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1489 lines
54 KiB
1489 lines
54 KiB
/* |
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* AC-3 Audio Decoder |
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* This code was developed as part of Google Summer of Code 2006. |
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* E-AC-3 support was added as part of Google Summer of Code 2007. |
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* |
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* Copyright (c) 2006 Kartikey Mahendra BHATT (bhattkm at gmail dot com) |
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* Copyright (c) 2007-2008 Bartlomiej Wolowiec <bartek.wolowiec@gmail.com> |
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* Copyright (c) 2007 Justin Ruggles <justin.ruggles@gmail.com> |
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* |
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* This file is part of FFmpeg. |
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* |
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* FFmpeg is free software; you can redistribute it and/or |
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* modify it under the terms of the GNU Lesser General Public |
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* License as published by the Free Software Foundation; either |
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* version 2.1 of the License, or (at your option) any later version. |
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* |
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* FFmpeg is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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* Lesser General Public License for more details. |
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* |
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* You should have received a copy of the GNU Lesser General Public |
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* License along with FFmpeg; if not, write to the Free Software |
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
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*/ |
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|
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#include <stdio.h> |
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#include <stddef.h> |
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#include <math.h> |
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#include <string.h> |
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|
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#include "libavutil/crc.h" |
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#include "libavutil/opt.h" |
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#include "internal.h" |
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#include "aac_ac3_parser.h" |
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#include "ac3_parser.h" |
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#include "ac3dec.h" |
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#include "ac3dec_data.h" |
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#include "kbdwin.h" |
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|
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/** |
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* table for ungrouping 3 values in 7 bits. |
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* used for exponents and bap=2 mantissas |
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*/ |
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static uint8_t ungroup_3_in_7_bits_tab[128][3]; |
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|
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/** tables for ungrouping mantissas */ |
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static int b1_mantissas[32][3]; |
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static int b2_mantissas[128][3]; |
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static int b3_mantissas[8]; |
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static int b4_mantissas[128][2]; |
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static int b5_mantissas[16]; |
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|
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/** |
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* Quantization table: levels for symmetric. bits for asymmetric. |
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* reference: Table 7.18 Mapping of bap to Quantizer |
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*/ |
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static const uint8_t quantization_tab[16] = { |
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0, 3, 5, 7, 11, 15, |
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5, 6, 7, 8, 9, 10, 11, 12, 14, 16 |
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}; |
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|
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/** dynamic range table. converts codes to scale factors. */ |
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static float dynamic_range_tab[256]; |
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|
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/** Adjustments in dB gain */ |
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static const float gain_levels[9] = { |
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LEVEL_PLUS_3DB, |
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LEVEL_PLUS_1POINT5DB, |
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LEVEL_ONE, |
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LEVEL_MINUS_1POINT5DB, |
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LEVEL_MINUS_3DB, |
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LEVEL_MINUS_4POINT5DB, |
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LEVEL_MINUS_6DB, |
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LEVEL_ZERO, |
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LEVEL_MINUS_9DB |
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}; |
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|
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/** |
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* Table for default stereo downmixing coefficients |
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* reference: Section 7.8.2 Downmixing Into Two Channels |
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*/ |
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static const uint8_t ac3_default_coeffs[8][5][2] = { |
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{ { 2, 7 }, { 7, 2 }, }, |
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{ { 4, 4 }, }, |
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{ { 2, 7 }, { 7, 2 }, }, |
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{ { 2, 7 }, { 5, 5 }, { 7, 2 }, }, |
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{ { 2, 7 }, { 7, 2 }, { 6, 6 }, }, |
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{ { 2, 7 }, { 5, 5 }, { 7, 2 }, { 8, 8 }, }, |
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{ { 2, 7 }, { 7, 2 }, { 6, 7 }, { 7, 6 }, }, |
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{ { 2, 7 }, { 5, 5 }, { 7, 2 }, { 6, 7 }, { 7, 6 }, }, |
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}; |
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|
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/** |
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* Symmetrical Dequantization |
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* reference: Section 7.3.3 Expansion of Mantissas for Symmetrical Quantization |
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* Tables 7.19 to 7.23 |
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*/ |
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static inline int |
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symmetric_dequant(int code, int levels) |
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{ |
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return ((code - (levels >> 1)) << 24) / levels; |
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} |
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|
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/* |
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* Initialize tables at runtime. |
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*/ |
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static av_cold void ac3_tables_init(void) |
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{ |
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int i; |
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|
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/* generate table for ungrouping 3 values in 7 bits |
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reference: Section 7.1.3 Exponent Decoding */ |
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for (i = 0; i < 128; i++) { |
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ungroup_3_in_7_bits_tab[i][0] = i / 25; |
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ungroup_3_in_7_bits_tab[i][1] = (i % 25) / 5; |
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ungroup_3_in_7_bits_tab[i][2] = (i % 25) % 5; |
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} |
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|
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/* generate grouped mantissa tables |
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reference: Section 7.3.5 Ungrouping of Mantissas */ |
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for (i = 0; i < 32; i++) { |
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/* bap=1 mantissas */ |
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b1_mantissas[i][0] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab[i][0], 3); |
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b1_mantissas[i][1] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab[i][1], 3); |
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b1_mantissas[i][2] = symmetric_dequant(ff_ac3_ungroup_3_in_5_bits_tab[i][2], 3); |
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} |
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for (i = 0; i < 128; i++) { |
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/* bap=2 mantissas */ |
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b2_mantissas[i][0] = symmetric_dequant(ungroup_3_in_7_bits_tab[i][0], 5); |
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b2_mantissas[i][1] = symmetric_dequant(ungroup_3_in_7_bits_tab[i][1], 5); |
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b2_mantissas[i][2] = symmetric_dequant(ungroup_3_in_7_bits_tab[i][2], 5); |
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|
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/* bap=4 mantissas */ |
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b4_mantissas[i][0] = symmetric_dequant(i / 11, 11); |
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b4_mantissas[i][1] = symmetric_dequant(i % 11, 11); |
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} |
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/* generate ungrouped mantissa tables |
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reference: Tables 7.21 and 7.23 */ |
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for (i = 0; i < 7; i++) { |
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/* bap=3 mantissas */ |
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b3_mantissas[i] = symmetric_dequant(i, 7); |
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} |
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for (i = 0; i < 15; i++) { |
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/* bap=5 mantissas */ |
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b5_mantissas[i] = symmetric_dequant(i, 15); |
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} |
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|
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/* generate dynamic range table |
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reference: Section 7.7.1 Dynamic Range Control */ |
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for (i = 0; i < 256; i++) { |
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int v = (i >> 5) - ((i >> 7) << 3) - 5; |
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dynamic_range_tab[i] = powf(2.0f, v) * ((i & 0x1F) | 0x20); |
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} |
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} |
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|
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/** |
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* AVCodec initialization |
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*/ |
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static av_cold int ac3_decode_init(AVCodecContext *avctx) |
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{ |
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AC3DecodeContext *s = avctx->priv_data; |
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s->avctx = avctx; |
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|
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ff_ac3_common_init(); |
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ac3_tables_init(); |
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ff_mdct_init(&s->imdct_256, 8, 1, 1.0); |
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ff_mdct_init(&s->imdct_512, 9, 1, 1.0); |
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ff_kbd_window_init(s->window, 5.0, 256); |
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ff_dsputil_init(&s->dsp, avctx); |
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ff_ac3dsp_init(&s->ac3dsp, avctx->flags & CODEC_FLAG_BITEXACT); |
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ff_fmt_convert_init(&s->fmt_conv, avctx); |
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av_lfg_init(&s->dith_state, 0); |
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|
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/* set scale value for float to int16 conversion */ |
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if (avctx->request_sample_fmt == AV_SAMPLE_FMT_FLT) { |
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s->mul_bias = 1.0f; |
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avctx->sample_fmt = AV_SAMPLE_FMT_FLT; |
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} else { |
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s->mul_bias = 32767.0f; |
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avctx->sample_fmt = AV_SAMPLE_FMT_S16; |
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} |
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|
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/* allow downmixing to stereo or mono */ |
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if (avctx->channels > 0 && avctx->request_channels > 0 && |
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avctx->request_channels < avctx->channels && |
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avctx->request_channels <= 2) { |
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avctx->channels = avctx->request_channels; |
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} |
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s->downmixed = 1; |
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|
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avcodec_get_frame_defaults(&s->frame); |
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avctx->coded_frame = &s->frame; |
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|
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return 0; |
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} |
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|
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/** |
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* Parse the 'sync info' and 'bit stream info' from the AC-3 bitstream. |
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* GetBitContext within AC3DecodeContext must point to |
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* the start of the synchronized AC-3 bitstream. |
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*/ |
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static int ac3_parse_header(AC3DecodeContext *s) |
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{ |
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GetBitContext *gbc = &s->gbc; |
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int i; |
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|
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/* read the rest of the bsi. read twice for dual mono mode. */ |
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i = !s->channel_mode; |
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do { |
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skip_bits(gbc, 5); // skip dialog normalization |
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if (get_bits1(gbc)) |
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skip_bits(gbc, 8); //skip compression |
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if (get_bits1(gbc)) |
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skip_bits(gbc, 8); //skip language code |
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if (get_bits1(gbc)) |
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skip_bits(gbc, 7); //skip audio production information |
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} while (i--); |
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|
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skip_bits(gbc, 2); //skip copyright bit and original bitstream bit |
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|
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/* skip the timecodes (or extra bitstream information for Alternate Syntax) |
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TODO: read & use the xbsi1 downmix levels */ |
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if (get_bits1(gbc)) |
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skip_bits(gbc, 14); //skip timecode1 / xbsi1 |
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if (get_bits1(gbc)) |
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skip_bits(gbc, 14); //skip timecode2 / xbsi2 |
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|
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/* skip additional bitstream info */ |
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if (get_bits1(gbc)) { |
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i = get_bits(gbc, 6); |
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do { |
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skip_bits(gbc, 8); |
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} while (i--); |
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} |
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|
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return 0; |
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} |
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|
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/** |
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* Common function to parse AC-3 or E-AC-3 frame header |
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*/ |
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static int parse_frame_header(AC3DecodeContext *s) |
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{ |
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AC3HeaderInfo hdr; |
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int err; |
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|
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err = avpriv_ac3_parse_header(&s->gbc, &hdr); |
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if (err) |
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return err; |
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|
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/* get decoding parameters from header info */ |
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s->bit_alloc_params.sr_code = hdr.sr_code; |
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s->bitstream_mode = hdr.bitstream_mode; |
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s->channel_mode = hdr.channel_mode; |
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s->channel_layout = hdr.channel_layout; |
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s->lfe_on = hdr.lfe_on; |
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s->bit_alloc_params.sr_shift = hdr.sr_shift; |
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s->sample_rate = hdr.sample_rate; |
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s->bit_rate = hdr.bit_rate; |
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s->channels = hdr.channels; |
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s->fbw_channels = s->channels - s->lfe_on; |
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s->lfe_ch = s->fbw_channels + 1; |
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s->frame_size = hdr.frame_size; |
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s->center_mix_level = hdr.center_mix_level; |
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s->surround_mix_level = hdr.surround_mix_level; |
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s->num_blocks = hdr.num_blocks; |
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s->frame_type = hdr.frame_type; |
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s->substreamid = hdr.substreamid; |
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|
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if (s->lfe_on) { |
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s->start_freq[s->lfe_ch] = 0; |
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s->end_freq[s->lfe_ch] = 7; |
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s->num_exp_groups[s->lfe_ch] = 2; |
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s->channel_in_cpl[s->lfe_ch] = 0; |
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} |
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|
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if (hdr.bitstream_id <= 10) { |
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s->eac3 = 0; |
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s->snr_offset_strategy = 2; |
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s->block_switch_syntax = 1; |
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s->dither_flag_syntax = 1; |
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s->bit_allocation_syntax = 1; |
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s->fast_gain_syntax = 0; |
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s->first_cpl_leak = 0; |
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s->dba_syntax = 1; |
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s->skip_syntax = 1; |
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memset(s->channel_uses_aht, 0, sizeof(s->channel_uses_aht)); |
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return ac3_parse_header(s); |
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} else if (CONFIG_EAC3_DECODER) { |
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s->eac3 = 1; |
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return ff_eac3_parse_header(s); |
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} else { |
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av_log(s->avctx, AV_LOG_ERROR, "E-AC-3 support not compiled in\n"); |
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return -1; |
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} |
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} |
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|
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/** |
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* Set stereo downmixing coefficients based on frame header info. |
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* reference: Section 7.8.2 Downmixing Into Two Channels |
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*/ |
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static void set_downmix_coeffs(AC3DecodeContext *s) |
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{ |
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int i; |
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float cmix = gain_levels[s-> center_mix_level]; |
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float smix = gain_levels[s->surround_mix_level]; |
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float norm0, norm1; |
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|
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for (i = 0; i < s->fbw_channels; i++) { |
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s->downmix_coeffs[i][0] = gain_levels[ac3_default_coeffs[s->channel_mode][i][0]]; |
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s->downmix_coeffs[i][1] = gain_levels[ac3_default_coeffs[s->channel_mode][i][1]]; |
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} |
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if (s->channel_mode > 1 && s->channel_mode & 1) { |
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s->downmix_coeffs[1][0] = s->downmix_coeffs[1][1] = cmix; |
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} |
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if (s->channel_mode == AC3_CHMODE_2F1R || s->channel_mode == AC3_CHMODE_3F1R) { |
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int nf = s->channel_mode - 2; |
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s->downmix_coeffs[nf][0] = s->downmix_coeffs[nf][1] = smix * LEVEL_MINUS_3DB; |
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} |
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if (s->channel_mode == AC3_CHMODE_2F2R || s->channel_mode == AC3_CHMODE_3F2R) { |
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int nf = s->channel_mode - 4; |
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s->downmix_coeffs[nf][0] = s->downmix_coeffs[nf+1][1] = smix; |
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} |
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|
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/* renormalize */ |
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norm0 = norm1 = 0.0; |
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for (i = 0; i < s->fbw_channels; i++) { |
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norm0 += s->downmix_coeffs[i][0]; |
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norm1 += s->downmix_coeffs[i][1]; |
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} |
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norm0 = 1.0f / norm0; |
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norm1 = 1.0f / norm1; |
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for (i = 0; i < s->fbw_channels; i++) { |
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s->downmix_coeffs[i][0] *= norm0; |
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s->downmix_coeffs[i][1] *= norm1; |
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} |
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|
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if (s->output_mode == AC3_CHMODE_MONO) { |
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for (i = 0; i < s->fbw_channels; i++) |
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s->downmix_coeffs[i][0] = (s->downmix_coeffs[i][0] + |
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s->downmix_coeffs[i][1]) * LEVEL_MINUS_3DB; |
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} |
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} |
|
|
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/** |
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* Decode the grouped exponents according to exponent strategy. |
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* reference: Section 7.1.3 Exponent Decoding |
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*/ |
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static int decode_exponents(GetBitContext *gbc, int exp_strategy, int ngrps, |
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uint8_t absexp, int8_t *dexps) |
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{ |
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int i, j, grp, group_size; |
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int dexp[256]; |
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int expacc, prevexp; |
|
|
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/* unpack groups */ |
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group_size = exp_strategy + (exp_strategy == EXP_D45); |
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for (grp = 0, i = 0; grp < ngrps; grp++) { |
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expacc = get_bits(gbc, 7); |
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dexp[i++] = ungroup_3_in_7_bits_tab[expacc][0]; |
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dexp[i++] = ungroup_3_in_7_bits_tab[expacc][1]; |
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dexp[i++] = ungroup_3_in_7_bits_tab[expacc][2]; |
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} |
|
|
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/* convert to absolute exps and expand groups */ |
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prevexp = absexp; |
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for (i = 0, j = 0; i < ngrps * 3; i++) { |
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prevexp += dexp[i] - 2; |
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if (prevexp > 24U) |
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return -1; |
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switch (group_size) { |
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case 4: dexps[j++] = prevexp; |
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dexps[j++] = prevexp; |
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case 2: dexps[j++] = prevexp; |
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case 1: dexps[j++] = prevexp; |
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} |
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} |
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return 0; |
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} |
|
|
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/** |
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* Generate transform coefficients for each coupled channel in the coupling |
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* range using the coupling coefficients and coupling coordinates. |
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* reference: Section 7.4.3 Coupling Coordinate Format |
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*/ |
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static void calc_transform_coeffs_cpl(AC3DecodeContext *s) |
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{ |
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int bin, band, ch; |
|
|
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bin = s->start_freq[CPL_CH]; |
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for (band = 0; band < s->num_cpl_bands; band++) { |
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int band_start = bin; |
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int band_end = bin + s->cpl_band_sizes[band]; |
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for (ch = 1; ch <= s->fbw_channels; ch++) { |
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if (s->channel_in_cpl[ch]) { |
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int cpl_coord = s->cpl_coords[ch][band] << 5; |
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for (bin = band_start; bin < band_end; bin++) { |
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s->fixed_coeffs[ch][bin] = |
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MULH(s->fixed_coeffs[CPL_CH][bin] << 4, cpl_coord); |
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} |
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if (ch == 2 && s->phase_flags[band]) { |
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for (bin = band_start; bin < band_end; bin++) |
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s->fixed_coeffs[2][bin] = -s->fixed_coeffs[2][bin]; |
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} |
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} |
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} |
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bin = band_end; |
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} |
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} |
|
|
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/** |
|
* Grouped mantissas for 3-level 5-level and 11-level quantization |
|
*/ |
|
typedef struct { |
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int b1_mant[2]; |
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int b2_mant[2]; |
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int b4_mant; |
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int b1; |
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int b2; |
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int b4; |
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} mant_groups; |
|
|
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/** |
|
* Decode the transform coefficients for a particular channel |
|
* reference: Section 7.3 Quantization and Decoding of Mantissas |
|
*/ |
|
static void ac3_decode_transform_coeffs_ch(AC3DecodeContext *s, int ch_index, mant_groups *m) |
|
{ |
|
int start_freq = s->start_freq[ch_index]; |
|
int end_freq = s->end_freq[ch_index]; |
|
uint8_t *baps = s->bap[ch_index]; |
|
int8_t *exps = s->dexps[ch_index]; |
|
int *coeffs = s->fixed_coeffs[ch_index]; |
|
int dither = (ch_index == CPL_CH) || s->dither_flag[ch_index]; |
|
GetBitContext *gbc = &s->gbc; |
|
int freq; |
|
|
|
for (freq = start_freq; freq < end_freq; freq++) { |
|
int bap = baps[freq]; |
|
int mantissa; |
|
switch (bap) { |
|
case 0: |
|
if (dither) |
|
mantissa = (av_lfg_get(&s->dith_state) & 0x7FFFFF) - 0x400000; |
|
else |
|
mantissa = 0; |
|
break; |
|
case 1: |
|
if (m->b1) { |
|
m->b1--; |
|
mantissa = m->b1_mant[m->b1]; |
|
} else { |
|
int bits = get_bits(gbc, 5); |
|
mantissa = b1_mantissas[bits][0]; |
|
m->b1_mant[1] = b1_mantissas[bits][1]; |
|
m->b1_mant[0] = b1_mantissas[bits][2]; |
|
m->b1 = 2; |
|
} |
|
break; |
|
case 2: |
|
if (m->b2) { |
|
m->b2--; |
|
mantissa = m->b2_mant[m->b2]; |
|
} else { |
|
int bits = get_bits(gbc, 7); |
|
mantissa = b2_mantissas[bits][0]; |
|
m->b2_mant[1] = b2_mantissas[bits][1]; |
|
m->b2_mant[0] = b2_mantissas[bits][2]; |
|
m->b2 = 2; |
|
} |
|
break; |
|
case 3: |
|
mantissa = b3_mantissas[get_bits(gbc, 3)]; |
|
break; |
|
case 4: |
|
if (m->b4) { |
|
m->b4 = 0; |
|
mantissa = m->b4_mant; |
|
} else { |
|
int bits = get_bits(gbc, 7); |
|
mantissa = b4_mantissas[bits][0]; |
|
m->b4_mant = b4_mantissas[bits][1]; |
|
m->b4 = 1; |
|
} |
|
break; |
|
case 5: |
|
mantissa = b5_mantissas[get_bits(gbc, 4)]; |
|
break; |
|
default: /* 6 to 15 */ |
|
/* Shift mantissa and sign-extend it. */ |
|
mantissa = get_sbits(gbc, quantization_tab[bap]); |
|
mantissa <<= 24 - quantization_tab[bap]; |
|
break; |
|
} |
|
coeffs[freq] = mantissa >> exps[freq]; |
|
} |
|
} |
|
|
|
/** |
|
* Remove random dithering from coupling range coefficients with zero-bit |
|
* mantissas for coupled channels which do not use dithering. |
|
* reference: Section 7.3.4 Dither for Zero Bit Mantissas (bap=0) |
|
*/ |
|
static void remove_dithering(AC3DecodeContext *s) { |
|
int ch, i; |
|
|
|
for (ch = 1; ch <= s->fbw_channels; ch++) { |
|
if (!s->dither_flag[ch] && s->channel_in_cpl[ch]) { |
|
for (i = s->start_freq[CPL_CH]; i < s->end_freq[CPL_CH]; i++) { |
|
if (!s->bap[CPL_CH][i]) |
|
s->fixed_coeffs[ch][i] = 0; |
|
} |
|
} |
|
} |
|
} |
|
|
|
static void decode_transform_coeffs_ch(AC3DecodeContext *s, int blk, int ch, |
|
mant_groups *m) |
|
{ |
|
if (!s->channel_uses_aht[ch]) { |
|
ac3_decode_transform_coeffs_ch(s, ch, m); |
|
} else { |
|
/* if AHT is used, mantissas for all blocks are encoded in the first |
|
block of the frame. */ |
|
int bin; |
|
if (!blk && CONFIG_EAC3_DECODER) |
|
ff_eac3_decode_transform_coeffs_aht_ch(s, ch); |
|
for (bin = s->start_freq[ch]; bin < s->end_freq[ch]; bin++) { |
|
s->fixed_coeffs[ch][bin] = s->pre_mantissa[ch][bin][blk] >> s->dexps[ch][bin]; |
|
} |
|
} |
|
} |
|
|
|
/** |
|
* Decode the transform coefficients. |
|
*/ |
|
static void decode_transform_coeffs(AC3DecodeContext *s, int blk) |
|
{ |
|
int ch, end; |
|
int got_cplchan = 0; |
|
mant_groups m; |
|
|
|
m.b1 = m.b2 = m.b4 = 0; |
|
|
|
for (ch = 1; ch <= s->channels; ch++) { |
|
/* transform coefficients for full-bandwidth channel */ |
|
decode_transform_coeffs_ch(s, blk, ch, &m); |
|
/* tranform coefficients for coupling channel come right after the |
|
coefficients for the first coupled channel*/ |
|
if (s->channel_in_cpl[ch]) { |
|
if (!got_cplchan) { |
|
decode_transform_coeffs_ch(s, blk, CPL_CH, &m); |
|
calc_transform_coeffs_cpl(s); |
|
got_cplchan = 1; |
|
} |
|
end = s->end_freq[CPL_CH]; |
|
} else { |
|
end = s->end_freq[ch]; |
|
} |
|
do |
|
s->fixed_coeffs[ch][end] = 0; |
|
while (++end < 256); |
|
} |
|
|
|
/* zero the dithered coefficients for appropriate channels */ |
|
remove_dithering(s); |
|
} |
|
|
|
/** |
|
* Stereo rematrixing. |
|
* reference: Section 7.5.4 Rematrixing : Decoding Technique |
|
*/ |
|
static void do_rematrixing(AC3DecodeContext *s) |
|
{ |
|
int bnd, i; |
|
int end, bndend; |
|
|
|
end = FFMIN(s->end_freq[1], s->end_freq[2]); |
|
|
|
for (bnd = 0; bnd < s->num_rematrixing_bands; bnd++) { |
|
if (s->rematrixing_flags[bnd]) { |
|
bndend = FFMIN(end, ff_ac3_rematrix_band_tab[bnd + 1]); |
|
for (i = ff_ac3_rematrix_band_tab[bnd]; i < bndend; i++) { |
|
int tmp0 = s->fixed_coeffs[1][i]; |
|
s->fixed_coeffs[1][i] += s->fixed_coeffs[2][i]; |
|
s->fixed_coeffs[2][i] = tmp0 - s->fixed_coeffs[2][i]; |
|
} |
|
} |
|
} |
|
} |
|
|
|
/** |
|
* Inverse MDCT Transform. |
|
* Convert frequency domain coefficients to time-domain audio samples. |
|
* reference: Section 7.9.4 Transformation Equations |
|
*/ |
|
static inline void do_imdct(AC3DecodeContext *s, int channels) |
|
{ |
|
int ch; |
|
|
|
for (ch = 1; ch <= channels; ch++) { |
|
if (s->block_switch[ch]) { |
|
int i; |
|
float *x = s->tmp_output + 128; |
|
for (i = 0; i < 128; i++) |
|
x[i] = s->transform_coeffs[ch][2 * i]; |
|
s->imdct_256.imdct_half(&s->imdct_256, s->tmp_output, x); |
|
s->dsp.vector_fmul_window(s->output[ch - 1], s->delay[ch - 1], |
|
s->tmp_output, s->window, 128); |
|
for (i = 0; i < 128; i++) |
|
x[i] = s->transform_coeffs[ch][2 * i + 1]; |
|
s->imdct_256.imdct_half(&s->imdct_256, s->delay[ch - 1], x); |
|
} else { |
|
s->imdct_512.imdct_half(&s->imdct_512, s->tmp_output, s->transform_coeffs[ch]); |
|
s->dsp.vector_fmul_window(s->output[ch - 1], s->delay[ch - 1], |
|
s->tmp_output, s->window, 128); |
|
memcpy(s->delay[ch - 1], s->tmp_output + 128, 128 * sizeof(float)); |
|
} |
|
} |
|
} |
|
|
|
/** |
|
* Upmix delay samples from stereo to original channel layout. |
|
*/ |
|
static void ac3_upmix_delay(AC3DecodeContext *s) |
|
{ |
|
int channel_data_size = sizeof(s->delay[0]); |
|
switch (s->channel_mode) { |
|
case AC3_CHMODE_DUALMONO: |
|
case AC3_CHMODE_STEREO: |
|
/* upmix mono to stereo */ |
|
memcpy(s->delay[1], s->delay[0], channel_data_size); |
|
break; |
|
case AC3_CHMODE_2F2R: |
|
memset(s->delay[3], 0, channel_data_size); |
|
case AC3_CHMODE_2F1R: |
|
memset(s->delay[2], 0, channel_data_size); |
|
break; |
|
case AC3_CHMODE_3F2R: |
|
memset(s->delay[4], 0, channel_data_size); |
|
case AC3_CHMODE_3F1R: |
|
memset(s->delay[3], 0, channel_data_size); |
|
case AC3_CHMODE_3F: |
|
memcpy(s->delay[2], s->delay[1], channel_data_size); |
|
memset(s->delay[1], 0, channel_data_size); |
|
break; |
|
} |
|
} |
|
|
|
/** |
|
* Decode band structure for coupling, spectral extension, or enhanced coupling. |
|
* The band structure defines how many subbands are in each band. For each |
|
* subband in the range, 1 means it is combined with the previous band, and 0 |
|
* means that it starts a new band. |
|
* |
|
* @param[in] gbc bit reader context |
|
* @param[in] blk block number |
|
* @param[in] eac3 flag to indicate E-AC-3 |
|
* @param[in] ecpl flag to indicate enhanced coupling |
|
* @param[in] start_subband subband number for start of range |
|
* @param[in] end_subband subband number for end of range |
|
* @param[in] default_band_struct default band structure table |
|
* @param[out] num_bands number of bands (optionally NULL) |
|
* @param[out] band_sizes array containing the number of bins in each band (optionally NULL) |
|
*/ |
|
static void decode_band_structure(GetBitContext *gbc, int blk, int eac3, |
|
int ecpl, int start_subband, int end_subband, |
|
const uint8_t *default_band_struct, |
|
int *num_bands, uint8_t *band_sizes) |
|
{ |
|
int subbnd, bnd, n_subbands, n_bands=0; |
|
uint8_t bnd_sz[22]; |
|
uint8_t coded_band_struct[22]; |
|
const uint8_t *band_struct; |
|
|
|
n_subbands = end_subband - start_subband; |
|
|
|
/* decode band structure from bitstream or use default */ |
|
if (!eac3 || get_bits1(gbc)) { |
|
for (subbnd = 0; subbnd < n_subbands - 1; subbnd++) { |
|
coded_band_struct[subbnd] = get_bits1(gbc); |
|
} |
|
band_struct = coded_band_struct; |
|
} else if (!blk) { |
|
band_struct = &default_band_struct[start_subband+1]; |
|
} else { |
|
/* no change in band structure */ |
|
return; |
|
} |
|
|
|
/* calculate number of bands and band sizes based on band structure. |
|
note that the first 4 subbands in enhanced coupling span only 6 bins |
|
instead of 12. */ |
|
if (num_bands || band_sizes ) { |
|
n_bands = n_subbands; |
|
bnd_sz[0] = ecpl ? 6 : 12; |
|
for (bnd = 0, subbnd = 1; subbnd < n_subbands; subbnd++) { |
|
int subbnd_size = (ecpl && subbnd < 4) ? 6 : 12; |
|
if (band_struct[subbnd - 1]) { |
|
n_bands--; |
|
bnd_sz[bnd] += subbnd_size; |
|
} else { |
|
bnd_sz[++bnd] = subbnd_size; |
|
} |
|
} |
|
} |
|
|
|
/* set optional output params */ |
|
if (num_bands) |
|
*num_bands = n_bands; |
|
if (band_sizes) |
|
memcpy(band_sizes, bnd_sz, n_bands); |
|
} |
|
|
|
/** |
|
* Decode a single audio block from the AC-3 bitstream. |
|
*/ |
|
static int decode_audio_block(AC3DecodeContext *s, int blk) |
|
{ |
|
int fbw_channels = s->fbw_channels; |
|
int channel_mode = s->channel_mode; |
|
int i, bnd, seg, ch; |
|
int different_transforms; |
|
int downmix_output; |
|
int cpl_in_use; |
|
GetBitContext *gbc = &s->gbc; |
|
uint8_t bit_alloc_stages[AC3_MAX_CHANNELS] = { 0 }; |
|
|
|
/* block switch flags */ |
|
different_transforms = 0; |
|
if (s->block_switch_syntax) { |
|
for (ch = 1; ch <= fbw_channels; ch++) { |
|
s->block_switch[ch] = get_bits1(gbc); |
|
if (ch > 1 && s->block_switch[ch] != s->block_switch[1]) |
|
different_transforms = 1; |
|
} |
|
} |
|
|
|
/* dithering flags */ |
|
if (s->dither_flag_syntax) { |
|
for (ch = 1; ch <= fbw_channels; ch++) { |
|
s->dither_flag[ch] = get_bits1(gbc); |
|
} |
|
} |
|
|
|
/* dynamic range */ |
|
i = !s->channel_mode; |
|
do { |
|
if (get_bits1(gbc)) { |
|
s->dynamic_range[i] = ((dynamic_range_tab[get_bits(gbc, 8)] - 1.0) * |
|
s->drc_scale) + 1.0; |
|
} else if (blk == 0) { |
|
s->dynamic_range[i] = 1.0f; |
|
} |
|
} while (i--); |
|
|
|
/* spectral extension strategy */ |
|
if (s->eac3 && (!blk || get_bits1(gbc))) { |
|
s->spx_in_use = get_bits1(gbc); |
|
if (s->spx_in_use) { |
|
int dst_start_freq, dst_end_freq, src_start_freq, |
|
start_subband, end_subband; |
|
|
|
/* determine which channels use spx */ |
|
if (s->channel_mode == AC3_CHMODE_MONO) { |
|
s->channel_uses_spx[1] = 1; |
|
} else { |
|
for (ch = 1; ch <= fbw_channels; ch++) |
|
s->channel_uses_spx[ch] = get_bits1(gbc); |
|
} |
|
|
|
/* get the frequency bins of the spx copy region and the spx start |
|
and end subbands */ |
|
dst_start_freq = get_bits(gbc, 2); |
|
start_subband = get_bits(gbc, 3) + 2; |
|
if (start_subband > 7) |
|
start_subband += start_subband - 7; |
|
end_subband = get_bits(gbc, 3) + 5; |
|
if (end_subband > 7) |
|
end_subband += end_subband - 7; |
|
dst_start_freq = dst_start_freq * 12 + 25; |
|
src_start_freq = start_subband * 12 + 25; |
|
dst_end_freq = end_subband * 12 + 25; |
|
|
|
/* check validity of spx ranges */ |
|
if (start_subband >= end_subband) { |
|
av_log(s->avctx, AV_LOG_ERROR, "invalid spectral extension " |
|
"range (%d >= %d)\n", start_subband, end_subband); |
|
return -1; |
|
} |
|
if (dst_start_freq >= src_start_freq) { |
|
av_log(s->avctx, AV_LOG_ERROR, "invalid spectral extension " |
|
"copy start bin (%d >= %d)\n", dst_start_freq, src_start_freq); |
|
return -1; |
|
} |
|
|
|
s->spx_dst_start_freq = dst_start_freq; |
|
s->spx_src_start_freq = src_start_freq; |
|
s->spx_dst_end_freq = dst_end_freq; |
|
|
|
decode_band_structure(gbc, blk, s->eac3, 0, |
|
start_subband, end_subband, |
|
ff_eac3_default_spx_band_struct, |
|
&s->num_spx_bands, |
|
s->spx_band_sizes); |
|
} else { |
|
for (ch = 1; ch <= fbw_channels; ch++) { |
|
s->channel_uses_spx[ch] = 0; |
|
s->first_spx_coords[ch] = 1; |
|
} |
|
} |
|
} |
|
|
|
/* spectral extension coordinates */ |
|
if (s->spx_in_use) { |
|
for (ch = 1; ch <= fbw_channels; ch++) { |
|
if (s->channel_uses_spx[ch]) { |
|
if (s->first_spx_coords[ch] || get_bits1(gbc)) { |
|
float spx_blend; |
|
int bin, master_spx_coord; |
|
|
|
s->first_spx_coords[ch] = 0; |
|
spx_blend = get_bits(gbc, 5) * (1.0f/32); |
|
master_spx_coord = get_bits(gbc, 2) * 3; |
|
|
|
bin = s->spx_src_start_freq; |
|
for (bnd = 0; bnd < s->num_spx_bands; bnd++) { |
|
int bandsize; |
|
int spx_coord_exp, spx_coord_mant; |
|
float nratio, sblend, nblend, spx_coord; |
|
|
|
/* calculate blending factors */ |
|
bandsize = s->spx_band_sizes[bnd]; |
|
nratio = ((float)((bin + (bandsize >> 1))) / s->spx_dst_end_freq) - spx_blend; |
|
nratio = av_clipf(nratio, 0.0f, 1.0f); |
|
nblend = sqrtf(3.0f * nratio); // noise is scaled by sqrt(3) |
|
// to give unity variance |
|
sblend = sqrtf(1.0f - nratio); |
|
bin += bandsize; |
|
|
|
/* decode spx coordinates */ |
|
spx_coord_exp = get_bits(gbc, 4); |
|
spx_coord_mant = get_bits(gbc, 2); |
|
if (spx_coord_exp == 15) spx_coord_mant <<= 1; |
|
else spx_coord_mant += 4; |
|
spx_coord_mant <<= (25 - spx_coord_exp - master_spx_coord); |
|
spx_coord = spx_coord_mant * (1.0f / (1 << 23)); |
|
|
|
/* multiply noise and signal blending factors by spx coordinate */ |
|
s->spx_noise_blend [ch][bnd] = nblend * spx_coord; |
|
s->spx_signal_blend[ch][bnd] = sblend * spx_coord; |
|
} |
|
} |
|
} else { |
|
s->first_spx_coords[ch] = 1; |
|
} |
|
} |
|
} |
|
|
|
/* coupling strategy */ |
|
if (s->eac3 ? s->cpl_strategy_exists[blk] : get_bits1(gbc)) { |
|
memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS); |
|
if (!s->eac3) |
|
s->cpl_in_use[blk] = get_bits1(gbc); |
|
if (s->cpl_in_use[blk]) { |
|
/* coupling in use */ |
|
int cpl_start_subband, cpl_end_subband; |
|
|
|
if (channel_mode < AC3_CHMODE_STEREO) { |
|
av_log(s->avctx, AV_LOG_ERROR, "coupling not allowed in mono or dual-mono\n"); |
|
return -1; |
|
} |
|
|
|
/* check for enhanced coupling */ |
|
if (s->eac3 && get_bits1(gbc)) { |
|
/* TODO: parse enhanced coupling strategy info */ |
|
av_log_missing_feature(s->avctx, "Enhanced coupling", 1); |
|
return -1; |
|
} |
|
|
|
/* determine which channels are coupled */ |
|
if (s->eac3 && s->channel_mode == AC3_CHMODE_STEREO) { |
|
s->channel_in_cpl[1] = 1; |
|
s->channel_in_cpl[2] = 1; |
|
} else { |
|
for (ch = 1; ch <= fbw_channels; ch++) |
|
s->channel_in_cpl[ch] = get_bits1(gbc); |
|
} |
|
|
|
/* phase flags in use */ |
|
if (channel_mode == AC3_CHMODE_STEREO) |
|
s->phase_flags_in_use = get_bits1(gbc); |
|
|
|
/* coupling frequency range */ |
|
cpl_start_subband = get_bits(gbc, 4); |
|
cpl_end_subband = s->spx_in_use ? (s->spx_src_start_freq - 37) / 12 : |
|
get_bits(gbc, 4) + 3; |
|
if (cpl_start_subband >= cpl_end_subband) { |
|
av_log(s->avctx, AV_LOG_ERROR, "invalid coupling range (%d >= %d)\n", |
|
cpl_start_subband, cpl_end_subband); |
|
return -1; |
|
} |
|
s->start_freq[CPL_CH] = cpl_start_subband * 12 + 37; |
|
s->end_freq[CPL_CH] = cpl_end_subband * 12 + 37; |
|
|
|
decode_band_structure(gbc, blk, s->eac3, 0, cpl_start_subband, |
|
cpl_end_subband, |
|
ff_eac3_default_cpl_band_struct, |
|
&s->num_cpl_bands, s->cpl_band_sizes); |
|
} else { |
|
/* coupling not in use */ |
|
for (ch = 1; ch <= fbw_channels; ch++) { |
|
s->channel_in_cpl[ch] = 0; |
|
s->first_cpl_coords[ch] = 1; |
|
} |
|
s->first_cpl_leak = s->eac3; |
|
s->phase_flags_in_use = 0; |
|
} |
|
} else if (!s->eac3) { |
|
if (!blk) { |
|
av_log(s->avctx, AV_LOG_ERROR, "new coupling strategy must " |
|
"be present in block 0\n"); |
|
return -1; |
|
} else { |
|
s->cpl_in_use[blk] = s->cpl_in_use[blk-1]; |
|
} |
|
} |
|
cpl_in_use = s->cpl_in_use[blk]; |
|
|
|
/* coupling coordinates */ |
|
if (cpl_in_use) { |
|
int cpl_coords_exist = 0; |
|
|
|
for (ch = 1; ch <= fbw_channels; ch++) { |
|
if (s->channel_in_cpl[ch]) { |
|
if ((s->eac3 && s->first_cpl_coords[ch]) || get_bits1(gbc)) { |
|
int master_cpl_coord, cpl_coord_exp, cpl_coord_mant; |
|
s->first_cpl_coords[ch] = 0; |
|
cpl_coords_exist = 1; |
|
master_cpl_coord = 3 * get_bits(gbc, 2); |
|
for (bnd = 0; bnd < s->num_cpl_bands; bnd++) { |
|
cpl_coord_exp = get_bits(gbc, 4); |
|
cpl_coord_mant = get_bits(gbc, 4); |
|
if (cpl_coord_exp == 15) |
|
s->cpl_coords[ch][bnd] = cpl_coord_mant << 22; |
|
else |
|
s->cpl_coords[ch][bnd] = (cpl_coord_mant + 16) << 21; |
|
s->cpl_coords[ch][bnd] >>= (cpl_coord_exp + master_cpl_coord); |
|
} |
|
} else if (!blk) { |
|
av_log(s->avctx, AV_LOG_ERROR, "new coupling coordinates must " |
|
"be present in block 0\n"); |
|
return -1; |
|
} |
|
} else { |
|
/* channel not in coupling */ |
|
s->first_cpl_coords[ch] = 1; |
|
} |
|
} |
|
/* phase flags */ |
|
if (channel_mode == AC3_CHMODE_STEREO && cpl_coords_exist) { |
|
for (bnd = 0; bnd < s->num_cpl_bands; bnd++) { |
|
s->phase_flags[bnd] = s->phase_flags_in_use? get_bits1(gbc) : 0; |
|
} |
|
} |
|
} |
|
|
|
/* stereo rematrixing strategy and band structure */ |
|
if (channel_mode == AC3_CHMODE_STEREO) { |
|
if ((s->eac3 && !blk) || get_bits1(gbc)) { |
|
s->num_rematrixing_bands = 4; |
|
if (cpl_in_use && s->start_freq[CPL_CH] <= 61) { |
|
s->num_rematrixing_bands -= 1 + (s->start_freq[CPL_CH] == 37); |
|
} else if (s->spx_in_use && s->spx_src_start_freq <= 61) { |
|
s->num_rematrixing_bands--; |
|
} |
|
for (bnd = 0; bnd < s->num_rematrixing_bands; bnd++) |
|
s->rematrixing_flags[bnd] = get_bits1(gbc); |
|
} else if (!blk) { |
|
av_log(s->avctx, AV_LOG_WARNING, "Warning: " |
|
"new rematrixing strategy not present in block 0\n"); |
|
s->num_rematrixing_bands = 0; |
|
} |
|
} |
|
|
|
/* exponent strategies for each channel */ |
|
for (ch = !cpl_in_use; ch <= s->channels; ch++) { |
|
if (!s->eac3) |
|
s->exp_strategy[blk][ch] = get_bits(gbc, 2 - (ch == s->lfe_ch)); |
|
if (s->exp_strategy[blk][ch] != EXP_REUSE) |
|
bit_alloc_stages[ch] = 3; |
|
} |
|
|
|
/* channel bandwidth */ |
|
for (ch = 1; ch <= fbw_channels; ch++) { |
|
s->start_freq[ch] = 0; |
|
if (s->exp_strategy[blk][ch] != EXP_REUSE) { |
|
int group_size; |
|
int prev = s->end_freq[ch]; |
|
if (s->channel_in_cpl[ch]) |
|
s->end_freq[ch] = s->start_freq[CPL_CH]; |
|
else if (s->channel_uses_spx[ch]) |
|
s->end_freq[ch] = s->spx_src_start_freq; |
|
else { |
|
int bandwidth_code = get_bits(gbc, 6); |
|
if (bandwidth_code > 60) { |
|
av_log(s->avctx, AV_LOG_ERROR, "bandwidth code = %d > 60\n", bandwidth_code); |
|
return -1; |
|
} |
|
s->end_freq[ch] = bandwidth_code * 3 + 73; |
|
} |
|
group_size = 3 << (s->exp_strategy[blk][ch] - 1); |
|
s->num_exp_groups[ch] = (s->end_freq[ch] + group_size-4) / group_size; |
|
if (blk > 0 && s->end_freq[ch] != prev) |
|
memset(bit_alloc_stages, 3, AC3_MAX_CHANNELS); |
|
} |
|
} |
|
if (cpl_in_use && s->exp_strategy[blk][CPL_CH] != EXP_REUSE) { |
|
s->num_exp_groups[CPL_CH] = (s->end_freq[CPL_CH] - s->start_freq[CPL_CH]) / |
|
(3 << (s->exp_strategy[blk][CPL_CH] - 1)); |
|
} |
|
|
|
/* decode exponents for each channel */ |
|
for (ch = !cpl_in_use; ch <= s->channels; ch++) { |
|
if (s->exp_strategy[blk][ch] != EXP_REUSE) { |
|
s->dexps[ch][0] = get_bits(gbc, 4) << !ch; |
|
if (decode_exponents(gbc, s->exp_strategy[blk][ch], |
|
s->num_exp_groups[ch], s->dexps[ch][0], |
|
&s->dexps[ch][s->start_freq[ch]+!!ch])) { |
|
av_log(s->avctx, AV_LOG_ERROR, "exponent out-of-range\n"); |
|
return -1; |
|
} |
|
if (ch != CPL_CH && ch != s->lfe_ch) |
|
skip_bits(gbc, 2); /* skip gainrng */ |
|
} |
|
} |
|
|
|
/* bit allocation information */ |
|
if (s->bit_allocation_syntax) { |
|
if (get_bits1(gbc)) { |
|
s->bit_alloc_params.slow_decay = ff_ac3_slow_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift; |
|
s->bit_alloc_params.fast_decay = ff_ac3_fast_decay_tab[get_bits(gbc, 2)] >> s->bit_alloc_params.sr_shift; |
|
s->bit_alloc_params.slow_gain = ff_ac3_slow_gain_tab[get_bits(gbc, 2)]; |
|
s->bit_alloc_params.db_per_bit = ff_ac3_db_per_bit_tab[get_bits(gbc, 2)]; |
|
s->bit_alloc_params.floor = ff_ac3_floor_tab[get_bits(gbc, 3)]; |
|
for (ch = !cpl_in_use; ch <= s->channels; ch++) |
|
bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2); |
|
} else if (!blk) { |
|
av_log(s->avctx, AV_LOG_ERROR, "new bit allocation info must " |
|
"be present in block 0\n"); |
|
return -1; |
|
} |
|
} |
|
|
|
/* signal-to-noise ratio offsets and fast gains (signal-to-mask ratios) */ |
|
if (!s->eac3 || !blk) { |
|
if (s->snr_offset_strategy && get_bits1(gbc)) { |
|
int snr = 0; |
|
int csnr; |
|
csnr = (get_bits(gbc, 6) - 15) << 4; |
|
for (i = ch = !cpl_in_use; ch <= s->channels; ch++) { |
|
/* snr offset */ |
|
if (ch == i || s->snr_offset_strategy == 2) |
|
snr = (csnr + get_bits(gbc, 4)) << 2; |
|
/* run at least last bit allocation stage if snr offset changes */ |
|
if (blk && s->snr_offset[ch] != snr) { |
|
bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 1); |
|
} |
|
s->snr_offset[ch] = snr; |
|
|
|
/* fast gain (normal AC-3 only) */ |
|
if (!s->eac3) { |
|
int prev = s->fast_gain[ch]; |
|
s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)]; |
|
/* run last 2 bit allocation stages if fast gain changes */ |
|
if (blk && prev != s->fast_gain[ch]) |
|
bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2); |
|
} |
|
} |
|
} else if (!s->eac3 && !blk) { |
|
av_log(s->avctx, AV_LOG_ERROR, "new snr offsets must be present in block 0\n"); |
|
return -1; |
|
} |
|
} |
|
|
|
/* fast gain (E-AC-3 only) */ |
|
if (s->fast_gain_syntax && get_bits1(gbc)) { |
|
for (ch = !cpl_in_use; ch <= s->channels; ch++) { |
|
int prev = s->fast_gain[ch]; |
|
s->fast_gain[ch] = ff_ac3_fast_gain_tab[get_bits(gbc, 3)]; |
|
/* run last 2 bit allocation stages if fast gain changes */ |
|
if (blk && prev != s->fast_gain[ch]) |
|
bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2); |
|
} |
|
} else if (s->eac3 && !blk) { |
|
for (ch = !cpl_in_use; ch <= s->channels; ch++) |
|
s->fast_gain[ch] = ff_ac3_fast_gain_tab[4]; |
|
} |
|
|
|
/* E-AC-3 to AC-3 converter SNR offset */ |
|
if (s->frame_type == EAC3_FRAME_TYPE_INDEPENDENT && get_bits1(gbc)) { |
|
skip_bits(gbc, 10); // skip converter snr offset |
|
} |
|
|
|
/* coupling leak information */ |
|
if (cpl_in_use) { |
|
if (s->first_cpl_leak || get_bits1(gbc)) { |
|
int fl = get_bits(gbc, 3); |
|
int sl = get_bits(gbc, 3); |
|
/* run last 2 bit allocation stages for coupling channel if |
|
coupling leak changes */ |
|
if (blk && (fl != s->bit_alloc_params.cpl_fast_leak || |
|
sl != s->bit_alloc_params.cpl_slow_leak)) { |
|
bit_alloc_stages[CPL_CH] = FFMAX(bit_alloc_stages[CPL_CH], 2); |
|
} |
|
s->bit_alloc_params.cpl_fast_leak = fl; |
|
s->bit_alloc_params.cpl_slow_leak = sl; |
|
} else if (!s->eac3 && !blk) { |
|
av_log(s->avctx, AV_LOG_ERROR, "new coupling leak info must " |
|
"be present in block 0\n"); |
|
return -1; |
|
} |
|
s->first_cpl_leak = 0; |
|
} |
|
|
|
/* delta bit allocation information */ |
|
if (s->dba_syntax && get_bits1(gbc)) { |
|
/* delta bit allocation exists (strategy) */ |
|
for (ch = !cpl_in_use; ch <= fbw_channels; ch++) { |
|
s->dba_mode[ch] = get_bits(gbc, 2); |
|
if (s->dba_mode[ch] == DBA_RESERVED) { |
|
av_log(s->avctx, AV_LOG_ERROR, "delta bit allocation strategy reserved\n"); |
|
return -1; |
|
} |
|
bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2); |
|
} |
|
/* channel delta offset, len and bit allocation */ |
|
for (ch = !cpl_in_use; ch <= fbw_channels; ch++) { |
|
if (s->dba_mode[ch] == DBA_NEW) { |
|
s->dba_nsegs[ch] = get_bits(gbc, 3) + 1; |
|
for (seg = 0; seg < s->dba_nsegs[ch]; seg++) { |
|
s->dba_offsets[ch][seg] = get_bits(gbc, 5); |
|
s->dba_lengths[ch][seg] = get_bits(gbc, 4); |
|
s->dba_values[ch][seg] = get_bits(gbc, 3); |
|
} |
|
/* run last 2 bit allocation stages if new dba values */ |
|
bit_alloc_stages[ch] = FFMAX(bit_alloc_stages[ch], 2); |
|
} |
|
} |
|
} else if (blk == 0) { |
|
for (ch = 0; ch <= s->channels; ch++) { |
|
s->dba_mode[ch] = DBA_NONE; |
|
} |
|
} |
|
|
|
/* Bit allocation */ |
|
for (ch = !cpl_in_use; ch <= s->channels; ch++) { |
|
if (bit_alloc_stages[ch] > 2) { |
|
/* Exponent mapping into PSD and PSD integration */ |
|
ff_ac3_bit_alloc_calc_psd(s->dexps[ch], |
|
s->start_freq[ch], s->end_freq[ch], |
|
s->psd[ch], s->band_psd[ch]); |
|
} |
|
if (bit_alloc_stages[ch] > 1) { |
|
/* Compute excitation function, Compute masking curve, and |
|
Apply delta bit allocation */ |
|
if (ff_ac3_bit_alloc_calc_mask(&s->bit_alloc_params, s->band_psd[ch], |
|
s->start_freq[ch], s->end_freq[ch], |
|
s->fast_gain[ch], (ch == s->lfe_ch), |
|
s->dba_mode[ch], s->dba_nsegs[ch], |
|
s->dba_offsets[ch], s->dba_lengths[ch], |
|
s->dba_values[ch], s->mask[ch])) { |
|
av_log(s->avctx, AV_LOG_ERROR, "error in bit allocation\n"); |
|
return -1; |
|
} |
|
} |
|
if (bit_alloc_stages[ch] > 0) { |
|
/* Compute bit allocation */ |
|
const uint8_t *bap_tab = s->channel_uses_aht[ch] ? |
|
ff_eac3_hebap_tab : ff_ac3_bap_tab; |
|
s->ac3dsp.bit_alloc_calc_bap(s->mask[ch], s->psd[ch], |
|
s->start_freq[ch], s->end_freq[ch], |
|
s->snr_offset[ch], |
|
s->bit_alloc_params.floor, |
|
bap_tab, s->bap[ch]); |
|
} |
|
} |
|
|
|
/* unused dummy data */ |
|
if (s->skip_syntax && get_bits1(gbc)) { |
|
int skipl = get_bits(gbc, 9); |
|
while (skipl--) |
|
skip_bits(gbc, 8); |
|
} |
|
|
|
/* unpack the transform coefficients |
|
this also uncouples channels if coupling is in use. */ |
|
decode_transform_coeffs(s, blk); |
|
|
|
/* TODO: generate enhanced coupling coordinates and uncouple */ |
|
|
|
/* recover coefficients if rematrixing is in use */ |
|
if (s->channel_mode == AC3_CHMODE_STEREO) |
|
do_rematrixing(s); |
|
|
|
/* apply scaling to coefficients (headroom, dynrng) */ |
|
for (ch = 1; ch <= s->channels; ch++) { |
|
float gain = s->mul_bias / 4194304.0f; |
|
if (s->channel_mode == AC3_CHMODE_DUALMONO) { |
|
gain *= s->dynamic_range[2 - ch]; |
|
} else { |
|
gain *= s->dynamic_range[0]; |
|
} |
|
s->fmt_conv.int32_to_float_fmul_scalar(s->transform_coeffs[ch], |
|
s->fixed_coeffs[ch], gain, 256); |
|
} |
|
|
|
/* apply spectral extension to high frequency bins */ |
|
if (s->spx_in_use && CONFIG_EAC3_DECODER) { |
|
ff_eac3_apply_spectral_extension(s); |
|
} |
|
|
|
/* downmix and MDCT. order depends on whether block switching is used for |
|
any channel in this block. this is because coefficients for the long |
|
and short transforms cannot be mixed. */ |
|
downmix_output = s->channels != s->out_channels && |
|
!((s->output_mode & AC3_OUTPUT_LFEON) && |
|
s->fbw_channels == s->out_channels); |
|
if (different_transforms) { |
|
/* the delay samples have already been downmixed, so we upmix the delay |
|
samples in order to reconstruct all channels before downmixing. */ |
|
if (s->downmixed) { |
|
s->downmixed = 0; |
|
ac3_upmix_delay(s); |
|
} |
|
|
|
do_imdct(s, s->channels); |
|
|
|
if (downmix_output) { |
|
s->ac3dsp.downmix(s->output, s->downmix_coeffs, |
|
s->out_channels, s->fbw_channels, 256); |
|
} |
|
} else { |
|
if (downmix_output) { |
|
s->ac3dsp.downmix(s->transform_coeffs + 1, s->downmix_coeffs, |
|
s->out_channels, s->fbw_channels, 256); |
|
} |
|
|
|
if (downmix_output && !s->downmixed) { |
|
s->downmixed = 1; |
|
s->ac3dsp.downmix(s->delay, s->downmix_coeffs, s->out_channels, |
|
s->fbw_channels, 128); |
|
} |
|
|
|
do_imdct(s, s->out_channels); |
|
} |
|
|
|
return 0; |
|
} |
|
|
|
/** |
|
* Decode a single AC-3 frame. |
|
*/ |
|
static int ac3_decode_frame(AVCodecContext * avctx, void *data, |
|
int *got_frame_ptr, AVPacket *avpkt) |
|
{ |
|
const uint8_t *buf = avpkt->data; |
|
int buf_size = avpkt->size; |
|
AC3DecodeContext *s = avctx->priv_data; |
|
float *out_samples_flt; |
|
int16_t *out_samples_s16; |
|
int blk, ch, err, ret; |
|
const uint8_t *channel_map; |
|
const float *output[AC3_MAX_CHANNELS]; |
|
|
|
/* copy input buffer to decoder context to avoid reading past the end |
|
of the buffer, which can be caused by a damaged input stream. */ |
|
if (buf_size >= 2 && AV_RB16(buf) == 0x770B) { |
|
// seems to be byte-swapped AC-3 |
|
int cnt = FFMIN(buf_size, AC3_FRAME_BUFFER_SIZE) >> 1; |
|
s->dsp.bswap16_buf((uint16_t *)s->input_buffer, (const uint16_t *)buf, cnt); |
|
} else |
|
memcpy(s->input_buffer, buf, FFMIN(buf_size, AC3_FRAME_BUFFER_SIZE)); |
|
buf = s->input_buffer; |
|
/* initialize the GetBitContext with the start of valid AC-3 Frame */ |
|
init_get_bits(&s->gbc, buf, buf_size * 8); |
|
|
|
/* parse the syncinfo */ |
|
err = parse_frame_header(s); |
|
|
|
if (err) { |
|
switch (err) { |
|
case AAC_AC3_PARSE_ERROR_SYNC: |
|
av_log(avctx, AV_LOG_ERROR, "frame sync error\n"); |
|
return -1; |
|
case AAC_AC3_PARSE_ERROR_BSID: |
|
av_log(avctx, AV_LOG_ERROR, "invalid bitstream id\n"); |
|
break; |
|
case AAC_AC3_PARSE_ERROR_SAMPLE_RATE: |
|
av_log(avctx, AV_LOG_ERROR, "invalid sample rate\n"); |
|
break; |
|
case AAC_AC3_PARSE_ERROR_FRAME_SIZE: |
|
av_log(avctx, AV_LOG_ERROR, "invalid frame size\n"); |
|
break; |
|
case AAC_AC3_PARSE_ERROR_FRAME_TYPE: |
|
/* skip frame if CRC is ok. otherwise use error concealment. */ |
|
/* TODO: add support for substreams and dependent frames */ |
|
if (s->frame_type == EAC3_FRAME_TYPE_DEPENDENT || s->substreamid) { |
|
av_log(avctx, AV_LOG_ERROR, "unsupported frame type : " |
|
"skipping frame\n"); |
|
*got_frame_ptr = 0; |
|
return s->frame_size; |
|
} else { |
|
av_log(avctx, AV_LOG_ERROR, "invalid frame type\n"); |
|
} |
|
break; |
|
default: |
|
av_log(avctx, AV_LOG_ERROR, "invalid header\n"); |
|
break; |
|
} |
|
} else { |
|
/* check that reported frame size fits in input buffer */ |
|
if (s->frame_size > buf_size) { |
|
av_log(avctx, AV_LOG_ERROR, "incomplete frame\n"); |
|
err = AAC_AC3_PARSE_ERROR_FRAME_SIZE; |
|
} else if (avctx->err_recognition & (AV_EF_CRCCHECK|AV_EF_CAREFUL)) { |
|
/* check for crc mismatch */ |
|
if (av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0, &buf[2], |
|
s->frame_size - 2)) { |
|
av_log(avctx, AV_LOG_ERROR, "frame CRC mismatch\n"); |
|
err = AAC_AC3_PARSE_ERROR_CRC; |
|
} |
|
} |
|
} |
|
|
|
/* if frame is ok, set audio parameters */ |
|
if (!err) { |
|
avctx->sample_rate = s->sample_rate; |
|
avctx->bit_rate = s->bit_rate; |
|
|
|
/* channel config */ |
|
s->out_channels = s->channels; |
|
s->output_mode = s->channel_mode; |
|
if (s->lfe_on) |
|
s->output_mode |= AC3_OUTPUT_LFEON; |
|
if (avctx->request_channels > 0 && avctx->request_channels <= 2 && |
|
avctx->request_channels < s->channels) { |
|
s->out_channels = avctx->request_channels; |
|
s->output_mode = avctx->request_channels == 1 ? AC3_CHMODE_MONO : AC3_CHMODE_STEREO; |
|
s->channel_layout = avpriv_ac3_channel_layout_tab[s->output_mode]; |
|
} |
|
avctx->channels = s->out_channels; |
|
avctx->channel_layout = s->channel_layout; |
|
|
|
s->loro_center_mix_level = gain_levels[s-> center_mix_level]; |
|
s->loro_surround_mix_level = gain_levels[s->surround_mix_level]; |
|
s->ltrt_center_mix_level = LEVEL_MINUS_3DB; |
|
s->ltrt_surround_mix_level = LEVEL_MINUS_3DB; |
|
/* set downmixing coefficients if needed */ |
|
if (s->channels != s->out_channels && !((s->output_mode & AC3_OUTPUT_LFEON) && |
|
s->fbw_channels == s->out_channels)) { |
|
set_downmix_coeffs(s); |
|
} |
|
} else if (!s->out_channels) { |
|
s->out_channels = avctx->channels; |
|
if (s->out_channels < s->channels) |
|
s->output_mode = s->out_channels == 1 ? AC3_CHMODE_MONO : AC3_CHMODE_STEREO; |
|
} |
|
if (avctx->channels != s->out_channels) { |
|
av_log(avctx, AV_LOG_ERROR, "channel number mismatching on damaged frame\n"); |
|
return AVERROR_INVALIDDATA; |
|
} |
|
/* set audio service type based on bitstream mode for AC-3 */ |
|
avctx->audio_service_type = s->bitstream_mode; |
|
if (s->bitstream_mode == 0x7 && s->channels > 1) |
|
avctx->audio_service_type = AV_AUDIO_SERVICE_TYPE_KARAOKE; |
|
|
|
/* get output buffer */ |
|
avctx->channels = s->out_channels; |
|
s->frame.nb_samples = s->num_blocks * 256; |
|
if ((ret = avctx->get_buffer(avctx, &s->frame)) < 0) { |
|
av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n"); |
|
return ret; |
|
} |
|
out_samples_flt = (float *)s->frame.data[0]; |
|
out_samples_s16 = (int16_t *)s->frame.data[0]; |
|
|
|
/* decode the audio blocks */ |
|
channel_map = ff_ac3_dec_channel_map[s->output_mode & ~AC3_OUTPUT_LFEON][s->lfe_on]; |
|
for (ch = 0; ch < s->out_channels; ch++) |
|
output[ch] = s->output[channel_map[ch]]; |
|
for (blk = 0; blk < s->num_blocks; blk++) { |
|
if (!err && decode_audio_block(s, blk)) { |
|
av_log(avctx, AV_LOG_ERROR, "error decoding the audio block\n"); |
|
err = 1; |
|
} |
|
if (avctx->sample_fmt == AV_SAMPLE_FMT_FLT) { |
|
s->fmt_conv.float_interleave(out_samples_flt, output, 256, |
|
s->out_channels); |
|
out_samples_flt += 256 * s->out_channels; |
|
} else { |
|
s->fmt_conv.float_to_int16_interleave(out_samples_s16, output, 256, |
|
s->out_channels); |
|
out_samples_s16 += 256 * s->out_channels; |
|
} |
|
} |
|
|
|
s->frame.decode_error_flags = err ? FF_DECODE_ERROR_INVALID_BITSTREAM : 0; |
|
|
|
*got_frame_ptr = 1; |
|
*(AVFrame *)data = s->frame; |
|
|
|
return FFMIN(buf_size, s->frame_size); |
|
} |
|
|
|
/** |
|
* Uninitialize the AC-3 decoder. |
|
*/ |
|
static av_cold int ac3_decode_end(AVCodecContext *avctx) |
|
{ |
|
AC3DecodeContext *s = avctx->priv_data; |
|
ff_mdct_end(&s->imdct_512); |
|
ff_mdct_end(&s->imdct_256); |
|
|
|
return 0; |
|
} |
|
|
|
#define OFFSET(x) offsetof(AC3DecodeContext, x) |
|
#define PAR (AV_OPT_FLAG_DECODING_PARAM | AV_OPT_FLAG_AUDIO_PARAM) |
|
static const AVOption options[] = { |
|
{ "drc_scale", "percentage of dynamic range compression to apply", OFFSET(drc_scale), AV_OPT_TYPE_FLOAT, {.dbl = 1.0}, 0.0, 1.0, PAR }, |
|
|
|
{"dmix_mode", "Preferred Stereo Downmix Mode", OFFSET(preferred_stereo_downmix), AV_OPT_TYPE_INT, {.i64 = -1 }, -1, 2, 0, "dmix_mode"}, |
|
{"ltrt_cmixlev", "Lt/Rt Center Mix Level", OFFSET(ltrt_center_mix_level), AV_OPT_TYPE_FLOAT, {.dbl = -1.0 }, -1.0, 2.0, 0}, |
|
{"ltrt_surmixlev", "Lt/Rt Surround Mix Level", OFFSET(ltrt_surround_mix_level), AV_OPT_TYPE_FLOAT, {.dbl = -1.0 }, -1.0, 2.0, 0}, |
|
{"loro_cmixlev", "Lo/Ro Center Mix Level", OFFSET(loro_center_mix_level), AV_OPT_TYPE_FLOAT, {.dbl = -1.0 }, -1.0, 2.0, 0}, |
|
{"loro_surmixlev", "Lo/Ro Surround Mix Level", OFFSET(loro_surround_mix_level), AV_OPT_TYPE_FLOAT, {.dbl = -1.0 }, -1.0, 2.0, 0}, |
|
|
|
{ NULL}, |
|
}; |
|
|
|
static const AVClass ac3_decoder_class = { |
|
.class_name = "AC3 decoder", |
|
.item_name = av_default_item_name, |
|
.option = options, |
|
.version = LIBAVUTIL_VERSION_INT, |
|
}; |
|
|
|
AVCodec ff_ac3_decoder = { |
|
.name = "ac3", |
|
.type = AVMEDIA_TYPE_AUDIO, |
|
.id = AV_CODEC_ID_AC3, |
|
.priv_data_size = sizeof (AC3DecodeContext), |
|
.init = ac3_decode_init, |
|
.close = ac3_decode_end, |
|
.decode = ac3_decode_frame, |
|
.capabilities = CODEC_CAP_DR1, |
|
.long_name = NULL_IF_CONFIG_SMALL("ATSC A/52A (AC-3)"), |
|
.sample_fmts = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_FLT, |
|
AV_SAMPLE_FMT_S16, |
|
AV_SAMPLE_FMT_NONE }, |
|
.priv_class = &ac3_decoder_class, |
|
}; |
|
|
|
#if CONFIG_EAC3_DECODER |
|
static const AVClass eac3_decoder_class = { |
|
.class_name = "E-AC3 decoder", |
|
.item_name = av_default_item_name, |
|
.option = options, |
|
.version = LIBAVUTIL_VERSION_INT, |
|
}; |
|
|
|
AVCodec ff_eac3_decoder = { |
|
.name = "eac3", |
|
.type = AVMEDIA_TYPE_AUDIO, |
|
.id = AV_CODEC_ID_EAC3, |
|
.priv_data_size = sizeof (AC3DecodeContext), |
|
.init = ac3_decode_init, |
|
.close = ac3_decode_end, |
|
.decode = ac3_decode_frame, |
|
.capabilities = CODEC_CAP_DR1, |
|
.long_name = NULL_IF_CONFIG_SMALL("ATSC A/52B (AC-3, E-AC-3)"), |
|
.sample_fmts = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_FLT, |
|
AV_SAMPLE_FMT_S16, |
|
AV_SAMPLE_FMT_NONE }, |
|
.priv_class = &eac3_decoder_class, |
|
}; |
|
#endif
|
|
|