falkTX
/
FFmpeg
mirror of https://github.com/falkTX/FFmpeg.git
1
0
Fork 0
Code Issues 0 Releases 338 Wiki Activity
You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
39979 Commits
32 Branches
356MB
Tree: 593886b5dd
Branches Tags
${ item.name }
Create branch ${ searchTerm }
from '593886b5dd'
${ noResults }
FFmpeg/libavcodec/ac3dec.h

244 lines
13KB
Raw Blame History 

  1. /*

  2.  * Common code between the AC-3 and E-AC-3 decoders

  3.  * Copyright (c) 2007 Bartlomiej Wolowiec <bartek.wolowiec@gmail.com>

  4.  *

  5.  * This file is part of Libav.

  6.  *

  7.  * Libav is free software; you can redistribute it and/or

  8.  * modify it under the terms of the GNU Lesser General Public

  9.  * License as published by the Free Software Foundation; either

  10.  * version 2.1 of the License, or (at your option) any later version.

  11.  *

  12.  * Libav is distributed in the hope that it will be useful,

  13.  * but WITHOUT ANY WARRANTY; without even the implied warranty of

  14.  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

  15.  * Lesser General Public License for more details.

  16.  *

  17.  * You should have received a copy of the GNU Lesser General Public

  18.  * License along with Libav; if not, write to the Free Software

  19.  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

  20.  */

  21. 

  22. /**

  23.  * @file

  24.  * Common code between the AC-3 and E-AC-3 decoders.

  25.  *

  26.  * Summary of MDCT Coefficient Grouping:

  27.  * The individual MDCT coefficient indices are often referred to in the

  28.  * (E-)AC-3 specification as frequency bins.  These bins are grouped together

  29.  * into subbands of 12 coefficients each.  The subbands are grouped together

  30.  * into bands as defined in the bitstream by the band structures, which

  31.  * determine the number of bands and the size of each band.  The full spectrum

  32.  * of 256 frequency bins is divided into 1 DC bin + 21 subbands = 253 bins.

  33.  * This system of grouping coefficients is used for channel bandwidth, stereo

  34.  * rematrixing, channel coupling, enhanced coupling, and spectral extension.

  35.  *

  36.  * +-+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+-+

  37.  * |1|  |12|  |  [12|12|12|12]  |  |  |  |  |  |  |  |  |  |  |  |  |3|

  38.  * +-+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+-+

  39.  * ~~~  ~~~~     ~~~~~~~~~~~~~                                      ~~~

  40.  *  |     |            |                                             |

  41.  *  |     |            |                    3 unused frequency bins--+

  42.  *  |     |            |

  43.  *  |     |            +--1 band containing 4 subbands

  44.  *  |     |

  45.  *  |     +--1 subband of 12 frequency bins

  46.  *  |

  47.  *  +--DC frequency bin

  48.  */

  49. 

  50. #ifndef AVCODEC_AC3DEC_H

  51. #define AVCODEC_AC3DEC_H

  52. 

  53. #include "libavutil/float_dsp.h"

  54. #include "libavutil/lfg.h"

  55. #include "ac3.h"

  56. #include "ac3dsp.h"

  57. #include "get_bits.h"

  58. #include "dsputil.h"

  59. #include "fft.h"

  60. #include "fmtconvert.h"

  61. 

  62. #define AC3_OUTPUT_LFEON  8

  63. 

  64. #define SPX_MAX_BANDS    17

  65. 

  66. /** Large enough for maximum possible frame size when the specification limit is ignored */

  67. #define AC3_FRAME_BUFFER_SIZE 32768

  68. 

  69. typedef struct AC3DecodeContext {

  70.     AVClass        *class;                  ///< class for AVOptions

  71.     AVCodecContext *avctx;                  ///< parent context

  72.     GetBitContext gbc;                      ///< bitstream reader

  73. 

  74. ///@name Bit stream information

  75. ///@{

  76.     int frame_type;                         ///< frame type                             (strmtyp)

  77.     int substreamid;                        ///< substream identification

  78.     int frame_size;                         ///< current frame size, in bytes

  79.     int bit_rate;                           ///< stream bit rate, in bits-per-second

  80.     int sample_rate;                        ///< sample frequency, in Hz

  81.     int num_blocks;                         ///< number of audio blocks

  82.     int bitstream_id;                       ///< bitstream id                           (bsid)

  83.     int bitstream_mode;                     ///< bitstream mode                         (bsmod)

  84.     int channel_mode;                       ///< channel mode                           (acmod)

  85.     int lfe_on;                             ///< lfe channel in use

  86.     int channel_map;                        ///< custom channel map

  87.     int preferred_downmix;                  ///< Preferred 2-channel downmix mode       (dmixmod)

  88.     int center_mix_level;                   ///< Center mix level index

  89.     int center_mix_level_ltrt;              ///< Center mix level index for Lt/Rt       (ltrtcmixlev)

  90.     int surround_mix_level;                 ///< Surround mix level index

  91.     int surround_mix_level_ltrt;            ///< Surround mix level index for Lt/Rt     (ltrtsurmixlev)

  92.     int lfe_mix_level_exists;               ///< indicates if lfemixlevcod is specified (lfemixlevcode)

  93.     int lfe_mix_level;                      ///< LFE mix level index                    (lfemixlevcod)

  94.     int eac3;                               ///< indicates if current frame is E-AC-3

  95.     int dolby_surround_mode;                ///< dolby surround mode                    (dsurmod)

  96.     int dolby_surround_ex_mode;             ///< dolby surround ex mode                 (dsurexmod)

  97.     int dolby_headphone_mode;               ///< dolby headphone mode                   (dheadphonmod)

  98. ///@}

  99. 

  100. ///@name Frame syntax parameters

  101.     int snr_offset_strategy;                ///< SNR offset strategy                    (snroffststr)

  102.     int block_switch_syntax;                ///< block switch syntax enabled            (blkswe)

  103.     int dither_flag_syntax;                 ///< dither flag syntax enabled             (dithflage)

  104.     int bit_allocation_syntax;              ///< bit allocation model syntax enabled    (bamode)

  105.     int fast_gain_syntax;                   ///< fast gain codes enabled                (frmfgaincode)

  106.     int dba_syntax;                         ///< delta bit allocation syntax enabled    (dbaflde)

  107.     int skip_syntax;                        ///< skip field syntax enabled              (skipflde)

  108.  ///@}

  109. 

  110. ///@name Standard coupling

  111.     int cpl_in_use[AC3_MAX_BLOCKS];         ///< coupling in use                        (cplinu)

  112.     int cpl_strategy_exists[AC3_MAX_BLOCKS];///< coupling strategy exists               (cplstre)

  113.     int channel_in_cpl[AC3_MAX_CHANNELS];   ///< channel in coupling                    (chincpl)

  114.     int phase_flags_in_use;                 ///< phase flags in use                     (phsflginu)

  115.     int phase_flags[AC3_MAX_CPL_BANDS];     ///< phase flags                            (phsflg)

  116.     int num_cpl_bands;                      ///< number of coupling bands               (ncplbnd)

  117.     uint8_t cpl_band_sizes[AC3_MAX_CPL_BANDS]; ///< number of coeffs in each coupling band

  118.     int firstchincpl;                       ///< first channel in coupling

  119.     int first_cpl_coords[AC3_MAX_CHANNELS]; ///< first coupling coordinates states      (firstcplcos)

  120.     int cpl_coords[AC3_MAX_CHANNELS][AC3_MAX_CPL_BANDS]; ///< coupling coordinates      (cplco)

  121. ///@}

  122. 

  123. ///@name Spectral extension

  124. ///@{

  125.     int spx_in_use;                             ///< spectral extension in use              (spxinu)

  126.     uint8_t channel_uses_spx[AC3_MAX_CHANNELS]; ///< channel uses spectral extension        (chinspx)

  127.     int8_t spx_atten_code[AC3_MAX_CHANNELS];    ///< spx attenuation code                   (spxattencod)

  128.     int spx_src_start_freq;                     ///< spx start frequency bin

  129.     int spx_dst_end_freq;                       ///< spx end frequency bin

  130.     int spx_dst_start_freq;                     ///< spx starting frequency bin for copying (copystartmant)

  131.                                                 ///< the copy region ends at the start of the spx region.

  132.     int num_spx_bands;                          ///< number of spx bands                    (nspxbnds)

  133.     uint8_t spx_band_sizes[SPX_MAX_BANDS];      ///< number of bins in each spx band

  134.     uint8_t first_spx_coords[AC3_MAX_CHANNELS]; ///< first spx coordinates states           (firstspxcos)

  135.     float spx_noise_blend[AC3_MAX_CHANNELS][SPX_MAX_BANDS]; ///< spx noise blending factor  (nblendfact)

  136.     float spx_signal_blend[AC3_MAX_CHANNELS][SPX_MAX_BANDS];///< spx signal blending factor (sblendfact)

  137. ///@}

  138. 

  139. ///@name Adaptive hybrid transform

  140.     int channel_uses_aht[AC3_MAX_CHANNELS];                         ///< channel AHT in use (chahtinu)

  141.     int pre_mantissa[AC3_MAX_CHANNELS][AC3_MAX_COEFS][AC3_MAX_BLOCKS];  ///< pre-IDCT mantissas

  142. ///@}

  143. 

  144. ///@name Channel

  145.     int fbw_channels;                           ///< number of full-bandwidth channels

  146.     int channels;                               ///< number of total channels

  147.     int lfe_ch;                                 ///< index of LFE channel

  148.     float downmix_coeffs[AC3_MAX_CHANNELS][2];  ///< stereo downmix coefficients

  149.     int downmixed;                              ///< indicates if coeffs are currently downmixed

  150.     int output_mode;                            ///< output channel configuration

  151.     int out_channels;                           ///< number of output channels

  152. ///@}

  153. 

  154. ///@name Dynamic range

  155.     float dynamic_range[2];                 ///< dynamic range

  156.     float drc_scale;                        ///< percentage of dynamic range compression to be applied

  157. ///@}

  158. 

  159. ///@name Bandwidth

  160.     int start_freq[AC3_MAX_CHANNELS];       ///< start frequency bin                    (strtmant)

  161.     int end_freq[AC3_MAX_CHANNELS];         ///< end frequency bin                      (endmant)

  162. ///@}

  163. 

  164. ///@name Rematrixing

  165.     int num_rematrixing_bands;              ///< number of rematrixing bands            (nrematbnd)

  166.     int rematrixing_flags[4];               ///< rematrixing flags                      (rematflg)

  167. ///@}

  168. 

  169. ///@name Exponents

  170.     int num_exp_groups[AC3_MAX_CHANNELS];           ///< Number of exponent groups      (nexpgrp)

  171.     int8_t dexps[AC3_MAX_CHANNELS][AC3_MAX_COEFS];  ///< decoded exponents

  172.     int exp_strategy[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS]; ///< exponent strategies        (expstr)

  173. ///@}

  174. 

  175. ///@name Bit allocation

  176.     AC3BitAllocParameters bit_alloc_params;         ///< bit allocation parameters

  177.     int first_cpl_leak;                             ///< first coupling leak state      (firstcplleak)

  178.     int snr_offset[AC3_MAX_CHANNELS];               ///< signal-to-noise ratio offsets  (snroffst)

  179.     int fast_gain[AC3_MAX_CHANNELS];                ///< fast gain values/SMR's         (fgain)

  180.     uint8_t bap[AC3_MAX_CHANNELS][AC3_MAX_COEFS];   ///< bit allocation pointers

  181.     int16_t psd[AC3_MAX_CHANNELS][AC3_MAX_COEFS];   ///< scaled exponents

  182.     int16_t band_psd[AC3_MAX_CHANNELS][AC3_CRITICAL_BANDS]; ///< interpolated exponents

  183.     int16_t mask[AC3_MAX_CHANNELS][AC3_CRITICAL_BANDS];     ///< masking curve values

  184.     int dba_mode[AC3_MAX_CHANNELS];                 ///< delta bit allocation mode

  185.     int dba_nsegs[AC3_MAX_CHANNELS];                ///< number of delta segments

  186.     uint8_t dba_offsets[AC3_MAX_CHANNELS][8];       ///< delta segment offsets

  187.     uint8_t dba_lengths[AC3_MAX_CHANNELS][8];       ///< delta segment lengths

  188.     uint8_t dba_values[AC3_MAX_CHANNELS][8];        ///< delta values for each segment

  189. ///@}

  190. 

  191. ///@name Zero-mantissa dithering

  192.     int dither_flag[AC3_MAX_CHANNELS];      ///< dither flags                           (dithflg)

  193.     AVLFG dith_state;                       ///< for dither generation

  194. ///@}

  195. 

  196. ///@name IMDCT

  197.     int block_switch[AC3_MAX_CHANNELS];     ///< block switch flags                     (blksw)

  198.     FFTContext imdct_512;                   ///< for 512 sample IMDCT

  199.     FFTContext imdct_256;                   ///< for 256 sample IMDCT

  200. ///@}

  201. 

  202. ///@name Optimization

  203.     DSPContext dsp;                         ///< for optimization

  204.     AVFloatDSPContext fdsp;

  205.     AC3DSPContext ac3dsp;

  206.     FmtConvertContext fmt_conv;             ///< optimized conversion functions

  207. ///@}

  208. 

  209.     float *outptr[AC3_MAX_CHANNELS];

  210.     float *xcfptr[AC3_MAX_CHANNELS];

  211.     float *dlyptr[AC3_MAX_CHANNELS];

  212. 

  213. ///@name Aligned arrays

  214.     DECLARE_ALIGNED(16, int32_t, fixed_coeffs)[AC3_MAX_CHANNELS][AC3_MAX_COEFS];     ///< fixed-point transform coefficients

  215.     DECLARE_ALIGNED(32, float, transform_coeffs)[AC3_MAX_CHANNELS][AC3_MAX_COEFS];   ///< transform coefficients

  216.     DECLARE_ALIGNED(32, float, delay)[AC3_MAX_CHANNELS][AC3_BLOCK_SIZE];             ///< delay - added to the next block

  217.     DECLARE_ALIGNED(32, float, window)[AC3_BLOCK_SIZE];                              ///< window coefficients

  218.     DECLARE_ALIGNED(32, float, tmp_output)[AC3_BLOCK_SIZE];                          ///< temporary storage for output before windowing

  219.     DECLARE_ALIGNED(32, float, output)[AC3_MAX_CHANNELS][AC3_BLOCK_SIZE];            ///< output after imdct transform and windowing

  220.     DECLARE_ALIGNED(32, uint8_t, input_buffer)[AC3_FRAME_BUFFER_SIZE + FF_INPUT_BUFFER_PADDING_SIZE]; ///< temp buffer to prevent overread

  221. ///@}

  222. } AC3DecodeContext;

  223. 

  224. /**

  225.  * Parse the E-AC-3 frame header.

  226.  * This parses both the bit stream info and audio frame header.

  227.  */

  228. int ff_eac3_parse_header(AC3DecodeContext *s);

  229. 

  230. /**

  231.  * Decode mantissas in a single channel for the entire frame.

  232.  * This is used when AHT mode is enabled.

  233.  */

  234. void ff_eac3_decode_transform_coeffs_aht_ch(AC3DecodeContext *s, int ch);

  235. 

  236. /**

  237.  * Apply spectral extension to each channel by copying lower frequency

  238.  * coefficients to higher frequency bins and applying side information to

  239.  * approximate the original high frequency signal.

  240.  */

  241. void ff_eac3_apply_spectral_extension(AC3DecodeContext *s);

  242. 

  243. #endif /* AVCODEC_AC3DEC_H */