx->bitres.bits), 00638 0.85f, 1.15f); 00639 pctx->pe.previous = PSY_3GPP_BITS_TO_PE(desired_bits); 00640 00641 if (desired_pe < pe) { 00642 /* 5.6.1.3.4 "First Estimation of the reduction value" */ 00643 for (w = 0; w < wi->num_windows*16; w += 16) { 00644 reduction = calc_reduction_3gpp(a, desired_pe, pe, active_lines); 00645 pe = 0.0f; 00646 a = 0.0f; 00647 active_lines = 0.0f; 00648 for (g = 0; g < num_bands; g++) { 00649 AacPsyBand *band = &pch->band[w+g]; 00650 00651 band->thr = calc_reduced_thr_3gpp(band, coeffs[g].min_snr, reduction); 00652 /* recalculate PE */ 00653 pe += calc_pe_3gpp(band); 00654 a += band->pe_const; 00655 active_lines += band->active_lines; 00656 } 00657 } 00658 00659 /* 5.6.1.3.5 "Second Estimation of the reduction value" */ 00660 for (i = 0; i < 2; i++) { 00661 float pe_no_ah = 0.0f, desired_pe_no_ah; 00662 active_lines = a = 0.0f; 00663 for (w = 0; w < wi->num_windows*16; w += 16) { 00664 for (g = 0; g < num_bands; g++) { 00665 AacPsyBand *band = &pch->band[w+g]; 00666 00667 if (band->avoid_holes != PSY_3GPP_AH_ACTIVE) { 00668 pe_no_ah += band->pe; 00669 a += band->pe_const; 00670 active_lines += band->active_lines; 00671 } 00672 } 00673 } 00674 desired_pe_no_ah = FFMAX(desired_pe - (pe - pe_no_ah), 0.0f); 00675 if (active_lines > 0.0f) 00676 reduction += calc_reduction_3gpp(a, desired_pe_no_ah, pe_no_ah, active_lines); 00677 00678 pe = 0.0f; 00679 for (w = 0; w < wi->num_windows*16; w += 16) { 00680 for (g = 0; g < num_bands; g++) { 00681 AacPsyBand *band = &pch->band[w+g]; 00682 00683 if (active_lines > 0.0f) 00684 band->thr = calc_reduced_thr_3gpp(band, coeffs[g].min_snr, reduction); 00685 pe += calc_pe_3gpp(band); 00686 band->norm_fac = band->active_lines / band->thr; 00687 norm_fac += band->norm_fac; 00688 } 00689 } 00690 delta_pe = desired_pe - pe; 00691 if (fabs(delta_pe) > 0.05f * desired_pe) 00692 break; 00693 } 00694 00695 if (pe < 1.15f * desired_pe) { 00696 /* 6.6.1.3.6 "Final threshold modification by linearization" */ 00697 norm_fac = 1.0f / norm_fac; 00698 for (w = 0; w < wi->num_windows*16; w += 16) { 00699 for (g = 0; g < num_bands; g++) { 00700 AacPsyBand *band = &pch->band[w+g]; 00701 00702 if (band->active_lines > 0.5f) { 00703 float delta_sfb_pe = band->norm_fac * norm_fac * delta_pe; 00704 float thr = band->thr; 00705 00706 thr *= powf(2.0f, delta_sfb_pe / band->active_lines); 00707 if (thr > coeffs[g].min_snr * band->energy && band->avoid_holes == PSY_3GPP_AH_INACTIVE) 00708 thr = FFMAX(band->thr, coeffs[g].min_snr * band->energy); 00709 band->thr = thr; 00710 } 00711 } 00712 } 00713 } else { 00714 /* 5.6.1.3.7 "Further perceptual entropy reduction" */ 00715 g = num_bands; 00716 while (pe > desired_pe && g--) { 00717 for (w = 0; w < wi->num_windows*16; w+= 16) { 00718 AacPsyBand *band = &pch->band[w+g]; 00719 if (band->avoid_holes != PSY_3GPP_AH_NONE && coeffs[g].min_snr < PSY_SNR_1DB) { 00720 coeffs[g].min_snr = PSY_SNR_1DB; 00721 band->thr = band->energy * PSY_SNR_1DB; 00722 pe += band->active_lines * 1.5f - band->pe; 00723 } 00724 } 00725 } 00726 /* TODO: allow more holes (unused without mid/side) */ 00727 } 00728 } 00729 00730 for (w = 0; w < wi->num_windows*16; w += 16) { 00731 for (g = 0; g < num_bands; g++) { 00732 AacPsyBand *band = &pch->band[w+g]; 00733 FFPsyBand *psy_band = &ctx->psy_bands[channel*PSY_MAX_BANDS+w+g]; 00734 00735 psy_band->threshold = band->thr; 00736 psy_band->energy = band->energy; 00737 } 00738 } 00739 00740 memcpy(pch->prev_band, pch->band, sizeof(pch->band)); 00741 } 00742 00743 static av_cold void psy_3gpp_end(FFPsyContext *apc) 00744 { 00745 AacPsyContext *pctx = (AacPsyContext*) apc->model_priv_data; 00746 av_freep(&pctx->ch); 00747 av_freep(&apc->model_priv_data); 00748 } 00749 00750 static void lame_apply_block_type(AacPsyChannel *ctx, FFPsyWindowInfo *wi, int uselongblock) 00751 { 00752 int blocktype = ONLY_LONG_SEQUENCE; 00753 if (uselongblock) { 00754 if (ctx->next_window_seq == EIGHT_SHORT_SEQUENCE) 00755 blocktype = LONG_STOP_SEQUENCE; 00756 } else { 00757 blocktype = EIGHT_SHORT_SEQUENCE; 00758 if (ctx->next_window_seq == ONLY_LONG_SEQUENCE) 00759 ctx->next_window_seq = LONG_START_SEQUENCE; 00760 if (ctx->next_window_seq == LONG_STOP_SEQUENCE) 00761 ctx->next_window_seq = EIGHT_SHORT_SEQUENCE; 00762 } 00763 00764 wi->window_type[0] = ctx->next_window_seq; 00765 ctx->next_window_seq = blocktype; 00766 } 00767 00768 static FFPsyWindowInfo psy_lame_window(FFPsyContext *ctx, 00769 const int16_t *audio, const int16_t *la, 00770 int channel, int prev_type) 00771 { 00772 AacPsyContext *pctx = (AacPsyContext*) ctx->model_priv_data; 00773 AacPsyChannel *pch = &pctx->ch[channel]; 00774 int grouping = 0; 00775 int uselongblock = 1; 00776 int attacks[AAC_NUM_BLOCKS_SHORT + 1] = { 0 }; 00777 int i; 00778 FFPsyWindowInfo wi; 00779 00780 memset(&wi, 0, sizeof(wi)); 00781 if (la) { 00782 float hpfsmpl[AAC_BLOCK_SIZE_LONG]; 00783 float const *pf = hpfsmpl; 00784 float attack_intensity[(AAC_NUM_BLOCKS_SHORT + 1) * PSY_LAME_NUM_SUBBLOCKS]; 00785 float energy_subshort[(AAC_NUM_BLOCKS_SHORT + 1) * PSY_LAME_NUM_SUBBLOCKS]; 00786 float energy_short[AAC_NUM_BLOCKS_SHORT + 1] = { 0 }; 00787 int chans = ctx->avctx->channels; 00788 const int16_t *firbuf = la + (AAC_BLOCK_SIZE_SHORT/4 - PSY_LAME_FIR_LEN) * chans; 00789 int j, att_sum = 0; 00790 00791 /* LAME comment: apply high pass filter of fs/4 */ 00792 for (i = 0; i < AAC_BLOCK_SIZE_LONG; i++) { 00793 float sum1, sum2; 00794 sum1 = firbuf[(i + ((PSY_LAME_FIR_LEN - 1) / 2)) * chans]; 00795 sum2 = 0.0; 00796 for (j = 0; j < ((PSY_LAME_FIR_LEN - 1) / 2) - 1; j += 2) { 00797 sum1 += psy_fir_coeffs[j] * (firbuf[(i + j) * chans] + firbuf[(i + PSY_LAME_FIR_LEN - j) * chans]); 00798 sum2 += psy_fir_coeffs[j + 1] * (firbuf[(i + j + 1) * chans] + firbuf[(i + PSY_LAME_FIR_LEN - j - 1) * chans]); 00799 } 00800 hpfsmpl[i] = sum1 + sum2; 00801 } 00802 00803 /* Calculate the energies of each sub-shortblock */ 00804 for (i = 0; i < PSY_LAME_NUM_SUBBLOCKS; i++) { 00805 energy_subshort[i] = pch->prev_energy_subshort[i + ((AAC_NUM_BLOCKS_SHORT - 1) * PSY_LAME_NUM_SUBBLOCKS)]; 00806 assert(pch->prev_energy_subshort[i + ((AAC_NUM_BLOCKS_SHORT - 2) * PSY_LAME_NUM_SUBBLOCKS + 1)] > 0); 00807 attack_intensity[i] = energy_subshort[i] / pch->prev_energy_subshort[i + ((AAC_NUM_BLOCKS_SHORT - 2) * PSY_LAME_NUM_SUBBLOCKS + 1)]; 00808 energy_short[0] += energy_subshort[i]; 00809 } 00810 00811 for (i = 0; i < AAC_NUM_BLOCKS_SHORT * PSY_LAME_NUM_SUBBLOCKS; i++) { 00812 float const *const pfe = pf + AAC_BLOCK_SIZE_LONG / (AAC_NUM_BLOCKS_SHORT * PSY_LAME_NUM_SUBBLOCKS); 00813 float p = 1.0f; 00814 for (; pf < pfe; pf++) 00815 if (p < fabsf(*pf)) 00816 p = fabsf(*pf); 00817 pch->prev_energy_subshort[i] = energy_subshort[i + PSY_LAME_NUM_SUBBLOCKS] = p; 00818 energy_short[1 + i / PSY_LAME_NUM_SUBBLOCKS] += p; 00819 /* FIXME: The indexes below are [i + 3 - 2] in the LAME source. 00820 * Obviously the 3 and 2 have some significance, or this would be just [i + 1] 00821 * (which is what we use here). What the 3 stands for is ambigious, as it is both 00822 * number of short blocks, and the number of sub-short blocks. 00823 * It seems that LAME is comparing each sub-block to sub-block + 1 in the 00824 * previous block. 00825 */ 00826 if (p > energy_subshort[i + 1]) 00827 p = p / energy_subshort[i + 1]; 00828 else if (energy_subshort[i + 1] > p * 10.0f) 00829 p = energy_subshort[i + 1] / (p * 10.0f); 00830 else 00831 p = 0.0; 00832 attack_intensity[i + PSY_LAME_NUM_SUBBLOCKS] = p; 00833 } 00834 00835 /* compare energy between sub-short blocks */ 00836 for (i = 0; i < (AAC_NUM_BLOCKS_SHORT + 1) * PSY_LAME_NUM_SUBBLOCKS; i++) 00837 if (!attacks[i / PSY_LAME_NUM_SUBBLOCKS]) 00838 if (attack_intensity[i] > pch->attack_threshold) 00839 attacks[i / PSY_LAME_NUM_SUBBLOCKS] = (i % PSY_LAME_NUM_SUBBLOCKS) + 1; 00840 00841 /* should have energy change between short blocks, in order to avoid periodic signals */ 00842 /* Good samples to show the effect are Trumpet test songs */ 00843 /* GB: tuned (1) to avoid too many short blocks for test sample TRUMPET */ 00844 /* RH: tuned (2) to let enough short blocks through for test sample FSOL and SNAPS */ 00845 for (i = 1; i < AAC_NUM_BLOCKS_SHORT + 1; i++) { 00846 float const u = energy_short[i - 1]; 00847 float const v = energy_short[i]; 00848 float const m = FFMAX(u, v); 00849 if (m < 40000) { /* (2) */ 00850 if (u < 1.7f * v && v < 1.7f * u) { /* (1) */ 00851 if (i == 1 && attacks[0] < attacks[i]) 00852 attacks[0] = 0; 00853 attacks[i] = 0; 00854 } 00855 } 00856 att_sum += attacks[i]; 00857 } 00858 00859 if (attacks[0] <= pch->prev_attack) 00860 attacks[0] = 0; 00861 00862 att_sum += attacks[0]; 00863 /* 3 below indicates the previous attack happened in the last sub-block of the previous sequence */ 00864 if (pch->prev_attack == 3 || att_sum) { 00865 uselongblock = 0; 00866 00867 for (i = 1; i < AAC_NUM_BLOCKS_SHORT + 1; i++) 00868 if (attacks[i] && attacks[i-1]) 00869 attacks[i] = 0; 00870 } 00871 } else { 00872 /* We have no lookahead info, so just use same type as the previous sequence. */ 00873 uselongblock = !(prev_type == EIGHT_SHORT_SEQUENCE); 00874 } 00875 00876 lame_apply_block_type(pch, &wi, uselongblock); 00877 00878 wi.window_type[1] = prev_type; 00879 if (wi.window_type[0] != EIGHT_SHORT_SEQUENCE) { 00880 wi.num_windows = 1; 00881 wi.grouping[0] = 1; 00882 if (wi.window_type[0] == LONG_START_SEQUENCE) 00883 wi.window_shape = 0; 00884 else 00885 wi.window_shape = 1; 00886 } else { 00887 int lastgrp = 0; 00888 00889 wi.num_windows = 8; 00890 wi.window_shape = 0; 00891 for (i = 0; i < 8; i++) { 00892 if (!((pch->next_grouping >> i) & 1)) 00893 lastgrp = i; 00894 wi.grouping[lastgrp]++; 00895 } 00896 } 00897 00898 /* Determine grouping, based on the location of the first attack, and save for 00899 * the next frame. 00900 * FIXME: Move this to analysis. 00901 * TODO: Tune groupings depending on attack location 00902 * TODO: Handle more than one attack in a group 00903 */ 00904 for (i = 0; i < 9; i++) { 00905 if (attacks[i]) { 00906 grouping = i; 00907 break; 00908 } 00909 } 00910 pch->next_grouping = window_grouping[grouping]; 00911 00912 pch->prev_attack = attacks[8]; 00913 00914 return wi; 00915 } 00916 00917 const FFPsyModel ff_aac_psy_model = 00918 { 00919 .name = "3GPP TS 26.403-inspired model", 00920 .init = psy_3gpp_init, 00921 .window = psy_lame_window, 00922 .analyze = psy_3gpp_analyze, 00923 .end = psy_3gpp_end, 00924 };