2 * AAC encoder psychoacoustic model
3 * Copyright (C) 2008 Konstantin Shishkov
5 * This file is part of FFmpeg.
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19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
24 * AAC encoder psychoacoustic model
27 #include "libavutil/attributes.h"
28 #include "libavutil/libm.h"
34 /***********************************
36 * try other bitrate controlling mechanism (maybe use ratecontrol.c?)
37 * control quality for quality-based output
38 **********************************/
41 * constants for 3GPP AAC psychoacoustic model
44 #define PSY_3GPP_THR_SPREAD_HI 1.5f // spreading factor for low-to-hi threshold spreading (15 dB/Bark)
45 #define PSY_3GPP_THR_SPREAD_LOW 3.0f // spreading factor for hi-to-low threshold spreading (30 dB/Bark)
46 /* spreading factor for low-to-hi energy spreading, long block, > 22kbps/channel (20dB/Bark) */
47 #define PSY_3GPP_EN_SPREAD_HI_L1 2.0f
48 /* spreading factor for low-to-hi energy spreading, long block, <= 22kbps/channel (15dB/Bark) */
49 #define PSY_3GPP_EN_SPREAD_HI_L2 1.5f
50 /* spreading factor for low-to-hi energy spreading, short block (15 dB/Bark) */
51 #define PSY_3GPP_EN_SPREAD_HI_S 1.5f
52 /* spreading factor for hi-to-low energy spreading, long block (30dB/Bark) */
53 #define PSY_3GPP_EN_SPREAD_LOW_L 3.0f
54 /* spreading factor for hi-to-low energy spreading, short block (20dB/Bark) */
55 #define PSY_3GPP_EN_SPREAD_LOW_S 2.0f
57 #define PSY_3GPP_RPEMIN 0.01f
58 #define PSY_3GPP_RPELEV 2.0f
60 #define PSY_3GPP_C1 3.0f /* log2(8) */
61 #define PSY_3GPP_C2 1.3219281f /* log2(2.5) */
62 #define PSY_3GPP_C3 0.55935729f /* 1 - C2 / C1 */
64 #define PSY_SNR_1DB 7.9432821e-1f /* -1dB */
65 #define PSY_SNR_25DB 3.1622776e-3f /* -25dB */
67 #define PSY_3GPP_SAVE_SLOPE_L -0.46666667f
68 #define PSY_3GPP_SAVE_SLOPE_S -0.36363637f
69 #define PSY_3GPP_SAVE_ADD_L -0.84285712f
70 #define PSY_3GPP_SAVE_ADD_S -0.75f
71 #define PSY_3GPP_SPEND_SLOPE_L 0.66666669f
72 #define PSY_3GPP_SPEND_SLOPE_S 0.81818181f
73 #define PSY_3GPP_SPEND_ADD_L -0.35f
74 #define PSY_3GPP_SPEND_ADD_S -0.26111111f
75 #define PSY_3GPP_CLIP_LO_L 0.2f
76 #define PSY_3GPP_CLIP_LO_S 0.2f
77 #define PSY_3GPP_CLIP_HI_L 0.95f
78 #define PSY_3GPP_CLIP_HI_S 0.75f
80 #define PSY_3GPP_AH_THR_LONG 0.5f
81 #define PSY_3GPP_AH_THR_SHORT 0.63f
89 #define PSY_3GPP_BITS_TO_PE(bits) ((bits) * 1.18f)
91 /* LAME psy model constants */
92 #define PSY_LAME_FIR_LEN 21 ///< LAME psy model FIR order
93 #define AAC_BLOCK_SIZE_LONG 1024 ///< long block size
94 #define AAC_BLOCK_SIZE_SHORT 128 ///< short block size
95 #define AAC_NUM_BLOCKS_SHORT 8 ///< number of blocks in a short sequence
96 #define PSY_LAME_NUM_SUBBLOCKS 3 ///< Number of sub-blocks in each short block
103 * information for single band used by 3GPP TS26.403-inspired psychoacoustic model
105 typedef struct AacPsyBand
{
106 float energy
; ///< band energy
107 float thr
; ///< energy threshold
108 float thr_quiet
; ///< threshold in quiet
109 float nz_lines
; ///< number of non-zero spectral lines
110 float active_lines
; ///< number of active spectral lines
111 float pe
; ///< perceptual entropy
112 float pe_const
; ///< constant part of the PE calculation
113 float norm_fac
; ///< normalization factor for linearization
114 int avoid_holes
; ///< hole avoidance flag
118 * single/pair channel context for psychoacoustic model
120 typedef struct AacPsyChannel
{
121 AacPsyBand band
[128]; ///< bands information
122 AacPsyBand prev_band
[128]; ///< bands information from the previous frame
124 float win_energy
; ///< sliding average of channel energy
125 float iir_state
[2]; ///< hi-pass IIR filter state
126 uint8_t next_grouping
; ///< stored grouping scheme for the next frame (in case of 8 short window sequence)
127 enum WindowSequence next_window_seq
; ///< window sequence to be used in the next frame
128 /* LAME psy model specific members */
129 float attack_threshold
; ///< attack threshold for this channel
130 float prev_energy_subshort
[AAC_NUM_BLOCKS_SHORT
* PSY_LAME_NUM_SUBBLOCKS
];
131 int prev_attack
; ///< attack value for the last short block in the previous sequence
135 * psychoacoustic model frame type-dependent coefficients
137 typedef struct AacPsyCoeffs
{
138 float ath
; ///< absolute threshold of hearing per bands
139 float barks
; ///< Bark value for each spectral band in long frame
140 float spread_low
[2]; ///< spreading factor for low-to-high threshold spreading in long frame
141 float spread_hi
[2]; ///< spreading factor for high-to-low threshold spreading in long frame
142 float min_snr
; ///< minimal SNR
146 * 3GPP TS26.403-inspired psychoacoustic model specific data
148 typedef struct AacPsyContext
{
149 int chan_bitrate
; ///< bitrate per channel
150 int frame_bits
; ///< average bits per frame
151 int fill_level
; ///< bit reservoir fill level
153 float min
; ///< minimum allowed PE for bit factor calculation
154 float max
; ///< maximum allowed PE for bit factor calculation
155 float previous
; ///< allowed PE of the previous frame
156 float correction
; ///< PE correction factor
158 AacPsyCoeffs psy_coef
[2][64];
163 * LAME psy model preset struct
166 int quality
; ///< Quality to map the rest of the vaules to.
167 /* This is overloaded to be both kbps per channel in ABR mode, and
168 * requested quality in constant quality mode.
170 float st_lrm
; ///< short threshold for L, R, and M channels
174 * LAME psy model preset table for ABR
176 static const PsyLamePreset psy_abr_map
[] = {
177 /* TODO: Tuning. These were taken from LAME. */
195 * LAME psy model preset table for constant quality
197 static const PsyLamePreset psy_vbr_map
[] = {
213 * LAME psy model FIR coefficient table
215 static const float psy_fir_coeffs
[] = {
216 -8.65163e-18 * 2, -0.00851586 * 2, -6.74764e-18 * 2, 0.0209036 * 2,
217 -3.36639e-17 * 2, -0.0438162 * 2, -1.54175e-17 * 2, 0.0931738 * 2,
218 -5.52212e-17 * 2, -0.313819 * 2
222 # include "mips/aacpsy_mips.h"
223 #endif /* ARCH_MIPS */
226 * Calculate the ABR attack threshold from the above LAME psymodel table.
228 static float lame_calc_attack_threshold(int bitrate
)
230 /* Assume max bitrate to start with */
231 int lower_range
= 12, upper_range
= 12;
232 int lower_range_kbps
= psy_abr_map
[12].quality
;
233 int upper_range_kbps
= psy_abr_map
[12].quality
;
236 /* Determine which bitrates the value specified falls between.
237 * If the loop ends without breaking our above assumption of 320kbps was correct.
239 for (i
= 1; i
< 13; i
++) {
240 if (FFMAX(bitrate
, psy_abr_map
[i
].quality
) != bitrate
) {
242 upper_range_kbps
= psy_abr_map
[i
].quality
;
244 lower_range_kbps
= psy_abr_map
[i
- 1].quality
;
245 break; /* Upper range found */
249 /* Determine which range the value specified is closer to */
250 if ((upper_range_kbps
- bitrate
) > (bitrate
- lower_range_kbps
))
251 return psy_abr_map
[lower_range
].st_lrm
;
252 return psy_abr_map
[upper_range
].st_lrm
;
256 * LAME psy model specific initialization
258 static av_cold
void lame_window_init(AacPsyContext
*ctx
, AVCodecContext
*avctx
)
262 for (i
= 0; i
< avctx
->channels
; i
++) {
263 AacPsyChannel
*pch
= &ctx
->ch
[i
];
265 if (avctx
->flags
& CODEC_FLAG_QSCALE
)
266 pch
->attack_threshold
= psy_vbr_map
[avctx
->global_quality
/ FF_QP2LAMBDA
].st_lrm
;
268 pch
->attack_threshold
= lame_calc_attack_threshold(avctx
->bit_rate
/ avctx
->channels
/ 1000);
270 for (j
= 0; j
< AAC_NUM_BLOCKS_SHORT
* PSY_LAME_NUM_SUBBLOCKS
; j
++)
271 pch
->prev_energy_subshort
[j
] = 10.0f
;
276 * Calculate Bark value for given line.
278 static av_cold
float calc_bark(float f
)
280 return 13.3f
* atanf(0.00076f
* f
) + 3.5f
* atanf((f
/ 7500.0f
) * (f
/ 7500.0f
));
285 * Calculate ATH value for given frequency.
286 * Borrowed from Lame.
288 static av_cold
float ath(float f
, float add
)
291 return 3.64 * pow(f
, -0.8)
292 - 6.8 * exp(-0.6 * (f
- 3.4) * (f
- 3.4))
293 + 6.0 * exp(-0.15 * (f
- 8.7) * (f
- 8.7))
294 + (0.6 + 0.04 * add
) * 0.001 * f
* f
* f
* f
;
297 static av_cold
int psy_3gpp_init(FFPsyContext
*ctx
) {
301 float prev
, minscale
, minath
, minsnr
, pe_min
;
302 const int chan_bitrate
= ctx
->avctx
->bit_rate
/ ctx
->avctx
->channels
;
303 const int bandwidth
= ctx
->avctx
->cutoff
? ctx
->avctx
->cutoff
: AAC_CUTOFF(ctx
->avctx
);
304 const float num_bark
= calc_bark((float)bandwidth
);
306 ctx
->model_priv_data
= av_mallocz(sizeof(AacPsyContext
));
307 pctx
= (AacPsyContext
*) ctx
->model_priv_data
;
309 pctx
->chan_bitrate
= chan_bitrate
;
310 pctx
->frame_bits
= chan_bitrate
* AAC_BLOCK_SIZE_LONG
/ ctx
->avctx
->sample_rate
;
311 pctx
->pe
.min
= 8.0f
* AAC_BLOCK_SIZE_LONG
* bandwidth
/ (ctx
->avctx
->sample_rate
* 2.0f
);
312 pctx
->pe
.max
= 12.0f
* AAC_BLOCK_SIZE_LONG
* bandwidth
/ (ctx
->avctx
->sample_rate
* 2.0f
);
313 ctx
->bitres
.size
= 6144 - pctx
->frame_bits
;
314 ctx
->bitres
.size
-= ctx
->bitres
.size
% 8;
315 pctx
->fill_level
= ctx
->bitres
.size
;
316 minath
= ath(3410, ATH_ADD
);
317 for (j
= 0; j
< 2; j
++) {
318 AacPsyCoeffs
*coeffs
= pctx
->psy_coef
[j
];
319 const uint8_t *band_sizes
= ctx
->bands
[j
];
320 float line_to_frequency
= ctx
->avctx
->sample_rate
/ (j
? 256.f
: 2048.0f
);
321 float avg_chan_bits
= chan_bitrate
* (j
? 128.0f
: 1024.0f
) / ctx
->avctx
->sample_rate
;
322 /* reference encoder uses 2.4% here instead of 60% like the spec says */
323 float bark_pe
= 0.024f
* PSY_3GPP_BITS_TO_PE(avg_chan_bits
) / num_bark
;
324 float en_spread_low
= j
? PSY_3GPP_EN_SPREAD_LOW_S
: PSY_3GPP_EN_SPREAD_LOW_L
;
325 /* High energy spreading for long blocks <= 22kbps/channel and short blocks are the same. */
326 float en_spread_hi
= (j
|| (chan_bitrate
<= 22.0f
)) ? PSY_3GPP_EN_SPREAD_HI_S
: PSY_3GPP_EN_SPREAD_HI_L1
;
330 for (g
= 0; g
< ctx
->num_bands
[j
]; g
++) {
332 bark
= calc_bark((i
-1) * line_to_frequency
);
333 coeffs
[g
].barks
= (bark
+ prev
) / 2.0;
336 for (g
= 0; g
< ctx
->num_bands
[j
] - 1; g
++) {
337 AacPsyCoeffs
*coeff
= &coeffs
[g
];
338 float bark_width
= coeffs
[g
+1].barks
- coeffs
->barks
;
339 coeff
->spread_low
[0] = pow(10.0, -bark_width
* PSY_3GPP_THR_SPREAD_LOW
);
340 coeff
->spread_hi
[0] = pow(10.0, -bark_width
* PSY_3GPP_THR_SPREAD_HI
);
341 coeff
->spread_low
[1] = pow(10.0, -bark_width
* en_spread_low
);
342 coeff
->spread_hi
[1] = pow(10.0, -bark_width
* en_spread_hi
);
343 pe_min
= bark_pe
* bark_width
;
344 minsnr
= exp2(pe_min
/ band_sizes
[g
]) - 1.5f
;
345 coeff
->min_snr
= av_clipf(1.0f
/ minsnr
, PSY_SNR_25DB
, PSY_SNR_1DB
);
348 for (g
= 0; g
< ctx
->num_bands
[j
]; g
++) {
349 minscale
= ath(start
* line_to_frequency
, ATH_ADD
);
350 for (i
= 1; i
< band_sizes
[g
]; i
++)
351 minscale
= FFMIN(minscale
, ath((start
+ i
) * line_to_frequency
, ATH_ADD
));
352 coeffs
[g
].ath
= minscale
- minath
;
353 start
+= band_sizes
[g
];
357 pctx
->ch
= av_mallocz_array(ctx
->avctx
->channels
, sizeof(AacPsyChannel
));
359 lame_window_init(pctx
, ctx
->avctx
);
365 * IIR filter used in block switching decision
367 static float iir_filter(int in
, float state
[2])
371 ret
= 0.7548f
* (in
- state
[0]) + 0.5095f
* state
[1];
378 * window grouping information stored as bits (0 - new group, 1 - group continues)
380 static const uint8_t window_grouping
[9] = {
381 0xB6, 0x6C, 0xD8, 0xB2, 0x66, 0xC6, 0x96, 0x36, 0x36
385 * Tell encoder which window types to use.
386 * @see 3GPP TS26.403 5.4.1 "Blockswitching"
388 static av_unused FFPsyWindowInfo
psy_3gpp_window(FFPsyContext
*ctx
,
389 const int16_t *audio
,
391 int channel
, int prev_type
)
394 int br
= ctx
->avctx
->bit_rate
/ ctx
->avctx
->channels
;
395 int attack_ratio
= br
<= 16000 ? 18 : 10;
396 AacPsyContext
*pctx
= (AacPsyContext
*) ctx
->model_priv_data
;
397 AacPsyChannel
*pch
= &pctx
->ch
[channel
];
398 uint8_t grouping
= 0;
399 int next_type
= pch
->next_window_seq
;
400 FFPsyWindowInfo wi
= { { 0 } };
404 int switch_to_eight
= 0;
405 float sum
= 0.0, sum2
= 0.0;
408 for (i
= 0; i
< 8; i
++) {
409 for (j
= 0; j
< 128; j
++) {
410 v
= iir_filter(la
[i
*128+j
], pch
->iir_state
);
416 for (i
= 0; i
< 8; i
++) {
417 if (s
[i
] > pch
->win_energy
* attack_ratio
) {
423 pch
->win_energy
= pch
->win_energy
*7/8 + sum2
/64;
425 wi
.window_type
[1] = prev_type
;
427 case ONLY_LONG_SEQUENCE
:
428 wi
.window_type
[0] = switch_to_eight
? LONG_START_SEQUENCE
: ONLY_LONG_SEQUENCE
;
429 next_type
= switch_to_eight
? EIGHT_SHORT_SEQUENCE
: ONLY_LONG_SEQUENCE
;
431 case LONG_START_SEQUENCE
:
432 wi
.window_type
[0] = EIGHT_SHORT_SEQUENCE
;
433 grouping
= pch
->next_grouping
;
434 next_type
= switch_to_eight
? EIGHT_SHORT_SEQUENCE
: LONG_STOP_SEQUENCE
;
436 case LONG_STOP_SEQUENCE
:
437 wi
.window_type
[0] = switch_to_eight
? LONG_START_SEQUENCE
: ONLY_LONG_SEQUENCE
;
438 next_type
= switch_to_eight
? EIGHT_SHORT_SEQUENCE
: ONLY_LONG_SEQUENCE
;
440 case EIGHT_SHORT_SEQUENCE
:
441 stay_short
= next_type
== EIGHT_SHORT_SEQUENCE
|| switch_to_eight
;
442 wi
.window_type
[0] = stay_short
? EIGHT_SHORT_SEQUENCE
: LONG_STOP_SEQUENCE
;
443 grouping
= next_type
== EIGHT_SHORT_SEQUENCE
? pch
->next_grouping
: 0;
444 next_type
= switch_to_eight
? EIGHT_SHORT_SEQUENCE
: LONG_STOP_SEQUENCE
;
448 pch
->next_grouping
= window_grouping
[attack_n
];
449 pch
->next_window_seq
= next_type
;
451 for (i
= 0; i
< 3; i
++)
452 wi
.window_type
[i
] = prev_type
;
453 grouping
= (prev_type
== EIGHT_SHORT_SEQUENCE
) ? window_grouping
[0] : 0;
457 if (wi
.window_type
[0] != EIGHT_SHORT_SEQUENCE
) {
463 for (i
= 0; i
< 8; i
++) {
464 if (!((grouping
>> i
) & 1))
466 wi
.grouping
[lastgrp
]++;
473 /* 5.6.1.2 "Calculation of Bit Demand" */
474 static int calc_bit_demand(AacPsyContext
*ctx
, float pe
, int bits
, int size
,
477 const float bitsave_slope
= short_window
? PSY_3GPP_SAVE_SLOPE_S
: PSY_3GPP_SAVE_SLOPE_L
;
478 const float bitsave_add
= short_window
? PSY_3GPP_SAVE_ADD_S
: PSY_3GPP_SAVE_ADD_L
;
479 const float bitspend_slope
= short_window
? PSY_3GPP_SPEND_SLOPE_S
: PSY_3GPP_SPEND_SLOPE_L
;
480 const float bitspend_add
= short_window
? PSY_3GPP_SPEND_ADD_S
: PSY_3GPP_SPEND_ADD_L
;
481 const float clip_low
= short_window
? PSY_3GPP_CLIP_LO_S
: PSY_3GPP_CLIP_LO_L
;
482 const float clip_high
= short_window
? PSY_3GPP_CLIP_HI_S
: PSY_3GPP_CLIP_HI_L
;
483 float clipped_pe
, bit_save
, bit_spend
, bit_factor
, fill_level
;
485 ctx
->fill_level
+= ctx
->frame_bits
- bits
;
486 ctx
->fill_level
= av_clip(ctx
->fill_level
, 0, size
);
487 fill_level
= av_clipf((float)ctx
->fill_level
/ size
, clip_low
, clip_high
);
488 clipped_pe
= av_clipf(pe
, ctx
->pe
.min
, ctx
->pe
.max
);
489 bit_save
= (fill_level
+ bitsave_add
) * bitsave_slope
;
490 assert(bit_save
<= 0.3f
&& bit_save
>= -0.05000001f
);
491 bit_spend
= (fill_level
+ bitspend_add
) * bitspend_slope
;
492 assert(bit_spend
<= 0.5f
&& bit_spend
>= -0.1f
);
493 /* The bit factor graph in the spec is obviously incorrect.
494 * bit_spend + ((bit_spend - bit_spend))...
495 * The reference encoder subtracts everything from 1, but also seems incorrect.
496 * 1 - bit_save + ((bit_spend + bit_save))...
497 * Hopefully below is correct.
499 bit_factor
= 1.0f
- bit_save
+ ((bit_spend
- bit_save
) / (ctx
->pe
.max
- ctx
->pe
.min
)) * (clipped_pe
- ctx
->pe
.min
);
500 /* NOTE: The reference encoder attempts to center pe max/min around the current pe. */
501 ctx
->pe
.max
= FFMAX(pe
, ctx
->pe
.max
);
502 ctx
->pe
.min
= FFMIN(pe
, ctx
->pe
.min
);
504 return FFMIN(ctx
->frame_bits
* bit_factor
, ctx
->frame_bits
+ size
- bits
);
507 static float calc_pe_3gpp(AacPsyBand
*band
)
512 band
->pe_const
= 0.0f
;
513 band
->active_lines
= 0.0f
;
514 if (band
->energy
> band
->thr
) {
515 a
= log2f(band
->energy
);
516 pe
= a
- log2f(band
->thr
);
517 band
->active_lines
= band
->nz_lines
;
518 if (pe
< PSY_3GPP_C1
) {
519 pe
= pe
* PSY_3GPP_C3
+ PSY_3GPP_C2
;
520 a
= a
* PSY_3GPP_C3
+ PSY_3GPP_C2
;
521 band
->active_lines
*= PSY_3GPP_C3
;
523 band
->pe
= pe
* band
->nz_lines
;
524 band
->pe_const
= a
* band
->nz_lines
;
530 static float calc_reduction_3gpp(float a
, float desired_pe
, float pe
,
533 float thr_avg
, reduction
;
535 if(active_lines
== 0.0)
538 thr_avg
= exp2f((a
- pe
) / (4.0f
* active_lines
));
539 reduction
= exp2f((a
- desired_pe
) / (4.0f
* active_lines
)) - thr_avg
;
541 return FFMAX(reduction
, 0.0f
);
544 static float calc_reduced_thr_3gpp(AacPsyBand
*band
, float min_snr
,
547 float thr
= band
->thr
;
549 if (band
->energy
> thr
) {
551 thr
= sqrtf(thr
) + reduction
;
555 /* This deviates from the 3GPP spec to match the reference encoder.
556 * It performs min(thr_reduced, max(thr, energy/min_snr)) only for bands
557 * that have hole avoidance on (active or inactive). It always reduces the
558 * threshold of bands with hole avoidance off.
560 if (thr
> band
->energy
* min_snr
&& band
->avoid_holes
!= PSY_3GPP_AH_NONE
) {
561 thr
= FFMAX(band
->thr
, band
->energy
* min_snr
);
562 band
->avoid_holes
= PSY_3GPP_AH_ACTIVE
;
569 #ifndef calc_thr_3gpp
570 static void calc_thr_3gpp(const FFPsyWindowInfo
*wi
, const int num_bands
, AacPsyChannel
*pch
,
571 const uint8_t *band_sizes
, const float *coefs
)
575 for (w
= 0; w
< wi
->num_windows
*16; w
+= 16) {
576 for (g
= 0; g
< num_bands
; g
++) {
577 AacPsyBand
*band
= &pch
->band
[w
+g
];
579 float form_factor
= 0.0f
;
582 for (i
= 0; i
< band_sizes
[g
]; i
++) {
583 band
->energy
+= coefs
[start
+i
] * coefs
[start
+i
];
584 form_factor
+= sqrtf(fabs(coefs
[start
+i
]));
586 Temp
= band
->energy
> 0 ? sqrtf((float)band_sizes
[g
] / band
->energy
) : 0;
587 band
->thr
= band
->energy
* 0.001258925f
;
588 band
->nz_lines
= form_factor
* sqrtf(Temp
);
590 start
+= band_sizes
[g
];
594 #endif /* calc_thr_3gpp */
596 #ifndef psy_hp_filter
597 static void psy_hp_filter(const float *firbuf
, float *hpfsmpl
, const float *psy_fir_coeffs
)
600 for (i
= 0; i
< AAC_BLOCK_SIZE_LONG
; i
++) {
602 sum1
= firbuf
[i
+ (PSY_LAME_FIR_LEN
- 1) / 2];
604 for (j
= 0; j
< ((PSY_LAME_FIR_LEN
- 1) / 2) - 1; j
+= 2) {
605 sum1
+= psy_fir_coeffs
[j
] * (firbuf
[i
+ j
] + firbuf
[i
+ PSY_LAME_FIR_LEN
- j
]);
606 sum2
+= psy_fir_coeffs
[j
+ 1] * (firbuf
[i
+ j
+ 1] + firbuf
[i
+ PSY_LAME_FIR_LEN
- j
- 1]);
608 /* NOTE: The LAME psymodel expects it's input in the range -32768 to 32768.
609 * Tuning this for normalized floats would be difficult. */
610 hpfsmpl
[i
] = (sum1
+ sum2
) * 32768.0f
;
613 #endif /* psy_hp_filter */
616 * Calculate band thresholds as suggested in 3GPP TS26.403
618 static void psy_3gpp_analyze_channel(FFPsyContext
*ctx
, int channel
,
619 const float *coefs
, const FFPsyWindowInfo
*wi
)
621 AacPsyContext
*pctx
= (AacPsyContext
*) ctx
->model_priv_data
;
622 AacPsyChannel
*pch
= &pctx
->ch
[channel
];
624 float desired_bits
, desired_pe
, delta_pe
, reduction
= NAN
, spread_en
[128] = {0};
625 float a
= 0.0f
, active_lines
= 0.0f
, norm_fac
= 0.0f
;
626 float pe
= pctx
->chan_bitrate
> 32000 ? 0.0f
: FFMAX(50.0f
, 100.0f
- pctx
->chan_bitrate
* 100.0f
/ 32000.0f
);
627 const int num_bands
= ctx
->num_bands
[wi
->num_windows
== 8];
628 const uint8_t *band_sizes
= ctx
->bands
[wi
->num_windows
== 8];
629 AacPsyCoeffs
*coeffs
= pctx
->psy_coef
[wi
->num_windows
== 8];
630 const float avoid_hole_thr
= wi
->num_windows
== 8 ? PSY_3GPP_AH_THR_SHORT
: PSY_3GPP_AH_THR_LONG
;
632 //calculate energies, initial thresholds and related values - 5.4.2 "Threshold Calculation"
633 calc_thr_3gpp(wi
, num_bands
, pch
, band_sizes
, coefs
);
635 //modify thresholds and energies - spread, threshold in quiet, pre-echo control
636 for (w
= 0; w
< wi
->num_windows
*16; w
+= 16) {
637 AacPsyBand
*bands
= &pch
->band
[w
];
639 /* 5.4.2.3 "Spreading" & 5.4.3 "Spread Energy Calculation" */
640 spread_en
[0] = bands
[0].energy
;
641 for (g
= 1; g
< num_bands
; g
++) {
642 bands
[g
].thr
= FFMAX(bands
[g
].thr
, bands
[g
-1].thr
* coeffs
[g
].spread_hi
[0]);
643 spread_en
[w
+g
] = FFMAX(bands
[g
].energy
, spread_en
[w
+g
-1] * coeffs
[g
].spread_hi
[1]);
645 for (g
= num_bands
- 2; g
>= 0; g
--) {
646 bands
[g
].thr
= FFMAX(bands
[g
].thr
, bands
[g
+1].thr
* coeffs
[g
].spread_low
[0]);
647 spread_en
[w
+g
] = FFMAX(spread_en
[w
+g
], spread_en
[w
+g
+1] * coeffs
[g
].spread_low
[1]);
649 //5.4.2.4 "Threshold in quiet"
650 for (g
= 0; g
< num_bands
; g
++) {
651 AacPsyBand
*band
= &bands
[g
];
653 band
->thr_quiet
= band
->thr
= FFMAX(band
->thr
, coeffs
[g
].ath
);
654 //5.4.2.5 "Pre-echo control"
655 if (!(wi
->window_type
[0] == LONG_STOP_SEQUENCE
|| (wi
->window_type
[1] == LONG_START_SEQUENCE
&& !w
)))
656 band
->thr
= FFMAX(PSY_3GPP_RPEMIN
*band
->thr
, FFMIN(band
->thr
,
657 PSY_3GPP_RPELEV
*pch
->prev_band
[w
+g
].thr_quiet
));
659 /* 5.6.1.3.1 "Preparatory steps of the perceptual entropy calculation" */
660 pe
+= calc_pe_3gpp(band
);
662 active_lines
+= band
->active_lines
;
664 /* 5.6.1.3.3 "Selection of the bands for avoidance of holes" */
665 if (spread_en
[w
+g
] * avoid_hole_thr
> band
->energy
|| coeffs
[g
].min_snr
> 1.0f
)
666 band
->avoid_holes
= PSY_3GPP_AH_NONE
;
668 band
->avoid_holes
= PSY_3GPP_AH_INACTIVE
;
672 /* 5.6.1.3.2 "Calculation of the desired perceptual entropy" */
673 ctx
->ch
[channel
].entropy
= pe
;
674 desired_bits
= calc_bit_demand(pctx
, pe
, ctx
->bitres
.bits
, ctx
->bitres
.size
, wi
->num_windows
== 8);
675 desired_pe
= PSY_3GPP_BITS_TO_PE(desired_bits
);
676 /* NOTE: PE correction is kept simple. During initial testing it had very
677 * little effect on the final bitrate. Probably a good idea to come
678 * back and do more testing later.
680 if (ctx
->bitres
.bits
> 0)
681 desired_pe
*= av_clipf(pctx
->pe
.previous
/ PSY_3GPP_BITS_TO_PE(ctx
->bitres
.bits
),
683 pctx
->pe
.previous
= PSY_3GPP_BITS_TO_PE(desired_bits
);
685 if (desired_pe
< pe
) {
686 /* 5.6.1.3.4 "First Estimation of the reduction value" */
687 for (w
= 0; w
< wi
->num_windows
*16; w
+= 16) {
688 reduction
= calc_reduction_3gpp(a
, desired_pe
, pe
, active_lines
);
692 for (g
= 0; g
< num_bands
; g
++) {
693 AacPsyBand
*band
= &pch
->band
[w
+g
];
695 band
->thr
= calc_reduced_thr_3gpp(band
, coeffs
[g
].min_snr
, reduction
);
697 pe
+= calc_pe_3gpp(band
);
699 active_lines
+= band
->active_lines
;
703 /* 5.6.1.3.5 "Second Estimation of the reduction value" */
704 for (i
= 0; i
< 2; i
++) {
705 float pe_no_ah
= 0.0f
, desired_pe_no_ah
;
706 active_lines
= a
= 0.0f
;
707 for (w
= 0; w
< wi
->num_windows
*16; w
+= 16) {
708 for (g
= 0; g
< num_bands
; g
++) {
709 AacPsyBand
*band
= &pch
->band
[w
+g
];
711 if (band
->avoid_holes
!= PSY_3GPP_AH_ACTIVE
) {
712 pe_no_ah
+= band
->pe
;
714 active_lines
+= band
->active_lines
;
718 desired_pe_no_ah
= FFMAX(desired_pe
- (pe
- pe_no_ah
), 0.0f
);
719 if (active_lines
> 0.0f
)
720 reduction
+= calc_reduction_3gpp(a
, desired_pe_no_ah
, pe_no_ah
, active_lines
);
723 for (w
= 0; w
< wi
->num_windows
*16; w
+= 16) {
724 for (g
= 0; g
< num_bands
; g
++) {
725 AacPsyBand
*band
= &pch
->band
[w
+g
];
727 if (active_lines
> 0.0f
)
728 band
->thr
= calc_reduced_thr_3gpp(band
, coeffs
[g
].min_snr
, reduction
);
729 pe
+= calc_pe_3gpp(band
);
730 band
->norm_fac
= band
->active_lines
/ band
->thr
;
731 norm_fac
+= band
->norm_fac
;
734 delta_pe
= desired_pe
- pe
;
735 if (fabs(delta_pe
) > 0.05f
* desired_pe
)
739 if (pe
< 1.15f
* desired_pe
) {
740 /* 6.6.1.3.6 "Final threshold modification by linearization" */
741 norm_fac
= 1.0f
/ norm_fac
;
742 for (w
= 0; w
< wi
->num_windows
*16; w
+= 16) {
743 for (g
= 0; g
< num_bands
; g
++) {
744 AacPsyBand
*band
= &pch
->band
[w
+g
];
746 if (band
->active_lines
> 0.5f
) {
747 float delta_sfb_pe
= band
->norm_fac
* norm_fac
* delta_pe
;
748 float thr
= band
->thr
;
750 thr
*= exp2f(delta_sfb_pe
/ band
->active_lines
);
751 if (thr
> coeffs
[g
].min_snr
* band
->energy
&& band
->avoid_holes
== PSY_3GPP_AH_INACTIVE
)
752 thr
= FFMAX(band
->thr
, coeffs
[g
].min_snr
* band
->energy
);
758 /* 5.6.1.3.7 "Further perceptual entropy reduction" */
760 while (pe
> desired_pe
&& g
--) {
761 for (w
= 0; w
< wi
->num_windows
*16; w
+= 16) {
762 AacPsyBand
*band
= &pch
->band
[w
+g
];
763 if (band
->avoid_holes
!= PSY_3GPP_AH_NONE
&& coeffs
[g
].min_snr
< PSY_SNR_1DB
) {
764 coeffs
[g
].min_snr
= PSY_SNR_1DB
;
765 band
->thr
= band
->energy
* PSY_SNR_1DB
;
766 pe
+= band
->active_lines
* 1.5f
- band
->pe
;
770 /* TODO: allow more holes (unused without mid/side) */
774 for (w
= 0; w
< wi
->num_windows
*16; w
+= 16) {
775 for (g
= 0; g
< num_bands
; g
++) {
776 AacPsyBand
*band
= &pch
->band
[w
+g
];
777 FFPsyBand
*psy_band
= &ctx
->ch
[channel
].psy_bands
[w
+g
];
779 psy_band
->threshold
= band
->thr
;
780 psy_band
->energy
= band
->energy
;
784 memcpy(pch
->prev_band
, pch
->band
, sizeof(pch
->band
));
787 static void psy_3gpp_analyze(FFPsyContext
*ctx
, int channel
,
788 const float **coeffs
, const FFPsyWindowInfo
*wi
)
791 FFPsyChannelGroup
*group
= ff_psy_find_group(ctx
, channel
);
793 for (ch
= 0; ch
< group
->num_ch
; ch
++)
794 psy_3gpp_analyze_channel(ctx
, channel
+ ch
, coeffs
[ch
], &wi
[ch
]);
797 static av_cold
void psy_3gpp_end(FFPsyContext
*apc
)
799 AacPsyContext
*pctx
= (AacPsyContext
*) apc
->model_priv_data
;
801 av_freep(&apc
->model_priv_data
);
804 static void lame_apply_block_type(AacPsyChannel
*ctx
, FFPsyWindowInfo
*wi
, int uselongblock
)
806 int blocktype
= ONLY_LONG_SEQUENCE
;
808 if (ctx
->next_window_seq
== EIGHT_SHORT_SEQUENCE
)
809 blocktype
= LONG_STOP_SEQUENCE
;
811 blocktype
= EIGHT_SHORT_SEQUENCE
;
812 if (ctx
->next_window_seq
== ONLY_LONG_SEQUENCE
)
813 ctx
->next_window_seq
= LONG_START_SEQUENCE
;
814 if (ctx
->next_window_seq
== LONG_STOP_SEQUENCE
)
815 ctx
->next_window_seq
= EIGHT_SHORT_SEQUENCE
;
818 wi
->window_type
[0] = ctx
->next_window_seq
;
819 ctx
->next_window_seq
= blocktype
;
822 static FFPsyWindowInfo
psy_lame_window(FFPsyContext
*ctx
, const float *audio
,
823 const float *la
, int channel
, int prev_type
)
825 AacPsyContext
*pctx
= (AacPsyContext
*) ctx
->model_priv_data
;
826 AacPsyChannel
*pch
= &pctx
->ch
[channel
];
828 int uselongblock
= 1;
829 int attacks
[AAC_NUM_BLOCKS_SHORT
+ 1] = { 0 };
831 FFPsyWindowInfo wi
= { { 0 } };
834 float hpfsmpl
[AAC_BLOCK_SIZE_LONG
];
835 float const *pf
= hpfsmpl
;
836 float attack_intensity
[(AAC_NUM_BLOCKS_SHORT
+ 1) * PSY_LAME_NUM_SUBBLOCKS
];
837 float energy_subshort
[(AAC_NUM_BLOCKS_SHORT
+ 1) * PSY_LAME_NUM_SUBBLOCKS
];
838 float energy_short
[AAC_NUM_BLOCKS_SHORT
+ 1] = { 0 };
839 const float *firbuf
= la
+ (AAC_BLOCK_SIZE_SHORT
/4 - PSY_LAME_FIR_LEN
);
842 /* LAME comment: apply high pass filter of fs/4 */
843 psy_hp_filter(firbuf
, hpfsmpl
, psy_fir_coeffs
);
845 /* Calculate the energies of each sub-shortblock */
846 for (i
= 0; i
< PSY_LAME_NUM_SUBBLOCKS
; i
++) {
847 energy_subshort
[i
] = pch
->prev_energy_subshort
[i
+ ((AAC_NUM_BLOCKS_SHORT
- 1) * PSY_LAME_NUM_SUBBLOCKS
)];
848 assert(pch
->prev_energy_subshort
[i
+ ((AAC_NUM_BLOCKS_SHORT
- 2) * PSY_LAME_NUM_SUBBLOCKS
+ 1)] > 0);
849 attack_intensity
[i
] = energy_subshort
[i
] / pch
->prev_energy_subshort
[i
+ ((AAC_NUM_BLOCKS_SHORT
- 2) * PSY_LAME_NUM_SUBBLOCKS
+ 1)];
850 energy_short
[0] += energy_subshort
[i
];
853 for (i
= 0; i
< AAC_NUM_BLOCKS_SHORT
* PSY_LAME_NUM_SUBBLOCKS
; i
++) {
854 float const *const pfe
= pf
+ AAC_BLOCK_SIZE_LONG
/ (AAC_NUM_BLOCKS_SHORT
* PSY_LAME_NUM_SUBBLOCKS
);
856 for (; pf
< pfe
; pf
++)
857 p
= FFMAX(p
, fabsf(*pf
));
858 pch
->prev_energy_subshort
[i
] = energy_subshort
[i
+ PSY_LAME_NUM_SUBBLOCKS
] = p
;
859 energy_short
[1 + i
/ PSY_LAME_NUM_SUBBLOCKS
] += p
;
860 /* NOTE: The indexes below are [i + 3 - 2] in the LAME source.
861 * Obviously the 3 and 2 have some significance, or this would be just [i + 1]
862 * (which is what we use here). What the 3 stands for is ambiguous, as it is both
863 * number of short blocks, and the number of sub-short blocks.
864 * It seems that LAME is comparing each sub-block to sub-block + 1 in the
867 if (p
> energy_subshort
[i
+ 1])
868 p
= p
/ energy_subshort
[i
+ 1];
869 else if (energy_subshort
[i
+ 1] > p
* 10.0f
)
870 p
= energy_subshort
[i
+ 1] / (p
* 10.0f
);
873 attack_intensity
[i
+ PSY_LAME_NUM_SUBBLOCKS
] = p
;
876 /* compare energy between sub-short blocks */
877 for (i
= 0; i
< (AAC_NUM_BLOCKS_SHORT
+ 1) * PSY_LAME_NUM_SUBBLOCKS
; i
++)
878 if (!attacks
[i
/ PSY_LAME_NUM_SUBBLOCKS
])
879 if (attack_intensity
[i
] > pch
->attack_threshold
)
880 attacks
[i
/ PSY_LAME_NUM_SUBBLOCKS
] = (i
% PSY_LAME_NUM_SUBBLOCKS
) + 1;
882 /* should have energy change between short blocks, in order to avoid periodic signals */
883 /* Good samples to show the effect are Trumpet test songs */
884 /* GB: tuned (1) to avoid too many short blocks for test sample TRUMPET */
885 /* RH: tuned (2) to let enough short blocks through for test sample FSOL and SNAPS */
886 for (i
= 1; i
< AAC_NUM_BLOCKS_SHORT
+ 1; i
++) {
887 float const u
= energy_short
[i
- 1];
888 float const v
= energy_short
[i
];
889 float const m
= FFMAX(u
, v
);
890 if (m
< 40000) { /* (2) */
891 if (u
< 1.7f
* v
&& v
< 1.7f
* u
) { /* (1) */
892 if (i
== 1 && attacks
[0] < attacks
[i
])
897 att_sum
+= attacks
[i
];
900 if (attacks
[0] <= pch
->prev_attack
)
903 att_sum
+= attacks
[0];
904 /* 3 below indicates the previous attack happened in the last sub-block of the previous sequence */
905 if (pch
->prev_attack
== 3 || att_sum
) {
908 for (i
= 1; i
< AAC_NUM_BLOCKS_SHORT
+ 1; i
++)
909 if (attacks
[i
] && attacks
[i
-1])
913 /* We have no lookahead info, so just use same type as the previous sequence. */
914 uselongblock
= !(prev_type
== EIGHT_SHORT_SEQUENCE
);
917 lame_apply_block_type(pch
, &wi
, uselongblock
);
919 wi
.window_type
[1] = prev_type
;
920 if (wi
.window_type
[0] != EIGHT_SHORT_SEQUENCE
) {
923 if (wi
.window_type
[0] == LONG_START_SEQUENCE
)
932 for (i
= 0; i
< 8; i
++) {
933 if (!((pch
->next_grouping
>> i
) & 1))
935 wi
.grouping
[lastgrp
]++;
939 /* Determine grouping, based on the location of the first attack, and save for
941 * FIXME: Move this to analysis.
942 * TODO: Tune groupings depending on attack location
943 * TODO: Handle more than one attack in a group
945 for (i
= 0; i
< 9; i
++) {
951 pch
->next_grouping
= window_grouping
[grouping
];
953 pch
->prev_attack
= attacks
[8];
958 const FFPsyModel ff_aac_psy_model
=
960 .name
= "3GPP TS 26.403-inspired model",
961 .init
= psy_3gpp_init
,
962 .window
= psy_lame_window
,
963 .analyze
= psy_3gpp_analyze
,