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 * Portions of this code are derived from liba52
11 * http://liba52.sourceforge.net
12 * Copyright (C) 2000-2003 Michel Lespinasse <walken@zoy.org>
13 * Copyright (C) 1999-2000 Aaron Holtzman <aholtzma@ess.engr.uvic.ca>
15 * This file is part of FFmpeg.
17 * FFmpeg is free software; you can redistribute it and/or
18 * modify it under the terms of the GNU General Public
19 * License as published by the Free Software Foundation; either
20 * version 2 of the License, or (at your option) any later version.
22 * FFmpeg is distributed in the hope that it will be useful,
23 * but WITHOUT ANY WARRANTY; without even the implied warranty of
24 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
25 * General Public License for more details.
27 * You should have received a copy of the GNU General Public
28 * License along with FFmpeg; if not, write to the Free Software
29 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
37 #include "libavutil/crc.h"
39 #include "ac3_parser.h"
41 #include "ac3dec_data.h"
43 /** Large enough for maximum possible frame size when the specification limit is ignored */
44 #define AC3_FRAME_BUFFER_SIZE 32768
47 * table for ungrouping 3 values in 7 bits.
48 * used for exponents and bap=2 mantissas
50 static uint8_t ungroup_3_in_7_bits_tab
[128][3];
53 /** tables for ungrouping mantissas */
54 static int b1_mantissas
[32][3];
55 static int b2_mantissas
[128][3];
56 static int b3_mantissas
[8];
57 static int b4_mantissas
[128][2];
58 static int b5_mantissas
[16];
61 * Quantization table: levels for symmetric. bits for asymmetric.
62 * reference: Table 7.18 Mapping of bap to Quantizer
64 static const uint8_t quantization_tab
[16] = {
66 5, 6, 7, 8, 9, 10, 11, 12, 14, 16
69 /** dynamic range table. converts codes to scale factors. */
70 static float dynamic_range_tab
[256];
72 /** Adjustments in dB gain */
73 #define LEVEL_PLUS_3DB 1.4142135623730950
74 #define LEVEL_PLUS_1POINT5DB 1.1892071150027209
75 #define LEVEL_MINUS_1POINT5DB 0.8408964152537145
76 #define LEVEL_MINUS_3DB 0.7071067811865476
77 #define LEVEL_MINUS_4POINT5DB 0.5946035575013605
78 #define LEVEL_MINUS_6DB 0.5000000000000000
79 #define LEVEL_MINUS_9DB 0.3535533905932738
80 #define LEVEL_ZERO 0.0000000000000000
81 #define LEVEL_ONE 1.0000000000000000
83 static const float gain_levels
[9] = {
87 LEVEL_MINUS_1POINT5DB
,
89 LEVEL_MINUS_4POINT5DB
,
96 * Table for center mix levels
97 * reference: Section 5.4.2.4 cmixlev
99 static const uint8_t center_levels
[4] = { 4, 5, 6, 5 };
102 * Table for surround mix levels
103 * reference: Section 5.4.2.5 surmixlev
105 static const uint8_t surround_levels
[4] = { 4, 6, 7, 6 };
108 * Table for default stereo downmixing coefficients
109 * reference: Section 7.8.2 Downmixing Into Two Channels
111 static const uint8_t ac3_default_coeffs
[8][5][2] = {
112 { { 2, 7 }, { 7, 2 }, },
114 { { 2, 7 }, { 7, 2 }, },
115 { { 2, 7 }, { 5, 5 }, { 7, 2 }, },
116 { { 2, 7 }, { 7, 2 }, { 6, 6 }, },
117 { { 2, 7 }, { 5, 5 }, { 7, 2 }, { 8, 8 }, },
118 { { 2, 7 }, { 7, 2 }, { 6, 7 }, { 7, 6 }, },
119 { { 2, 7 }, { 5, 5 }, { 7, 2 }, { 6, 7 }, { 7, 6 }, },
123 * Symmetrical Dequantization
124 * reference: Section 7.3.3 Expansion of Mantissas for Symmetrical Quantization
125 * Tables 7.19 to 7.23
128 symmetric_dequant(int code
, int levels
)
130 return ((code
- (levels
>> 1)) << 24) / levels
;
134 * Initialize tables at runtime.
136 static av_cold
void ac3_tables_init(void)
140 /* generate table for ungrouping 3 values in 7 bits
141 reference: Section 7.1.3 Exponent Decoding */
142 for(i
=0; i
<128; i
++) {
143 ungroup_3_in_7_bits_tab
[i
][0] = i
/ 25;
144 ungroup_3_in_7_bits_tab
[i
][1] = (i
% 25) / 5;
145 ungroup_3_in_7_bits_tab
[i
][2] = (i
% 25) % 5;
148 /* generate grouped mantissa tables
149 reference: Section 7.3.5 Ungrouping of Mantissas */
150 for(i
=0; i
<32; i
++) {
151 /* bap=1 mantissas */
152 b1_mantissas
[i
][0] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab
[i
][0], 3);
153 b1_mantissas
[i
][1] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab
[i
][1], 3);
154 b1_mantissas
[i
][2] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab
[i
][2], 3);
156 for(i
=0; i
<128; i
++) {
157 /* bap=2 mantissas */
158 b2_mantissas
[i
][0] = symmetric_dequant(ungroup_3_in_7_bits_tab
[i
][0], 5);
159 b2_mantissas
[i
][1] = symmetric_dequant(ungroup_3_in_7_bits_tab
[i
][1], 5);
160 b2_mantissas
[i
][2] = symmetric_dequant(ungroup_3_in_7_bits_tab
[i
][2], 5);
162 /* bap=4 mantissas */
163 b4_mantissas
[i
][0] = symmetric_dequant(i
/ 11, 11);
164 b4_mantissas
[i
][1] = symmetric_dequant(i
% 11, 11);
166 /* generate ungrouped mantissa tables
167 reference: Tables 7.21 and 7.23 */
169 /* bap=3 mantissas */
170 b3_mantissas
[i
] = symmetric_dequant(i
, 7);
172 for(i
=0; i
<15; i
++) {
173 /* bap=5 mantissas */
174 b5_mantissas
[i
] = symmetric_dequant(i
, 15);
177 /* generate dynamic range table
178 reference: Section 7.7.1 Dynamic Range Control */
179 for(i
=0; i
<256; i
++) {
180 int v
= (i
>> 5) - ((i
>> 7) << 3) - 5;
181 dynamic_range_tab
[i
] = powf(2.0f
, v
) * ((i
& 0x1F) | 0x20);
187 * AVCodec initialization
189 static av_cold
int ac3_decode_init(AVCodecContext
*avctx
)
191 AC3DecodeContext
*s
= avctx
->priv_data
;
196 ff_mdct_init(&s
->imdct_256
, 8, 1);
197 ff_mdct_init(&s
->imdct_512
, 9, 1);
198 ff_kbd_window_init(s
->window
, 5.0, 256);
199 dsputil_init(&s
->dsp
, avctx
);
200 av_lfg_init(&s
->dith_state
, 0);
202 /* set bias values for float to int16 conversion */
203 if(s
->dsp
.float_to_int16_interleave
== ff_float_to_int16_interleave_c
) {
204 s
->add_bias
= 385.0f
;
208 s
->mul_bias
= 32767.0f
;
211 /* allow downmixing to stereo or mono */
212 if (avctx
->channels
> 0 && avctx
->request_channels
> 0 &&
213 avctx
->request_channels
< avctx
->channels
&&
214 avctx
->request_channels
<= 2) {
215 avctx
->channels
= avctx
->request_channels
;
219 /* allocate context input buffer */
220 if (avctx
->error_recognition
>= FF_ER_CAREFUL
) {
221 s
->input_buffer
= av_mallocz(AC3_FRAME_BUFFER_SIZE
+ FF_INPUT_BUFFER_PADDING_SIZE
);
222 if (!s
->input_buffer
)
223 return AVERROR_NOMEM
;
226 avctx
->sample_fmt
= SAMPLE_FMT_S16
;
231 * Parse the 'sync info' and 'bit stream info' from the AC-3 bitstream.
232 * GetBitContext within AC3DecodeContext must point to
233 * the start of the synchronized AC-3 bitstream.
235 static int ac3_parse_header(AC3DecodeContext
*s
)
237 GetBitContext
*gbc
= &s
->gbc
;
240 /* read the rest of the bsi. read twice for dual mono mode. */
241 i
= !(s
->channel_mode
);
243 skip_bits(gbc
, 5); // skip dialog normalization
245 skip_bits(gbc
, 8); //skip compression
247 skip_bits(gbc
, 8); //skip language code
249 skip_bits(gbc
, 7); //skip audio production information
252 skip_bits(gbc
, 2); //skip copyright bit and original bitstream bit
254 /* skip the timecodes (or extra bitstream information for Alternate Syntax)
255 TODO: read & use the xbsi1 downmix levels */
257 skip_bits(gbc
, 14); //skip timecode1 / xbsi1
259 skip_bits(gbc
, 14); //skip timecode2 / xbsi2
261 /* skip additional bitstream info */
262 if (get_bits1(gbc
)) {
263 i
= get_bits(gbc
, 6);
273 * Common function to parse AC-3 or E-AC-3 frame header
275 static int parse_frame_header(AC3DecodeContext
*s
)
280 err
= ff_ac3_parse_header(&s
->gbc
, &hdr
);
284 /* get decoding parameters from header info */
285 s
->bit_alloc_params
.sr_code
= hdr
.sr_code
;
286 s
->channel_mode
= hdr
.channel_mode
;
287 s
->lfe_on
= hdr
.lfe_on
;
288 s
->bit_alloc_params
.sr_shift
= hdr
.sr_shift
;
289 s
->sample_rate
= hdr
.sample_rate
;
290 s
->bit_rate
= hdr
.bit_rate
;
291 s
->channels
= hdr
.channels
;
292 s
->fbw_channels
= s
->channels
- s
->lfe_on
;
293 s
->lfe_ch
= s
->fbw_channels
+ 1;
294 s
->frame_size
= hdr
.frame_size
;
295 s
->center_mix_level
= hdr
.center_mix_level
;
296 s
->surround_mix_level
= hdr
.surround_mix_level
;
297 s
->num_blocks
= hdr
.num_blocks
;
298 s
->frame_type
= hdr
.frame_type
;
299 s
->substreamid
= hdr
.substreamid
;
302 s
->start_freq
[s
->lfe_ch
] = 0;
303 s
->end_freq
[s
->lfe_ch
] = 7;
304 s
->num_exp_groups
[s
->lfe_ch
] = 2;
305 s
->channel_in_cpl
[s
->lfe_ch
] = 0;
308 if (hdr
.bitstream_id
<= 10) {
310 s
->snr_offset_strategy
= 2;
311 s
->block_switch_syntax
= 1;
312 s
->dither_flag_syntax
= 1;
313 s
->bit_allocation_syntax
= 1;
314 s
->fast_gain_syntax
= 0;
315 s
->first_cpl_leak
= 0;
318 memset(s
->channel_uses_aht
, 0, sizeof(s
->channel_uses_aht
));
319 return ac3_parse_header(s
);
322 return ff_eac3_parse_header(s
);
327 * Set stereo downmixing coefficients based on frame header info.
328 * reference: Section 7.8.2 Downmixing Into Two Channels
330 static void set_downmix_coeffs(AC3DecodeContext
*s
)
333 float cmix
= gain_levels
[center_levels
[s
->center_mix_level
]];
334 float smix
= gain_levels
[surround_levels
[s
->surround_mix_level
]];
337 for(i
=0; i
<s
->fbw_channels
; i
++) {
338 s
->downmix_coeffs
[i
][0] = gain_levels
[ac3_default_coeffs
[s
->channel_mode
][i
][0]];
339 s
->downmix_coeffs
[i
][1] = gain_levels
[ac3_default_coeffs
[s
->channel_mode
][i
][1]];
341 if(s
->channel_mode
> 1 && s
->channel_mode
& 1) {
342 s
->downmix_coeffs
[1][0] = s
->downmix_coeffs
[1][1] = cmix
;
344 if(s
->channel_mode
== AC3_CHMODE_2F1R
|| s
->channel_mode
== AC3_CHMODE_3F1R
) {
345 int nf
= s
->channel_mode
- 2;
346 s
->downmix_coeffs
[nf
][0] = s
->downmix_coeffs
[nf
][1] = smix
* LEVEL_MINUS_3DB
;
348 if(s
->channel_mode
== AC3_CHMODE_2F2R
|| s
->channel_mode
== AC3_CHMODE_3F2R
) {
349 int nf
= s
->channel_mode
- 4;
350 s
->downmix_coeffs
[nf
][0] = s
->downmix_coeffs
[nf
+1][1] = smix
;
355 for(i
=0; i
<s
->fbw_channels
; i
++) {
356 norm0
+= s
->downmix_coeffs
[i
][0];
357 norm1
+= s
->downmix_coeffs
[i
][1];
359 norm0
= 1.0f
/ norm0
;
360 norm1
= 1.0f
/ norm1
;
361 for(i
=0; i
<s
->fbw_channels
; i
++) {
362 s
->downmix_coeffs
[i
][0] *= norm0
;
363 s
->downmix_coeffs
[i
][1] *= norm1
;
366 if(s
->output_mode
== AC3_CHMODE_MONO
) {
367 for(i
=0; i
<s
->fbw_channels
; i
++)
368 s
->downmix_coeffs
[i
][0] = (s
->downmix_coeffs
[i
][0] + s
->downmix_coeffs
[i
][1]) * LEVEL_MINUS_3DB
;
373 * Decode the grouped exponents according to exponent strategy.
374 * reference: Section 7.1.3 Exponent Decoding
376 static int decode_exponents(GetBitContext
*gbc
, int exp_strategy
, int ngrps
,
377 uint8_t absexp
, int8_t *dexps
)
379 int i
, j
, grp
, group_size
;
384 group_size
= exp_strategy
+ (exp_strategy
== EXP_D45
);
385 for(grp
=0,i
=0; grp
<ngrps
; grp
++) {
386 expacc
= get_bits(gbc
, 7);
387 dexp
[i
++] = ungroup_3_in_7_bits_tab
[expacc
][0];
388 dexp
[i
++] = ungroup_3_in_7_bits_tab
[expacc
][1];
389 dexp
[i
++] = ungroup_3_in_7_bits_tab
[expacc
][2];
392 /* convert to absolute exps and expand groups */
394 for(i
=0,j
=0; i
<ngrps
*3; i
++) {
395 prevexp
+= dexp
[i
] - 2;
398 switch (group_size
) {
399 case 4: dexps
[j
++] = prevexp
;
400 dexps
[j
++] = prevexp
;
401 case 2: dexps
[j
++] = prevexp
;
402 case 1: dexps
[j
++] = prevexp
;
409 * Generate transform coefficients for each coupled channel in the coupling
410 * range using the coupling coefficients and coupling coordinates.
411 * reference: Section 7.4.3 Coupling Coordinate Format
413 static void calc_transform_coeffs_cpl(AC3DecodeContext
*s
)
415 int i
, j
, ch
, bnd
, subbnd
;
418 i
= s
->start_freq
[CPL_CH
];
419 for(bnd
=0; bnd
<s
->num_cpl_bands
; bnd
++) {
422 for(j
=0; j
<12; j
++) {
423 for(ch
=1; ch
<=s
->fbw_channels
; ch
++) {
424 if(s
->channel_in_cpl
[ch
]) {
425 s
->fixed_coeffs
[ch
][i
] = ((int64_t)s
->fixed_coeffs
[CPL_CH
][i
] * (int64_t)s
->cpl_coords
[ch
][bnd
]) >> 23;
426 if (ch
== 2 && s
->phase_flags
[bnd
])
427 s
->fixed_coeffs
[ch
][i
] = -s
->fixed_coeffs
[ch
][i
];
432 } while(s
->cpl_band_struct
[subbnd
]);
437 * Grouped mantissas for 3-level 5-level and 11-level quantization
449 * Decode the transform coefficients for a particular channel
450 * reference: Section 7.3 Quantization and Decoding of Mantissas
452 static void ac3_decode_transform_coeffs_ch(AC3DecodeContext
*s
, int ch_index
, mant_groups
*m
)
454 GetBitContext
*gbc
= &s
->gbc
;
455 int i
, gcode
, tbap
, start
, end
;
460 exps
= s
->dexps
[ch_index
];
461 bap
= s
->bap
[ch_index
];
462 coeffs
= s
->fixed_coeffs
[ch_index
];
463 start
= s
->start_freq
[ch_index
];
464 end
= s
->end_freq
[ch_index
];
466 for (i
= start
; i
< end
; i
++) {
470 coeffs
[i
] = (av_lfg_get(&s
->dith_state
) & 0x7FFFFF) - 0x400000;
475 gcode
= get_bits(gbc
, 5);
476 m
->b1_mant
[0] = b1_mantissas
[gcode
][0];
477 m
->b1_mant
[1] = b1_mantissas
[gcode
][1];
478 m
->b1_mant
[2] = b1_mantissas
[gcode
][2];
481 coeffs
[i
] = m
->b1_mant
[m
->b1ptr
++];
486 gcode
= get_bits(gbc
, 7);
487 m
->b2_mant
[0] = b2_mantissas
[gcode
][0];
488 m
->b2_mant
[1] = b2_mantissas
[gcode
][1];
489 m
->b2_mant
[2] = b2_mantissas
[gcode
][2];
492 coeffs
[i
] = m
->b2_mant
[m
->b2ptr
++];
496 coeffs
[i
] = b3_mantissas
[get_bits(gbc
, 3)];
501 gcode
= get_bits(gbc
, 7);
502 m
->b4_mant
[0] = b4_mantissas
[gcode
][0];
503 m
->b4_mant
[1] = b4_mantissas
[gcode
][1];
506 coeffs
[i
] = m
->b4_mant
[m
->b4ptr
++];
510 coeffs
[i
] = b5_mantissas
[get_bits(gbc
, 4)];
514 /* asymmetric dequantization */
515 int qlevel
= quantization_tab
[tbap
];
516 coeffs
[i
] = get_sbits(gbc
, qlevel
) << (24 - qlevel
);
520 coeffs
[i
] >>= exps
[i
];
525 * Remove random dithering from coefficients with zero-bit mantissas
526 * reference: Section 7.3.4 Dither for Zero Bit Mantissas (bap=0)
528 static void remove_dithering(AC3DecodeContext
*s
) {
534 for(ch
=1; ch
<=s
->fbw_channels
; ch
++) {
535 if(!s
->dither_flag
[ch
]) {
536 coeffs
= s
->fixed_coeffs
[ch
];
538 if(s
->channel_in_cpl
[ch
])
539 end
= s
->start_freq
[CPL_CH
];
541 end
= s
->end_freq
[ch
];
542 for(i
=0; i
<end
; i
++) {
546 if(s
->channel_in_cpl
[ch
]) {
547 bap
= s
->bap
[CPL_CH
];
548 for(; i
<s
->end_freq
[CPL_CH
]; i
++) {
557 static void decode_transform_coeffs_ch(AC3DecodeContext
*s
, int blk
, int ch
,
560 if (!s
->channel_uses_aht
[ch
]) {
561 ac3_decode_transform_coeffs_ch(s
, ch
, m
);
563 /* if AHT is used, mantissas for all blocks are encoded in the first
564 block of the frame. */
567 ff_eac3_decode_transform_coeffs_aht_ch(s
, ch
);
568 for (bin
= s
->start_freq
[ch
]; bin
< s
->end_freq
[ch
]; bin
++) {
569 s
->fixed_coeffs
[ch
][bin
] = s
->pre_mantissa
[ch
][bin
][blk
] >> s
->dexps
[ch
][bin
];
575 * Decode the transform coefficients.
577 static void decode_transform_coeffs(AC3DecodeContext
*s
, int blk
)
583 m
.b1ptr
= m
.b2ptr
= m
.b4ptr
= 3;
585 for (ch
= 1; ch
<= s
->channels
; ch
++) {
586 /* transform coefficients for full-bandwidth channel */
587 decode_transform_coeffs_ch(s
, blk
, ch
, &m
);
588 /* tranform coefficients for coupling channel come right after the
589 coefficients for the first coupled channel*/
590 if (s
->channel_in_cpl
[ch
]) {
592 decode_transform_coeffs_ch(s
, blk
, CPL_CH
, &m
);
593 calc_transform_coeffs_cpl(s
);
596 end
= s
->end_freq
[CPL_CH
];
598 end
= s
->end_freq
[ch
];
601 s
->fixed_coeffs
[ch
][end
] = 0;
605 /* zero the dithered coefficients for appropriate channels */
610 * Stereo rematrixing.
611 * reference: Section 7.5.4 Rematrixing : Decoding Technique
613 static void do_rematrixing(AC3DecodeContext
*s
)
619 end
= FFMIN(s
->end_freq
[1], s
->end_freq
[2]);
621 for(bnd
=0; bnd
<s
->num_rematrixing_bands
; bnd
++) {
622 if(s
->rematrixing_flags
[bnd
]) {
623 bndend
= FFMIN(end
, ff_ac3_rematrix_band_tab
[bnd
+1]);
624 for(i
=ff_ac3_rematrix_band_tab
[bnd
]; i
<bndend
; i
++) {
625 tmp0
= s
->fixed_coeffs
[1][i
];
626 tmp1
= s
->fixed_coeffs
[2][i
];
627 s
->fixed_coeffs
[1][i
] = tmp0
+ tmp1
;
628 s
->fixed_coeffs
[2][i
] = tmp0
- tmp1
;
635 * Inverse MDCT Transform.
636 * Convert frequency domain coefficients to time-domain audio samples.
637 * reference: Section 7.9.4 Transformation Equations
639 static inline void do_imdct(AC3DecodeContext
*s
, int channels
)
642 float add_bias
= s
->add_bias
;
643 if(s
->out_channels
==1 && channels
>1)
644 add_bias
*= LEVEL_MINUS_3DB
; // compensate for the gain in downmix
646 for (ch
=1; ch
<=channels
; ch
++) {
647 if (s
->block_switch
[ch
]) {
649 float *x
= s
->tmp_output
+128;
651 x
[i
] = s
->transform_coeffs
[ch
][2*i
];
652 ff_imdct_half(&s
->imdct_256
, s
->tmp_output
, x
);
653 s
->dsp
.vector_fmul_window(s
->output
[ch
-1], s
->delay
[ch
-1], s
->tmp_output
, s
->window
, add_bias
, 128);
655 x
[i
] = s
->transform_coeffs
[ch
][2*i
+1];
656 ff_imdct_half(&s
->imdct_256
, s
->delay
[ch
-1], x
);
658 ff_imdct_half(&s
->imdct_512
, s
->tmp_output
, s
->transform_coeffs
[ch
]);
659 s
->dsp
.vector_fmul_window(s
->output
[ch
-1], s
->delay
[ch
-1], s
->tmp_output
, s
->window
, add_bias
, 128);
660 memcpy(s
->delay
[ch
-1], s
->tmp_output
+128, 128*sizeof(float));
666 * Downmix the output to mono or stereo.
668 void ff_ac3_downmix_c(float (*samples
)[256], float (*matrix
)[2], int out_ch
, int in_ch
, int len
)
673 for(i
=0; i
<len
; i
++) {
675 for(j
=0; j
<in_ch
; j
++) {
676 v0
+= samples
[j
][i
] * matrix
[j
][0];
677 v1
+= samples
[j
][i
] * matrix
[j
][1];
682 } else if(out_ch
== 1) {
683 for(i
=0; i
<len
; i
++) {
685 for(j
=0; j
<in_ch
; j
++)
686 v0
+= samples
[j
][i
] * matrix
[j
][0];
693 * Upmix delay samples from stereo to original channel layout.
695 static void ac3_upmix_delay(AC3DecodeContext
*s
)
697 int channel_data_size
= sizeof(s
->delay
[0]);
698 switch(s
->channel_mode
) {
699 case AC3_CHMODE_DUALMONO
:
700 case AC3_CHMODE_STEREO
:
701 /* upmix mono to stereo */
702 memcpy(s
->delay
[1], s
->delay
[0], channel_data_size
);
704 case AC3_CHMODE_2F2R
:
705 memset(s
->delay
[3], 0, channel_data_size
);
706 case AC3_CHMODE_2F1R
:
707 memset(s
->delay
[2], 0, channel_data_size
);
709 case AC3_CHMODE_3F2R
:
710 memset(s
->delay
[4], 0, channel_data_size
);
711 case AC3_CHMODE_3F1R
:
712 memset(s
->delay
[3], 0, channel_data_size
);
714 memcpy(s
->delay
[2], s
->delay
[1], channel_data_size
);
715 memset(s
->delay
[1], 0, channel_data_size
);
721 * Decode band structure for coupling, spectral extension, or enhanced coupling.
722 * @param[in] gbc bit reader context
723 * @param[in] blk block number
724 * @param[in] eac3 flag to indicate E-AC-3
725 * @param[in] ecpl flag to indicate enhanced coupling
726 * @param[in] start_subband subband number for start of range
727 * @param[in] end_subband subband number for end of range
728 * @param[in] default_band_struct default band structure table
729 * @param[out] band_struct decoded band structure
730 * @param[out] num_subbands number of subbands (optionally NULL)
731 * @param[out] num_bands number of bands (optionally NULL)
732 * @param[out] band_sizes array containing the number of bins in each band (optionally NULL)
734 static void decode_band_structure(GetBitContext
*gbc
, int blk
, int eac3
,
735 int ecpl
, int start_subband
, int end_subband
,
736 const uint8_t *default_band_struct
,
737 uint8_t *band_struct
, int *num_subbands
,
738 int *num_bands
, uint8_t *band_sizes
)
740 int subbnd
, bnd
, n_subbands
, n_bands
=0;
743 n_subbands
= end_subband
- start_subband
;
745 /* decode band structure from bitstream or use default */
746 if (!eac3
|| get_bits1(gbc
)) {
747 for (subbnd
= 0; subbnd
< n_subbands
- 1; subbnd
++) {
748 band_struct
[subbnd
] = get_bits1(gbc
);
752 &default_band_struct
[start_subband
+1],
755 band_struct
[n_subbands
-1] = 0;
757 /* calculate number of bands and band sizes based on band structure.
758 note that the first 4 subbands in enhanced coupling span only 6 bins
760 if (num_bands
|| band_sizes
) {
761 n_bands
= n_subbands
;
762 bnd_sz
[0] = ecpl
? 6 : 12;
763 for (bnd
= 0, subbnd
= 1; subbnd
< n_subbands
; subbnd
++) {
764 int subbnd_size
= (ecpl
&& subbnd
< 4) ? 6 : 12;
765 if (band_struct
[subbnd
-1]) {
767 bnd_sz
[bnd
] += subbnd_size
;
769 bnd_sz
[++bnd
] = subbnd_size
;
774 /* set optional output params */
776 *num_subbands
= n_subbands
;
778 *num_bands
= n_bands
;
780 memcpy(band_sizes
, bnd_sz
, n_bands
);
784 * Decode a single audio block from the AC-3 bitstream.
786 static int decode_audio_block(AC3DecodeContext
*s
, int blk
)
788 int fbw_channels
= s
->fbw_channels
;
789 int channel_mode
= s
->channel_mode
;
791 int different_transforms
;
794 GetBitContext
*gbc
= &s
->gbc
;
795 uint8_t bit_alloc_stages
[AC3_MAX_CHANNELS
];
797 memset(bit_alloc_stages
, 0, AC3_MAX_CHANNELS
);
799 /* block switch flags */
800 different_transforms
= 0;
801 if (s
->block_switch_syntax
) {
802 for (ch
= 1; ch
<= fbw_channels
; ch
++) {
803 s
->block_switch
[ch
] = get_bits1(gbc
);
804 if(ch
> 1 && s
->block_switch
[ch
] != s
->block_switch
[1])
805 different_transforms
= 1;
809 /* dithering flags */
810 if (s
->dither_flag_syntax
) {
811 for (ch
= 1; ch
<= fbw_channels
; ch
++) {
812 s
->dither_flag
[ch
] = get_bits1(gbc
);
817 i
= !(s
->channel_mode
);
820 s
->dynamic_range
[i
] = ((dynamic_range_tab
[get_bits(gbc
, 8)]-1.0) *
821 s
->avctx
->drc_scale
)+1.0;
822 } else if(blk
== 0) {
823 s
->dynamic_range
[i
] = 1.0f
;
827 /* spectral extension strategy */
828 if (s
->eac3
&& (!blk
|| get_bits1(gbc
))) {
829 if (get_bits1(gbc
)) {
830 ff_log_missing_feature(s
->avctx
, "Spectral extension", 1);
833 /* TODO: parse spectral extension strategy info */
836 /* TODO: spectral extension coordinates */
838 /* coupling strategy */
839 if (s
->eac3
? s
->cpl_strategy_exists
[blk
] : get_bits1(gbc
)) {
840 memset(bit_alloc_stages
, 3, AC3_MAX_CHANNELS
);
842 s
->cpl_in_use
[blk
] = get_bits1(gbc
);
843 if (s
->cpl_in_use
[blk
]) {
844 /* coupling in use */
845 int cpl_start_subband
, cpl_end_subband
;
847 if (channel_mode
< AC3_CHMODE_STEREO
) {
848 av_log(s
->avctx
, AV_LOG_ERROR
, "coupling not allowed in mono or dual-mono\n");
852 /* check for enhanced coupling */
853 if (s
->eac3
&& get_bits1(gbc
)) {
854 /* TODO: parse enhanced coupling strategy info */
855 ff_log_missing_feature(s
->avctx
, "Enhanced coupling", 1);
859 /* determine which channels are coupled */
860 if (s
->eac3
&& s
->channel_mode
== AC3_CHMODE_STEREO
) {
861 s
->channel_in_cpl
[1] = 1;
862 s
->channel_in_cpl
[2] = 1;
864 for (ch
= 1; ch
<= fbw_channels
; ch
++)
865 s
->channel_in_cpl
[ch
] = get_bits1(gbc
);
868 /* phase flags in use */
869 if (channel_mode
== AC3_CHMODE_STEREO
)
870 s
->phase_flags_in_use
= get_bits1(gbc
);
872 /* coupling frequency range */
873 /* TODO: modify coupling end freq if spectral extension is used */
874 cpl_start_subband
= get_bits(gbc
, 4);
875 cpl_end_subband
= get_bits(gbc
, 4) + 3;
876 s
->num_cpl_subbands
= cpl_end_subband
- cpl_start_subband
;
877 if (s
->num_cpl_subbands
< 0) {
878 av_log(s
->avctx
, AV_LOG_ERROR
, "invalid coupling range (%d > %d)\n",
879 cpl_start_subband
, cpl_end_subband
);
882 s
->start_freq
[CPL_CH
] = cpl_start_subband
* 12 + 37;
883 s
->end_freq
[CPL_CH
] = cpl_end_subband
* 12 + 37;
885 decode_band_structure(gbc
, blk
, s
->eac3
, 0,
886 cpl_start_subband
, cpl_end_subband
,
887 ff_eac3_default_cpl_band_struct
,
888 s
->cpl_band_struct
, &s
->num_cpl_subbands
,
889 &s
->num_cpl_bands
, NULL
);
891 /* coupling not in use */
892 for (ch
= 1; ch
<= fbw_channels
; ch
++) {
893 s
->channel_in_cpl
[ch
] = 0;
894 s
->first_cpl_coords
[ch
] = 1;
896 s
->first_cpl_leak
= s
->eac3
;
897 s
->phase_flags_in_use
= 0;
899 } else if (!s
->eac3
) {
901 av_log(s
->avctx
, AV_LOG_ERROR
, "new coupling strategy must be present in block 0\n");
904 s
->cpl_in_use
[blk
] = s
->cpl_in_use
[blk
-1];
907 cpl_in_use
= s
->cpl_in_use
[blk
];
909 /* coupling coordinates */
911 int cpl_coords_exist
= 0;
913 for (ch
= 1; ch
<= fbw_channels
; ch
++) {
914 if (s
->channel_in_cpl
[ch
]) {
915 if ((s
->eac3
&& s
->first_cpl_coords
[ch
]) || get_bits1(gbc
)) {
916 int master_cpl_coord
, cpl_coord_exp
, cpl_coord_mant
;
917 s
->first_cpl_coords
[ch
] = 0;
918 cpl_coords_exist
= 1;
919 master_cpl_coord
= 3 * get_bits(gbc
, 2);
920 for (bnd
= 0; bnd
< s
->num_cpl_bands
; bnd
++) {
921 cpl_coord_exp
= get_bits(gbc
, 4);
922 cpl_coord_mant
= get_bits(gbc
, 4);
923 if (cpl_coord_exp
== 15)
924 s
->cpl_coords
[ch
][bnd
] = cpl_coord_mant
<< 22;
926 s
->cpl_coords
[ch
][bnd
] = (cpl_coord_mant
+ 16) << 21;
927 s
->cpl_coords
[ch
][bnd
] >>= (cpl_coord_exp
+ master_cpl_coord
);
930 av_log(s
->avctx
, AV_LOG_ERROR
, "new coupling coordinates must be present in block 0\n");
934 /* channel not in coupling */
935 s
->first_cpl_coords
[ch
] = 1;
939 if (channel_mode
== AC3_CHMODE_STEREO
&& cpl_coords_exist
) {
940 for (bnd
= 0; bnd
< s
->num_cpl_bands
; bnd
++) {
941 s
->phase_flags
[bnd
] = s
->phase_flags_in_use
? get_bits1(gbc
) : 0;
946 /* stereo rematrixing strategy and band structure */
947 if (channel_mode
== AC3_CHMODE_STEREO
) {
948 if ((s
->eac3
&& !blk
) || get_bits1(gbc
)) {
949 s
->num_rematrixing_bands
= 4;
950 if(cpl_in_use
&& s
->start_freq
[CPL_CH
] <= 61)
951 s
->num_rematrixing_bands
-= 1 + (s
->start_freq
[CPL_CH
] == 37);
952 for(bnd
=0; bnd
<s
->num_rematrixing_bands
; bnd
++)
953 s
->rematrixing_flags
[bnd
] = get_bits1(gbc
);
955 av_log(s
->avctx
, AV_LOG_ERROR
, "new rematrixing strategy must be present in block 0\n");
960 /* exponent strategies for each channel */
961 for (ch
= !cpl_in_use
; ch
<= s
->channels
; ch
++) {
963 s
->exp_strategy
[blk
][ch
] = get_bits(gbc
, 2 - (ch
== s
->lfe_ch
));
964 if(s
->exp_strategy
[blk
][ch
] != EXP_REUSE
)
965 bit_alloc_stages
[ch
] = 3;
968 /* channel bandwidth */
969 for (ch
= 1; ch
<= fbw_channels
; ch
++) {
970 s
->start_freq
[ch
] = 0;
971 if (s
->exp_strategy
[blk
][ch
] != EXP_REUSE
) {
973 int prev
= s
->end_freq
[ch
];
974 if (s
->channel_in_cpl
[ch
])
975 s
->end_freq
[ch
] = s
->start_freq
[CPL_CH
];
977 int bandwidth_code
= get_bits(gbc
, 6);
978 if (bandwidth_code
> 60) {
979 av_log(s
->avctx
, AV_LOG_ERROR
, "bandwidth code = %d > 60\n", bandwidth_code
);
982 s
->end_freq
[ch
] = bandwidth_code
* 3 + 73;
984 group_size
= 3 << (s
->exp_strategy
[blk
][ch
] - 1);
985 s
->num_exp_groups
[ch
] = (s
->end_freq
[ch
]+group_size
-4) / group_size
;
986 if(blk
> 0 && s
->end_freq
[ch
] != prev
)
987 memset(bit_alloc_stages
, 3, AC3_MAX_CHANNELS
);
990 if (cpl_in_use
&& s
->exp_strategy
[blk
][CPL_CH
] != EXP_REUSE
) {
991 s
->num_exp_groups
[CPL_CH
] = (s
->end_freq
[CPL_CH
] - s
->start_freq
[CPL_CH
]) /
992 (3 << (s
->exp_strategy
[blk
][CPL_CH
] - 1));
995 /* decode exponents for each channel */
996 for (ch
= !cpl_in_use
; ch
<= s
->channels
; ch
++) {
997 if (s
->exp_strategy
[blk
][ch
] != EXP_REUSE
) {
998 s
->dexps
[ch
][0] = get_bits(gbc
, 4) << !ch
;
999 if (decode_exponents(gbc
, s
->exp_strategy
[blk
][ch
],
1000 s
->num_exp_groups
[ch
], s
->dexps
[ch
][0],
1001 &s
->dexps
[ch
][s
->start_freq
[ch
]+!!ch
])) {
1002 av_log(s
->avctx
, AV_LOG_ERROR
, "exponent out-of-range\n");
1005 if(ch
!= CPL_CH
&& ch
!= s
->lfe_ch
)
1006 skip_bits(gbc
, 2); /* skip gainrng */
1010 /* bit allocation information */
1011 if (s
->bit_allocation_syntax
) {
1012 if (get_bits1(gbc
)) {
1013 s
->bit_alloc_params
.slow_decay
= ff_ac3_slow_decay_tab
[get_bits(gbc
, 2)] >> s
->bit_alloc_params
.sr_shift
;
1014 s
->bit_alloc_params
.fast_decay
= ff_ac3_fast_decay_tab
[get_bits(gbc
, 2)] >> s
->bit_alloc_params
.sr_shift
;
1015 s
->bit_alloc_params
.slow_gain
= ff_ac3_slow_gain_tab
[get_bits(gbc
, 2)];
1016 s
->bit_alloc_params
.db_per_bit
= ff_ac3_db_per_bit_tab
[get_bits(gbc
, 2)];
1017 s
->bit_alloc_params
.floor
= ff_ac3_floor_tab
[get_bits(gbc
, 3)];
1018 for(ch
=!cpl_in_use
; ch
<=s
->channels
; ch
++)
1019 bit_alloc_stages
[ch
] = FFMAX(bit_alloc_stages
[ch
], 2);
1021 av_log(s
->avctx
, AV_LOG_ERROR
, "new bit allocation info must be present in block 0\n");
1026 /* signal-to-noise ratio offsets and fast gains (signal-to-mask ratios) */
1027 if(!s
->eac3
|| !blk
){
1028 if(s
->snr_offset_strategy
&& get_bits1(gbc
)) {
1031 csnr
= (get_bits(gbc
, 6) - 15) << 4;
1032 for (i
= ch
= !cpl_in_use
; ch
<= s
->channels
; ch
++) {
1034 if (ch
== i
|| s
->snr_offset_strategy
== 2)
1035 snr
= (csnr
+ get_bits(gbc
, 4)) << 2;
1036 /* run at least last bit allocation stage if snr offset changes */
1037 if(blk
&& s
->snr_offset
[ch
] != snr
) {
1038 bit_alloc_stages
[ch
] = FFMAX(bit_alloc_stages
[ch
], 1);
1040 s
->snr_offset
[ch
] = snr
;
1042 /* fast gain (normal AC-3 only) */
1044 int prev
= s
->fast_gain
[ch
];
1045 s
->fast_gain
[ch
] = ff_ac3_fast_gain_tab
[get_bits(gbc
, 3)];
1046 /* run last 2 bit allocation stages if fast gain changes */
1047 if(blk
&& prev
!= s
->fast_gain
[ch
])
1048 bit_alloc_stages
[ch
] = FFMAX(bit_alloc_stages
[ch
], 2);
1051 } else if (!s
->eac3
&& !blk
) {
1052 av_log(s
->avctx
, AV_LOG_ERROR
, "new snr offsets must be present in block 0\n");
1057 /* fast gain (E-AC-3 only) */
1058 if (s
->fast_gain_syntax
&& get_bits1(gbc
)) {
1059 for (ch
= !cpl_in_use
; ch
<= s
->channels
; ch
++) {
1060 int prev
= s
->fast_gain
[ch
];
1061 s
->fast_gain
[ch
] = ff_ac3_fast_gain_tab
[get_bits(gbc
, 3)];
1062 /* run last 2 bit allocation stages if fast gain changes */
1063 if(blk
&& prev
!= s
->fast_gain
[ch
])
1064 bit_alloc_stages
[ch
] = FFMAX(bit_alloc_stages
[ch
], 2);
1066 } else if (s
->eac3
&& !blk
) {
1067 for (ch
= !cpl_in_use
; ch
<= s
->channels
; ch
++)
1068 s
->fast_gain
[ch
] = ff_ac3_fast_gain_tab
[4];
1071 /* E-AC-3 to AC-3 converter SNR offset */
1072 if (s
->frame_type
== EAC3_FRAME_TYPE_INDEPENDENT
&& get_bits1(gbc
)) {
1073 skip_bits(gbc
, 10); // skip converter snr offset
1076 /* coupling leak information */
1078 if (s
->first_cpl_leak
|| get_bits1(gbc
)) {
1079 int fl
= get_bits(gbc
, 3);
1080 int sl
= get_bits(gbc
, 3);
1081 /* run last 2 bit allocation stages for coupling channel if
1082 coupling leak changes */
1083 if(blk
&& (fl
!= s
->bit_alloc_params
.cpl_fast_leak
||
1084 sl
!= s
->bit_alloc_params
.cpl_slow_leak
)) {
1085 bit_alloc_stages
[CPL_CH
] = FFMAX(bit_alloc_stages
[CPL_CH
], 2);
1087 s
->bit_alloc_params
.cpl_fast_leak
= fl
;
1088 s
->bit_alloc_params
.cpl_slow_leak
= sl
;
1089 } else if (!s
->eac3
&& !blk
) {
1090 av_log(s
->avctx
, AV_LOG_ERROR
, "new coupling leak info must be present in block 0\n");
1093 s
->first_cpl_leak
= 0;
1096 /* delta bit allocation information */
1097 if (s
->dba_syntax
&& get_bits1(gbc
)) {
1098 /* delta bit allocation exists (strategy) */
1099 for (ch
= !cpl_in_use
; ch
<= fbw_channels
; ch
++) {
1100 s
->dba_mode
[ch
] = get_bits(gbc
, 2);
1101 if (s
->dba_mode
[ch
] == DBA_RESERVED
) {
1102 av_log(s
->avctx
, AV_LOG_ERROR
, "delta bit allocation strategy reserved\n");
1105 bit_alloc_stages
[ch
] = FFMAX(bit_alloc_stages
[ch
], 2);
1107 /* channel delta offset, len and bit allocation */
1108 for (ch
= !cpl_in_use
; ch
<= fbw_channels
; ch
++) {
1109 if (s
->dba_mode
[ch
] == DBA_NEW
) {
1110 s
->dba_nsegs
[ch
] = get_bits(gbc
, 3);
1111 for (seg
= 0; seg
<= s
->dba_nsegs
[ch
]; seg
++) {
1112 s
->dba_offsets
[ch
][seg
] = get_bits(gbc
, 5);
1113 s
->dba_lengths
[ch
][seg
] = get_bits(gbc
, 4);
1114 s
->dba_values
[ch
][seg
] = get_bits(gbc
, 3);
1116 /* run last 2 bit allocation stages if new dba values */
1117 bit_alloc_stages
[ch
] = FFMAX(bit_alloc_stages
[ch
], 2);
1120 } else if(blk
== 0) {
1121 for(ch
=0; ch
<=s
->channels
; ch
++) {
1122 s
->dba_mode
[ch
] = DBA_NONE
;
1126 /* Bit allocation */
1127 for(ch
=!cpl_in_use
; ch
<=s
->channels
; ch
++) {
1128 if(bit_alloc_stages
[ch
] > 2) {
1129 /* Exponent mapping into PSD and PSD integration */
1130 ff_ac3_bit_alloc_calc_psd(s
->dexps
[ch
],
1131 s
->start_freq
[ch
], s
->end_freq
[ch
],
1132 s
->psd
[ch
], s
->band_psd
[ch
]);
1134 if(bit_alloc_stages
[ch
] > 1) {
1135 /* Compute excitation function, Compute masking curve, and
1136 Apply delta bit allocation */
1137 if (ff_ac3_bit_alloc_calc_mask(&s
->bit_alloc_params
, s
->band_psd
[ch
],
1138 s
->start_freq
[ch
], s
->end_freq
[ch
],
1139 s
->fast_gain
[ch
], (ch
== s
->lfe_ch
),
1140 s
->dba_mode
[ch
], s
->dba_nsegs
[ch
],
1141 s
->dba_offsets
[ch
], s
->dba_lengths
[ch
],
1142 s
->dba_values
[ch
], s
->mask
[ch
])) {
1143 av_log(s
->avctx
, AV_LOG_ERROR
, "error in bit allocation\n");
1147 if(bit_alloc_stages
[ch
] > 0) {
1148 /* Compute bit allocation */
1149 const uint8_t *bap_tab
= s
->channel_uses_aht
[ch
] ?
1150 ff_eac3_hebap_tab
: ff_ac3_bap_tab
;
1151 ff_ac3_bit_alloc_calc_bap(s
->mask
[ch
], s
->psd
[ch
],
1152 s
->start_freq
[ch
], s
->end_freq
[ch
],
1154 s
->bit_alloc_params
.floor
,
1155 bap_tab
, s
->bap
[ch
]);
1159 /* unused dummy data */
1160 if (s
->skip_syntax
&& get_bits1(gbc
)) {
1161 int skipl
= get_bits(gbc
, 9);
1166 /* unpack the transform coefficients
1167 this also uncouples channels if coupling is in use. */
1168 decode_transform_coeffs(s
, blk
);
1170 /* TODO: generate enhanced coupling coordinates and uncouple */
1172 /* TODO: apply spectral extension */
1174 /* recover coefficients if rematrixing is in use */
1175 if(s
->channel_mode
== AC3_CHMODE_STEREO
)
1178 /* apply scaling to coefficients (headroom, dynrng) */
1179 for(ch
=1; ch
<=s
->channels
; ch
++) {
1180 float gain
= s
->mul_bias
/ 4194304.0f
;
1181 if(s
->channel_mode
== AC3_CHMODE_DUALMONO
) {
1182 gain
*= s
->dynamic_range
[ch
-1];
1184 gain
*= s
->dynamic_range
[0];
1186 s
->dsp
.int32_to_float_fmul_scalar(s
->transform_coeffs
[ch
], s
->fixed_coeffs
[ch
], gain
, 256);
1189 /* downmix and MDCT. order depends on whether block switching is used for
1190 any channel in this block. this is because coefficients for the long
1191 and short transforms cannot be mixed. */
1192 downmix_output
= s
->channels
!= s
->out_channels
&&
1193 !((s
->output_mode
& AC3_OUTPUT_LFEON
) &&
1194 s
->fbw_channels
== s
->out_channels
);
1195 if(different_transforms
) {
1196 /* the delay samples have already been downmixed, so we upmix the delay
1197 samples in order to reconstruct all channels before downmixing. */
1203 do_imdct(s
, s
->channels
);
1205 if(downmix_output
) {
1206 s
->dsp
.ac3_downmix(s
->output
, s
->downmix_coeffs
, s
->out_channels
, s
->fbw_channels
, 256);
1209 if(downmix_output
) {
1210 s
->dsp
.ac3_downmix(s
->transform_coeffs
+1, s
->downmix_coeffs
, s
->out_channels
, s
->fbw_channels
, 256);
1213 if(downmix_output
&& !s
->downmixed
) {
1215 s
->dsp
.ac3_downmix(s
->delay
, s
->downmix_coeffs
, s
->out_channels
, s
->fbw_channels
, 128);
1218 do_imdct(s
, s
->out_channels
);
1225 * Decode a single AC-3 frame.
1227 static int ac3_decode_frame(AVCodecContext
* avctx
, void *data
, int *data_size
,
1228 const uint8_t *buf
, int buf_size
)
1230 AC3DecodeContext
*s
= avctx
->priv_data
;
1231 int16_t *out_samples
= (int16_t *)data
;
1234 /* initialize the GetBitContext with the start of valid AC-3 Frame */
1235 if (s
->input_buffer
) {
1236 /* copy input buffer to decoder context to avoid reading past the end
1237 of the buffer, which can be caused by a damaged input stream. */
1238 memcpy(s
->input_buffer
, buf
, FFMIN(buf_size
, AC3_FRAME_BUFFER_SIZE
));
1239 init_get_bits(&s
->gbc
, s
->input_buffer
, buf_size
* 8);
1241 init_get_bits(&s
->gbc
, buf
, buf_size
* 8);
1244 /* parse the syncinfo */
1246 err
= parse_frame_header(s
);
1248 /* check that reported frame size fits in input buffer */
1249 if(s
->frame_size
> buf_size
) {
1250 av_log(avctx
, AV_LOG_ERROR
, "incomplete frame\n");
1251 err
= AC3_PARSE_ERROR_FRAME_SIZE
;
1254 /* check for crc mismatch */
1255 if(err
!= AC3_PARSE_ERROR_FRAME_SIZE
&& avctx
->error_recognition
>= FF_ER_CAREFUL
) {
1256 if(av_crc(av_crc_get_table(AV_CRC_16_ANSI
), 0, &buf
[2], s
->frame_size
-2)) {
1257 av_log(avctx
, AV_LOG_ERROR
, "frame CRC mismatch\n");
1258 err
= AC3_PARSE_ERROR_CRC
;
1262 if(err
&& err
!= AC3_PARSE_ERROR_CRC
) {
1264 case AC3_PARSE_ERROR_SYNC
:
1265 av_log(avctx
, AV_LOG_ERROR
, "frame sync error\n");
1267 case AC3_PARSE_ERROR_BSID
:
1268 av_log(avctx
, AV_LOG_ERROR
, "invalid bitstream id\n");
1270 case AC3_PARSE_ERROR_SAMPLE_RATE
:
1271 av_log(avctx
, AV_LOG_ERROR
, "invalid sample rate\n");
1273 case AC3_PARSE_ERROR_FRAME_SIZE
:
1274 av_log(avctx
, AV_LOG_ERROR
, "invalid frame size\n");
1276 case AC3_PARSE_ERROR_FRAME_TYPE
:
1277 /* skip frame if CRC is ok. otherwise use error concealment. */
1278 /* TODO: add support for substreams and dependent frames */
1279 if(s
->frame_type
== EAC3_FRAME_TYPE_DEPENDENT
|| s
->substreamid
) {
1280 av_log(avctx
, AV_LOG_ERROR
, "unsupported frame type : skipping frame\n");
1281 return s
->frame_size
;
1283 av_log(avctx
, AV_LOG_ERROR
, "invalid frame type\n");
1287 av_log(avctx
, AV_LOG_ERROR
, "invalid header\n");
1292 /* if frame is ok, set audio parameters */
1294 avctx
->sample_rate
= s
->sample_rate
;
1295 avctx
->bit_rate
= s
->bit_rate
;
1297 /* channel config */
1298 s
->out_channels
= s
->channels
;
1299 s
->output_mode
= s
->channel_mode
;
1301 s
->output_mode
|= AC3_OUTPUT_LFEON
;
1302 if (avctx
->request_channels
> 0 && avctx
->request_channels
<= 2 &&
1303 avctx
->request_channels
< s
->channels
) {
1304 s
->out_channels
= avctx
->request_channels
;
1305 s
->output_mode
= avctx
->request_channels
== 1 ? AC3_CHMODE_MONO
: AC3_CHMODE_STEREO
;
1307 avctx
->channels
= s
->out_channels
;
1309 /* set downmixing coefficients if needed */
1310 if(s
->channels
!= s
->out_channels
&& !((s
->output_mode
& AC3_OUTPUT_LFEON
) &&
1311 s
->fbw_channels
== s
->out_channels
)) {
1312 set_downmix_coeffs(s
);
1314 } else if (!s
->out_channels
) {
1315 s
->out_channels
= avctx
->channels
;
1316 if(s
->out_channels
< s
->channels
)
1317 s
->output_mode
= s
->out_channels
== 1 ? AC3_CHMODE_MONO
: AC3_CHMODE_STEREO
;
1320 /* decode the audio blocks */
1321 for (blk
= 0; blk
< s
->num_blocks
; blk
++) {
1322 const float *output
[s
->out_channels
];
1323 if (!err
&& decode_audio_block(s
, blk
)) {
1324 av_log(avctx
, AV_LOG_ERROR
, "error decoding the audio block\n");
1327 for (ch
= 0; ch
< s
->out_channels
; ch
++)
1328 output
[ch
] = s
->output
[ch
];
1329 s
->dsp
.float_to_int16_interleave(out_samples
, output
, 256, s
->out_channels
);
1330 out_samples
+= 256 * s
->out_channels
;
1332 *data_size
= s
->num_blocks
* 256 * avctx
->channels
* sizeof (int16_t);
1333 return s
->frame_size
;
1337 * Uninitialize the AC-3 decoder.
1339 static av_cold
int ac3_decode_end(AVCodecContext
*avctx
)
1341 AC3DecodeContext
*s
= avctx
->priv_data
;
1342 ff_mdct_end(&s
->imdct_512
);
1343 ff_mdct_end(&s
->imdct_256
);
1345 av_freep(&s
->input_buffer
);
1350 AVCodec ac3_decoder
= {
1352 .type
= CODEC_TYPE_AUDIO
,
1354 .priv_data_size
= sizeof (AC3DecodeContext
),
1355 .init
= ac3_decode_init
,
1356 .close
= ac3_decode_end
,
1357 .decode
= ac3_decode_frame
,
1358 .long_name
= NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"),
1361 AVCodec eac3_decoder
= {
1363 .type
= CODEC_TYPE_AUDIO
,
1364 .id
= CODEC_ID_EAC3
,
1365 .priv_data_size
= sizeof (AC3DecodeContext
),
1366 .init
= ac3_decode_init
,
1367 .close
= ac3_decode_end
,
1368 .decode
= ac3_decode_frame
,
1369 .long_name
= NULL_IF_CONFIG_SMALL("ATSC A/52B (AC-3, E-AC-3)"),