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"
38 #include "ac3_parser.h"
40 #include "ac3dec_data.h"
42 /** Large enough for maximum possible frame size when the specification limit is ignored */
43 #define AC3_FRAME_BUFFER_SIZE 32768
46 * table for ungrouping 3 values in 7 bits.
47 * used for exponents and bap=2 mantissas
49 static uint8_t ungroup_3_in_7_bits_tab
[128][3];
52 /** tables for ungrouping mantissas */
53 static int b1_mantissas
[32][3];
54 static int b2_mantissas
[128][3];
55 static int b3_mantissas
[8];
56 static int b4_mantissas
[128][2];
57 static int b5_mantissas
[16];
60 * Quantization table: levels for symmetric. bits for asymmetric.
61 * reference: Table 7.18 Mapping of bap to Quantizer
63 static const uint8_t quantization_tab
[16] = {
65 5, 6, 7, 8, 9, 10, 11, 12, 14, 16
68 /** dynamic range table. converts codes to scale factors. */
69 static float dynamic_range_tab
[256];
71 /** Adjustments in dB gain */
72 #define LEVEL_PLUS_3DB 1.4142135623730950
73 #define LEVEL_PLUS_1POINT5DB 1.1892071150027209
74 #define LEVEL_MINUS_1POINT5DB 0.8408964152537145
75 #define LEVEL_MINUS_3DB 0.7071067811865476
76 #define LEVEL_MINUS_4POINT5DB 0.5946035575013605
77 #define LEVEL_MINUS_6DB 0.5000000000000000
78 #define LEVEL_MINUS_9DB 0.3535533905932738
79 #define LEVEL_ZERO 0.0000000000000000
80 #define LEVEL_ONE 1.0000000000000000
82 static const float gain_levels
[9] = {
86 LEVEL_MINUS_1POINT5DB
,
88 LEVEL_MINUS_4POINT5DB
,
95 * Table for center mix levels
96 * reference: Section 5.4.2.4 cmixlev
98 static const uint8_t center_levels
[4] = { 4, 5, 6, 5 };
101 * Table for surround mix levels
102 * reference: Section 5.4.2.5 surmixlev
104 static const uint8_t surround_levels
[4] = { 4, 6, 7, 6 };
107 * Table for default stereo downmixing coefficients
108 * reference: Section 7.8.2 Downmixing Into Two Channels
110 static const uint8_t ac3_default_coeffs
[8][5][2] = {
111 { { 2, 7 }, { 7, 2 }, },
113 { { 2, 7 }, { 7, 2 }, },
114 { { 2, 7 }, { 5, 5 }, { 7, 2 }, },
115 { { 2, 7 }, { 7, 2 }, { 6, 6 }, },
116 { { 2, 7 }, { 5, 5 }, { 7, 2 }, { 8, 8 }, },
117 { { 2, 7 }, { 7, 2 }, { 6, 7 }, { 7, 6 }, },
118 { { 2, 7 }, { 5, 5 }, { 7, 2 }, { 6, 7 }, { 7, 6 }, },
122 * Symmetrical Dequantization
123 * reference: Section 7.3.3 Expansion of Mantissas for Symmetrical Quantization
124 * Tables 7.19 to 7.23
127 symmetric_dequant(int code
, int levels
)
129 return ((code
- (levels
>> 1)) << 24) / levels
;
133 * Initialize tables at runtime.
135 static av_cold
void ac3_tables_init(void)
139 /* generate table for ungrouping 3 values in 7 bits
140 reference: Section 7.1.3 Exponent Decoding */
141 for(i
=0; i
<128; i
++) {
142 ungroup_3_in_7_bits_tab
[i
][0] = i
/ 25;
143 ungroup_3_in_7_bits_tab
[i
][1] = (i
% 25) / 5;
144 ungroup_3_in_7_bits_tab
[i
][2] = (i
% 25) % 5;
147 /* generate grouped mantissa tables
148 reference: Section 7.3.5 Ungrouping of Mantissas */
149 for(i
=0; i
<32; i
++) {
150 /* bap=1 mantissas */
151 b1_mantissas
[i
][0] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab
[i
][0], 3);
152 b1_mantissas
[i
][1] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab
[i
][1], 3);
153 b1_mantissas
[i
][2] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab
[i
][2], 3);
155 for(i
=0; i
<128; i
++) {
156 /* bap=2 mantissas */
157 b2_mantissas
[i
][0] = symmetric_dequant(ungroup_3_in_7_bits_tab
[i
][0], 5);
158 b2_mantissas
[i
][1] = symmetric_dequant(ungroup_3_in_7_bits_tab
[i
][1], 5);
159 b2_mantissas
[i
][2] = symmetric_dequant(ungroup_3_in_7_bits_tab
[i
][2], 5);
161 /* bap=4 mantissas */
162 b4_mantissas
[i
][0] = symmetric_dequant(i
/ 11, 11);
163 b4_mantissas
[i
][1] = symmetric_dequant(i
% 11, 11);
165 /* generate ungrouped mantissa tables
166 reference: Tables 7.21 and 7.23 */
168 /* bap=3 mantissas */
169 b3_mantissas
[i
] = symmetric_dequant(i
, 7);
171 for(i
=0; i
<15; i
++) {
172 /* bap=5 mantissas */
173 b5_mantissas
[i
] = symmetric_dequant(i
, 15);
176 /* generate dynamic range table
177 reference: Section 7.7.1 Dynamic Range Control */
178 for(i
=0; i
<256; i
++) {
179 int v
= (i
>> 5) - ((i
>> 7) << 3) - 5;
180 dynamic_range_tab
[i
] = powf(2.0f
, v
) * ((i
& 0x1F) | 0x20);
186 * AVCodec initialization
188 static av_cold
int ac3_decode_init(AVCodecContext
*avctx
)
190 AC3DecodeContext
*s
= avctx
->priv_data
;
195 ff_mdct_init(&s
->imdct_256
, 8, 1);
196 ff_mdct_init(&s
->imdct_512
, 9, 1);
197 ff_kbd_window_init(s
->window
, 5.0, 256);
198 dsputil_init(&s
->dsp
, avctx
);
199 av_lfg_init(&s
->dith_state
, 0);
201 /* set bias values for float to int16 conversion */
202 if(s
->dsp
.float_to_int16_interleave
== ff_float_to_int16_interleave_c
) {
203 s
->add_bias
= 385.0f
;
207 s
->mul_bias
= 32767.0f
;
210 /* allow downmixing to stereo or mono */
211 if (avctx
->channels
> 0 && avctx
->request_channels
> 0 &&
212 avctx
->request_channels
< avctx
->channels
&&
213 avctx
->request_channels
<= 2) {
214 avctx
->channels
= avctx
->request_channels
;
218 /* allocate context input buffer */
219 if (avctx
->error_recognition
>= FF_ER_CAREFUL
) {
220 s
->input_buffer
= av_mallocz(AC3_FRAME_BUFFER_SIZE
+ FF_INPUT_BUFFER_PADDING_SIZE
);
221 if (!s
->input_buffer
)
222 return AVERROR_NOMEM
;
225 avctx
->sample_fmt
= SAMPLE_FMT_S16
;
230 * Parse the 'sync info' and 'bit stream info' from the AC-3 bitstream.
231 * GetBitContext within AC3DecodeContext must point to
232 * the start of the synchronized AC-3 bitstream.
234 static int ac3_parse_header(AC3DecodeContext
*s
)
236 GetBitContext
*gbc
= &s
->gbc
;
239 /* read the rest of the bsi. read twice for dual mono mode. */
240 i
= !(s
->channel_mode
);
242 skip_bits(gbc
, 5); // skip dialog normalization
244 skip_bits(gbc
, 8); //skip compression
246 skip_bits(gbc
, 8); //skip language code
248 skip_bits(gbc
, 7); //skip audio production information
251 skip_bits(gbc
, 2); //skip copyright bit and original bitstream bit
253 /* skip the timecodes (or extra bitstream information for Alternate Syntax)
254 TODO: read & use the xbsi1 downmix levels */
256 skip_bits(gbc
, 14); //skip timecode1 / xbsi1
258 skip_bits(gbc
, 14); //skip timecode2 / xbsi2
260 /* skip additional bitstream info */
261 if (get_bits1(gbc
)) {
262 i
= get_bits(gbc
, 6);
272 * Common function to parse AC-3 or E-AC-3 frame header
274 static int parse_frame_header(AC3DecodeContext
*s
)
279 err
= ff_ac3_parse_header(&s
->gbc
, &hdr
);
283 /* get decoding parameters from header info */
284 s
->bit_alloc_params
.sr_code
= hdr
.sr_code
;
285 s
->channel_mode
= hdr
.channel_mode
;
286 s
->lfe_on
= hdr
.lfe_on
;
287 s
->bit_alloc_params
.sr_shift
= hdr
.sr_shift
;
288 s
->sample_rate
= hdr
.sample_rate
;
289 s
->bit_rate
= hdr
.bit_rate
;
290 s
->channels
= hdr
.channels
;
291 s
->fbw_channels
= s
->channels
- s
->lfe_on
;
292 s
->lfe_ch
= s
->fbw_channels
+ 1;
293 s
->frame_size
= hdr
.frame_size
;
294 s
->center_mix_level
= hdr
.center_mix_level
;
295 s
->surround_mix_level
= hdr
.surround_mix_level
;
296 s
->num_blocks
= hdr
.num_blocks
;
297 s
->frame_type
= hdr
.frame_type
;
298 s
->substreamid
= hdr
.substreamid
;
301 s
->start_freq
[s
->lfe_ch
] = 0;
302 s
->end_freq
[s
->lfe_ch
] = 7;
303 s
->num_exp_groups
[s
->lfe_ch
] = 2;
304 s
->channel_in_cpl
[s
->lfe_ch
] = 0;
307 if (hdr
.bitstream_id
<= 10) {
309 s
->snr_offset_strategy
= 2;
310 s
->block_switch_syntax
= 1;
311 s
->dither_flag_syntax
= 1;
312 s
->bit_allocation_syntax
= 1;
313 s
->fast_gain_syntax
= 0;
314 s
->first_cpl_leak
= 0;
317 memset(s
->channel_uses_aht
, 0, sizeof(s
->channel_uses_aht
));
318 return ac3_parse_header(s
);
321 return ff_eac3_parse_header(s
);
326 * Set stereo downmixing coefficients based on frame header info.
327 * reference: Section 7.8.2 Downmixing Into Two Channels
329 static void set_downmix_coeffs(AC3DecodeContext
*s
)
332 float cmix
= gain_levels
[center_levels
[s
->center_mix_level
]];
333 float smix
= gain_levels
[surround_levels
[s
->surround_mix_level
]];
336 for(i
=0; i
<s
->fbw_channels
; i
++) {
337 s
->downmix_coeffs
[i
][0] = gain_levels
[ac3_default_coeffs
[s
->channel_mode
][i
][0]];
338 s
->downmix_coeffs
[i
][1] = gain_levels
[ac3_default_coeffs
[s
->channel_mode
][i
][1]];
340 if(s
->channel_mode
> 1 && s
->channel_mode
& 1) {
341 s
->downmix_coeffs
[1][0] = s
->downmix_coeffs
[1][1] = cmix
;
343 if(s
->channel_mode
== AC3_CHMODE_2F1R
|| s
->channel_mode
== AC3_CHMODE_3F1R
) {
344 int nf
= s
->channel_mode
- 2;
345 s
->downmix_coeffs
[nf
][0] = s
->downmix_coeffs
[nf
][1] = smix
* LEVEL_MINUS_3DB
;
347 if(s
->channel_mode
== AC3_CHMODE_2F2R
|| s
->channel_mode
== AC3_CHMODE_3F2R
) {
348 int nf
= s
->channel_mode
- 4;
349 s
->downmix_coeffs
[nf
][0] = s
->downmix_coeffs
[nf
+1][1] = smix
;
354 for(i
=0; i
<s
->fbw_channels
; i
++) {
355 norm0
+= s
->downmix_coeffs
[i
][0];
356 norm1
+= s
->downmix_coeffs
[i
][1];
358 norm0
= 1.0f
/ norm0
;
359 norm1
= 1.0f
/ norm1
;
360 for(i
=0; i
<s
->fbw_channels
; i
++) {
361 s
->downmix_coeffs
[i
][0] *= norm0
;
362 s
->downmix_coeffs
[i
][1] *= norm1
;
365 if(s
->output_mode
== AC3_CHMODE_MONO
) {
366 for(i
=0; i
<s
->fbw_channels
; i
++)
367 s
->downmix_coeffs
[i
][0] = (s
->downmix_coeffs
[i
][0] + s
->downmix_coeffs
[i
][1]) * LEVEL_MINUS_3DB
;
372 * Decode the grouped exponents according to exponent strategy.
373 * reference: Section 7.1.3 Exponent Decoding
375 static void decode_exponents(GetBitContext
*gbc
, int exp_strategy
, int ngrps
,
376 uint8_t absexp
, int8_t *dexps
)
378 int i
, j
, grp
, group_size
;
383 group_size
= exp_strategy
+ (exp_strategy
== EXP_D45
);
384 for(grp
=0,i
=0; grp
<ngrps
; grp
++) {
385 expacc
= get_bits(gbc
, 7);
386 dexp
[i
++] = ungroup_3_in_7_bits_tab
[expacc
][0];
387 dexp
[i
++] = ungroup_3_in_7_bits_tab
[expacc
][1];
388 dexp
[i
++] = ungroup_3_in_7_bits_tab
[expacc
][2];
391 /* convert to absolute exps and expand groups */
393 for(i
=0; i
<ngrps
*3; i
++) {
394 prevexp
= av_clip(prevexp
+ dexp
[i
]-2, 0, 24);
395 for(j
=0; j
<group_size
; j
++) {
396 dexps
[(i
*group_size
)+j
] = prevexp
;
402 * Generate transform coefficients for each coupled channel in the coupling
403 * range using the coupling coefficients and coupling coordinates.
404 * reference: Section 7.4.3 Coupling Coordinate Format
406 static void calc_transform_coeffs_cpl(AC3DecodeContext
*s
)
408 int i
, j
, ch
, bnd
, subbnd
;
411 i
= s
->start_freq
[CPL_CH
];
412 for(bnd
=0; bnd
<s
->num_cpl_bands
; bnd
++) {
415 for(j
=0; j
<12; j
++) {
416 for(ch
=1; ch
<=s
->fbw_channels
; ch
++) {
417 if(s
->channel_in_cpl
[ch
]) {
418 s
->fixed_coeffs
[ch
][i
] = ((int64_t)s
->fixed_coeffs
[CPL_CH
][i
] * (int64_t)s
->cpl_coords
[ch
][bnd
]) >> 23;
419 if (ch
== 2 && s
->phase_flags
[bnd
])
420 s
->fixed_coeffs
[ch
][i
] = -s
->fixed_coeffs
[ch
][i
];
425 } while(s
->cpl_band_struct
[subbnd
]);
430 * Grouped mantissas for 3-level 5-level and 11-level quantization
442 * Decode the transform coefficients for a particular channel
443 * reference: Section 7.3 Quantization and Decoding of Mantissas
445 static void ac3_decode_transform_coeffs_ch(AC3DecodeContext
*s
, int ch_index
, mant_groups
*m
)
447 GetBitContext
*gbc
= &s
->gbc
;
448 int i
, gcode
, tbap
, start
, end
;
453 exps
= s
->dexps
[ch_index
];
454 bap
= s
->bap
[ch_index
];
455 coeffs
= s
->fixed_coeffs
[ch_index
];
456 start
= s
->start_freq
[ch_index
];
457 end
= s
->end_freq
[ch_index
];
459 for (i
= start
; i
< end
; i
++) {
463 coeffs
[i
] = (av_lfg_get(&s
->dith_state
) & 0x7FFFFF) - 0x400000;
468 gcode
= get_bits(gbc
, 5);
469 m
->b1_mant
[0] = b1_mantissas
[gcode
][0];
470 m
->b1_mant
[1] = b1_mantissas
[gcode
][1];
471 m
->b1_mant
[2] = b1_mantissas
[gcode
][2];
474 coeffs
[i
] = m
->b1_mant
[m
->b1ptr
++];
479 gcode
= get_bits(gbc
, 7);
480 m
->b2_mant
[0] = b2_mantissas
[gcode
][0];
481 m
->b2_mant
[1] = b2_mantissas
[gcode
][1];
482 m
->b2_mant
[2] = b2_mantissas
[gcode
][2];
485 coeffs
[i
] = m
->b2_mant
[m
->b2ptr
++];
489 coeffs
[i
] = b3_mantissas
[get_bits(gbc
, 3)];
494 gcode
= get_bits(gbc
, 7);
495 m
->b4_mant
[0] = b4_mantissas
[gcode
][0];
496 m
->b4_mant
[1] = b4_mantissas
[gcode
][1];
499 coeffs
[i
] = m
->b4_mant
[m
->b4ptr
++];
503 coeffs
[i
] = b5_mantissas
[get_bits(gbc
, 4)];
507 /* asymmetric dequantization */
508 int qlevel
= quantization_tab
[tbap
];
509 coeffs
[i
] = get_sbits(gbc
, qlevel
) << (24 - qlevel
);
513 coeffs
[i
] >>= exps
[i
];
518 * Remove random dithering from coefficients with zero-bit mantissas
519 * reference: Section 7.3.4 Dither for Zero Bit Mantissas (bap=0)
521 static void remove_dithering(AC3DecodeContext
*s
) {
527 for(ch
=1; ch
<=s
->fbw_channels
; ch
++) {
528 if(!s
->dither_flag
[ch
]) {
529 coeffs
= s
->fixed_coeffs
[ch
];
531 if(s
->channel_in_cpl
[ch
])
532 end
= s
->start_freq
[CPL_CH
];
534 end
= s
->end_freq
[ch
];
535 for(i
=0; i
<end
; i
++) {
539 if(s
->channel_in_cpl
[ch
]) {
540 bap
= s
->bap
[CPL_CH
];
541 for(; i
<s
->end_freq
[CPL_CH
]; i
++) {
550 static void decode_transform_coeffs_ch(AC3DecodeContext
*s
, int blk
, int ch
,
553 if (!s
->channel_uses_aht
[ch
]) {
554 ac3_decode_transform_coeffs_ch(s
, ch
, m
);
556 /* if AHT is used, mantissas for all blocks are encoded in the first
557 block of the frame. */
560 ff_eac3_decode_transform_coeffs_aht_ch(s
, ch
);
561 for (bin
= s
->start_freq
[ch
]; bin
< s
->end_freq
[ch
]; bin
++) {
562 s
->fixed_coeffs
[ch
][bin
] = s
->pre_mantissa
[ch
][bin
][blk
] >> s
->dexps
[ch
][bin
];
568 * Decode the transform coefficients.
570 static void decode_transform_coeffs(AC3DecodeContext
*s
, int blk
)
576 m
.b1ptr
= m
.b2ptr
= m
.b4ptr
= 3;
578 for (ch
= 1; ch
<= s
->channels
; ch
++) {
579 /* transform coefficients for full-bandwidth channel */
580 decode_transform_coeffs_ch(s
, blk
, ch
, &m
);
581 /* tranform coefficients for coupling channel come right after the
582 coefficients for the first coupled channel*/
583 if (s
->channel_in_cpl
[ch
]) {
585 decode_transform_coeffs_ch(s
, blk
, CPL_CH
, &m
);
586 calc_transform_coeffs_cpl(s
);
589 end
= s
->end_freq
[CPL_CH
];
591 end
= s
->end_freq
[ch
];
594 s
->fixed_coeffs
[ch
][end
] = 0;
598 /* zero the dithered coefficients for appropriate channels */
603 * Stereo rematrixing.
604 * reference: Section 7.5.4 Rematrixing : Decoding Technique
606 static void do_rematrixing(AC3DecodeContext
*s
)
612 end
= FFMIN(s
->end_freq
[1], s
->end_freq
[2]);
614 for(bnd
=0; bnd
<s
->num_rematrixing_bands
; bnd
++) {
615 if(s
->rematrixing_flags
[bnd
]) {
616 bndend
= FFMIN(end
, ff_ac3_rematrix_band_tab
[bnd
+1]);
617 for(i
=ff_ac3_rematrix_band_tab
[bnd
]; i
<bndend
; i
++) {
618 tmp0
= s
->fixed_coeffs
[1][i
];
619 tmp1
= s
->fixed_coeffs
[2][i
];
620 s
->fixed_coeffs
[1][i
] = tmp0
+ tmp1
;
621 s
->fixed_coeffs
[2][i
] = tmp0
- tmp1
;
628 * Inverse MDCT Transform.
629 * Convert frequency domain coefficients to time-domain audio samples.
630 * reference: Section 7.9.4 Transformation Equations
632 static inline void do_imdct(AC3DecodeContext
*s
, int channels
)
635 float add_bias
= s
->add_bias
;
636 if(s
->out_channels
==1 && channels
>1)
637 add_bias
*= LEVEL_MINUS_3DB
; // compensate for the gain in downmix
639 for (ch
=1; ch
<=channels
; ch
++) {
640 if (s
->block_switch
[ch
]) {
642 float *x
= s
->tmp_output
+128;
644 x
[i
] = s
->transform_coeffs
[ch
][2*i
];
645 ff_imdct_half(&s
->imdct_256
, s
->tmp_output
, x
);
646 s
->dsp
.vector_fmul_window(s
->output
[ch
-1], s
->delay
[ch
-1], s
->tmp_output
, s
->window
, add_bias
, 128);
648 x
[i
] = s
->transform_coeffs
[ch
][2*i
+1];
649 ff_imdct_half(&s
->imdct_256
, s
->delay
[ch
-1], x
);
651 ff_imdct_half(&s
->imdct_512
, s
->tmp_output
, s
->transform_coeffs
[ch
]);
652 s
->dsp
.vector_fmul_window(s
->output
[ch
-1], s
->delay
[ch
-1], s
->tmp_output
, s
->window
, add_bias
, 128);
653 memcpy(s
->delay
[ch
-1], s
->tmp_output
+128, 128*sizeof(float));
659 * Downmix the output to mono or stereo.
661 void ff_ac3_downmix_c(float (*samples
)[256], float (*matrix
)[2], int out_ch
, int in_ch
, int len
)
666 for(i
=0; i
<len
; i
++) {
668 for(j
=0; j
<in_ch
; j
++) {
669 v0
+= samples
[j
][i
] * matrix
[j
][0];
670 v1
+= samples
[j
][i
] * matrix
[j
][1];
675 } else if(out_ch
== 1) {
676 for(i
=0; i
<len
; i
++) {
678 for(j
=0; j
<in_ch
; j
++)
679 v0
+= samples
[j
][i
] * matrix
[j
][0];
686 * Upmix delay samples from stereo to original channel layout.
688 static void ac3_upmix_delay(AC3DecodeContext
*s
)
690 int channel_data_size
= sizeof(s
->delay
[0]);
691 switch(s
->channel_mode
) {
692 case AC3_CHMODE_DUALMONO
:
693 case AC3_CHMODE_STEREO
:
694 /* upmix mono to stereo */
695 memcpy(s
->delay
[1], s
->delay
[0], channel_data_size
);
697 case AC3_CHMODE_2F2R
:
698 memset(s
->delay
[3], 0, channel_data_size
);
699 case AC3_CHMODE_2F1R
:
700 memset(s
->delay
[2], 0, channel_data_size
);
702 case AC3_CHMODE_3F2R
:
703 memset(s
->delay
[4], 0, channel_data_size
);
704 case AC3_CHMODE_3F1R
:
705 memset(s
->delay
[3], 0, channel_data_size
);
707 memcpy(s
->delay
[2], s
->delay
[1], channel_data_size
);
708 memset(s
->delay
[1], 0, channel_data_size
);
714 * Decode band structure for coupling, spectral extension, or enhanced coupling.
715 * @param[in] gbc bit reader context
716 * @param[in] blk block number
717 * @param[in] eac3 flag to indicate E-AC-3
718 * @param[in] ecpl flag to indicate enhanced coupling
719 * @param[in] start_subband subband number for start of range
720 * @param[in] end_subband subband number for end of range
721 * @param[in] default_band_struct default band structure table
722 * @param[out] band_struct decoded band structure
723 * @param[out] num_subbands number of subbands (optionally NULL)
724 * @param[out] num_bands number of bands (optionally NULL)
725 * @param[out] band_sizes array containing the number of bins in each band (optionally NULL)
727 static void decode_band_structure(GetBitContext
*gbc
, int blk
, int eac3
,
728 int ecpl
, int start_subband
, int end_subband
,
729 const uint8_t *default_band_struct
,
730 uint8_t *band_struct
, int *num_subbands
,
731 int *num_bands
, int *band_sizes
)
733 int subbnd
, bnd
, n_subbands
, n_bands
, bnd_sz
[22];
735 n_subbands
= end_subband
- start_subband
;
737 /* decode band structure from bitstream or use default */
738 if (!eac3
|| get_bits1(gbc
)) {
739 for (subbnd
= 0; subbnd
< n_subbands
- 1; subbnd
++) {
740 band_struct
[subbnd
] = get_bits1(gbc
);
744 &default_band_struct
[start_subband
+1],
747 band_struct
[n_subbands
-1] = 0;
749 /* calculate number of bands and band sizes based on band structure.
750 note that the first 4 subbands in enhanced coupling span only 6 bins
752 if (num_bands
|| band_sizes
) {
753 n_bands
= n_subbands
;
754 bnd_sz
[0] = ecpl
? 6 : 12;
755 for (bnd
= 0, subbnd
= 1; subbnd
< n_subbands
; subbnd
++) {
756 int subbnd_size
= (ecpl
&& subbnd
< 4) ? 6 : 12;
757 if (band_struct
[subbnd
-1]) {
759 bnd_sz
[bnd
] += subbnd_size
;
761 bnd_sz
[++bnd
] = subbnd_size
;
766 /* set optional output params */
768 *num_subbands
= n_subbands
;
770 *num_bands
= n_bands
;
772 memcpy(band_sizes
, bnd_sz
, sizeof(int)*n_bands
);
776 * Decode a single audio block from the AC-3 bitstream.
778 static int decode_audio_block(AC3DecodeContext
*s
, int blk
)
780 int fbw_channels
= s
->fbw_channels
;
781 int channel_mode
= s
->channel_mode
;
783 int different_transforms
;
786 GetBitContext
*gbc
= &s
->gbc
;
787 uint8_t bit_alloc_stages
[AC3_MAX_CHANNELS
];
789 memset(bit_alloc_stages
, 0, AC3_MAX_CHANNELS
);
791 /* block switch flags */
792 different_transforms
= 0;
793 if (s
->block_switch_syntax
) {
794 for (ch
= 1; ch
<= fbw_channels
; ch
++) {
795 s
->block_switch
[ch
] = get_bits1(gbc
);
796 if(ch
> 1 && s
->block_switch
[ch
] != s
->block_switch
[1])
797 different_transforms
= 1;
801 /* dithering flags */
802 if (s
->dither_flag_syntax
) {
803 for (ch
= 1; ch
<= fbw_channels
; ch
++) {
804 s
->dither_flag
[ch
] = get_bits1(gbc
);
809 i
= !(s
->channel_mode
);
812 s
->dynamic_range
[i
] = ((dynamic_range_tab
[get_bits(gbc
, 8)]-1.0) *
813 s
->avctx
->drc_scale
)+1.0;
814 } else if(blk
== 0) {
815 s
->dynamic_range
[i
] = 1.0f
;
819 /* spectral extension strategy */
820 if (s
->eac3
&& (!blk
|| get_bits1(gbc
))) {
821 if (get_bits1(gbc
)) {
822 av_log_missing_feature(s
->avctx
, "Spectral extension", 1);
825 /* TODO: parse spectral extension strategy info */
828 /* TODO: spectral extension coordinates */
830 /* coupling strategy */
831 if (s
->eac3
? s
->cpl_strategy_exists
[blk
] : get_bits1(gbc
)) {
832 memset(bit_alloc_stages
, 3, AC3_MAX_CHANNELS
);
834 s
->cpl_in_use
[blk
] = get_bits1(gbc
);
835 if (s
->cpl_in_use
[blk
]) {
836 /* coupling in use */
837 int cpl_start_subband
, cpl_end_subband
;
839 if (channel_mode
< AC3_CHMODE_STEREO
) {
840 av_log(s
->avctx
, AV_LOG_ERROR
, "coupling not allowed in mono or dual-mono\n");
844 /* check for enhanced coupling */
845 if (s
->eac3
&& get_bits1(gbc
)) {
846 /* TODO: parse enhanced coupling strategy info */
847 av_log_missing_feature(s
->avctx
, "Enhanced coupling", 1);
851 /* determine which channels are coupled */
852 if (s
->eac3
&& s
->channel_mode
== AC3_CHMODE_STEREO
) {
853 s
->channel_in_cpl
[1] = 1;
854 s
->channel_in_cpl
[2] = 1;
856 for (ch
= 1; ch
<= fbw_channels
; ch
++)
857 s
->channel_in_cpl
[ch
] = get_bits1(gbc
);
860 /* phase flags in use */
861 if (channel_mode
== AC3_CHMODE_STEREO
)
862 s
->phase_flags_in_use
= get_bits1(gbc
);
864 /* coupling frequency range */
865 /* TODO: modify coupling end freq if spectral extension is used */
866 cpl_start_subband
= get_bits(gbc
, 4);
867 cpl_end_subband
= get_bits(gbc
, 4) + 3;
868 s
->num_cpl_subbands
= cpl_end_subband
- cpl_start_subband
;
869 if (s
->num_cpl_subbands
< 0) {
870 av_log(s
->avctx
, AV_LOG_ERROR
, "invalid coupling range (%d > %d)\n",
871 cpl_start_subband
, cpl_end_subband
);
874 s
->start_freq
[CPL_CH
] = cpl_start_subband
* 12 + 37;
875 s
->end_freq
[CPL_CH
] = cpl_end_subband
* 12 + 37;
877 decode_band_structure(gbc
, blk
, s
->eac3
, 0,
878 cpl_start_subband
, cpl_end_subband
,
879 ff_eac3_default_cpl_band_struct
,
880 s
->cpl_band_struct
, &s
->num_cpl_subbands
,
881 &s
->num_cpl_bands
, NULL
);
883 /* coupling not in use */
884 for (ch
= 1; ch
<= fbw_channels
; ch
++) {
885 s
->channel_in_cpl
[ch
] = 0;
886 s
->first_cpl_coords
[ch
] = 1;
888 s
->first_cpl_leak
= s
->eac3
;
889 s
->phase_flags_in_use
= 0;
891 } else if (!s
->eac3
) {
893 av_log(s
->avctx
, AV_LOG_ERROR
, "new coupling strategy must be present in block 0\n");
896 s
->cpl_in_use
[blk
] = s
->cpl_in_use
[blk
-1];
899 cpl_in_use
= s
->cpl_in_use
[blk
];
901 /* coupling coordinates */
903 int cpl_coords_exist
= 0;
905 for (ch
= 1; ch
<= fbw_channels
; ch
++) {
906 if (s
->channel_in_cpl
[ch
]) {
907 if ((s
->eac3
&& s
->first_cpl_coords
[ch
]) || get_bits1(gbc
)) {
908 int master_cpl_coord
, cpl_coord_exp
, cpl_coord_mant
;
909 s
->first_cpl_coords
[ch
] = 0;
910 cpl_coords_exist
= 1;
911 master_cpl_coord
= 3 * get_bits(gbc
, 2);
912 for (bnd
= 0; bnd
< s
->num_cpl_bands
; bnd
++) {
913 cpl_coord_exp
= get_bits(gbc
, 4);
914 cpl_coord_mant
= get_bits(gbc
, 4);
915 if (cpl_coord_exp
== 15)
916 s
->cpl_coords
[ch
][bnd
] = cpl_coord_mant
<< 22;
918 s
->cpl_coords
[ch
][bnd
] = (cpl_coord_mant
+ 16) << 21;
919 s
->cpl_coords
[ch
][bnd
] >>= (cpl_coord_exp
+ master_cpl_coord
);
922 av_log(s
->avctx
, AV_LOG_ERROR
, "new coupling coordinates must be present in block 0\n");
926 /* channel not in coupling */
927 s
->first_cpl_coords
[ch
] = 1;
931 if (channel_mode
== AC3_CHMODE_STEREO
&& cpl_coords_exist
) {
932 for (bnd
= 0; bnd
< s
->num_cpl_bands
; bnd
++) {
933 s
->phase_flags
[bnd
] = s
->phase_flags_in_use
? get_bits1(gbc
) : 0;
938 /* stereo rematrixing strategy and band structure */
939 if (channel_mode
== AC3_CHMODE_STEREO
) {
940 if ((s
->eac3
&& !blk
) || get_bits1(gbc
)) {
941 s
->num_rematrixing_bands
= 4;
942 if(cpl_in_use
&& s
->start_freq
[CPL_CH
] <= 61)
943 s
->num_rematrixing_bands
-= 1 + (s
->start_freq
[CPL_CH
] == 37);
944 for(bnd
=0; bnd
<s
->num_rematrixing_bands
; bnd
++)
945 s
->rematrixing_flags
[bnd
] = get_bits1(gbc
);
947 av_log(s
->avctx
, AV_LOG_ERROR
, "new rematrixing strategy must be present in block 0\n");
952 /* exponent strategies for each channel */
953 for (ch
= !cpl_in_use
; ch
<= s
->channels
; ch
++) {
955 s
->exp_strategy
[blk
][ch
] = get_bits(gbc
, 2 - (ch
== s
->lfe_ch
));
956 if(s
->exp_strategy
[blk
][ch
] != EXP_REUSE
)
957 bit_alloc_stages
[ch
] = 3;
960 /* channel bandwidth */
961 for (ch
= 1; ch
<= fbw_channels
; ch
++) {
962 s
->start_freq
[ch
] = 0;
963 if (s
->exp_strategy
[blk
][ch
] != EXP_REUSE
) {
965 int prev
= s
->end_freq
[ch
];
966 if (s
->channel_in_cpl
[ch
])
967 s
->end_freq
[ch
] = s
->start_freq
[CPL_CH
];
969 int bandwidth_code
= get_bits(gbc
, 6);
970 if (bandwidth_code
> 60) {
971 av_log(s
->avctx
, AV_LOG_ERROR
, "bandwidth code = %d > 60\n", bandwidth_code
);
974 s
->end_freq
[ch
] = bandwidth_code
* 3 + 73;
976 group_size
= 3 << (s
->exp_strategy
[blk
][ch
] - 1);
977 s
->num_exp_groups
[ch
] = (s
->end_freq
[ch
]+group_size
-4) / group_size
;
978 if(blk
> 0 && s
->end_freq
[ch
] != prev
)
979 memset(bit_alloc_stages
, 3, AC3_MAX_CHANNELS
);
982 if (cpl_in_use
&& s
->exp_strategy
[blk
][CPL_CH
] != EXP_REUSE
) {
983 s
->num_exp_groups
[CPL_CH
] = (s
->end_freq
[CPL_CH
] - s
->start_freq
[CPL_CH
]) /
984 (3 << (s
->exp_strategy
[blk
][CPL_CH
] - 1));
987 /* decode exponents for each channel */
988 for (ch
= !cpl_in_use
; ch
<= s
->channels
; ch
++) {
989 if (s
->exp_strategy
[blk
][ch
] != EXP_REUSE
) {
990 s
->dexps
[ch
][0] = get_bits(gbc
, 4) << !ch
;
991 decode_exponents(gbc
, s
->exp_strategy
[blk
][ch
],
992 s
->num_exp_groups
[ch
], s
->dexps
[ch
][0],
993 &s
->dexps
[ch
][s
->start_freq
[ch
]+!!ch
]);
994 if(ch
!= CPL_CH
&& ch
!= s
->lfe_ch
)
995 skip_bits(gbc
, 2); /* skip gainrng */
999 /* bit allocation information */
1000 if (s
->bit_allocation_syntax
) {
1001 if (get_bits1(gbc
)) {
1002 s
->bit_alloc_params
.slow_decay
= ff_ac3_slow_decay_tab
[get_bits(gbc
, 2)] >> s
->bit_alloc_params
.sr_shift
;
1003 s
->bit_alloc_params
.fast_decay
= ff_ac3_fast_decay_tab
[get_bits(gbc
, 2)] >> s
->bit_alloc_params
.sr_shift
;
1004 s
->bit_alloc_params
.slow_gain
= ff_ac3_slow_gain_tab
[get_bits(gbc
, 2)];
1005 s
->bit_alloc_params
.db_per_bit
= ff_ac3_db_per_bit_tab
[get_bits(gbc
, 2)];
1006 s
->bit_alloc_params
.floor
= ff_ac3_floor_tab
[get_bits(gbc
, 3)];
1007 for(ch
=!cpl_in_use
; ch
<=s
->channels
; ch
++)
1008 bit_alloc_stages
[ch
] = FFMAX(bit_alloc_stages
[ch
], 2);
1010 av_log(s
->avctx
, AV_LOG_ERROR
, "new bit allocation info must be present in block 0\n");
1015 /* signal-to-noise ratio offsets and fast gains (signal-to-mask ratios) */
1016 if(!s
->eac3
|| !blk
){
1017 if(s
->snr_offset_strategy
&& get_bits1(gbc
)) {
1020 csnr
= (get_bits(gbc
, 6) - 15) << 4;
1021 for (i
= ch
= !cpl_in_use
; ch
<= s
->channels
; ch
++) {
1023 if (ch
== i
|| s
->snr_offset_strategy
== 2)
1024 snr
= (csnr
+ get_bits(gbc
, 4)) << 2;
1025 /* run at least last bit allocation stage if snr offset changes */
1026 if(blk
&& s
->snr_offset
[ch
] != snr
) {
1027 bit_alloc_stages
[ch
] = FFMAX(bit_alloc_stages
[ch
], 1);
1029 s
->snr_offset
[ch
] = snr
;
1031 /* fast gain (normal AC-3 only) */
1033 int prev
= s
->fast_gain
[ch
];
1034 s
->fast_gain
[ch
] = ff_ac3_fast_gain_tab
[get_bits(gbc
, 3)];
1035 /* run last 2 bit allocation stages if fast gain changes */
1036 if(blk
&& prev
!= s
->fast_gain
[ch
])
1037 bit_alloc_stages
[ch
] = FFMAX(bit_alloc_stages
[ch
], 2);
1040 } else if (!s
->eac3
&& !blk
) {
1041 av_log(s
->avctx
, AV_LOG_ERROR
, "new snr offsets must be present in block 0\n");
1046 /* fast gain (E-AC-3 only) */
1047 if (s
->fast_gain_syntax
&& get_bits1(gbc
)) {
1048 for (ch
= !cpl_in_use
; ch
<= s
->channels
; ch
++) {
1049 int prev
= s
->fast_gain
[ch
];
1050 s
->fast_gain
[ch
] = ff_ac3_fast_gain_tab
[get_bits(gbc
, 3)];
1051 /* run last 2 bit allocation stages if fast gain changes */
1052 if(blk
&& prev
!= s
->fast_gain
[ch
])
1053 bit_alloc_stages
[ch
] = FFMAX(bit_alloc_stages
[ch
], 2);
1055 } else if (s
->eac3
&& !blk
) {
1056 for (ch
= !cpl_in_use
; ch
<= s
->channels
; ch
++)
1057 s
->fast_gain
[ch
] = ff_ac3_fast_gain_tab
[4];
1060 /* E-AC-3 to AC-3 converter SNR offset */
1061 if (s
->frame_type
== EAC3_FRAME_TYPE_INDEPENDENT
&& get_bits1(gbc
)) {
1062 skip_bits(gbc
, 10); // skip converter snr offset
1065 /* coupling leak information */
1067 if (s
->first_cpl_leak
|| get_bits1(gbc
)) {
1068 int fl
= get_bits(gbc
, 3);
1069 int sl
= get_bits(gbc
, 3);
1070 /* run last 2 bit allocation stages for coupling channel if
1071 coupling leak changes */
1072 if(blk
&& (fl
!= s
->bit_alloc_params
.cpl_fast_leak
||
1073 sl
!= s
->bit_alloc_params
.cpl_slow_leak
)) {
1074 bit_alloc_stages
[CPL_CH
] = FFMAX(bit_alloc_stages
[CPL_CH
], 2);
1076 s
->bit_alloc_params
.cpl_fast_leak
= fl
;
1077 s
->bit_alloc_params
.cpl_slow_leak
= sl
;
1078 } else if (!s
->eac3
&& !blk
) {
1079 av_log(s
->avctx
, AV_LOG_ERROR
, "new coupling leak info must be present in block 0\n");
1082 s
->first_cpl_leak
= 0;
1085 /* delta bit allocation information */
1086 if (s
->dba_syntax
&& get_bits1(gbc
)) {
1087 /* delta bit allocation exists (strategy) */
1088 for (ch
= !cpl_in_use
; ch
<= fbw_channels
; ch
++) {
1089 s
->dba_mode
[ch
] = get_bits(gbc
, 2);
1090 if (s
->dba_mode
[ch
] == DBA_RESERVED
) {
1091 av_log(s
->avctx
, AV_LOG_ERROR
, "delta bit allocation strategy reserved\n");
1094 bit_alloc_stages
[ch
] = FFMAX(bit_alloc_stages
[ch
], 2);
1096 /* channel delta offset, len and bit allocation */
1097 for (ch
= !cpl_in_use
; ch
<= fbw_channels
; ch
++) {
1098 if (s
->dba_mode
[ch
] == DBA_NEW
) {
1099 s
->dba_nsegs
[ch
] = get_bits(gbc
, 3);
1100 for (seg
= 0; seg
<= s
->dba_nsegs
[ch
]; seg
++) {
1101 s
->dba_offsets
[ch
][seg
] = get_bits(gbc
, 5);
1102 s
->dba_lengths
[ch
][seg
] = get_bits(gbc
, 4);
1103 s
->dba_values
[ch
][seg
] = get_bits(gbc
, 3);
1105 /* run last 2 bit allocation stages if new dba values */
1106 bit_alloc_stages
[ch
] = FFMAX(bit_alloc_stages
[ch
], 2);
1109 } else if(blk
== 0) {
1110 for(ch
=0; ch
<=s
->channels
; ch
++) {
1111 s
->dba_mode
[ch
] = DBA_NONE
;
1115 /* Bit allocation */
1116 for(ch
=!cpl_in_use
; ch
<=s
->channels
; ch
++) {
1117 if(bit_alloc_stages
[ch
] > 2) {
1118 /* Exponent mapping into PSD and PSD integration */
1119 ff_ac3_bit_alloc_calc_psd(s
->dexps
[ch
],
1120 s
->start_freq
[ch
], s
->end_freq
[ch
],
1121 s
->psd
[ch
], s
->band_psd
[ch
]);
1123 if(bit_alloc_stages
[ch
] > 1) {
1124 /* Compute excitation function, Compute masking curve, and
1125 Apply delta bit allocation */
1126 ff_ac3_bit_alloc_calc_mask(&s
->bit_alloc_params
, s
->band_psd
[ch
],
1127 s
->start_freq
[ch
], s
->end_freq
[ch
],
1128 s
->fast_gain
[ch
], (ch
== s
->lfe_ch
),
1129 s
->dba_mode
[ch
], s
->dba_nsegs
[ch
],
1130 s
->dba_offsets
[ch
], s
->dba_lengths
[ch
],
1131 s
->dba_values
[ch
], s
->mask
[ch
]);
1133 if(bit_alloc_stages
[ch
] > 0) {
1134 /* Compute bit allocation */
1135 const uint8_t *bap_tab
= s
->channel_uses_aht
[ch
] ?
1136 ff_eac3_hebap_tab
: ff_ac3_bap_tab
;
1137 ff_ac3_bit_alloc_calc_bap(s
->mask
[ch
], s
->psd
[ch
],
1138 s
->start_freq
[ch
], s
->end_freq
[ch
],
1140 s
->bit_alloc_params
.floor
,
1141 bap_tab
, s
->bap
[ch
]);
1145 /* unused dummy data */
1146 if (s
->skip_syntax
&& get_bits1(gbc
)) {
1147 int skipl
= get_bits(gbc
, 9);
1152 /* unpack the transform coefficients
1153 this also uncouples channels if coupling is in use. */
1154 decode_transform_coeffs(s
, blk
);
1156 /* TODO: generate enhanced coupling coordinates and uncouple */
1158 /* TODO: apply spectral extension */
1160 /* recover coefficients if rematrixing is in use */
1161 if(s
->channel_mode
== AC3_CHMODE_STEREO
)
1164 /* apply scaling to coefficients (headroom, dynrng) */
1165 for(ch
=1; ch
<=s
->channels
; ch
++) {
1166 float gain
= s
->mul_bias
/ 4194304.0f
;
1167 if(s
->channel_mode
== AC3_CHMODE_DUALMONO
) {
1168 gain
*= s
->dynamic_range
[ch
-1];
1170 gain
*= s
->dynamic_range
[0];
1172 s
->dsp
.int32_to_float_fmul_scalar(s
->transform_coeffs
[ch
], s
->fixed_coeffs
[ch
], gain
, 256);
1175 /* downmix and MDCT. order depends on whether block switching is used for
1176 any channel in this block. this is because coefficients for the long
1177 and short transforms cannot be mixed. */
1178 downmix_output
= s
->channels
!= s
->out_channels
&&
1179 !((s
->output_mode
& AC3_OUTPUT_LFEON
) &&
1180 s
->fbw_channels
== s
->out_channels
);
1181 if(different_transforms
) {
1182 /* the delay samples have already been downmixed, so we upmix the delay
1183 samples in order to reconstruct all channels before downmixing. */
1189 do_imdct(s
, s
->channels
);
1191 if(downmix_output
) {
1192 s
->dsp
.ac3_downmix(s
->output
, s
->downmix_coeffs
, s
->out_channels
, s
->fbw_channels
, 256);
1195 if(downmix_output
) {
1196 s
->dsp
.ac3_downmix(s
->transform_coeffs
+1, s
->downmix_coeffs
, s
->out_channels
, s
->fbw_channels
, 256);
1199 if(downmix_output
&& !s
->downmixed
) {
1201 s
->dsp
.ac3_downmix(s
->delay
, s
->downmix_coeffs
, s
->out_channels
, s
->fbw_channels
, 128);
1204 do_imdct(s
, s
->out_channels
);
1211 * Decode a single AC-3 frame.
1213 static int ac3_decode_frame(AVCodecContext
* avctx
, void *data
, int *data_size
,
1214 const uint8_t *buf
, int buf_size
)
1216 AC3DecodeContext
*s
= avctx
->priv_data
;
1217 int16_t *out_samples
= (int16_t *)data
;
1220 /* initialize the GetBitContext with the start of valid AC-3 Frame */
1221 if (s
->input_buffer
) {
1222 /* copy input buffer to decoder context to avoid reading past the end
1223 of the buffer, which can be caused by a damaged input stream. */
1224 memcpy(s
->input_buffer
, buf
, FFMIN(buf_size
, AC3_FRAME_BUFFER_SIZE
));
1225 init_get_bits(&s
->gbc
, s
->input_buffer
, buf_size
* 8);
1227 init_get_bits(&s
->gbc
, buf
, buf_size
* 8);
1230 /* parse the syncinfo */
1232 err
= parse_frame_header(s
);
1234 /* check that reported frame size fits in input buffer */
1235 if(s
->frame_size
> buf_size
) {
1236 av_log(avctx
, AV_LOG_ERROR
, "incomplete frame\n");
1237 err
= AC3_PARSE_ERROR_FRAME_SIZE
;
1240 /* check for crc mismatch */
1241 if(err
!= AC3_PARSE_ERROR_FRAME_SIZE
&& avctx
->error_recognition
>= FF_ER_CAREFUL
) {
1242 if(av_crc(av_crc_get_table(AV_CRC_16_ANSI
), 0, &buf
[2], s
->frame_size
-2)) {
1243 av_log(avctx
, AV_LOG_ERROR
, "frame CRC mismatch\n");
1244 err
= AC3_PARSE_ERROR_CRC
;
1248 if(err
&& err
!= AC3_PARSE_ERROR_CRC
) {
1250 case AC3_PARSE_ERROR_SYNC
:
1251 av_log(avctx
, AV_LOG_ERROR
, "frame sync error\n");
1253 case AC3_PARSE_ERROR_BSID
:
1254 av_log(avctx
, AV_LOG_ERROR
, "invalid bitstream id\n");
1256 case AC3_PARSE_ERROR_SAMPLE_RATE
:
1257 av_log(avctx
, AV_LOG_ERROR
, "invalid sample rate\n");
1259 case AC3_PARSE_ERROR_FRAME_SIZE
:
1260 av_log(avctx
, AV_LOG_ERROR
, "invalid frame size\n");
1262 case AC3_PARSE_ERROR_FRAME_TYPE
:
1263 /* skip frame if CRC is ok. otherwise use error concealment. */
1264 /* TODO: add support for substreams and dependent frames */
1265 if(s
->frame_type
== EAC3_FRAME_TYPE_DEPENDENT
|| s
->substreamid
) {
1266 av_log(avctx
, AV_LOG_ERROR
, "unsupported frame type : skipping frame\n");
1267 return s
->frame_size
;
1269 av_log(avctx
, AV_LOG_ERROR
, "invalid frame type\n");
1273 av_log(avctx
, AV_LOG_ERROR
, "invalid header\n");
1278 /* if frame is ok, set audio parameters */
1280 avctx
->sample_rate
= s
->sample_rate
;
1281 avctx
->bit_rate
= s
->bit_rate
;
1283 /* channel config */
1284 s
->out_channels
= s
->channels
;
1285 s
->output_mode
= s
->channel_mode
;
1287 s
->output_mode
|= AC3_OUTPUT_LFEON
;
1288 if (avctx
->request_channels
> 0 && avctx
->request_channels
<= 2 &&
1289 avctx
->request_channels
< s
->channels
) {
1290 s
->out_channels
= avctx
->request_channels
;
1291 s
->output_mode
= avctx
->request_channels
== 1 ? AC3_CHMODE_MONO
: AC3_CHMODE_STEREO
;
1293 avctx
->channels
= s
->out_channels
;
1295 /* set downmixing coefficients if needed */
1296 if(s
->channels
!= s
->out_channels
&& !((s
->output_mode
& AC3_OUTPUT_LFEON
) &&
1297 s
->fbw_channels
== s
->out_channels
)) {
1298 set_downmix_coeffs(s
);
1300 } else if (!s
->out_channels
) {
1301 s
->out_channels
= avctx
->channels
;
1302 if(s
->out_channels
< s
->channels
)
1303 s
->output_mode
= s
->out_channels
== 1 ? AC3_CHMODE_MONO
: AC3_CHMODE_STEREO
;
1306 /* decode the audio blocks */
1307 for (blk
= 0; blk
< s
->num_blocks
; blk
++) {
1308 const float *output
[s
->out_channels
];
1309 if (!err
&& decode_audio_block(s
, blk
)) {
1310 av_log(avctx
, AV_LOG_ERROR
, "error decoding the audio block\n");
1312 for (ch
= 0; ch
< s
->out_channels
; ch
++)
1313 output
[ch
] = s
->output
[ch
];
1314 s
->dsp
.float_to_int16_interleave(out_samples
, output
, 256, s
->out_channels
);
1315 out_samples
+= 256 * s
->out_channels
;
1317 *data_size
= s
->num_blocks
* 256 * avctx
->channels
* sizeof (int16_t);
1318 return s
->frame_size
;
1322 * Uninitialize the AC-3 decoder.
1324 static av_cold
int ac3_decode_end(AVCodecContext
*avctx
)
1326 AC3DecodeContext
*s
= avctx
->priv_data
;
1327 ff_mdct_end(&s
->imdct_512
);
1328 ff_mdct_end(&s
->imdct_256
);
1330 av_freep(&s
->input_buffer
);
1335 AVCodec ac3_decoder
= {
1337 .type
= CODEC_TYPE_AUDIO
,
1339 .priv_data_size
= sizeof (AC3DecodeContext
),
1340 .init
= ac3_decode_init
,
1341 .close
= ac3_decode_end
,
1342 .decode
= ac3_decode_frame
,
1343 .long_name
= NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"),
1346 AVCodec eac3_decoder
= {
1348 .type
= CODEC_TYPE_AUDIO
,
1349 .id
= CODEC_ID_EAC3
,
1350 .priv_data_size
= sizeof (AC3DecodeContext
),
1351 .init
= ac3_decode_init
,
1352 .close
= ac3_decode_end
,
1353 .decode
= ac3_decode_frame
,
1354 .long_name
= NULL_IF_CONFIG_SMALL("ATSC A/52B (AC-3, E-AC-3)"),