mirror of https://code.videolan.org/videolan/vlc
380 lines
11 KiB
C
380 lines
11 KiB
C
/*****************************************************************************
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* ac3_decoder.h : ac3 decoder interface
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*****************************************************************************
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* Copyright (C) 1999, 2000 VideoLAN
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*
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* Authors:
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* Michel Kaempf <maxx@via.ecp.fr>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program 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
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111, USA.
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*****************************************************************************/
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/**** ac3 decoder API - public ac3 decoder structures */
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typedef struct ac3dec_s ac3dec_t;
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typedef struct ac3_sync_info_s {
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int sample_rate; /* sample rate in Hz */
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int frame_size; /* frame size in bytes */
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int bit_rate; /* nominal bit rate in kbps */
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} ac3_sync_info_t;
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typedef struct ac3_byte_stream_s {
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u8 * p_byte;
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u8 * p_end;
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void * info;
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} ac3_byte_stream_t;
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/**** ac3 decoder API - functions publically provided by the ac3 decoder ****/
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int ac3_init (ac3dec_t * p_ac3dec);
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int ac3_sync_frame (ac3dec_t * p_ac3dec, ac3_sync_info_t * p_sync_info);
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int ac3_decode_frame (ac3dec_t * p_ac3dec, s16 * buffer);
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static ac3_byte_stream_t * ac3_byte_stream (ac3dec_t * p_ac3dec);
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/**** ac3 decoder API - user functions to be provided to the ac3 decoder ****/
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void ac3_byte_stream_next (ac3_byte_stream_t * p_byte_stream);
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/**** EVERYTHING AFTER THIS POINT IS PRIVATE ! DO NOT USE DIRECTLY ****/
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/**** ac3 decoder internal structures ****/
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/* The following structures are filled in by their corresponding parse_*
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* functions. See http://www.atsc.org/Standards/A52/a_52.pdf for
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* full details on each field. Indented fields are used to denote
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* conditional fields.
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*/
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typedef struct syncinfo_s {
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/* Sync word == 0x0B77 */
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/* u16 syncword; */
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/* crc for the first 5/8 of the sync block */
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/* u16 crc1; */
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/* Stream Sampling Rate (kHz) 0 = 48, 1 = 44.1, 2 = 32, 3 = reserved */
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u16 fscod;
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/* Frame size code */
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u16 frmsizecod;
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/* Information not in the AC-3 bitstream, but derived */
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/* Frame size in 16 bit words */
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u16 frame_size;
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/* Bit rate in kilobits */
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//u16 bit_rate;
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} syncinfo_t;
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typedef struct bsi_s {
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/* Bit stream identification == 0x8 */
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u16 bsid;
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/* Bit stream mode */
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u16 bsmod;
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/* Audio coding mode */
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u16 acmod;
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/* If we're using the centre channel then */
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/* centre mix level */
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u16 cmixlev;
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/* If we're using the surround channel then */
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/* surround mix level */
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u16 surmixlev;
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/* If we're in 2/0 mode then */
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/* Dolby surround mix level - NOT USED - */
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u16 dsurmod;
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/* Low frequency effects on */
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u16 lfeon;
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/* Dialogue Normalization level */
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u16 dialnorm;
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/* Compression exists */
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u16 compre;
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/* Compression level */
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u16 compr;
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/* Language code exists */
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u16 langcode;
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/* Language code */
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u16 langcod;
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/* Audio production info exists*/
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u16 audprodie;
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u16 mixlevel;
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u16 roomtyp;
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/* If we're in dual mono mode (acmod == 0) then extra stuff */
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u16 dialnorm2;
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u16 compr2e;
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u16 compr2;
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u16 langcod2e;
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u16 langcod2;
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u16 audprodi2e;
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u16 mixlevel2;
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u16 roomtyp2;
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/* Copyright bit */
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u16 copyrightb;
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/* Original bit */
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u16 origbs;
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/* Timecode 1 exists */
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u16 timecod1e;
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/* Timecode 1 */
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u16 timecod1;
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/* Timecode 2 exists */
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u16 timecod2e;
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/* Timecode 2 */
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u16 timecod2;
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/* Additional bit stream info exists */
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u16 addbsie;
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/* Additional bit stream length - 1 (in bytes) */
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u16 addbsil;
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/* Additional bit stream information (max 64 bytes) */
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u8 addbsi[64];
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/* Information not in the AC-3 bitstream, but derived */
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/* Number of channels (excluding LFE)
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* Derived from acmod */
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u16 nfchans;
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} bsi_t;
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/* more pain */
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typedef struct audblk_s {
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/* block switch bit indexed by channel num */
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u16 blksw[5];
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/* dither enable bit indexed by channel num */
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u16 dithflag[5];
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/* dynamic range gain exists */
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u16 dynrnge;
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/* dynamic range gain */
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u16 dynrng;
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/* if acmod==0 then */
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/* dynamic range 2 gain exists */
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u16 dynrng2e;
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/* dynamic range 2 gain */
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u16 dynrng2;
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/* coupling strategy exists */
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u16 cplstre;
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/* coupling in use */
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u16 cplinu;
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/* channel coupled */
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u16 chincpl[5];
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/* if acmod==2 then */
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/* Phase flags in use */
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u16 phsflginu;
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/* coupling begin frequency code */
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u16 cplbegf;
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/* coupling end frequency code */
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u16 cplendf;
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/* coupling band structure bits */
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u16 cplbndstrc[18];
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/* Do coupling co-ords exist for this channel? */
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u16 cplcoe[5];
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/* Master coupling co-ordinate */
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u16 mstrcplco[5];
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/* Per coupling band coupling co-ordinates */
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u16 cplcoexp[5][18];
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u16 cplcomant[5][18];
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/* Phase flags for dual mono */
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u16 phsflg[18];
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/* Is there a rematrixing strategy */
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u16 rematstr;
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/* Rematrixing bits */
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u16 rematflg[4];
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/* Coupling exponent strategy */
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u16 cplexpstr;
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/* Exponent strategy for full bandwidth channels */
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u16 chexpstr[5];
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/* Exponent strategy for lfe channel */
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u16 lfeexpstr;
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/* Channel bandwidth for independent channels */
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u16 chbwcod[5];
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/* The absolute coupling exponent */
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u16 cplabsexp;
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/* Coupling channel exponents (D15 mode gives 18 * 12 /3 encoded exponents */
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u16 cplexps[18 * 12 / 3];
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/* Sanity checking constant */
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u32 magic2;
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/* fbw channel exponents */
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u16 exps[5][252 / 3];
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/* channel gain range */
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u16 gainrng[5];
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/* low frequency exponents */
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u16 lfeexps[3];
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/* Bit allocation info */
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u16 baie;
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/* Slow decay code */
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u16 sdcycod;
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/* Fast decay code */
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u16 fdcycod;
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/* Slow gain code */
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u16 sgaincod;
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/* dB per bit code */
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u16 dbpbcod;
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/* masking floor code */
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u16 floorcod;
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/* SNR offset info */
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u16 snroffste;
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/* coarse SNR offset */
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u16 csnroffst;
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/* coupling fine SNR offset */
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u16 cplfsnroffst;
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/* coupling fast gain code */
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u16 cplfgaincod;
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/* fbw fine SNR offset */
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u16 fsnroffst[5];
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/* fbw fast gain code */
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u16 fgaincod[5];
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/* lfe fine SNR offset */
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u16 lfefsnroffst;
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/* lfe fast gain code */
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u16 lfefgaincod;
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/* Coupling leak info */
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u16 cplleake;
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/* coupling fast leak initialization */
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u16 cplfleak;
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/* coupling slow leak initialization */
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u16 cplsleak;
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/* delta bit allocation info */
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u16 deltbaie;
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/* coupling delta bit allocation exists */
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u16 cpldeltbae;
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/* fbw delta bit allocation exists */
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u16 deltbae[5];
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/* number of cpl delta bit segments */
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u16 cpldeltnseg;
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/* coupling delta bit allocation offset */
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u16 cpldeltoffst[8];
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/* coupling delta bit allocation length */
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u16 cpldeltlen[8];
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/* coupling delta bit allocation length */
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u16 cpldeltba[8];
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/* number of delta bit segments */
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u16 deltnseg[5];
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/* fbw delta bit allocation offset */
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u16 deltoffst[5][8];
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/* fbw delta bit allocation length */
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u16 deltlen[5][8];
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/* fbw delta bit allocation length */
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u16 deltba[5][8];
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/* skip length exists */
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u16 skiple;
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/* skip length */
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u16 skipl;
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/* channel mantissas */
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// u16 chmant[5][256];
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/* coupling mantissas */
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float cplfbw[ 256 ];
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// u16 cplmant[256];
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/* coupling mantissas */
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// u16 lfemant[7];
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/* -- Information not in the bitstream, but derived thereof -- */
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/* Number of coupling sub-bands */
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u16 ncplsubnd;
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/* Number of combined coupling sub-bands
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* Derived from ncplsubnd and cplbndstrc */
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u16 ncplbnd;
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/* Number of exponent groups by channel
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* Derived from strmant, endmant */
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u16 nchgrps[5];
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/* Number of coupling exponent groups
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* Derived from cplbegf, cplendf, cplexpstr */
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u16 ncplgrps;
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/* End mantissa numbers of fbw channels */
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u16 endmant[5];
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/* Start and end mantissa numbers for the coupling channel */
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u16 cplstrtmant;
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u16 cplendmant;
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/* Decoded exponent info */
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u16 fbw_exp[5][256];
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u16 cpl_exp[256];
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u16 lfe_exp[7];
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/* Bit allocation pointer results */
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u16 fbw_bap[5][256];
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/* FIXME?? figure out exactly how many entries there should be (253-37?) */
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u16 cpl_bap[256];
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u16 lfe_bap[7];
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} audblk_t;
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/* Everything you wanted to know about band structure */
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/*
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* The entire frequency domain is represented by 256 real
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* floating point fourier coefficients. Only the lower 253
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* coefficients are actually utilized however. We use arrays
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* of 256 to be efficient in some cases.
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*
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* The 5 full bandwidth channels (fbw) can have their higher
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* frequencies coupled together. These coupled channels then
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* share their high frequency components.
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*
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* This coupling band is broken up into 18 sub-bands starting
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* at mantissa number 37. Each sub-band is 12 bins wide.
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*
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* There are 50 bit allocation sub-bands which cover the entire
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* frequency range. The sub-bands are of non-uniform width, and
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* approximate a 1/6 octave scale.
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*/
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typedef struct stream_coeffs_s {
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float fbw[5][256];
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float lfe[256];
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} stream_coeffs_t;
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typedef struct stream_samples_s {
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float channel[6][256];
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} stream_samples_t;
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typedef struct ac3_bit_stream_s {
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u32 buffer;
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int i_available;
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ac3_byte_stream_t byte_stream;
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unsigned int total_bits_read; /* temporary */
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} ac3_bit_stream_t;
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struct ac3dec_s {
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/*
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* Input properties
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*/
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/* The bit stream structure handles the PES stream at the bit level */
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ac3_bit_stream_t bit_stream;
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/*
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* Decoder properties
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*/
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syncinfo_t syncinfo;
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bsi_t bsi;
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audblk_t audblk;
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stream_coeffs_t coeffs;
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stream_samples_t samples;
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};
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/**** ac3 decoder inline functions ****/
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static ac3_byte_stream_t * ac3_byte_stream (ac3dec_t * p_ac3dec)
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{
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return &(p_ac3dec->bit_stream.byte_stream);
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}
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