3 * This code was developed as part of Google Summer of Code 2006.
4 * E-AC-3 support was added as part of Google Summer of Code 2007.
6 * Copyright (c) 2006 Kartikey Mahendra BHATT (bhattkm at gmail dot com)
7 * Copyright (c) 2007-2008 Bartlomiej Wolowiec <bartek.wolowiec@gmail.com>
8 * Copyright (c) 2007 Justin Ruggles <justin.ruggles@gmail.com>
10 * This file is part of Libav.
12 * Libav is free software; you can redistribute it and/or
13 * modify it under the terms of the GNU Lesser General Public
14 * License as published by the Free Software Foundation; either
15 * version 2.1 of the License, or (at your option) any later version.
17 * Libav is distributed in the hope that it will be useful,
18 * but WITHOUT ANY WARRANTY; without even the implied warranty of
19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
20 * Lesser General Public License for more details.
22 * You should have received a copy of the GNU Lesser General Public
23 * License along with Libav; if not, write to the Free Software
24 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
32 #include "libavutil/crc.h"
34 #include "aac_ac3_parser.h"
35 #include "ac3_parser.h"
37 #include "ac3dec_data.h"
40 /** Large enough for maximum possible frame size when the specification limit is ignored */
41 #define AC3_FRAME_BUFFER_SIZE 32768
44 * table for ungrouping 3 values in 7 bits.
45 * used for exponents and bap=2 mantissas
47 static uint8_t ungroup_3_in_7_bits_tab[128][3];
50 /** tables for ungrouping mantissas */
51 static int b1_mantissas[32][3];
52 static int b2_mantissas[128][3];
53 static int b3_mantissas[8];
54 static int b4_mantissas[128][2];
55 static int b5_mantissas[16];
58 * Quantization table: levels for symmetric. bits for asymmetric.
59 * reference: Table 7.18 Mapping of bap to Quantizer
61 static const uint8_t quantization_tab[16] = {
63 5, 6, 7, 8, 9, 10, 11, 12, 14, 16
66 /** dynamic range table. converts codes to scale factors. */
67 static float dynamic_range_tab[256];
69 /** Adjustments in dB gain */
70 static const float gain_levels[9] = {
74 LEVEL_MINUS_1POINT5DB,
76 LEVEL_MINUS_4POINT5DB,
83 * Table for center mix levels
84 * reference: Section 5.4.2.4 cmixlev
86 static const uint8_t center_levels[4] = { 4, 5, 6, 5 };
89 * Table for surround mix levels
90 * reference: Section 5.4.2.5 surmixlev
92 static const uint8_t surround_levels[4] = { 4, 6, 7, 6 };
95 * Table for default stereo downmixing coefficients
96 * reference: Section 7.8.2 Downmixing Into Two Channels
98 static const uint8_t ac3_default_coeffs[8][5][2] = {
99 { { 2, 7 }, { 7, 2 }, },
101 { { 2, 7 }, { 7, 2 }, },
102 { { 2, 7 }, { 5, 5 }, { 7, 2 }, },
103 { { 2, 7 }, { 7, 2 }, { 6, 6 }, },
104 { { 2, 7 }, { 5, 5 }, { 7, 2 }, { 8, 8 }, },
105 { { 2, 7 }, { 7, 2 }, { 6, 7 }, { 7, 6 }, },
106 { { 2, 7 }, { 5, 5 }, { 7, 2 }, { 6, 7 }, { 7, 6 }, },
110 * Symmetrical Dequantization
111 * reference: Section 7.3.3 Expansion of Mantissas for Symmetrical Quantization
112 * Tables 7.19 to 7.23
115 symmetric_dequant(int code, int levels)
117 return ((code - (levels >> 1)) << 24) / levels;
121 * Initialize tables at runtime.
123 static av_cold void ac3_tables_init(void)
127 /* generate table for ungrouping 3 values in 7 bits
128 reference: Section 7.1.3 Exponent Decoding */
129 for(i=0; i<128; i++) {
130 ungroup_3_in_7_bits_tab[i][0] = i / 25;
131 ungroup_3_in_7_bits_tab[i][1] = (i % 25) / 5;
132 ungroup_3_in_7_bits_tab[i][2] = (i % 25) % 5;
135 /* generate grouped mantissa tables
136 reference: Section 7.3.5 Ungrouping of Mantissas */
137 for(i=0; i<32; i++) {
138 /* bap=1 mantissas */
139 b1_mantissas[i][0] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab[i][0], 3);
140 b1_mantissas[i][1] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab[i][1], 3);
141 b1_mantissas[i][2] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab[i][2], 3);
143 for(i=0; i<128; i++) {
144 /* bap=2 mantissas */
145 b2_mantissas[i][0] = symmetric_dequant(ungroup_3_in_7_bits_tab[i][0], 5);
146 b2_mantissas[i][1] = symmetric_dequant(ungroup_3_in_7_bits_tab[i][1], 5);
147 b2_mantissas[i][2] = symmetric_dequant(ungroup_3_in_7_bits_tab[i][2], 5);
149 /* bap=4 mantissas */
150 b4_mantissas[i][0] = symmetric_dequant(i / 11, 11);
151 b4_mantissas[i][1] = symmetric_dequant(i % 11, 11);
153 /* generate ungrouped mantissa tables
154 reference: Tables 7.21 and 7.23 */
156 /* bap=3 mantissas */
157 b3_mantissas[i] = symmetric_dequant(i, 7);
159 for(i=0; i<15; i++) {
160 /* bap=5 mantissas */
161 b5_mantissas[i] = symmetric_dequant(i, 15);
164 /* generate dynamic range table
165 reference: Section 7.7.1 Dynamic Range Control */
166 for(i=0; i<256; i++) {
167 int v = (i >> 5) - ((i >> 7) << 3) - 5;
168 dynamic_range_tab[i] = powf(2.0f, v) * ((i & 0x1F) | 0x20);
174 * AVCodec initialization
176 static av_cold int ac3_decode_init(AVCodecContext *avctx)
178 AC3DecodeContext *s = avctx->priv_data;
181 ff_ac3_common_init();
183 ff_mdct_init(&s->imdct_256, 8, 1, 1.0);
184 ff_mdct_init(&s->imdct_512, 9, 1, 1.0);
185 ff_kbd_window_init(s->window, 5.0, 256);
186 dsputil_init(&s->dsp, avctx);
187 ff_ac3dsp_init(&s->ac3dsp, avctx->flags & CODEC_FLAG_BITEXACT);
188 ff_fmt_convert_init(&s->fmt_conv, avctx);
189 av_lfg_init(&s->dith_state, 0);
191 /* set scale value for float to int16 conversion */
192 if (avctx->request_sample_fmt == AV_SAMPLE_FMT_FLT) {
194 avctx->sample_fmt = AV_SAMPLE_FMT_FLT;
196 s->mul_bias = 32767.0f;
197 avctx->sample_fmt = AV_SAMPLE_FMT_S16;
200 /* allow downmixing to stereo or mono */
201 if (avctx->channels > 0 && avctx->request_channels > 0 &&
202 avctx->request_channels < avctx->channels &&
203 avctx->request_channels <= 2) {
204 avctx->channels = avctx->request_channels;
208 /* allocate context input buffer */
209 s->input_buffer = av_mallocz(AC3_FRAME_BUFFER_SIZE + FF_INPUT_BUFFER_PADDING_SIZE);
210 if (!s->input_buffer)
211 return AVERROR(ENOMEM);
217 * Parse the 'sync info' and 'bit stream info' from the AC-3 bitstream.
218 * GetBitContext within AC3DecodeContext must point to
219 * the start of the synchronized AC-3 bitstream.
221 static int ac3_parse_header(AC3DecodeContext *s)
223 GetBitContext *gbc = &s->gbc;
226 /* read the rest of the bsi. read twice for dual mono mode. */
227 i = !(s->channel_mode);
229 skip_bits(gbc, 5); // skip dialog normalization
231 skip_bits(gbc, 8); //skip compression
233 skip_bits(gbc, 8); //skip language code
235 skip_bits(gbc, 7); //skip audio production information
238 skip_bits(gbc, 2); //skip copyright bit and original bitstream bit
240 /* skip the timecodes (or extra bitstream information for Alternate Syntax)
241 TODO: read & use the xbsi1 downmix levels */
243 skip_bits(gbc, 14); //skip timecode1 / xbsi1
245 skip_bits(gbc, 14); //skip timecode2 / xbsi2
247 /* skip additional bitstream info */
248 if (get_bits1(gbc)) {
249 i = get_bits(gbc, 6);
259 * Common function to parse AC-3 or E-AC-3 frame header
261 static int parse_frame_header(AC3DecodeContext *s)
266 err = ff_ac3_parse_header(&s->gbc, &hdr);
270 /* get decoding parameters from header info */
271 s->bit_alloc_params.sr_code = hdr.sr_code;
272 s->bitstream_mode = hdr.bitstream_mode;
273 s->channel_mode = hdr.channel_mode;
274 s->channel_layout = hdr.channel_layout;
275 s->lfe_on = hdr.lfe_on;
276 s->bit_alloc_params.sr_shift = hdr.sr_shift;
277 s->sample_rate = hdr.sample_rate;
278 s->bit_rate = hdr.bit_rate;
279 s->channels = hdr.channels;
280 s->fbw_channels = s->channels - s->lfe_on;
281 s->lfe_ch = s->fbw_channels + 1;
282 s->frame_size = hdr.frame_size;
283 s->center_mix_level = hdr.center_mix_level;
284 s->surround_mix_level = hdr.surround_mix_level;
285 s->num_blocks = hdr.num_blocks;
286 s->frame_type = hdr.frame_type;
287 s->substreamid = hdr.substreamid;
290 s->start_freq[s->lfe_ch] = 0;
291 s->end_freq[s->lfe_ch] = 7;
292 s->num_exp_groups[s->lfe_ch] = 2;
293 s->channel_in_cpl[s->lfe_ch] = 0;
296 if (hdr.bitstream_id <= 10) {
298 s->snr_offset_strategy = 2;
299 s->block_switch_syntax = 1;
300 s->dither_flag_syntax = 1;
301 s->bit_allocation_syntax = 1;
302 s->fast_gain_syntax = 0;
303 s->first_cpl_leak = 0;
306 memset(s->channel_uses_aht, 0, sizeof(s->channel_uses_aht));
307 return ac3_parse_header(s);
308 } else if (CONFIG_EAC3_DECODER) {
310 return ff_eac3_parse_header(s);
312 av_log(s->avctx, AV_LOG_ERROR, "E-AC-3 support not compiled in\n");
318 * Set stereo downmixing coefficients based on frame header info.
319 * reference: Section 7.8.2 Downmixing Into Two Channels
321 static void set_downmix_coeffs(AC3DecodeContext *s)
324 float cmix = gain_levels[center_levels[s->center_mix_level]];
325 float smix = gain_levels[surround_levels[s->surround_mix_level]];
328 for(i=0; i<s->fbw_channels; i++) {
329 s->downmix_coeffs[i][0] = gain_levels[ac3_default_coeffs[s->channel_mode][i][0]];
330 s->downmix_coeffs[i][1] = gain_levels[ac3_default_coeffs[s->channel_mode][i][1]];
332 if(s->channel_mode > 1 && s->channel_mode & 1) {
333 s->downmix_coeffs[1][0] = s->downmix_coeffs[1][1] = cmix;
335 if(s->channel_mode == AC3_CHMODE_2F1R || s->channel_mode == AC3_CHMODE_3F1R) {
336 int nf = s->channel_mode - 2;
337 s->downmix_coeffs[nf][0] = s->downmix_coeffs[nf][1] = smix * LEVEL_MINUS_3DB;
339 if(s->channel_mode == AC3_CHMODE_2F2R || s->channel_mode == AC3_CHMODE_3F2R) {
340 int nf = s->channel_mode - 4;
341 s->downmix_coeffs[nf][0] = s->downmix_coeffs[nf+1][1] = smix;
346 for(i=0; i<s->fbw_channels; i++) {
347 norm0 += s->downmix_coeffs[i][0];
348 norm1 += s->downmix_coeffs[i][1];
350 norm0 = 1.0f / norm0;
351 norm1 = 1.0f / norm1;
352 for(i=0; i<s->fbw_channels; i++) {
353 s->downmix_coeffs[i][0] *= norm0;
354 s->downmix_coeffs[i][1] *= norm1;
357 if(s->output_mode == AC3_CHMODE_MONO) {
358 for(i=0; i<s->fbw_channels; i++)
359 s->downmix_coeffs[i][0] = (s->downmix_coeffs[i][0] + s->downmix_coeffs[i][1]) * LEVEL_MINUS_3DB;
364 * Decode the grouped exponents according to exponent strategy.
365 * reference: Section 7.1.3 Exponent Decoding
367 static int decode_exponents(GetBitContext *gbc, int exp_strategy, int ngrps,
368 uint8_t absexp, int8_t *dexps)
370 int i, j, grp, group_size;
375 group_size = exp_strategy + (exp_strategy == EXP_D45);
376 for(grp=0,i=0; grp<ngrps; grp++) {
377 expacc = get_bits(gbc, 7);
378 dexp[i++] = ungroup_3_in_7_bits_tab[expacc][0];
379 dexp[i++] = ungroup_3_in_7_bits_tab[expacc][1];
380 dexp[i++] = ungroup_3_in_7_bits_tab[expacc][2];
383 /* convert to absolute exps and expand groups */
385 for(i=0,j=0; i<ngrps*3; i++) {
386 prevexp += dexp[i] - 2;
389 switch (group_size) {
390 case 4: dexps[j++] = prevexp;
391 dexps[j++] = prevexp;
392 case 2: dexps[j++] = prevexp;
393 case 1: dexps[j++] = prevexp;
400 * Generate transform coefficients for each coupled channel in the coupling
401 * range using the coupling coefficients and coupling coordinates.
402 * reference: Section 7.4.3 Coupling Coordinate Format
404 static void calc_transform_coeffs_cpl(AC3DecodeContext *s)
408 bin = s->start_freq[CPL_CH];
409 for (band = 0; band < s->num_cpl_bands; band++) {
410 int band_start = bin;
411 int band_end = bin + s->cpl_band_sizes[band];
412 for (ch = 1; ch <= s->fbw_channels; ch++) {
413 if (s->channel_in_cpl[ch]) {
414 int cpl_coord = s->cpl_coords[ch][band] << 5;
415 for (bin = band_start; bin < band_end; bin++) {
416 s->fixed_coeffs[ch][bin] = MULH(s->fixed_coeffs[CPL_CH][bin] << 4, cpl_coord);
418 if (ch == 2 && s->phase_flags[band]) {
419 for (bin = band_start; bin < band_end; bin++)
420 s->fixed_coeffs[2][bin] = -s->fixed_coeffs[2][bin];
429 * Grouped mantissas for 3-level 5-level and 11-level quantization
441 * Decode the transform coefficients for a particular channel
442 * reference: Section 7.3 Quantization and Decoding of Mantissas
444 static void ac3_decode_transform_coeffs_ch(AC3DecodeContext *s, int ch_index, mant_groups *m)
446 int start_freq = s->start_freq[ch_index];
447 int end_freq = s->end_freq[ch_index];
448 uint8_t *baps = s->bap[ch_index];
449 int8_t *exps = s->dexps[ch_index];
450 int *coeffs = s->fixed_coeffs[ch_index];
451 int dither = (ch_index == CPL_CH) || s->dither_flag[ch_index];
452 GetBitContext *gbc = &s->gbc;
455 for(freq = start_freq; freq < end_freq; freq++){
456 int bap = baps[freq];
461 mantissa = (av_lfg_get(&s->dith_state) & 0x7FFFFF) - 0x400000;
468 mantissa = m->b1_mant[m->b1];
471 int bits = get_bits(gbc, 5);
472 mantissa = b1_mantissas[bits][0];
473 m->b1_mant[1] = b1_mantissas[bits][1];
474 m->b1_mant[0] = b1_mantissas[bits][2];
481 mantissa = m->b2_mant[m->b2];
484 int bits = get_bits(gbc, 7);
485 mantissa = b2_mantissas[bits][0];
486 m->b2_mant[1] = b2_mantissas[bits][1];
487 m->b2_mant[0] = b2_mantissas[bits][2];
492 mantissa = b3_mantissas[get_bits(gbc, 3)];
497 mantissa = m->b4_mant;
500 int bits = get_bits(gbc, 7);
501 mantissa = b4_mantissas[bits][0];
502 m->b4_mant = b4_mantissas[bits][1];
507 mantissa = b5_mantissas[get_bits(gbc, 4)];
509 default: /* 6 to 15 */
510 mantissa = get_bits(gbc, quantization_tab[bap]);
511 /* Shift mantissa and sign-extend it. */
512 mantissa = (mantissa << (32-quantization_tab[bap]))>>8;
515 coeffs[freq] = mantissa >> exps[freq];
520 * Remove random dithering from coupling range coefficients with zero-bit
521 * mantissas for coupled channels which do not use dithering.
522 * reference: Section 7.3.4 Dither for Zero Bit Mantissas (bap=0)
524 static void remove_dithering(AC3DecodeContext *s) {
527 for(ch=1; ch<=s->fbw_channels; ch++) {
528 if(!s->dither_flag[ch] && s->channel_in_cpl[ch]) {
529 for(i = s->start_freq[CPL_CH]; i<s->end_freq[CPL_CH]; i++) {
530 if(!s->bap[CPL_CH][i])
531 s->fixed_coeffs[ch][i] = 0;
537 static void decode_transform_coeffs_ch(AC3DecodeContext *s, int blk, int ch,
540 if (!s->channel_uses_aht[ch]) {
541 ac3_decode_transform_coeffs_ch(s, ch, m);
543 /* if AHT is used, mantissas for all blocks are encoded in the first
544 block of the frame. */
546 if (!blk && CONFIG_EAC3_DECODER)
547 ff_eac3_decode_transform_coeffs_aht_ch(s, ch);
548 for (bin = s->start_freq[ch]; bin < s->end_freq[ch]; bin++) {
549 s->fixed_coeffs[ch][bin] = s->pre_mantissa[ch][bin][blk] >> s->dexps[ch][bin];
555 * Decode the transform coefficients.
557 static void decode_transform_coeffs(AC3DecodeContext *s, int blk)
563 m.b1 = m.b2 = m.b4 = 0;
565 for (ch = 1; ch <= s->channels; ch++) {
566 /* transform coefficients for full-bandwidth channel */
567 decode_transform_coeffs_ch(s, blk, ch, &m);
568 /* tranform coefficients for coupling channel come right after the
569 coefficients for the first coupled channel*/
570 if (s->channel_in_cpl[ch]) {
572 decode_transform_coeffs_ch(s, blk, CPL_CH, &m);
573 calc_transform_coeffs_cpl(s);
576 end = s->end_freq[CPL_CH];
578 end = s->end_freq[ch];
581 s->fixed_coeffs[ch][end] = 0;
585 /* zero the dithered coefficients for appropriate channels */
590 * Stereo rematrixing.
591 * reference: Section 7.5.4 Rematrixing : Decoding Technique
593 static void do_rematrixing(AC3DecodeContext *s)
598 end = FFMIN(s->end_freq[1], s->end_freq[2]);
600 for(bnd=0; bnd<s->num_rematrixing_bands; bnd++) {
601 if(s->rematrixing_flags[bnd]) {
602 bndend = FFMIN(end, ff_ac3_rematrix_band_tab[bnd+1]);
603 for(i=ff_ac3_rematrix_band_tab[bnd]; i<bndend; i++) {
604 int tmp0 = s->fixed_coeffs[1][i];
605 s->fixed_coeffs[1][i] += s->fixed_coeffs[2][i];
606 s->fixed_coeffs[2][i] = tmp0 - s->fixed_coeffs[2][i];
613 * Inverse MDCT Transform.
614 * Convert frequency domain coefficients to time-domain audio samples.
615 * reference: Section 7.9.4 Transformation Equations
617 static inline void do_imdct(AC3DecodeContext *s, int channels)
621 for (ch=1; ch<=channels; ch++) {
622 if (s->block_switch[ch]) {
624 float *x = s->tmp_output+128;
626 x[i] = s->transform_coeffs[ch][2*i];
627 s->imdct_256.imdct_half(&s->imdct_256, s->tmp_output, x);
628 s->dsp.vector_fmul_window(s->output[ch-1], s->delay[ch-1], s->tmp_output, s->window, 128);
630 x[i] = s->transform_coeffs[ch][2*i+1];
631 s->imdct_256.imdct_half(&s->imdct_256, s->delay[ch-1], x);
633 s->imdct_512.imdct_half(&s->imdct_512, s->tmp_output, s->transform_coeffs[ch]);
634 s->dsp.vector_fmul_window(s->output[ch-1], s->delay[ch-1], s->tmp_output, s->window, 128);
635 memcpy(s->delay[ch-1], s->tmp_output+128, 128*sizeof(float));
641 * Downmix the output to mono or stereo.
643 void ff_ac3_downmix_c(float (*samples)[256], float (*matrix)[2], int out_ch, int in_ch, int len)
648 for(i=0; i<len; i++) {
650 for(j=0; j<in_ch; j++) {
651 v0 += samples[j][i] * matrix[j][0];
652 v1 += samples[j][i] * matrix[j][1];
657 } else if(out_ch == 1) {
658 for(i=0; i<len; i++) {
660 for(j=0; j<in_ch; j++)
661 v0 += samples[j][i] * matrix[j][0];
668 * Upmix delay samples from stereo to original channel layout.
670 static void ac3_upmix_delay(AC3DecodeContext *s)
672 int channel_data_size = sizeof(s->delay[0]);
673 switch(s->channel_mode) {
674 case AC3_CHMODE_DUALMONO:
675 case AC3_CHMODE_STEREO:
676 /* upmix mono to stereo */
677 memcpy(s->delay[1], s->delay[0], channel_data_size);
679 case AC3_CHMODE_2F2R:
680 memset(s->delay[3], 0, channel_data_size);
681 case AC3_CHMODE_2F1R:
682 memset(s->delay[2], 0, channel_data_size);
684 case AC3_CHMODE_3F2R:
685 memset(s->delay[4], 0, channel_data_size);
686 case AC3_CHMODE_3F1R:
687 memset(s->delay[3], 0, channel_data_size);
689 memcpy(s->delay[2], s->delay[1], channel_data_size);
690 memset(s->delay[1], 0, channel_data_size);
696 * Decode band structure for coupling, spectral extension, or enhanced coupling.
697 * The band structure defines how many subbands are in each band. For each
698 * subband in the range, 1 means it is combined with the previous band, and 0
699 * means that it starts a new band.
701 * @param[in] gbc bit reader context
702 * @param[in] blk block number
703 * @param[in] eac3 flag to indicate E-AC-3
704 * @param[in] ecpl flag to indicate enhanced coupling
705 * @param[in] start_subband subband number for start of range
706 * @param[in] end_subband subband number for end of range
707 * @param[in] default_band_struct default band structure table
708 * @param[out] num_bands number of bands (optionally NULL)
709 * @param[out] band_sizes array containing the number of bins in each band (optionally NULL)
711 static void decode_band_structure(GetBitContext *gbc, int blk, int eac3,
712 int ecpl, int start_subband, int end_subband,
713 const uint8_t *default_band_struct,
714 int *num_bands, uint8_t *band_sizes)
716 int subbnd, bnd, n_subbands, n_bands=0;
718 uint8_t coded_band_struct[22];
719 const uint8_t *band_struct;
721 n_subbands = end_subband - start_subband;
723 /* decode band structure from bitstream or use default */
724 if (!eac3 || get_bits1(gbc)) {
725 for (subbnd = 0; subbnd < n_subbands - 1; subbnd++) {
726 coded_band_struct[subbnd] = get_bits1(gbc);
728 band_struct = coded_band_struct;
730 band_struct = &default_band_struct[start_subband+1];
732 /* no change in band structure */
736 /* calculate number of bands and band sizes based on band structure.
737 note that the first 4 subbands in enhanced coupling span only 6 bins
739 if (num_bands || band_sizes ) {
740 n_bands = n_subbands;
741 bnd_sz[0] = ecpl ? 6 : 12;
742 for (bnd = 0, subbnd = 1; subbnd < n_subbands; subbnd++) {
743 int subbnd_size = (ecpl && subbnd < 4) ? 6 : 12;
744 if (band_struct[subbnd-1]) {
746 bnd_sz[bnd] += subbnd_size;
748 bnd_sz[++bnd] = subbnd_size;
753 /* set optional output params */
755 *num_bands = n_bands;
757 memcpy(band_sizes, bnd_sz, n_bands);
761 * Decode a single audio block from the AC-3 bitstream.
763 static int decode_audio_block(AC3DecodeContext *s, int blk)
765 int fbw_channels = s->fbw_channels;
766 int channel_mode = s->channel_mode;
768 int different_transforms;
771 GetBitContext *gbc = &s->gbc;
772 uint8_t bit_alloc_stages[AC3_MAX_CHANNELS];
774 memset(bit_alloc_stages, 0, AC3_MAX_CHANNELS);
776 /* block switch flags */
777 different_transforms = 0;
778 if (s->block_switch_syntax) {
779 for (ch = 1; ch <= fbw_channels; ch++) {
780 s->block_switch[ch] = get_bits1(gbc);
781 if(ch > 1 && s->block_switch[ch] != s->block_switch[1])
782 different_transforms = 1;
786 /* dithering flags */
787 if (s->dither_flag_syntax) {
788 for (ch = 1; ch <= fbw_channels; ch++) {
789 s->dither_flag[ch] = get_bits1(gbc);
794 i = !(s->channel_mode);
797 s->dynamic_range[i] = ((dynamic_range_tab[get_bits(gbc, 8)]-1.0) *
798 s->avctx->drc_scale)+1.0;
799 } else if(blk == 0) {
800 s->dynamic_range[i] = 1.0f;
804 /* spectral extension strategy */
805 if (s->eac3 && (!blk || get_bits1(gbc))) {
806 s->spx_in_use = get_bits1(gbc);
808 int dst_start_freq, dst_end_freq, src_start_freq,
809 start_subband, end_subband;
811 /* determine which channels use spx */
812 if (s->channel_mode == AC3_CHMODE_MONO) {
813 s->channel_uses_spx[1] = 1;
815 for (ch = 1; ch <= fbw_channels; ch++)
816 s->channel_uses_spx[ch] = get_bits1(gbc);
819 /* get the frequency bins of the spx copy region and the spx start
821 dst_start_freq = get_bits(gbc, 2);
822 start_subband = get_bits(gbc, 3) + 2;
823 if (start_subband > 7)
824 start_subband += start_subband - 7;
825 end_subband = get_bits(gbc, 3) + 5;
827 end_subband += end_subband - 7;
828 dst_start_freq = dst_start_freq * 12 + 25;
829 src_start_freq = start_subband * 12 + 25;
830 dst_end_freq = end_subband * 12 + 25;
832 /* check validity of spx ranges */
833 if (start_subband >= end_subband) {
834 av_log(s->avctx, AV_LOG_ERROR, "invalid spectral extension "
835 "range (%d >= %d)\n", start_subband, end_subband);
838 if (dst_start_freq >= src_start_freq) {
839 av_log(s->avctx, AV_LOG_ERROR, "invalid spectral extension "
840 "copy start bin (%d >= %d)\n", dst_start_freq, src_start_freq);
844 s->spx_dst_start_freq = dst_start_freq;
845 s->spx_src_start_freq = src_start_freq;
846 s->spx_dst_end_freq = dst_end_freq;
848 decode_band_structure(gbc, blk, s->eac3, 0,
849 start_subband, end_subband,
850 ff_eac3_default_spx_band_struct,
854 for (ch = 1; ch <= fbw_channels; ch++) {
855 s->channel_uses_spx[ch] = 0;
856 s->first_spx_coords[ch] = 1;
861 /* spectral extension coordinates */
863 for (ch = 1; ch <= fbw_channels; ch++) {
864 if (s->channel_uses_spx[ch]) {
865 if (s->first_spx_coords[ch] || get_bits1(gbc)) {
867 int bin, master_spx_coord;
869 s->first_spx_coords[ch] = 0;
870 spx_blend = get_bits(gbc, 5) * (1.0f/32);
871 master_spx_coord = get_bits(gbc, 2) * 3;
873 bin = s->spx_src_start_freq;
874 for (bnd = 0; bnd < s->num_spx_bands; bnd++) {
876 int spx_coord_exp, spx_coord_mant;
877 float nratio, sblend, nblend, spx_coord;
879 /* calculate blending factors */
880 bandsize = s->spx_band_sizes[bnd];
881 nratio = ((float)((bin + (bandsize >> 1))) / s->spx_dst_end_freq) - spx_blend;
882 nratio = av_clipf(nratio, 0.0f, 1.0f);
883 nblend = sqrtf(3.0f * nratio); // noise is scaled by sqrt(3) to give unity variance
884 sblend = sqrtf(1.0f - nratio);
887 /* decode spx coordinates */
888 spx_coord_exp = get_bits(gbc, 4);
889 spx_coord_mant = get_bits(gbc, 2);
890 if (spx_coord_exp == 15) spx_coord_mant <<= 1;
891 else spx_coord_mant += 4;
892 spx_coord_mant <<= (25 - spx_coord_exp - master_spx_coord);
893 spx_coord = spx_coord_mant * (1.0f/(1<<23));
895 /* multiply noise and signal blending factors by spx coordinate */
896 s->spx_noise_blend [ch][bnd] = nblend * spx_coord;
897 s->spx_signal_blend[ch][bnd] = sblend * spx_coord;
901 s->first_spx_coords[ch] = 1;
906 /* coupling strategy */
907 if (s->eac3 ? s->cpl_strategy_exists[blk] : get_bits1(gbc)) {
908 memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
910 s->cpl_in_use[blk] = get_bits1(gbc);
911 if (s->cpl_in_use[blk]) {
912 /* coupling in use */
913 int cpl_start_subband, cpl_end_subband;
915 if (channel_mode < AC3_CHMODE_STEREO) {
916 av_log(s->avctx, AV_LOG_ERROR, "coupling not allowed in mono or dual-mono\n");
920 /* check for enhanced coupling */
921 if (s->eac3 && get_bits1(gbc)) {
922 /* TODO: parse enhanced coupling strategy info */
923 av_log_missing_feature(s->avctx, "Enhanced coupling", 1);
927 /* determine which channels are coupled */
928 if (s->eac3 && s->channel_mode == AC3_CHMODE_STEREO) {
929 s->channel_in_cpl[1] = 1;
930 s->channel_in_cpl[2] = 1;
932 for (ch = 1; ch <= fbw_channels; ch++)
933 s->channel_in_cpl[ch] = get_bits1(gbc);
936 /* phase flags in use */
937 if (channel_mode == AC3_CHMODE_STEREO)
938 s->phase_flags_in_use = get_bits1(gbc);
940 /* coupling frequency range */
941 cpl_start_subband = get_bits(gbc, 4);
942 cpl_end_subband = s->spx_in_use ? (s->spx_src_start_freq - 37) / 12 :
943 get_bits(gbc, 4) + 3;
944 if (cpl_start_subband >= cpl_end_subband) {
945 av_log(s->avctx, AV_LOG_ERROR, "invalid coupling range (%d >= %d)\n",
946 cpl_start_subband, cpl_end_subband);
949 s->start_freq[CPL_CH] = cpl_start_subband * 12 + 37;
950 s->end_freq[CPL_CH] = cpl_end_subband * 12 + 37;
952 decode_band_structure(gbc, blk, s->eac3, 0, cpl_start_subband,
954 ff_eac3_default_cpl_band_struct,
955 &s->num_cpl_bands, s->cpl_band_sizes);
957 /* coupling not in use */
958 for (ch = 1; ch <= fbw_channels; ch++) {
959 s->channel_in_cpl[ch] = 0;
960 s->first_cpl_coords[ch] = 1;
962 s->first_cpl_leak = s->eac3;
963 s->phase_flags_in_use = 0;
965 } else if (!s->eac3) {
967 av_log(s->avctx, AV_LOG_ERROR, "new coupling strategy must be present in block 0\n");
970 s->cpl_in_use[blk] = s->cpl_in_use[blk-1];
973 cpl_in_use = s->cpl_in_use[blk];
975 /* coupling coordinates */
977 int cpl_coords_exist = 0;
979 for (ch = 1; ch <= fbw_channels; ch++) {
980 if (s->channel_in_cpl[ch]) {
981 if ((s->eac3 && s->first_cpl_coords[ch]) || get_bits1(gbc)) {
982 int master_cpl_coord, cpl_coord_exp, cpl_coord_mant;
983 s->first_cpl_coords[ch] = 0;
984 cpl_coords_exist = 1;
985 master_cpl_coord = 3 * get_bits(gbc, 2);
986 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
987 cpl_coord_exp = get_bits(gbc, 4);
988 cpl_coord_mant = get_bits(gbc, 4);
989 if (cpl_coord_exp == 15)
990 s->cpl_coords[ch][bnd] = cpl_coord_mant << 22;
992 s->cpl_coords[ch][bnd] = (cpl_coord_mant + 16) << 21;
993 s->cpl_coords[ch][bnd] >>= (cpl_coord_exp + master_cpl_coord);
996 av_log(s->avctx, AV_LOG_ERROR, "new coupling coordinates must be present in block 0\n");
1000 /* channel not in coupling */
1001 s->first_cpl_coords[ch] = 1;
1005 if (channel_mode == AC3_CHMODE_STEREO && cpl_coords_exist) {
1006 for (bnd = 0; bnd < s->num_cpl_bands; bnd++) {
1007 s->phase_flags[bnd] = s->phase_flags_in_use? get_bits1(gbc) : 0;
1012 /* stereo rematrixing strategy and band structure */
1013 if (channel_mode == AC3_CHMODE_STEREO) {
1014 if ((s->eac3 && !blk) || get_bits1(gbc)) {
1015 s->num_rematrixing_bands = 4;
1016 if (cpl_in_use && s->start_freq[CPL_CH] <= 61) {
1017 s->num_rematrixing_bands -= 1 + (s->start_freq[CPL_CH] == 37);
1018 } else if (s->spx_in_use && s->spx_src_start_freq <= 61) {
1019 s->num_rematrixing_bands--;
1021 for(bnd=0; bnd<s->num_rematrixing_bands; bnd++)
1022 s->rematrixing_flags[bnd] = get_bits1(gbc);
1024 av_log(s->avctx, AV_LOG_WARNING, "Warning: new rematrixing strategy not present in block 0\n");
1025 s->num_rematrixing_bands = 0;
1029 /* exponent strategies for each channel */
1030 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1032 s->exp_strategy[blk][ch] = get_bits(gbc, 2 - (ch == s->lfe_ch));
1033 if(s->exp_strategy[blk][ch] != EXP_REUSE)
1034 bit_alloc_stages[ch] = 3;
1037 /* channel bandwidth */
1038 for (ch = 1; ch <= fbw_channels; ch++) {
1039 s->start_freq[ch] = 0;
1040 if (s->exp_strategy[blk][ch] != EXP_REUSE) {
1042 int prev = s->end_freq[ch];
1043 if (s->channel_in_cpl[ch])
1044 s->end_freq[ch] = s->start_freq[CPL_CH];
1045 else if (s->channel_uses_spx[ch])
1046 s->end_freq[ch] = s->spx_src_start_freq;
1048 int bandwidth_code = get_bits(gbc, 6);
1049 if (bandwidth_code > 60) {
1050 av_log(s->avctx, AV_LOG_ERROR, "bandwidth code = %d > 60\n", bandwidth_code);
1053 s->end_freq[ch] = bandwidth_code * 3 + 73;
1055 group_size = 3 << (s->exp_strategy[blk][ch] - 1);
1056 s->num_exp_groups[ch] = (s->end_freq[ch]+group_size-4) / group_size;
1057 if(blk > 0 && s->end_freq[ch] != prev)
1058 memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS);
1061 if (cpl_in_use && s->exp_strategy[blk][CPL_CH] != EXP_REUSE) {
1062 s->num_exp_groups[CPL_CH] = (s->end_freq[CPL_CH] - s->start_freq[CPL_CH]) /
1063 (3 << (s->exp_strategy[blk][CPL_CH] - 1));
1066 /* decode exponents for each channel */
1067 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1068 if (s->exp_strategy[blk][ch] != EXP_REUSE) {
1069 s->dexps[ch][0] = get_bits(gbc, 4) << !ch;
1070 if (decode_exponents(gbc, s->exp_strategy[blk][ch],
1071 s->num_exp_groups[ch], s->dexps[ch][0],
1072 &s->dexps[ch][s->start_freq[ch]+!!ch])) {
1073 av_log(s->avctx, AV_LOG_ERROR, "exponent out-of-range\n");
1076 if(ch != CPL_CH && ch != s->lfe_ch)
1077 skip_bits(gbc, 2); /* skip gainrng */
1081 /* bit allocation information */
1082 if (s->bit_allocation_syntax) {
1083 if (get_bits1(gbc)) {
1084 s->bit_alloc_params.slow_decay = ff_ac3_slow_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
1085 s->bit_alloc_params.fast_decay = ff_ac3_fast_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift;
1086 s->bit_alloc_params.slow_gain = ff_ac3_slow_gain_tab[get_bits(gbc, 2)];
1087 s->bit_alloc_params.db_per_bit = ff_ac3_db_per_bit_tab[get_bits(gbc, 2)];
1088 s->bit_alloc_params.floor = ff_ac3_floor_tab[get_bits(gbc, 3)];
1089 for(ch=!cpl_in_use; ch<=s->channels; ch++)
1090 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1092 av_log(s->avctx, AV_LOG_ERROR, "new bit allocation info must be present in block 0\n");
1097 /* signal-to-noise ratio offsets and fast gains (signal-to-mask ratios) */
1098 if(!s->eac3 || !blk){
1099 if(s->snr_offset_strategy && get_bits1(gbc)) {
1102 csnr = (get_bits(gbc, 6) - 15) << 4;
1103 for (i = ch = !cpl_in_use; ch <= s->channels; ch++) {
1105 if (ch == i || s->snr_offset_strategy == 2)
1106 snr = (csnr + get_bits(gbc, 4)) << 2;
1107 /* run at least last bit allocation stage if snr offset changes */
1108 if(blk && s->snr_offset[ch] != snr) {
1109 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 1);
1111 s->snr_offset[ch] = snr;
1113 /* fast gain (normal AC-3 only) */
1115 int prev = s->fast_gain[ch];
1116 s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)];
1117 /* run last 2 bit allocation stages if fast gain changes */
1118 if(blk && prev != s->fast_gain[ch])
1119 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1122 } else if (!s->eac3 && !blk) {
1123 av_log(s->avctx, AV_LOG_ERROR, "new snr offsets must be present in block 0\n");
1128 /* fast gain (E-AC-3 only) */
1129 if (s->fast_gain_syntax && get_bits1(gbc)) {
1130 for (ch = !cpl_in_use; ch <= s->channels; ch++) {
1131 int prev = s->fast_gain[ch];
1132 s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)];
1133 /* run last 2 bit allocation stages if fast gain changes */
1134 if(blk && prev != s->fast_gain[ch])
1135 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1137 } else if (s->eac3 && !blk) {
1138 for (ch = !cpl_in_use; ch <= s->channels; ch++)
1139 s->fast_gain[ch] = ff_ac3_fast_gain_tab[4];
1142 /* E-AC-3 to AC-3 converter SNR offset */
1143 if (s->frame_type == EAC3_FRAME_TYPE_INDEPENDENT && get_bits1(gbc)) {
1144 skip_bits(gbc, 10); // skip converter snr offset
1147 /* coupling leak information */
1149 if (s->first_cpl_leak || get_bits1(gbc)) {
1150 int fl = get_bits(gbc, 3);
1151 int sl = get_bits(gbc, 3);
1152 /* run last 2 bit allocation stages for coupling channel if
1153 coupling leak changes */
1154 if(blk && (fl != s->bit_alloc_params.cpl_fast_leak ||
1155 sl != s->bit_alloc_params.cpl_slow_leak)) {
1156 bit_alloc_stages[CPL_CH] = FFMAX(bit_alloc_stages[CPL_CH], 2);
1158 s->bit_alloc_params.cpl_fast_leak = fl;
1159 s->bit_alloc_params.cpl_slow_leak = sl;
1160 } else if (!s->eac3 && !blk) {
1161 av_log(s->avctx, AV_LOG_ERROR, "new coupling leak info must be present in block 0\n");
1164 s->first_cpl_leak = 0;
1167 /* delta bit allocation information */
1168 if (s->dba_syntax && get_bits1(gbc)) {
1169 /* delta bit allocation exists (strategy) */
1170 for (ch = !cpl_in_use; ch <= fbw_channels; ch++) {
1171 s->dba_mode[ch] = get_bits(gbc, 2);
1172 if (s->dba_mode[ch] == DBA_RESERVED) {
1173 av_log(s->avctx, AV_LOG_ERROR, "delta bit allocation strategy reserved\n");
1176 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1178 /* channel delta offset, len and bit allocation */
1179 for (ch = !cpl_in_use; ch <= fbw_channels; ch++) {
1180 if (s->dba_mode[ch] == DBA_NEW) {
1181 s->dba_nsegs[ch] = get_bits(gbc, 3) + 1;
1182 for (seg = 0; seg < s->dba_nsegs[ch]; seg++) {
1183 s->dba_offsets[ch][seg] = get_bits(gbc, 5);
1184 s->dba_lengths[ch][seg] = get_bits(gbc, 4);
1185 s->dba_values[ch][seg] = get_bits(gbc, 3);
1187 /* run last 2 bit allocation stages if new dba values */
1188 bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2);
1191 } else if(blk == 0) {
1192 for(ch=0; ch<=s->channels; ch++) {
1193 s->dba_mode[ch] = DBA_NONE;
1197 /* Bit allocation */
1198 for(ch=!cpl_in_use; ch<=s->channels; ch++) {
1199 if(bit_alloc_stages[ch] > 2) {
1200 /* Exponent mapping into PSD and PSD integration */
1201 ff_ac3_bit_alloc_calc_psd(s->dexps[ch],
1202 s->start_freq[ch], s->end_freq[ch],
1203 s->psd[ch], s->band_psd[ch]);
1205 if(bit_alloc_stages[ch] > 1) {
1206 /* Compute excitation function, Compute masking curve, and
1207 Apply delta bit allocation */
1208 if (ff_ac3_bit_alloc_calc_mask(&s->bit_alloc_params, s->band_psd[ch],
1209 s->start_freq[ch], s->end_freq[ch],
1210 s->fast_gain[ch], (ch == s->lfe_ch),
1211 s->dba_mode[ch], s->dba_nsegs[ch],
1212 s->dba_offsets[ch], s->dba_lengths[ch],
1213 s->dba_values[ch], s->mask[ch])) {
1214 av_log(s->avctx, AV_LOG_ERROR, "error in bit allocation\n");
1218 if(bit_alloc_stages[ch] > 0) {
1219 /* Compute bit allocation */
1220 const uint8_t *bap_tab = s->channel_uses_aht[ch] ?
1221 ff_eac3_hebap_tab : ff_ac3_bap_tab;
1222 s->ac3dsp.bit_alloc_calc_bap(s->mask[ch], s->psd[ch],
1223 s->start_freq[ch], s->end_freq[ch],
1225 s->bit_alloc_params.floor,
1226 bap_tab, s->bap[ch]);
1230 /* unused dummy data */
1231 if (s->skip_syntax && get_bits1(gbc)) {
1232 int skipl = get_bits(gbc, 9);
1237 /* unpack the transform coefficients
1238 this also uncouples channels if coupling is in use. */
1239 decode_transform_coeffs(s, blk);
1241 /* TODO: generate enhanced coupling coordinates and uncouple */
1243 /* recover coefficients if rematrixing is in use */
1244 if(s->channel_mode == AC3_CHMODE_STEREO)
1247 /* apply scaling to coefficients (headroom, dynrng) */
1248 for(ch=1; ch<=s->channels; ch++) {
1249 float gain = s->mul_bias / 4194304.0f;
1250 if(s->channel_mode == AC3_CHMODE_DUALMONO) {
1251 gain *= s->dynamic_range[2-ch];
1253 gain *= s->dynamic_range[0];
1255 s->fmt_conv.int32_to_float_fmul_scalar(s->transform_coeffs[ch], s->fixed_coeffs[ch], gain, 256);
1258 /* apply spectral extension to high frequency bins */
1259 if (s->spx_in_use && CONFIG_EAC3_DECODER) {
1260 ff_eac3_apply_spectral_extension(s);
1263 /* downmix and MDCT. order depends on whether block switching is used for
1264 any channel in this block. this is because coefficients for the long
1265 and short transforms cannot be mixed. */
1266 downmix_output = s->channels != s->out_channels &&
1267 !((s->output_mode & AC3_OUTPUT_LFEON) &&
1268 s->fbw_channels == s->out_channels);
1269 if(different_transforms) {
1270 /* the delay samples have already been downmixed, so we upmix the delay
1271 samples in order to reconstruct all channels before downmixing. */
1277 do_imdct(s, s->channels);
1279 if(downmix_output) {
1280 s->dsp.ac3_downmix(s->output, s->downmix_coeffs, s->out_channels, s->fbw_channels, 256);
1283 if(downmix_output) {
1284 s->dsp.ac3_downmix(s->transform_coeffs+1, s->downmix_coeffs, s->out_channels, s->fbw_channels, 256);
1287 if(downmix_output && !s->downmixed) {
1289 s->dsp.ac3_downmix(s->delay, s->downmix_coeffs, s->out_channels, s->fbw_channels, 128);
1292 do_imdct(s, s->out_channels);
1299 * Decode a single AC-3 frame.
1301 static int ac3_decode_frame(AVCodecContext * avctx, void *data, int *data_size,
1304 const uint8_t *buf = avpkt->data;
1305 int buf_size = avpkt->size;
1306 AC3DecodeContext *s = avctx->priv_data;
1307 float *out_samples_flt = data;
1308 int16_t *out_samples_s16 = data;
1310 const uint8_t *channel_map;
1311 const float *output[AC3_MAX_CHANNELS];
1313 /* copy input buffer to decoder context to avoid reading past the end
1314 of the buffer, which can be caused by a damaged input stream. */
1315 if (buf_size >= 2 && AV_RB16(buf) == 0x770B) {
1316 // seems to be byte-swapped AC-3
1317 int cnt = FFMIN(buf_size, AC3_FRAME_BUFFER_SIZE) >> 1;
1318 s->dsp.bswap16_buf((uint16_t *)s->input_buffer, (const uint16_t *)buf, cnt);
1320 memcpy(s->input_buffer, buf, FFMIN(buf_size, AC3_FRAME_BUFFER_SIZE));
1321 buf = s->input_buffer;
1322 /* initialize the GetBitContext with the start of valid AC-3 Frame */
1323 init_get_bits(&s->gbc, buf, buf_size * 8);
1325 /* parse the syncinfo */
1327 err = parse_frame_header(s);
1331 case AAC_AC3_PARSE_ERROR_SYNC:
1332 av_log(avctx, AV_LOG_ERROR, "frame sync error\n");
1334 case AAC_AC3_PARSE_ERROR_BSID:
1335 av_log(avctx, AV_LOG_ERROR, "invalid bitstream id\n");
1337 case AAC_AC3_PARSE_ERROR_SAMPLE_RATE:
1338 av_log(avctx, AV_LOG_ERROR, "invalid sample rate\n");
1340 case AAC_AC3_PARSE_ERROR_FRAME_SIZE:
1341 av_log(avctx, AV_LOG_ERROR, "invalid frame size\n");
1343 case AAC_AC3_PARSE_ERROR_FRAME_TYPE:
1344 /* skip frame if CRC is ok. otherwise use error concealment. */
1345 /* TODO: add support for substreams and dependent frames */
1346 if(s->frame_type == EAC3_FRAME_TYPE_DEPENDENT || s->substreamid) {
1347 av_log(avctx, AV_LOG_ERROR, "unsupported frame type : skipping frame\n");
1348 return s->frame_size;
1350 av_log(avctx, AV_LOG_ERROR, "invalid frame type\n");
1354 av_log(avctx, AV_LOG_ERROR, "invalid header\n");
1358 /* check that reported frame size fits in input buffer */
1359 if (s->frame_size > buf_size) {
1360 av_log(avctx, AV_LOG_ERROR, "incomplete frame\n");
1361 err = AAC_AC3_PARSE_ERROR_FRAME_SIZE;
1362 } else if (avctx->error_recognition >= FF_ER_CAREFUL) {
1363 /* check for crc mismatch */
1364 if (av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, &buf[2], s->frame_size-2)) {
1365 av_log(avctx, AV_LOG_ERROR, "frame CRC mismatch\n");
1366 err = AAC_AC3_PARSE_ERROR_CRC;
1371 /* if frame is ok, set audio parameters */
1373 avctx->sample_rate = s->sample_rate;
1374 avctx->bit_rate = s->bit_rate;
1376 /* channel config */
1377 s->out_channels = s->channels;
1378 s->output_mode = s->channel_mode;
1380 s->output_mode |= AC3_OUTPUT_LFEON;
1381 if (avctx->request_channels > 0 && avctx->request_channels <= 2 &&
1382 avctx->request_channels < s->channels) {
1383 s->out_channels = avctx->request_channels;
1384 s->output_mode = avctx->request_channels == 1 ? AC3_CHMODE_MONO : AC3_CHMODE_STEREO;
1385 s->channel_layout = ff_ac3_channel_layout_tab[s->output_mode];
1387 avctx->channels = s->out_channels;
1388 avctx->channel_layout = s->channel_layout;
1390 /* set downmixing coefficients if needed */
1391 if(s->channels != s->out_channels && !((s->output_mode & AC3_OUTPUT_LFEON) &&
1392 s->fbw_channels == s->out_channels)) {
1393 set_downmix_coeffs(s);
1395 } else if (!s->out_channels) {
1396 s->out_channels = avctx->channels;
1397 if(s->out_channels < s->channels)
1398 s->output_mode = s->out_channels == 1 ? AC3_CHMODE_MONO : AC3_CHMODE_STEREO;
1400 /* set audio service type based on bitstream mode for AC-3 */
1401 avctx->audio_service_type = s->bitstream_mode;
1402 if (s->bitstream_mode == 0x7 && s->channels > 1)
1403 avctx->audio_service_type = AV_AUDIO_SERVICE_TYPE_KARAOKE;
1405 /* decode the audio blocks */
1406 channel_map = ff_ac3_dec_channel_map[s->output_mode & ~AC3_OUTPUT_LFEON][s->lfe_on];
1407 for (ch = 0; ch < s->out_channels; ch++)
1408 output[ch] = s->output[channel_map[ch]];
1409 for (blk = 0; blk < s->num_blocks; blk++) {
1410 if (!err && decode_audio_block(s, blk)) {
1411 av_log(avctx, AV_LOG_ERROR, "error decoding the audio block\n");
1414 if (avctx->sample_fmt == AV_SAMPLE_FMT_FLT) {
1415 s->fmt_conv.float_interleave(out_samples_flt, output, 256,
1417 out_samples_flt += 256 * s->out_channels;
1419 s->fmt_conv.float_to_int16_interleave(out_samples_s16, output, 256,
1421 out_samples_s16 += 256 * s->out_channels;
1424 *data_size = s->num_blocks * 256 * avctx->channels *
1425 av_get_bytes_per_sample(avctx->sample_fmt);
1426 return FFMIN(buf_size, s->frame_size);
1430 * Uninitialize the AC-3 decoder.
1432 static av_cold int ac3_decode_end(AVCodecContext *avctx)
1434 AC3DecodeContext *s = avctx->priv_data;
1435 ff_mdct_end(&s->imdct_512);
1436 ff_mdct_end(&s->imdct_256);
1438 av_freep(&s->input_buffer);
1443 AVCodec ff_ac3_decoder = {
1445 .type = AVMEDIA_TYPE_AUDIO,
1447 .priv_data_size = sizeof (AC3DecodeContext),
1448 .init = ac3_decode_init,
1449 .close = ac3_decode_end,
1450 .decode = ac3_decode_frame,
1451 .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"),
1452 .sample_fmts = (const enum AVSampleFormat[]) {
1453 AV_SAMPLE_FMT_FLT, AV_SAMPLE_FMT_S16, AV_SAMPLE_FMT_NONE
1457 #if CONFIG_EAC3_DECODER
1458 AVCodec ff_eac3_decoder = {
1460 .type = AVMEDIA_TYPE_AUDIO,
1461 .id = CODEC_ID_EAC3,
1462 .priv_data_size = sizeof (AC3DecodeContext),
1463 .init = ac3_decode_init,
1464 .close = ac3_decode_end,
1465 .decode = ac3_decode_frame,
1466 .long_name = NULL_IF_CONFIG_SMALL("ATSC A/52B (AC-3, E-AC-3)"),
1467 .sample_fmts = (const enum AVSampleFormat[]) {
1468 AV_SAMPLE_FMT_FLT, AV_SAMPLE_FMT_S16, AV_SAMPLE_FMT_NONE