2 * The simplest AC-3 encoder
3 * Copyright (c) 2000 Fabrice Bellard
4 * Copyright (c) 2006-2010 Justin Ruggles <justin.ruggles@gmail.com>
5 * Copyright (c) 2006-2010 Prakash Punnoor <prakash@punnoor.de>
7 * This file is part of FFmpeg.
9 * FFmpeg is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU Lesser General Public
11 * License as published by the Free Software Foundation; either
12 * version 2.1 of the License, or (at your option) any later version.
14 * FFmpeg is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17 * Lesser General Public License for more details.
19 * You should have received a copy of the GNU Lesser General Public
20 * License along with FFmpeg; if not, write to the Free Software
21 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
26 * The simplest AC-3 encoder.
31 #include "libavcore/audioconvert.h"
32 #include "libavutil/crc.h"
37 #include "audioconvert.h"
40 #ifndef CONFIG_AC3ENC_FLOAT
41 #define CONFIG_AC3ENC_FLOAT 0
45 /** Maximum number of exponent groups. +1 for separate DC exponent. */
46 #define AC3_MAX_EXP_GROUPS 85
48 /** Scale a float value by 2^bits and convert to an integer. */
49 #define SCALE_FLOAT(a, bits) lrintf((a) * (float)(1 << (bits)))
52 #if CONFIG_AC3ENC_FLOAT
53 #include "ac3enc_float.h"
55 #include "ac3enc_fixed.h"
60 * Data for a single audio block.
62 typedef struct AC3Block {
63 uint8_t **bap; ///< bit allocation pointers (bap)
64 CoefType **mdct_coef; ///< MDCT coefficients
65 uint8_t **exp; ///< original exponents
66 uint8_t **grouped_exp; ///< grouped exponents
67 int16_t **psd; ///< psd per frequency bin
68 int16_t **band_psd; ///< psd per critical band
69 int16_t **mask; ///< masking curve
70 uint16_t **qmant; ///< quantized mantissas
71 uint8_t exp_strategy[AC3_MAX_CHANNELS]; ///< exponent strategies
72 int8_t exp_shift[AC3_MAX_CHANNELS]; ///< exponent shift values
76 * AC-3 encoder private context.
78 typedef struct AC3EncodeContext {
79 PutBitContext pb; ///< bitstream writer context
81 AC3MDCTContext mdct; ///< MDCT context
83 AC3Block blocks[AC3_MAX_BLOCKS]; ///< per-block info
85 int bitstream_id; ///< bitstream id (bsid)
86 int bitstream_mode; ///< bitstream mode (bsmod)
88 int bit_rate; ///< target bit rate, in bits-per-second
89 int sample_rate; ///< sampling frequency, in Hz
91 int frame_size_min; ///< minimum frame size in case rounding is necessary
92 int frame_size; ///< current frame size in bytes
93 int frame_size_code; ///< frame size code (frmsizecod)
95 int bits_written; ///< bit count (used to avg. bitrate)
96 int samples_written; ///< sample count (used to avg. bitrate)
98 int fbw_channels; ///< number of full-bandwidth channels (nfchans)
99 int channels; ///< total number of channels (nchans)
100 int lfe_on; ///< indicates if there is an LFE channel (lfeon)
101 int lfe_channel; ///< channel index of the LFE channel
102 int channel_mode; ///< channel mode (acmod)
103 const uint8_t *channel_map; ///< channel map used to reorder channels
105 int cutoff; ///< user-specified cutoff frequency, in Hz
106 int bandwidth_code[AC3_MAX_CHANNELS]; ///< bandwidth code (0 to 60) (chbwcod)
107 int nb_coefs[AC3_MAX_CHANNELS];
109 /* bitrate allocation control */
110 int slow_gain_code; ///< slow gain code (sgaincod)
111 int slow_decay_code; ///< slow decay code (sdcycod)
112 int fast_decay_code; ///< fast decay code (fdcycod)
113 int db_per_bit_code; ///< dB/bit code (dbpbcod)
114 int floor_code; ///< floor code (floorcod)
115 AC3BitAllocParameters bit_alloc; ///< bit allocation parameters
116 int coarse_snr_offset; ///< coarse SNR offsets (csnroffst)
117 int fast_gain_code[AC3_MAX_CHANNELS]; ///< fast gain codes (signal-to-mask ratio) (fgaincod)
118 int fine_snr_offset[AC3_MAX_CHANNELS]; ///< fine SNR offsets (fsnroffst)
119 int frame_bits_fixed; ///< number of non-coefficient bits for fixed parameters
120 int frame_bits; ///< all frame bits except exponents and mantissas
121 int exponent_bits; ///< number of bits used for exponents
123 /* mantissa encoding */
124 int mant1_cnt, mant2_cnt, mant4_cnt; ///< mantissa counts for bap=1,2,4
125 uint16_t *qmant1_ptr, *qmant2_ptr, *qmant4_ptr; ///< mantissa pointers for bap=1,2,4
127 SampleType **planar_samples;
129 uint8_t *bap1_buffer;
130 CoefType *mdct_coef_buffer;
132 uint8_t *grouped_exp_buffer;
134 int16_t *band_psd_buffer;
135 int16_t *mask_buffer;
136 uint16_t *qmant_buffer;
138 DECLARE_ALIGNED(16, SampleType, windowed_samples)[AC3_WINDOW_SIZE];
142 /* prototypes for functions in ac3enc_fixed.c and ac3enc_float.c */
144 static av_cold void mdct_end(AC3MDCTContext *mdct);
146 static av_cold int mdct_init(AVCodecContext *avctx, AC3MDCTContext *mdct,
149 static void mdct512(AC3MDCTContext *mdct, CoefType *out, SampleType *in);
151 static void apply_window(SampleType *output, const SampleType *input,
152 const SampleType *window, int n);
154 static int normalize_samples(AC3EncodeContext *s);
158 * LUT for number of exponent groups.
159 * exponent_group_tab[exponent strategy-1][number of coefficients]
161 static uint8_t exponent_group_tab[3][256];
165 * List of supported channel layouts.
167 static const int64_t ac3_channel_layouts[] = {
171 AV_CH_LAYOUT_SURROUND,
174 AV_CH_LAYOUT_4POINT0,
175 AV_CH_LAYOUT_5POINT0,
176 AV_CH_LAYOUT_5POINT0_BACK,
177 (AV_CH_LAYOUT_MONO | AV_CH_LOW_FREQUENCY),
178 (AV_CH_LAYOUT_STEREO | AV_CH_LOW_FREQUENCY),
179 (AV_CH_LAYOUT_2_1 | AV_CH_LOW_FREQUENCY),
180 (AV_CH_LAYOUT_SURROUND | AV_CH_LOW_FREQUENCY),
181 (AV_CH_LAYOUT_2_2 | AV_CH_LOW_FREQUENCY),
182 (AV_CH_LAYOUT_QUAD | AV_CH_LOW_FREQUENCY),
183 (AV_CH_LAYOUT_4POINT0 | AV_CH_LOW_FREQUENCY),
184 AV_CH_LAYOUT_5POINT1,
185 AV_CH_LAYOUT_5POINT1_BACK,
191 * Adjust the frame size to make the average bit rate match the target bit rate.
192 * This is only needed for 11025, 22050, and 44100 sample rates.
194 static void adjust_frame_size(AC3EncodeContext *s)
196 while (s->bits_written >= s->bit_rate && s->samples_written >= s->sample_rate) {
197 s->bits_written -= s->bit_rate;
198 s->samples_written -= s->sample_rate;
200 s->frame_size = s->frame_size_min +
201 2 * (s->bits_written * s->sample_rate < s->samples_written * s->bit_rate);
202 s->bits_written += s->frame_size * 8;
203 s->samples_written += AC3_FRAME_SIZE;
208 * Deinterleave input samples.
209 * Channels are reordered from FFmpeg's default order to AC-3 order.
211 static void deinterleave_input_samples(AC3EncodeContext *s,
212 const SampleType *samples)
216 /* deinterleave and remap input samples */
217 for (ch = 0; ch < s->channels; ch++) {
218 const SampleType *sptr;
221 /* copy last 256 samples of previous frame to the start of the current frame */
222 memcpy(&s->planar_samples[ch][0], &s->planar_samples[ch][AC3_FRAME_SIZE],
223 AC3_BLOCK_SIZE * sizeof(s->planar_samples[0][0]));
227 sptr = samples + s->channel_map[ch];
228 for (i = AC3_BLOCK_SIZE; i < AC3_FRAME_SIZE+AC3_BLOCK_SIZE; i++) {
229 s->planar_samples[ch][i] = *sptr;
237 * Apply the MDCT to input samples to generate frequency coefficients.
238 * This applies the KBD window and normalizes the input to reduce precision
239 * loss due to fixed-point calculations.
241 static void apply_mdct(AC3EncodeContext *s)
245 for (ch = 0; ch < s->channels; ch++) {
246 for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
247 AC3Block *block = &s->blocks[blk];
248 const SampleType *input_samples = &s->planar_samples[ch][blk * AC3_BLOCK_SIZE];
250 apply_window(s->windowed_samples, input_samples, s->mdct.window, AC3_WINDOW_SIZE);
252 block->exp_shift[ch] = normalize_samples(s);
254 mdct512(&s->mdct, block->mdct_coef[ch], s->windowed_samples);
261 * Initialize exponent tables.
263 static av_cold void exponent_init(AC3EncodeContext *s)
266 for (i = 73; i < 256; i++) {
267 exponent_group_tab[0][i] = (i - 1) / 3;
268 exponent_group_tab[1][i] = (i + 2) / 6;
269 exponent_group_tab[2][i] = (i + 8) / 12;
272 exponent_group_tab[0][7] = 2;
277 * Extract exponents from the MDCT coefficients.
278 * This takes into account the normalization that was done to the input samples
279 * by adjusting the exponents by the exponent shift values.
281 static void extract_exponents(AC3EncodeContext *s)
285 for (ch = 0; ch < s->channels; ch++) {
286 for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
287 AC3Block *block = &s->blocks[blk];
288 uint8_t *exp = block->exp[ch];
289 CoefType *coef = block->mdct_coef[ch];
290 int exp_shift = block->exp_shift[ch];
291 for (i = 0; i < AC3_MAX_COEFS; i++) {
293 int v = abs(SCALE_COEF(coef[i]));
297 e = 23 - av_log2(v) + exp_shift;
311 * Exponent Difference Threshold.
312 * New exponents are sent if their SAD exceed this number.
314 #define EXP_DIFF_THRESHOLD 1000
318 * Calculate exponent strategies for all blocks in a single channel.
320 static void compute_exp_strategy_ch(AC3EncodeContext *s, uint8_t *exp_strategy,
326 /* estimate if the exponent variation & decide if they should be
327 reused in the next frame */
328 exp_strategy[0] = EXP_NEW;
329 for (blk = 1; blk < AC3_MAX_BLOCKS; blk++) {
330 exp_diff = s->dsp.sad[0](NULL, exp[blk], exp[blk-1], 16, 16);
331 if (exp_diff > EXP_DIFF_THRESHOLD)
332 exp_strategy[blk] = EXP_NEW;
334 exp_strategy[blk] = EXP_REUSE;
338 /* now select the encoding strategy type : if exponents are often
339 recoded, we use a coarse encoding */
341 while (blk < AC3_MAX_BLOCKS) {
343 while (blk1 < AC3_MAX_BLOCKS && exp_strategy[blk1] == EXP_REUSE)
345 switch (blk1 - blk) {
346 case 1: exp_strategy[blk] = EXP_D45; break;
348 case 3: exp_strategy[blk] = EXP_D25; break;
349 default: exp_strategy[blk] = EXP_D15; break;
357 * Calculate exponent strategies for all channels.
358 * Array arrangement is reversed to simplify the per-channel calculation.
360 static void compute_exp_strategy(AC3EncodeContext *s)
362 uint8_t *exp1[AC3_MAX_CHANNELS][AC3_MAX_BLOCKS];
363 uint8_t exp_str1[AC3_MAX_CHANNELS][AC3_MAX_BLOCKS];
366 for (ch = 0; ch < s->fbw_channels; ch++) {
367 for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
368 exp1[ch][blk] = s->blocks[blk].exp[ch];
369 exp_str1[ch][blk] = s->blocks[blk].exp_strategy[ch];
372 compute_exp_strategy_ch(s, exp_str1[ch], exp1[ch]);
374 for (blk = 0; blk < AC3_MAX_BLOCKS; blk++)
375 s->blocks[blk].exp_strategy[ch] = exp_str1[ch][blk];
379 s->blocks[0].exp_strategy[ch] = EXP_D15;
380 for (blk = 1; blk < AC3_MAX_BLOCKS; blk++)
381 s->blocks[blk].exp_strategy[ch] = EXP_REUSE;
387 * Set each encoded exponent in a block to the minimum of itself and the
388 * exponent in the same frequency bin of a following block.
389 * exp[i] = min(exp[i], exp1[i]
391 static void exponent_min(uint8_t *exp, uint8_t *exp1, int n)
394 for (i = 0; i < n; i++) {
395 if (exp1[i] < exp[i])
402 * Update the exponents so that they are the ones the decoder will decode.
404 static void encode_exponents_blk_ch(uint8_t *exp, int nb_exps, int exp_strategy)
408 nb_groups = exponent_group_tab[exp_strategy-1][nb_exps] * 3;
410 /* for each group, compute the minimum exponent */
411 switch(exp_strategy) {
413 for (i = 1, k = 1; i <= nb_groups; i++) {
414 uint8_t exp_min = exp[k];
415 if (exp[k+1] < exp_min)
422 for (i = 1, k = 1; i <= nb_groups; i++) {
423 uint8_t exp_min = exp[k];
424 if (exp[k+1] < exp_min)
426 if (exp[k+2] < exp_min)
428 if (exp[k+3] < exp_min)
436 /* constraint for DC exponent */
440 /* decrease the delta between each groups to within 2 so that they can be
441 differentially encoded */
442 for (i = 1; i <= nb_groups; i++)
443 exp[i] = FFMIN(exp[i], exp[i-1] + 2);
446 exp[i] = FFMIN(exp[i], exp[i+1] + 2);
448 /* now we have the exponent values the decoder will see */
449 switch (exp_strategy) {
451 for (i = nb_groups, k = nb_groups * 2; i > 0; i--) {
452 uint8_t exp1 = exp[i];
458 for (i = nb_groups, k = nb_groups * 4; i > 0; i--) {
459 exp[k] = exp[k-1] = exp[k-2] = exp[k-3] = exp[i];
468 * Encode exponents from original extracted form to what the decoder will see.
469 * This copies and groups exponents based on exponent strategy and reduces
470 * deltas between adjacent exponent groups so that they can be differentially
473 static void encode_exponents(AC3EncodeContext *s)
475 int blk, blk1, blk2, ch;
476 AC3Block *block, *block1, *block2;
478 for (ch = 0; ch < s->channels; ch++) {
480 block = &s->blocks[0];
481 while (blk < AC3_MAX_BLOCKS) {
484 /* for the EXP_REUSE case we select the min of the exponents */
485 while (blk1 < AC3_MAX_BLOCKS && block1->exp_strategy[ch] == EXP_REUSE) {
486 exponent_min(block->exp[ch], block1->exp[ch], s->nb_coefs[ch]);
490 encode_exponents_blk_ch(block->exp[ch], s->nb_coefs[ch],
491 block->exp_strategy[ch]);
492 /* copy encoded exponents for reuse case */
494 for (blk2 = blk+1; blk2 < blk1; blk2++, block2++) {
495 memcpy(block2->exp[ch], block->exp[ch],
496 s->nb_coefs[ch] * sizeof(uint8_t));
507 * 3 delta-encoded exponents are in each 7-bit group. The number of groups
508 * varies depending on exponent strategy and bandwidth.
510 static void group_exponents(AC3EncodeContext *s)
513 int group_size, nb_groups, bit_count;
515 int delta0, delta1, delta2;
519 for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
520 AC3Block *block = &s->blocks[blk];
521 for (ch = 0; ch < s->channels; ch++) {
522 if (block->exp_strategy[ch] == EXP_REUSE) {
525 group_size = block->exp_strategy[ch] + (block->exp_strategy[ch] == EXP_D45);
526 nb_groups = exponent_group_tab[block->exp_strategy[ch]-1][s->nb_coefs[ch]];
527 bit_count += 4 + (nb_groups * 7);
532 block->grouped_exp[ch][0] = exp1;
534 /* remaining exponents are delta encoded */
535 for (i = 1; i <= nb_groups; i++) {
536 /* merge three delta in one code */
540 delta0 = exp1 - exp0 + 2;
545 delta1 = exp1 - exp0 + 2;
550 delta2 = exp1 - exp0 + 2;
552 block->grouped_exp[ch][i] = ((delta0 * 5 + delta1) * 5) + delta2;
557 s->exponent_bits = bit_count;
562 * Calculate final exponents from the supplied MDCT coefficients and exponent shift.
563 * Extract exponents from MDCT coefficients, calculate exponent strategies,
564 * and encode final exponents.
566 static void process_exponents(AC3EncodeContext *s)
568 extract_exponents(s);
570 compute_exp_strategy(s);
579 * Count frame bits that are based solely on fixed parameters.
580 * This only has to be run once when the encoder is initialized.
582 static void count_frame_bits_fixed(AC3EncodeContext *s)
584 static const int frame_bits_inc[8] = { 0, 0, 2, 2, 2, 4, 2, 4 };
589 * no dynamic range codes
590 * no channel coupling
592 * bit allocation parameters do not change between blocks
593 * SNR offsets do not change between blocks
594 * no delta bit allocation
601 frame_bits += frame_bits_inc[s->channel_mode];
604 for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
605 frame_bits += s->fbw_channels * 2 + 2; /* blksw * c, dithflag * c, dynrnge, cplstre */
606 if (s->channel_mode == AC3_CHMODE_STEREO) {
607 frame_bits++; /* rematstr */
611 frame_bits += 2 * s->fbw_channels; /* chexpstr[2] * c */
613 frame_bits++; /* lfeexpstr */
614 frame_bits++; /* baie */
615 frame_bits++; /* snr */
616 frame_bits += 2; /* delta / skip */
618 frame_bits++; /* cplinu for block 0 */
620 /* sdcycod[2], fdcycod[2], sgaincod[2], dbpbcod[2], floorcod[3] */
622 /* (fsnoffset[4] + fgaincod[4]) * c */
623 frame_bits += 2*4 + 3 + 6 + s->channels * (4 + 3);
625 /* auxdatae, crcrsv */
631 s->frame_bits_fixed = frame_bits;
636 * Initialize bit allocation.
637 * Set default parameter codes and calculate parameter values.
639 static void bit_alloc_init(AC3EncodeContext *s)
643 /* init default parameters */
644 s->slow_decay_code = 2;
645 s->fast_decay_code = 1;
646 s->slow_gain_code = 1;
647 s->db_per_bit_code = 3;
649 for (ch = 0; ch < s->channels; ch++)
650 s->fast_gain_code[ch] = 4;
652 /* initial snr offset */
653 s->coarse_snr_offset = 40;
655 /* compute real values */
656 /* currently none of these values change during encoding, so we can just
657 set them once at initialization */
658 s->bit_alloc.slow_decay = ff_ac3_slow_decay_tab[s->slow_decay_code] >> s->bit_alloc.sr_shift;
659 s->bit_alloc.fast_decay = ff_ac3_fast_decay_tab[s->fast_decay_code] >> s->bit_alloc.sr_shift;
660 s->bit_alloc.slow_gain = ff_ac3_slow_gain_tab[s->slow_gain_code];
661 s->bit_alloc.db_per_bit = ff_ac3_db_per_bit_tab[s->db_per_bit_code];
662 s->bit_alloc.floor = ff_ac3_floor_tab[s->floor_code];
664 count_frame_bits_fixed(s);
669 * Count the bits used to encode the frame, minus exponents and mantissas.
670 * Bits based on fixed parameters have already been counted, so now we just
671 * have to add the bits based on parameters that change during encoding.
673 static void count_frame_bits(AC3EncodeContext *s)
678 for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
679 uint8_t *exp_strategy = s->blocks[blk].exp_strategy;
680 for (ch = 0; ch < s->fbw_channels; ch++) {
681 if (exp_strategy[ch] != EXP_REUSE)
682 frame_bits += 6 + 2; /* chbwcod[6], gainrng[2] */
685 s->frame_bits = s->frame_bits_fixed + frame_bits;
690 * Calculate the number of bits needed to encode a set of mantissas.
692 static int compute_mantissa_size(int mant_cnt[5], uint8_t *bap, int nb_coefs)
697 for (i = 0; i < nb_coefs; i++) {
700 // bap=1 to bap=4 will be counted in compute_mantissa_size_final
702 } else if (b <= 13) {
703 // bap=5 to bap=13 use (bap-1) bits
706 // bap=14 uses 14 bits and bap=15 uses 16 bits
707 bits += (b == 14) ? 14 : 16;
715 * Finalize the mantissa bit count by adding in the grouped mantissas.
717 static int compute_mantissa_size_final(int mant_cnt[5])
719 // bap=1 : 3 mantissas in 5 bits
720 int bits = (mant_cnt[1] / 3) * 5;
721 // bap=2 : 3 mantissas in 7 bits
722 // bap=4 : 2 mantissas in 7 bits
723 bits += ((mant_cnt[2] / 3) + (mant_cnt[4] >> 1)) * 7;
724 // bap=3 : each mantissa is 3 bits
725 bits += mant_cnt[3] * 3;
731 * Calculate masking curve based on the final exponents.
732 * Also calculate the power spectral densities to use in future calculations.
734 static void bit_alloc_masking(AC3EncodeContext *s)
738 for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
739 AC3Block *block = &s->blocks[blk];
740 for (ch = 0; ch < s->channels; ch++) {
741 /* We only need psd and mask for calculating bap.
742 Since we currently do not calculate bap when exponent
743 strategy is EXP_REUSE we do not need to calculate psd or mask. */
744 if (block->exp_strategy[ch] != EXP_REUSE) {
745 ff_ac3_bit_alloc_calc_psd(block->exp[ch], 0,
747 block->psd[ch], block->band_psd[ch]);
748 ff_ac3_bit_alloc_calc_mask(&s->bit_alloc, block->band_psd[ch],
750 ff_ac3_fast_gain_tab[s->fast_gain_code[ch]],
751 ch == s->lfe_channel,
752 DBA_NONE, 0, NULL, NULL, NULL,
761 * Ensure that bap for each block and channel point to the current bap_buffer.
762 * They may have been switched during the bit allocation search.
764 static void reset_block_bap(AC3EncodeContext *s)
767 if (s->blocks[0].bap[0] == s->bap_buffer)
769 for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
770 for (ch = 0; ch < s->channels; ch++) {
771 s->blocks[blk].bap[ch] = &s->bap_buffer[AC3_MAX_COEFS * (blk * s->channels + ch)];
778 * Run the bit allocation with a given SNR offset.
779 * This calculates the bit allocation pointers that will be used to determine
780 * the quantization of each mantissa.
781 * @return the number of bits needed for mantissas if the given SNR offset is
784 static int bit_alloc(AC3EncodeContext *s, int snr_offset)
790 snr_offset = (snr_offset - 240) << 2;
794 for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
795 AC3Block *block = &s->blocks[blk];
796 // initialize grouped mantissa counts. these are set so that they are
797 // padded to the next whole group size when bits are counted in
798 // compute_mantissa_size_final
799 mant_cnt[0] = mant_cnt[3] = 0;
800 mant_cnt[1] = mant_cnt[2] = 2;
802 for (ch = 0; ch < s->channels; ch++) {
803 /* Currently the only bit allocation parameters which vary across
804 blocks within a frame are the exponent values. We can take
805 advantage of that by reusing the bit allocation pointers
806 whenever we reuse exponents. */
807 if (block->exp_strategy[ch] == EXP_REUSE) {
808 memcpy(block->bap[ch], s->blocks[blk-1].bap[ch], AC3_MAX_COEFS);
810 ff_ac3_bit_alloc_calc_bap(block->mask[ch], block->psd[ch], 0,
811 s->nb_coefs[ch], snr_offset,
812 s->bit_alloc.floor, ff_ac3_bap_tab,
815 mantissa_bits += compute_mantissa_size(mant_cnt, block->bap[ch], s->nb_coefs[ch]);
817 mantissa_bits += compute_mantissa_size_final(mant_cnt);
819 return mantissa_bits;
824 * Constant bitrate bit allocation search.
825 * Find the largest SNR offset that will allow data to fit in the frame.
827 static int cbr_bit_allocation(AC3EncodeContext *s)
831 int snr_offset, snr_incr;
833 bits_left = 8 * s->frame_size - (s->frame_bits + s->exponent_bits);
835 snr_offset = s->coarse_snr_offset << 4;
837 /* if previous frame SNR offset was 1023, check if current frame can also
838 use SNR offset of 1023. if so, skip the search. */
839 if ((snr_offset | s->fine_snr_offset[0]) == 1023) {
840 if (bit_alloc(s, 1023) <= bits_left)
844 while (snr_offset >= 0 &&
845 bit_alloc(s, snr_offset) > bits_left) {
849 return AVERROR(EINVAL);
851 FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
852 for (snr_incr = 64; snr_incr > 0; snr_incr >>= 2) {
853 while (snr_offset + snr_incr <= 1023 &&
854 bit_alloc(s, snr_offset + snr_incr) <= bits_left) {
855 snr_offset += snr_incr;
856 FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
859 FFSWAP(uint8_t *, s->bap_buffer, s->bap1_buffer);
862 s->coarse_snr_offset = snr_offset >> 4;
863 for (ch = 0; ch < s->channels; ch++)
864 s->fine_snr_offset[ch] = snr_offset & 0xF;
871 * Downgrade exponent strategies to reduce the bits used by the exponents.
872 * This is a fallback for when bit allocation fails with the normal exponent
873 * strategies. Each time this function is run it only downgrades the
874 * strategy in 1 channel of 1 block.
875 * @return non-zero if downgrade was unsuccessful
877 static int downgrade_exponents(AC3EncodeContext *s)
881 for (ch = 0; ch < s->fbw_channels; ch++) {
882 for (blk = AC3_MAX_BLOCKS-1; blk >= 0; blk--) {
883 if (s->blocks[blk].exp_strategy[ch] == EXP_D15) {
884 s->blocks[blk].exp_strategy[ch] = EXP_D25;
889 for (ch = 0; ch < s->fbw_channels; ch++) {
890 for (blk = AC3_MAX_BLOCKS-1; blk >= 0; blk--) {
891 if (s->blocks[blk].exp_strategy[ch] == EXP_D25) {
892 s->blocks[blk].exp_strategy[ch] = EXP_D45;
897 for (ch = 0; ch < s->fbw_channels; ch++) {
898 /* block 0 cannot reuse exponents, so only downgrade D45 to REUSE if
899 the block number > 0 */
900 for (blk = AC3_MAX_BLOCKS-1; blk > 0; blk--) {
901 if (s->blocks[blk].exp_strategy[ch] > EXP_REUSE) {
902 s->blocks[blk].exp_strategy[ch] = EXP_REUSE;
912 * Reduce the bandwidth to reduce the number of bits used for a given SNR offset.
913 * This is a second fallback for when bit allocation still fails after exponents
914 * have been downgraded.
915 * @return non-zero if bandwidth reduction was unsuccessful
917 static int reduce_bandwidth(AC3EncodeContext *s, int min_bw_code)
921 if (s->bandwidth_code[0] > min_bw_code) {
922 for (ch = 0; ch < s->fbw_channels; ch++) {
923 s->bandwidth_code[ch]--;
924 s->nb_coefs[ch] = s->bandwidth_code[ch] * 3 + 73;
933 * Perform bit allocation search.
934 * Finds the SNR offset value that maximizes quality and fits in the specified
935 * frame size. Output is the SNR offset and a set of bit allocation pointers
936 * used to quantize the mantissas.
938 static int compute_bit_allocation(AC3EncodeContext *s)
944 bit_alloc_masking(s);
946 ret = cbr_bit_allocation(s);
948 /* fallback 1: downgrade exponents */
949 if (!downgrade_exponents(s)) {
950 extract_exponents(s);
953 ret = compute_bit_allocation(s);
957 /* fallback 2: reduce bandwidth */
958 /* only do this if the user has not specified a specific cutoff
960 if (!s->cutoff && !reduce_bandwidth(s, 0)) {
961 process_exponents(s);
962 ret = compute_bit_allocation(s);
966 /* fallbacks were not enough... */
975 * Symmetric quantization on 'levels' levels.
977 static inline int sym_quant(int c, int e, int levels)
982 v = (levels * (c << e)) >> 24;
984 v = (levels >> 1) + v;
986 v = (levels * ((-c) << e)) >> 24;
988 v = (levels >> 1) - v;
990 assert(v >= 0 && v < levels);
996 * Asymmetric quantization on 2^qbits levels.
998 static inline int asym_quant(int c, int e, int qbits)
1002 lshift = e + qbits - 24;
1009 m = (1 << (qbits-1));
1013 return v & ((1 << qbits)-1);
1018 * Quantize a set of mantissas for a single channel in a single block.
1020 static void quantize_mantissas_blk_ch(AC3EncodeContext *s, CoefType *mdct_coef,
1021 int8_t exp_shift, uint8_t *exp,
1022 uint8_t *bap, uint16_t *qmant, int n)
1026 for (i = 0; i < n; i++) {
1028 int c = SCALE_COEF(mdct_coef[i]);
1029 int e = exp[i] - exp_shift;
1036 v = sym_quant(c, e, 3);
1037 switch (s->mant1_cnt) {
1039 s->qmant1_ptr = &qmant[i];
1044 *s->qmant1_ptr += 3 * v;
1049 *s->qmant1_ptr += v;
1056 v = sym_quant(c, e, 5);
1057 switch (s->mant2_cnt) {
1059 s->qmant2_ptr = &qmant[i];
1064 *s->qmant2_ptr += 5 * v;
1069 *s->qmant2_ptr += v;
1076 v = sym_quant(c, e, 7);
1079 v = sym_quant(c, e, 11);
1080 switch (s->mant4_cnt) {
1082 s->qmant4_ptr = &qmant[i];
1087 *s->qmant4_ptr += v;
1094 v = sym_quant(c, e, 15);
1097 v = asym_quant(c, e, 14);
1100 v = asym_quant(c, e, 16);
1103 v = asym_quant(c, e, b - 1);
1112 * Quantize mantissas using coefficients, exponents, and bit allocation pointers.
1114 static void quantize_mantissas(AC3EncodeContext *s)
1119 for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
1120 AC3Block *block = &s->blocks[blk];
1121 s->mant1_cnt = s->mant2_cnt = s->mant4_cnt = 0;
1122 s->qmant1_ptr = s->qmant2_ptr = s->qmant4_ptr = NULL;
1124 for (ch = 0; ch < s->channels; ch++) {
1125 quantize_mantissas_blk_ch(s, block->mdct_coef[ch], block->exp_shift[ch],
1126 block->exp[ch], block->bap[ch],
1127 block->qmant[ch], s->nb_coefs[ch]);
1134 * Write the AC-3 frame header to the output bitstream.
1136 static void output_frame_header(AC3EncodeContext *s)
1138 put_bits(&s->pb, 16, 0x0b77); /* frame header */
1139 put_bits(&s->pb, 16, 0); /* crc1: will be filled later */
1140 put_bits(&s->pb, 2, s->bit_alloc.sr_code);
1141 put_bits(&s->pb, 6, s->frame_size_code + (s->frame_size - s->frame_size_min) / 2);
1142 put_bits(&s->pb, 5, s->bitstream_id);
1143 put_bits(&s->pb, 3, s->bitstream_mode);
1144 put_bits(&s->pb, 3, s->channel_mode);
1145 if ((s->channel_mode & 0x01) && s->channel_mode != AC3_CHMODE_MONO)
1146 put_bits(&s->pb, 2, 1); /* XXX -4.5 dB */
1147 if (s->channel_mode & 0x04)
1148 put_bits(&s->pb, 2, 1); /* XXX -6 dB */
1149 if (s->channel_mode == AC3_CHMODE_STEREO)
1150 put_bits(&s->pb, 2, 0); /* surround not indicated */
1151 put_bits(&s->pb, 1, s->lfe_on); /* LFE */
1152 put_bits(&s->pb, 5, 31); /* dialog norm: -31 db */
1153 put_bits(&s->pb, 1, 0); /* no compression control word */
1154 put_bits(&s->pb, 1, 0); /* no lang code */
1155 put_bits(&s->pb, 1, 0); /* no audio production info */
1156 put_bits(&s->pb, 1, 0); /* no copyright */
1157 put_bits(&s->pb, 1, 1); /* original bitstream */
1158 put_bits(&s->pb, 1, 0); /* no time code 1 */
1159 put_bits(&s->pb, 1, 0); /* no time code 2 */
1160 put_bits(&s->pb, 1, 0); /* no additional bit stream info */
1165 * Write one audio block to the output bitstream.
1167 static void output_audio_block(AC3EncodeContext *s, int block_num)
1169 int ch, i, baie, rbnd;
1170 AC3Block *block = &s->blocks[block_num];
1172 /* block switching */
1173 for (ch = 0; ch < s->fbw_channels; ch++)
1174 put_bits(&s->pb, 1, 0);
1177 for (ch = 0; ch < s->fbw_channels; ch++)
1178 put_bits(&s->pb, 1, 1);
1180 /* dynamic range codes */
1181 put_bits(&s->pb, 1, 0);
1183 /* channel coupling */
1185 put_bits(&s->pb, 1, 1); /* coupling strategy present */
1186 put_bits(&s->pb, 1, 0); /* no coupling strategy */
1188 put_bits(&s->pb, 1, 0); /* no new coupling strategy */
1191 /* stereo rematrixing */
1192 if (s->channel_mode == AC3_CHMODE_STEREO) {
1194 /* first block must define rematrixing (rematstr) */
1195 put_bits(&s->pb, 1, 1);
1197 /* dummy rematrixing rematflg(1:4)=0 */
1198 for (rbnd = 0; rbnd < 4; rbnd++)
1199 put_bits(&s->pb, 1, 0);
1201 /* no matrixing (but should be used in the future) */
1202 put_bits(&s->pb, 1, 0);
1206 /* exponent strategy */
1207 for (ch = 0; ch < s->fbw_channels; ch++)
1208 put_bits(&s->pb, 2, block->exp_strategy[ch]);
1210 put_bits(&s->pb, 1, block->exp_strategy[s->lfe_channel]);
1213 for (ch = 0; ch < s->fbw_channels; ch++) {
1214 if (block->exp_strategy[ch] != EXP_REUSE)
1215 put_bits(&s->pb, 6, s->bandwidth_code[ch]);
1219 for (ch = 0; ch < s->channels; ch++) {
1222 if (block->exp_strategy[ch] == EXP_REUSE)
1226 put_bits(&s->pb, 4, block->grouped_exp[ch][0]);
1228 /* exponent groups */
1229 nb_groups = exponent_group_tab[block->exp_strategy[ch]-1][s->nb_coefs[ch]];
1230 for (i = 1; i <= nb_groups; i++)
1231 put_bits(&s->pb, 7, block->grouped_exp[ch][i]);
1233 /* gain range info */
1234 if (ch != s->lfe_channel)
1235 put_bits(&s->pb, 2, 0);
1238 /* bit allocation info */
1239 baie = (block_num == 0);
1240 put_bits(&s->pb, 1, baie);
1242 put_bits(&s->pb, 2, s->slow_decay_code);
1243 put_bits(&s->pb, 2, s->fast_decay_code);
1244 put_bits(&s->pb, 2, s->slow_gain_code);
1245 put_bits(&s->pb, 2, s->db_per_bit_code);
1246 put_bits(&s->pb, 3, s->floor_code);
1250 put_bits(&s->pb, 1, baie);
1252 put_bits(&s->pb, 6, s->coarse_snr_offset);
1253 for (ch = 0; ch < s->channels; ch++) {
1254 put_bits(&s->pb, 4, s->fine_snr_offset[ch]);
1255 put_bits(&s->pb, 3, s->fast_gain_code[ch]);
1259 put_bits(&s->pb, 1, 0); /* no delta bit allocation */
1260 put_bits(&s->pb, 1, 0); /* no data to skip */
1263 for (ch = 0; ch < s->channels; ch++) {
1265 for (i = 0; i < s->nb_coefs[ch]; i++) {
1266 q = block->qmant[ch][i];
1267 b = block->bap[ch][i];
1270 case 1: if (q != 128) put_bits(&s->pb, 5, q); break;
1271 case 2: if (q != 128) put_bits(&s->pb, 7, q); break;
1272 case 3: put_bits(&s->pb, 3, q); break;
1273 case 4: if (q != 128) put_bits(&s->pb, 7, q); break;
1274 case 14: put_bits(&s->pb, 14, q); break;
1275 case 15: put_bits(&s->pb, 16, q); break;
1276 default: put_bits(&s->pb, b-1, q); break;
1283 /** CRC-16 Polynomial */
1284 #define CRC16_POLY ((1 << 0) | (1 << 2) | (1 << 15) | (1 << 16))
1287 static unsigned int mul_poly(unsigned int a, unsigned int b, unsigned int poly)
1304 static unsigned int pow_poly(unsigned int a, unsigned int n, unsigned int poly)
1310 r = mul_poly(r, a, poly);
1311 a = mul_poly(a, a, poly);
1319 * Fill the end of the frame with 0's and compute the two CRCs.
1321 static void output_frame_end(AC3EncodeContext *s)
1323 const AVCRC *crc_ctx = av_crc_get_table(AV_CRC_16_ANSI);
1324 int frame_size_58, pad_bytes, crc1, crc2_partial, crc2, crc_inv;
1327 frame_size_58 = ((s->frame_size >> 2) + (s->frame_size >> 4)) << 1;
1329 /* pad the remainder of the frame with zeros */
1330 flush_put_bits(&s->pb);
1332 pad_bytes = s->frame_size - (put_bits_ptr(&s->pb) - frame) - 2;
1333 assert(pad_bytes >= 0);
1335 memset(put_bits_ptr(&s->pb), 0, pad_bytes);
1338 /* this is not so easy because it is at the beginning of the data... */
1339 crc1 = av_bswap16(av_crc(crc_ctx, 0, frame + 4, frame_size_58 - 4));
1340 crc_inv = s->crc_inv[s->frame_size > s->frame_size_min];
1341 crc1 = mul_poly(crc_inv, crc1, CRC16_POLY);
1342 AV_WB16(frame + 2, crc1);
1345 crc2_partial = av_crc(crc_ctx, 0, frame + frame_size_58,
1346 s->frame_size - frame_size_58 - 3);
1347 crc2 = av_crc(crc_ctx, crc2_partial, frame + s->frame_size - 3, 1);
1348 /* ensure crc2 does not match sync word by flipping crcrsv bit if needed */
1349 if (crc2 == 0x770B) {
1350 frame[s->frame_size - 3] ^= 0x1;
1351 crc2 = av_crc(crc_ctx, crc2_partial, frame + s->frame_size - 3, 1);
1353 crc2 = av_bswap16(crc2);
1354 AV_WB16(frame + s->frame_size - 2, crc2);
1359 * Write the frame to the output bitstream.
1361 static void output_frame(AC3EncodeContext *s, unsigned char *frame)
1365 init_put_bits(&s->pb, frame, AC3_MAX_CODED_FRAME_SIZE);
1367 output_frame_header(s);
1369 for (blk = 0; blk < AC3_MAX_BLOCKS; blk++)
1370 output_audio_block(s, blk);
1372 output_frame_end(s);
1377 * Encode a single AC-3 frame.
1379 static int ac3_encode_frame(AVCodecContext *avctx, unsigned char *frame,
1380 int buf_size, void *data)
1382 AC3EncodeContext *s = avctx->priv_data;
1383 const SampleType *samples = data;
1386 if (s->bit_alloc.sr_code == 1)
1387 adjust_frame_size(s);
1389 deinterleave_input_samples(s, samples);
1393 process_exponents(s);
1395 ret = compute_bit_allocation(s);
1397 av_log(avctx, AV_LOG_ERROR, "Bit allocation failed. Try increasing the bitrate.\n");
1401 quantize_mantissas(s);
1403 output_frame(s, frame);
1405 return s->frame_size;
1410 * Finalize encoding and free any memory allocated by the encoder.
1412 static av_cold int ac3_encode_close(AVCodecContext *avctx)
1415 AC3EncodeContext *s = avctx->priv_data;
1417 for (ch = 0; ch < s->channels; ch++)
1418 av_freep(&s->planar_samples[ch]);
1419 av_freep(&s->planar_samples);
1420 av_freep(&s->bap_buffer);
1421 av_freep(&s->bap1_buffer);
1422 av_freep(&s->mdct_coef_buffer);
1423 av_freep(&s->exp_buffer);
1424 av_freep(&s->grouped_exp_buffer);
1425 av_freep(&s->psd_buffer);
1426 av_freep(&s->band_psd_buffer);
1427 av_freep(&s->mask_buffer);
1428 av_freep(&s->qmant_buffer);
1429 for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
1430 AC3Block *block = &s->blocks[blk];
1431 av_freep(&block->bap);
1432 av_freep(&block->mdct_coef);
1433 av_freep(&block->exp);
1434 av_freep(&block->grouped_exp);
1435 av_freep(&block->psd);
1436 av_freep(&block->band_psd);
1437 av_freep(&block->mask);
1438 av_freep(&block->qmant);
1443 av_freep(&avctx->coded_frame);
1449 * Set channel information during initialization.
1451 static av_cold int set_channel_info(AC3EncodeContext *s, int channels,
1452 int64_t *channel_layout)
1456 if (channels < 1 || channels > AC3_MAX_CHANNELS)
1457 return AVERROR(EINVAL);
1458 if ((uint64_t)*channel_layout > 0x7FF)
1459 return AVERROR(EINVAL);
1460 ch_layout = *channel_layout;
1462 ch_layout = avcodec_guess_channel_layout(channels, CODEC_ID_AC3, NULL);
1463 if (av_get_channel_layout_nb_channels(ch_layout) != channels)
1464 return AVERROR(EINVAL);
1466 s->lfe_on = !!(ch_layout & AV_CH_LOW_FREQUENCY);
1467 s->channels = channels;
1468 s->fbw_channels = channels - s->lfe_on;
1469 s->lfe_channel = s->lfe_on ? s->fbw_channels : -1;
1471 ch_layout -= AV_CH_LOW_FREQUENCY;
1473 switch (ch_layout) {
1474 case AV_CH_LAYOUT_MONO: s->channel_mode = AC3_CHMODE_MONO; break;
1475 case AV_CH_LAYOUT_STEREO: s->channel_mode = AC3_CHMODE_STEREO; break;
1476 case AV_CH_LAYOUT_SURROUND: s->channel_mode = AC3_CHMODE_3F; break;
1477 case AV_CH_LAYOUT_2_1: s->channel_mode = AC3_CHMODE_2F1R; break;
1478 case AV_CH_LAYOUT_4POINT0: s->channel_mode = AC3_CHMODE_3F1R; break;
1479 case AV_CH_LAYOUT_QUAD:
1480 case AV_CH_LAYOUT_2_2: s->channel_mode = AC3_CHMODE_2F2R; break;
1481 case AV_CH_LAYOUT_5POINT0:
1482 case AV_CH_LAYOUT_5POINT0_BACK: s->channel_mode = AC3_CHMODE_3F2R; break;
1484 return AVERROR(EINVAL);
1487 s->channel_map = ff_ac3_enc_channel_map[s->channel_mode][s->lfe_on];
1488 *channel_layout = ch_layout;
1490 *channel_layout |= AV_CH_LOW_FREQUENCY;
1496 static av_cold int validate_options(AVCodecContext *avctx, AC3EncodeContext *s)
1500 /* validate channel layout */
1501 if (!avctx->channel_layout) {
1502 av_log(avctx, AV_LOG_WARNING, "No channel layout specified. The "
1503 "encoder will guess the layout, but it "
1504 "might be incorrect.\n");
1506 ret = set_channel_info(s, avctx->channels, &avctx->channel_layout);
1508 av_log(avctx, AV_LOG_ERROR, "invalid channel layout\n");
1512 /* validate sample rate */
1513 for (i = 0; i < 9; i++) {
1514 if ((ff_ac3_sample_rate_tab[i / 3] >> (i % 3)) == avctx->sample_rate)
1518 av_log(avctx, AV_LOG_ERROR, "invalid sample rate\n");
1519 return AVERROR(EINVAL);
1521 s->sample_rate = avctx->sample_rate;
1522 s->bit_alloc.sr_shift = i % 3;
1523 s->bit_alloc.sr_code = i / 3;
1525 /* validate bit rate */
1526 for (i = 0; i < 19; i++) {
1527 if ((ff_ac3_bitrate_tab[i] >> s->bit_alloc.sr_shift)*1000 == avctx->bit_rate)
1531 av_log(avctx, AV_LOG_ERROR, "invalid bit rate\n");
1532 return AVERROR(EINVAL);
1534 s->bit_rate = avctx->bit_rate;
1535 s->frame_size_code = i << 1;
1537 /* validate cutoff */
1538 if (avctx->cutoff < 0) {
1539 av_log(avctx, AV_LOG_ERROR, "invalid cutoff frequency\n");
1540 return AVERROR(EINVAL);
1542 s->cutoff = avctx->cutoff;
1543 if (s->cutoff > (s->sample_rate >> 1))
1544 s->cutoff = s->sample_rate >> 1;
1551 * Set bandwidth for all channels.
1552 * The user can optionally supply a cutoff frequency. Otherwise an appropriate
1553 * default value will be used.
1555 static av_cold void set_bandwidth(AC3EncodeContext *s)
1560 /* calculate bandwidth based on user-specified cutoff frequency */
1562 fbw_coeffs = s->cutoff * 2 * AC3_MAX_COEFS / s->sample_rate;
1563 bw_code = av_clip((fbw_coeffs - 73) / 3, 0, 60);
1565 /* use default bandwidth setting */
1566 /* XXX: should compute the bandwidth according to the frame
1567 size, so that we avoid annoying high frequency artifacts */
1571 /* set number of coefficients for each channel */
1572 for (ch = 0; ch < s->fbw_channels; ch++) {
1573 s->bandwidth_code[ch] = bw_code;
1574 s->nb_coefs[ch] = bw_code * 3 + 73;
1577 s->nb_coefs[s->lfe_channel] = 7; /* LFE channel always has 7 coefs */
1581 static av_cold int allocate_buffers(AVCodecContext *avctx)
1584 AC3EncodeContext *s = avctx->priv_data;
1586 FF_ALLOC_OR_GOTO(avctx, s->planar_samples, s->channels * sizeof(*s->planar_samples),
1588 for (ch = 0; ch < s->channels; ch++) {
1589 FF_ALLOCZ_OR_GOTO(avctx, s->planar_samples[ch],
1590 (AC3_FRAME_SIZE+AC3_BLOCK_SIZE) * sizeof(**s->planar_samples),
1593 FF_ALLOC_OR_GOTO(avctx, s->bap_buffer, AC3_MAX_BLOCKS * s->channels *
1594 AC3_MAX_COEFS * sizeof(*s->bap_buffer), alloc_fail);
1595 FF_ALLOC_OR_GOTO(avctx, s->bap1_buffer, AC3_MAX_BLOCKS * s->channels *
1596 AC3_MAX_COEFS * sizeof(*s->bap1_buffer), alloc_fail);
1597 FF_ALLOC_OR_GOTO(avctx, s->mdct_coef_buffer, AC3_MAX_BLOCKS * s->channels *
1598 AC3_MAX_COEFS * sizeof(*s->mdct_coef_buffer), alloc_fail);
1599 FF_ALLOC_OR_GOTO(avctx, s->exp_buffer, AC3_MAX_BLOCKS * s->channels *
1600 AC3_MAX_COEFS * sizeof(*s->exp_buffer), alloc_fail);
1601 FF_ALLOC_OR_GOTO(avctx, s->grouped_exp_buffer, AC3_MAX_BLOCKS * s->channels *
1602 128 * sizeof(*s->grouped_exp_buffer), alloc_fail);
1603 FF_ALLOC_OR_GOTO(avctx, s->psd_buffer, AC3_MAX_BLOCKS * s->channels *
1604 AC3_MAX_COEFS * sizeof(*s->psd_buffer), alloc_fail);
1605 FF_ALLOC_OR_GOTO(avctx, s->band_psd_buffer, AC3_MAX_BLOCKS * s->channels *
1606 64 * sizeof(*s->band_psd_buffer), alloc_fail);
1607 FF_ALLOC_OR_GOTO(avctx, s->mask_buffer, AC3_MAX_BLOCKS * s->channels *
1608 64 * sizeof(*s->mask_buffer), alloc_fail);
1609 FF_ALLOC_OR_GOTO(avctx, s->qmant_buffer, AC3_MAX_BLOCKS * s->channels *
1610 AC3_MAX_COEFS * sizeof(*s->qmant_buffer), alloc_fail);
1611 for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
1612 AC3Block *block = &s->blocks[blk];
1613 FF_ALLOC_OR_GOTO(avctx, block->bap, s->channels * sizeof(*block->bap),
1615 FF_ALLOCZ_OR_GOTO(avctx, block->mdct_coef, s->channels * sizeof(*block->mdct_coef),
1617 FF_ALLOCZ_OR_GOTO(avctx, block->exp, s->channels * sizeof(*block->exp),
1619 FF_ALLOCZ_OR_GOTO(avctx, block->grouped_exp, s->channels * sizeof(*block->grouped_exp),
1621 FF_ALLOCZ_OR_GOTO(avctx, block->psd, s->channels * sizeof(*block->psd),
1623 FF_ALLOCZ_OR_GOTO(avctx, block->band_psd, s->channels * sizeof(*block->band_psd),
1625 FF_ALLOCZ_OR_GOTO(avctx, block->mask, s->channels * sizeof(*block->mask),
1627 FF_ALLOCZ_OR_GOTO(avctx, block->qmant, s->channels * sizeof(*block->qmant),
1630 for (ch = 0; ch < s->channels; ch++) {
1631 block->bap[ch] = &s->bap_buffer [AC3_MAX_COEFS * (blk * s->channels + ch)];
1632 block->mdct_coef[ch] = &s->mdct_coef_buffer [AC3_MAX_COEFS * (blk * s->channels + ch)];
1633 block->exp[ch] = &s->exp_buffer [AC3_MAX_COEFS * (blk * s->channels + ch)];
1634 block->grouped_exp[ch] = &s->grouped_exp_buffer[128 * (blk * s->channels + ch)];
1635 block->psd[ch] = &s->psd_buffer [AC3_MAX_COEFS * (blk * s->channels + ch)];
1636 block->band_psd[ch] = &s->band_psd_buffer [64 * (blk * s->channels + ch)];
1637 block->mask[ch] = &s->mask_buffer [64 * (blk * s->channels + ch)];
1638 block->qmant[ch] = &s->qmant_buffer [AC3_MAX_COEFS * (blk * s->channels + ch)];
1644 return AVERROR(ENOMEM);
1649 * Initialize the encoder.
1651 static av_cold int ac3_encode_init(AVCodecContext *avctx)
1653 AC3EncodeContext *s = avctx->priv_data;
1654 int ret, frame_size_58;
1656 avctx->frame_size = AC3_FRAME_SIZE;
1660 ret = validate_options(avctx, s);
1664 s->bitstream_id = 8 + s->bit_alloc.sr_shift;
1665 s->bitstream_mode = 0; /* complete main audio service */
1667 s->frame_size_min = 2 * ff_ac3_frame_size_tab[s->frame_size_code][s->bit_alloc.sr_code];
1668 s->bits_written = 0;
1669 s->samples_written = 0;
1670 s->frame_size = s->frame_size_min;
1672 /* calculate crc_inv for both possible frame sizes */
1673 frame_size_58 = (( s->frame_size >> 2) + ( s->frame_size >> 4)) << 1;
1674 s->crc_inv[0] = pow_poly((CRC16_POLY >> 1), (8 * frame_size_58) - 16, CRC16_POLY);
1675 if (s->bit_alloc.sr_code == 1) {
1676 frame_size_58 = (((s->frame_size+2) >> 2) + ((s->frame_size+2) >> 4)) << 1;
1677 s->crc_inv[1] = pow_poly((CRC16_POLY >> 1), (8 * frame_size_58) - 16, CRC16_POLY);
1686 ret = mdct_init(avctx, &s->mdct, 9);
1690 ret = allocate_buffers(avctx);
1694 avctx->coded_frame= avcodec_alloc_frame();
1696 dsputil_init(&s->dsp, avctx);
1700 ac3_encode_close(avctx);