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1b29343731
ffmpeg/libavcodec/ac3dec.c
Justin Ruggles 1b29343731 AC-3 decoder, soc revision 26, Jul 5 04:55:15 2006 UTC by cloud9 
Mersenne Twister
Dynamic Range
Downmixing
IMDCT

Originally committed as revision 9652 to svn://svn.ffmpeg.org/ffmpeg/trunk
2007-07-14 15:41:27 +00:00

1792 lines
60 KiB
C
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/* AC3 Audio Decoder.
*
* Copyright (c) 2006 Kartikey Mahendra BHATT (bhattkm at gmail dot com).
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <stdio.h>
#include <stddef.h>
#include <math.h>
#include <inttypes.h>
#include <string.h>
#define ALT_BITSTREAM_READER
#include "ac3.h"
#include "ac3tab.h"
#include "ac3_decoder.h"
#include "avcodec.h"
#include "bitstream.h"
#include "dsputil.h"
#include "avutil.h"
#include "common.h"
/* Synchronization information. */
typedef struct {
uint16_t sync_word; //synchronization word = always 0x0b77
uint16_t crc1; //crc for the first 5/8 of the frame
uint8_t fscod; //sampling rate code
uint8_t frmsizecod; //frame size code
/* Derived Attributes */
int sampling_rate; //sampling rate - 48, 44.1 or 32 kHz (value in Hz)
int bit_rate; //nominal bit rate (value in kbps)
} ac3_sync_info;
/* flags for the BSI. */
#define AC3_BSI_LFEON 0x00000001 //low frequency effects channel on
#define AC3_BSI_COMPRE 0x00000002 //compression exists
#define AC3_BSI_LANGCODE 0x00000004 //langcode exists
#define AC3_BSI_AUDPRODIE 0x00000008 //audio production information exists
#define AC3_BSI_COMPR2E 0x00000010 //compr2 exists
#define AC3_BSI_LANGCOD2E 0x00000020 //langcod2 exists
#define AC3_BSI_AUDPRODI2E 0x00000040 //audio production information 2 exists
#define AC3_BSI_COPYRIGHTB 0x00000080 //copyright
#define AC3_BSI_ORIGBS 0x00000100 //original bit stream
#define AC3_BSI_TIMECOD1E 0x00000200 //timecod1 exists
#define AC3_BSI_TIMECOD2E 0x00000400 //timecod2 exists
#define AC3_BSI_ADDBSIE 0x00000800 //additional bit stream information exists
/* Bit Stream Information. */
typedef struct {
uint32_t flags;
uint8_t bsid; //bit stream identification
uint8_t bsmod; //bit stream mode - type of service
uint8_t acmod; //audio coding mode - which channels are in use
uint8_t cmixlev; //center mix level
uint8_t surmixlev; //surround mix level
uint8_t dsurmod; //dynamic surround encoded
uint8_t dialnorm; //dialog normalization
uint8_t compr; //compression gain word
uint8_t langcod; //language code
uint8_t mixlevel; //mixing level
uint8_t roomtyp; //room type
uint8_t dialnorm2; //dialogue normalization for 1+1 mode
uint8_t compr2; //compression gain word for 1+1 mode
uint8_t langcod2; //language code for 1+1 mode
uint8_t mixlevel2; //mixing level for 1+1 mode
uint8_t roomtyp2; //room type for 1+1 mode
uint16_t timecod1; //timecode 1
uint16_t timecod2; //timecode 2
uint8_t addbsil; //additional bit stream information length
/* Dervied Attributes */
int nfchans; //number of full bandwidth channels - derived from acmod
} ac3_bsi;
/* #defs relevant to Audio Block. */
#define MAX_FBW_CHANNELS 5 //maximum full bandwidth channels
#define NUM_LFE_GROUPS 3 //number of LFE Groups
#define MAX_NUM_SEGS 8 //maximum number of segments per delta bit allocation
#define NUM_LFE_MANTS 7 //number of lfe mantissas
#define MAX_CPL_SUBNDS 18 //maximum number of coupling sub bands
#define MAX_CPL_BNDS 18 //maximum number of coupling bands
#define MAX_CPL_GRPS 253 //maximum number of coupling groups
#define MAX_CHNL_GRPS 88 //maximum number of channel groups
#define MAX_NUM_MANTISSAS 256 //maximum number of mantissas
/* flags for the Audio Block. */
#define AC3_AB_DYNRNGE 0x00000001 //dynamic range control exists
#define AC3_AB_DYNRNG2E 0x00000002 //dynamic range control 2 exists
#define AC3_AB_CPLSTRE 0x00000004 //coupling strategy exists
#define AC3_AB_CPLINU 0x00000008 //coupling in use
#define AC3_AB_PHSFLGINU 0x00000010 //phase flag in use
#define AC3_AB_REMATSTR 0x00000020 //rematrixing required
#define AC3_AB_LFEEXPSTR 0x00000100 //lfe exponent strategy
#define AC3_AB_BAIE 0x00000200 //bit allocation information exists
#define AC3_AB_SNROFFSTE 0x00000400 //SNR offset exists
#define AC3_AB_CPLLEAKE 0x00000800 //coupling leak initialization exists
#define AC3_AB_DELTBAIE 0x00001000 //delta bit allocation information exists
#define AC3_AB_SKIPLE 0x00002000 //skip length exists
/* Exponent strategies. */
#define AC3_EXPSTR_D15 0x01
#define AC3_EXPSTR_D25 0x02
#define AC3_EXPSTR_D45 0x03
#define AC3_EXPSTR_REUSE 0x00
/* Bit allocation strategies */
#define AC3_DBASTR_NEW 0x01
#define AC3_DBASTR_NONE 0x02
#define AC3_DBASTR_RESERVED 0x03
#define AC3_DBASTR_REUSE 0x00
/* Audio Block */
typedef struct {
uint32_t flags;
uint8_t blksw; //block switch flags for channels in use
uint8_t dithflag; //dithering flags for channels in use
int8_t dynrng; //dynamic range word
int8_t dynrng2; //dynamic range word for 1+1 mode
uint8_t chincpl; //channel in coupling flags for channels in use
uint8_t cplbegf; //coupling begin frequency code
uint8_t cplendf; //coupling end frequency code
uint32_t cplbndstrc; //coupling band structure
uint8_t cplcoe; //coupling co-ordinates exists for the channel in use
uint8_t mstrcplco[5]; //master coupling co-ordinate for channels in use
uint8_t cplcoexp[5][18]; //coupling co-ordinate exponenets
uint8_t cplcomant[5][18]; //coupling co-ordinate mantissas
uint32_t phsflg; //phase flag per band
uint8_t rematflg; //rematrixing flag
uint8_t cplexpstr; //coupling exponent strategy
uint8_t chexpstr[5]; //channel exponent strategy
uint8_t lfeexpstr; //lfe exponent strategy
uint8_t chbwcod[5]; //channel bandwdith code for channels in use
uint8_t cplabsexp; //coupling absolute exponent
uint8_t cplexps[72]; //coupling exponents
uint8_t exps[5][88]; //channel exponents
uint8_t gainrng[5]; //gain range
uint8_t lfeexps[3]; //LFE exponents
uint8_t sdcycod; //slow decay code
uint8_t fdcycod; //fast decay code
uint8_t sgaincod; //slow gain code
uint8_t dbpbcod; //dB per bit code
uint8_t floorcod; //masking floor code
uint8_t csnroffst; //coarse SNR offset
uint8_t cplfsnroffst; //coupling fine SNR offset
uint8_t cplfgaincod; //coupling fast gain code
uint8_t fsnroffst[5]; //fine SNR offset for channels in use
uint8_t fgaincod[5]; //fast gain code for channels in use
uint8_t lfefsnroffst; //lfe fine SNR offset
uint8_t lfefgaincod; //lfe fast gain code
uint8_t cplfleak; //coupling fast leak initialization value
uint8_t cplsleak; //coupling slow leak initialization value
uint8_t cpldeltbae; //coupling delta bit allocation exists
uint8_t deltbae[5]; //delta bit allocation exists for channels in use
uint8_t cpldeltnseg; //coupling delta bit allocation number of segments
uint8_t cpldeltoffst[8]; //coupling delta offset
uint8_t cpldeltlen[8]; //coupling delta len
uint8_t cpldeltba[8]; //coupling delta bit allocation
uint8_t deltnseg[5]; //delta bit allocation number of segments per channel
uint8_t deltoffst[5][8]; //delta offset for channels in use
uint8_t deltlen[5][8]; //delta len for channels in use
uint8_t deltba[5][8]; //delta bit allocation
uint16_t skipl; //skip length
/* Derived Attributes */
int ncplsubnd; //number of active coupling sub bands = 3 + cplendf - cplbegf
int ncplbnd; //derived from ncplsubnd and cplbndstrc
int ncplgrps; //derived from ncplsubnd, cplexpstr
int nchgrps[5]; //derived from chexpstr, and cplbegf or chbwcod
int nchmant[5]; //derived from cplbegf or chbwcod
int ncplmant; //derived from ncplsubnd = 12 * ncplsubnd
uint8_t cplstrtbnd; //coupling start band for bit allocation
uint8_t cplstrtmant; //coupling start mantissa
uint8_t cplendmant; //coupling end mantissa
uint8_t endmant[5]; //channel end mantissas
uint8_t dcplexps[256]; //decoded coupling exponents
uint8_t dexps[5][256]; //decoded fbw channel exponents
uint8_t dlfeexps[256]; //decoded lfe exponents
uint8_t cplbap[256]; //coupling bit allocation parameters table
uint8_t bap[5][256]; //fbw channels bit allocation parameters table
uint8_t lfebap[256]; //lfe bit allocaiton parameters table
float cplcoeffs[256]; //temporary storage for coupling transform coefficients
float cplco[5][18]; //coupling co-ordinates
float chcoeffs[6]; //channel coefficients for downmix
} ac3_audio_block;
#define AC3_OUTPUT_UNMODIFIED 0x00
#define AC3_OUTPUT_MONO 0x01
#define AC3_OUTPUT_STEREO 0x02
#define AC3_OUTPUT_DOLBY 0x03
#define AC3_INPUT_DUALMONO 0x00
#define AC3_INPUT_MONO 0x01
#define AC3_INPUT_STEREO 0x02
#define AC3_INPUT_3F 0x03
#define AC3_INPUT_2F_1R 0x04
#define AC3_INPUT_3F_1R 0x05
#define AC3_INPUT_2F_2R 0x06
#define AC3_INPUT_3F_2R 0x07
/* BEGIN Mersenne Twister Code. */
#define N 624
#define M 397
#define MATRIX_A 0x9908b0df
#define UPPER_MASK 0x80000000
#define LOWER_MASK 0x7fffffff
typedef struct {
uint32_t mt[N];
int mti;
} dither_state;
static void dither_seed(dither_state *state, uint32_t seed)
{
if (seed == 0)
seed = 0x1f2e3d4c;
state->mt[0] = seed;
for (state->mti = 1; state->mti < N; state->mti++)
state->mt[state->mti] = ((69069 * state->mt[state->mti - 1]) + 1);
}
static uint32_t dither_uint32(dither_state *state)
{
uint32_t y;
static const uint32_t mag01[2] = { 0x00, MATRIX_A };
int kk;
if (state->mti >= N) {
for (kk = 0; kk < N - M; kk++) {
y = (state->mt[kk] & UPPER_MASK) | (state->mt[kk + 1] & LOWER_MASK);
state->mt[kk] = state->mt[kk + M] ^ (y >> 1) ^ mag01[y & 0x01];
}
for (;kk < N - 1; kk++) {
y = (state->mt[kk] & UPPER_MASK) | (state->mt[kk + 1] & LOWER_MASK);
state->mt[kk] = state->mt[kk + (M - N)] ^ (y >> 1) ^ mag01[y & 0x01];
}
y = (state->mt[N - 1] & UPPER_MASK) | (state->mt[0] & LOWER_MASK);
state->mt[N - 1] = state->mt[M - 1] ^ (y >> 1) ^ mag01[y & 0x01];
state->mti = 0;
}
y = state->mt[state->mti++];
y ^= (y >> 11);
y ^= ((y << 7) & 0x9d2c5680);
y ^= ((y << 15) & 0xefc60000);
y ^= (y >> 18);
return y;
}
static inline int16_t dither_int16(dither_state *state)
{
return ((dither_uint32(state) << 16) >> 16);
}
/* END Mersenne Twister */
/* AC3 Context. */
typedef struct {
ac3_sync_info sync_info;
ac3_bsi bsi;
ac3_audio_block audio_block;
float *samples;
int output;
dither_state state;
MDCTContext imdct_ctx_256;
MDCTContext imdct_ctx_512;
GetBitContext gb;
} AC3DecodeContext;
static int ac3_decode_init(AVCodecContext *avctx)
{
AC3DecodeContext *ctx = avctx->priv_data;
ac3_common_init();
ff_mdct_init(&ctx->imdct_ctx_256, 8, 1);
ff_mdct_init(&ctx->imdct_ctx_512, 9, 1);
ctx->samples = av_mallocz(6 * 256 * sizeof (float));
if (!ctx->samples) {
av_log(avctx, AV_LOG_ERROR, "Cannot allocate memory for samples\n");
return -1;
}
dither_seed(&ctx->state, 0);
return 0;
}
static int ac3_synchronize(uint8_t *buf, int buf_size)
{
int i;
for (i = 0; i < buf_size - 1; i++)
if (buf[i] == 0x0b && buf[i + 1] == 0x77)
return i;
return -1;
}
//Returns -1 when 'fscod' is not valid;
static int ac3_parse_sync_info(AC3DecodeContext *ctx)
{
ac3_sync_info *sync_info = &ctx->sync_info;
GetBitContext *gb = &ctx->gb;
sync_info->sync_word = get_bits(gb, 16);
sync_info->crc1 = get_bits(gb, 16);
sync_info->fscod = get_bits(gb, 2);
if (sync_info->fscod == 0x03)
return -1;
sync_info->frmsizecod = get_bits(gb, 6);
if (sync_info->frmsizecod >= 0x38)
return -1;
sync_info->sampling_rate = ac3_freqs[sync_info->fscod];
sync_info->bit_rate = ac3_bitratetab[sync_info->frmsizecod >> 1];
return 0;
}
//Returns -1 when
static int ac3_parse_bsi(AC3DecodeContext *ctx)
{
ac3_bsi *bsi = &ctx->bsi;
uint32_t *flags = &bsi->flags;
GetBitContext *gb = &ctx->gb;
*flags = 0;
bsi->cmixlev = 0;
bsi->surmixlev = 0;
bsi->dsurmod = 0;
bsi->bsid = get_bits(gb, 5);
if (bsi->bsid > 0x08)
return -1;
bsi->bsmod = get_bits(gb, 3);
bsi->acmod = get_bits(gb, 3);
if (bsi->acmod & 0x01 && bsi->acmod != 0x01)
bsi->cmixlev = get_bits(gb, 2);
if (bsi->acmod & 0x04)
bsi->surmixlev = get_bits(gb, 2);
if (bsi->acmod == 0x02)
bsi->dsurmod = get_bits(gb, 2);
if (get_bits(gb, 1))
*flags |= AC3_BSI_LFEON;
bsi->dialnorm = get_bits(gb, 5);
if (get_bits(gb, 1)) {
*flags |= AC3_BSI_COMPRE;
bsi->compr = get_bits(gb, 5);
}
if (get_bits(gb, 1)) {
*flags |= AC3_BSI_LANGCODE;
bsi->langcod = get_bits(gb, 8);
}
if (get_bits(gb, 1)) {
*flags |= AC3_BSI_AUDPRODIE;
bsi->mixlevel = get_bits(gb, 5);
bsi->roomtyp = get_bits(gb, 2);
}
if (bsi->acmod == 0x00) {
bsi->dialnorm2 = get_bits(gb, 5);
if (get_bits(gb, 1)) {
*flags |= AC3_BSI_COMPR2E;
bsi->compr2 = get_bits(gb, 5);
}
if (get_bits(gb, 1)) {
*flags |= AC3_BSI_LANGCOD2E;
bsi->langcod2 = get_bits(gb, 8);
}
if (get_bits(gb, 1)) {
*flags |= AC3_BSI_AUDPRODIE;
bsi->mixlevel2 = get_bits(gb, 5);
bsi->roomtyp2 = get_bits(gb, 2);
}
}
if (get_bits(gb, 1))
*flags |= AC3_BSI_COPYRIGHTB;
if (get_bits(gb, 1))
*flags |= AC3_BSI_ORIGBS;
if (get_bits(gb, 1)) {
*flags |= AC3_BSI_TIMECOD1E;
bsi->timecod1 = get_bits(gb, 14);
}
if (get_bits(gb, 1)) {
*flags |= AC3_BSI_TIMECOD2E;
bsi->timecod2 = get_bits(gb, 14);
}
if (get_bits(gb, 1)) {
*flags |= AC3_BSI_ADDBSIE;
bsi->addbsil = get_bits(gb, 6);
do {
get_bits(gb, 8);
} while (bsi->addbsil--);
}
bsi->nfchans = nfchans_tbl[bsi->acmod];
return 0;
}
/* Decodes the grouped exponents (gexps) and stores them
* in decoded exponents (dexps).
* The code is derived from liba52.
* Uses liba52 tables.
*/
static int _decode_exponents(int expstr, int ngrps, uint8_t absexp, uint8_t *gexps, uint8_t *dexps)
{
int exps;
int i = 0;
while (ngrps--) {
exps = gexps[i++];
absexp += exp_1[exps];
assert(absexp <= 24);
switch (expstr) {
case AC3_EXPSTR_D45:
*(dexps++) = absexp;
*(dexps++) = absexp;
case AC3_EXPSTR_D25:
*(dexps++) = absexp;
case AC3_EXPSTR_D15:
*(dexps++) = absexp;
}
absexp += exp_2[exps];
assert(absexp <= 24);
switch (expstr) {
case AC3_EXPSTR_D45:
*(dexps++) = absexp;
*(dexps++) = absexp;
case AC3_EXPSTR_D25:
*(dexps++) = absexp;
case AC3_EXPSTR_D15:
*(dexps++) = absexp;
}
absexp += exp_3[exps];
assert(absexp <= 24);
switch (expstr) {
case AC3_EXPSTR_D45:
*(dexps++) = absexp;
*(dexps++) = absexp;
case AC3_EXPSTR_D25:
*(dexps++) = absexp;
case AC3_EXPSTR_D15:
*(dexps++) = absexp;
}
}
return 0;
}
static int decode_exponents(AC3DecodeContext *ctx)
{
ac3_audio_block *ab = &ctx->audio_block;
int i;
uint8_t *exps;
uint8_t *dexps;
if (ab->flags & AC3_AB_CPLINU && ab->cplexpstr != AC3_EXPSTR_REUSE)
if (_decode_exponents(ab->cplexpstr, ab->ncplgrps, ab->cplabsexp,
ab->cplexps, ab->dcplexps + ab->cplstrtmant))
return -1;
for (i = 0; i < ctx->bsi.nfchans; i++)
if (ab->chexpstr[i] != AC3_EXPSTR_REUSE) {
exps = ab->exps[i];
dexps = ab->dexps[i];
if (_decode_exponents(ab->chexpstr[i], ab->nchgrps[i], exps[0], exps + 1, dexps + 1))
return -1;
}
if (ctx->bsi.flags & AC3_BSI_LFEON && ab->lfeexpstr != AC3_EXPSTR_REUSE)
if (_decode_exponents(ab->lfeexpstr, 2, ab->lfeexps[0], ab->lfeexps + 1, ab->dlfeexps))
return -1;
return 0;
}
static inline int16_t logadd(int16_t a, int16_t b)
{
int16_t c = a - b;
uint8_t address = FFMIN((ABS(c) >> 1), 255);
return ((c >= 0) ? (a + latab[address]) : (b + latab[address]));
}
static inline int16_t calc_lowcomp(int16_t a, int16_t b0, int16_t b1, uint8_t bin)
{
if (bin < 7) {
if ((b0 + 256) == b1)
a = 384;
else if (b0 > b1)
a = FFMAX(0, a - 64);
}
else if (bin < 20) {
if ((b0 + 256) == b1)
a = 320;
else if (b0 > b1)
a = FFMAX(0, a - 64);
}
else {
a = FFMAX(0, a - 128);
}
return a;
}
/* do the bit allocation for chnl.
* chnl = 0 to 4 - fbw channel
* chnl = 5 coupling channel
* chnl = 6 lfe channel
*/
static int _do_bit_allocation(AC3DecodeContext *ctx, int chnl)
{
ac3_audio_block *ab = &ctx->audio_block;
int16_t sdecay, fdecay, sgain, dbknee, floor;
int16_t lowcomp, fgain, snroffset, fastleak, slowleak;
int16_t psd[256], bndpsd[50], excite[50], mask[50], delta;
uint8_t start, end, bin, i, j, k, lastbin, bndstrt, bndend, begin, deltnseg, band, seg, address;
uint8_t fscod = ctx->sync_info.fscod;
uint8_t *exps, *deltoffst, *deltlen, *deltba;
uint8_t *baps;
int do_delta = 0;
/* initialization */
sdecay = sdecaytab[ab->sdcycod];
fdecay = fdecaytab[ab->fdcycod];
sgain = sgaintab[ab->sgaincod];
dbknee = dbkneetab[ab->dbpbcod];
floor = floortab[ab->floorcod];
if (chnl == 5) {
start = ab->cplstrtmant;
end = ab->cplendmant;
fgain = fgaintab[ab->cplfgaincod];
snroffset = (((ab->csnroffst - 15) << 4) + ab->cplfsnroffst) << 2;
fastleak = (ab->cplfleak << 8) + 768;
slowleak = (ab->cplsleak << 8) + 768;
exps = ab->dcplexps;
baps = ab->cplbap;
if (ab->cpldeltbae == 0 || ab->cpldeltbae == 1) {
do_delta = 1;
deltnseg = ab->cpldeltnseg;
deltoffst = ab->cpldeltoffst;
deltlen = ab->cpldeltlen;
deltba = ab->cpldeltba;
}
}
else if (chnl == 6) {
start = 0;
end = 7;
lowcomp = 0;
fgain = fgaintab[ab->lfefgaincod];
snroffset = (((ab->csnroffst - 15) << 4) + ab->lfefsnroffst) << 2;
exps = ab->dlfeexps;
baps = ab->lfebap;
}
else {
start = 0;
end = ab->endmant[chnl];
lowcomp = 0;
fgain = fgaintab[ab->fgaincod[chnl]];
snroffset = (((ab->csnroffst - 15) << 4) + ab->fsnroffst[chnl]) << 2;
exps = ab->dexps[chnl];
baps = ab->bap[chnl];
if (ab->deltbae[chnl] == 0 || ab->deltbae[chnl] == 1) {
do_delta = 1;
deltnseg = ab->deltnseg[chnl];
deltoffst = ab->deltoffst[chnl];
deltlen = ab->deltlen[chnl];
deltba = ab->deltba[chnl];
}
}
for (bin = start; bin < end; bin++) /* exponent mapping into psd */
psd[bin] = (3072 - ((int16_t) (exps[bin] << 7)));
/* psd integration */
j = start;
k = masktab[start];
do {
lastbin = FFMIN(bndtab[k] + bndsz[k], end);
bndpsd[k] = psd[j];
j++;
for (i = j; i < lastbin; i++) {
bndpsd[k] = logadd(bndpsd[k], psd[j]);
j++;
}
k++;
} while (end > lastbin);
/* compute the excite function */
bndstrt = masktab[start];
bndend = masktab[end - 1] + 1;
if (bndstrt == 0) {
lowcomp = calc_lowcomp(lowcomp, bndpsd[0], bndpsd[1], 0);
excite[0] = bndpsd[0] - fgain - lowcomp;
lowcomp = calc_lowcomp(lowcomp, bndpsd[1], bndpsd[2], 1);
excite[1] = bndpsd[1] - fgain - lowcomp;
begin = 7;
for (bin = 2; bin < 7; bin++) {
if (bndend != 7 || bin != 6)
lowcomp = calc_lowcomp(lowcomp, bndpsd[bin], bndpsd[bin + 1], bin);
fastleak = bndpsd[bin] - fgain;
slowleak = bndpsd[bin] - sgain;
excite[bin] = fastleak - lowcomp;
if (bndend != 7 || bin != 6)
if (bndpsd[bin] <= bndpsd[bin + 1]) {
begin = bin + 1;
break;
}
}
for (bin = begin; bin < (FFMIN(bndend, 22)); bin++) {
if (bndend != 7 || bin != 6)
lowcomp = calc_lowcomp(lowcomp, bndpsd[bin], bndpsd[bin + 1], bin);
fastleak -= fdecay;
fastleak = FFMAX(fastleak, bndpsd[bin] - fgain);
slowleak -= sdecay;
slowleak = FFMAX(slowleak, bndpsd[bin] - sgain);
excite[bin] = FFMAX(fastleak - lowcomp, slowleak);
}
begin = 22;
}
else {
begin = bndstrt;
}
for (bin = begin; bin < bndend; bin++) {
fastleak -= fdecay;
fastleak = FFMAX(fastleak, bndpsd[bin] - fgain);
slowleak -= sdecay;
slowleak = FFMAX(slowleak, bndpsd[bin] - sgain);
excite[bin] = FFMAX(fastleak, slowleak);
}
/* compute the masking curve */
for (bin = bndstrt; bin < bndend; bin++) {
if (bndpsd[bin] < dbknee)
excite[bin] += ((dbknee - bndpsd[bin]) >> 2);
mask[bin] = FFMAX(excite[bin], hth[bin][fscod]);
}
/* apply the delta bit allocation */
if (do_delta) {
band = 0;
for (seg = 0; seg < deltnseg + 1; seg++) {
band += deltoffst[seg];
if (deltba[seg] >= 4)
delta = (deltba[seg] - 3) << 7;
else
delta = (deltba[seg] - 4) << 7;
for (k = 0; k < deltlen[seg]; k++) {
mask[band] += delta;
band++;
}
}
}
/*compute the bit allocation */
i = start;
j = masktab[start];
do {
lastbin = FFMIN(bndtab[j] + bndsz[j], end);
mask[j] -= snroffset;
mask[j] -= floor;
if (mask[j] < 0)
mask[j] = 0;
mask[j] &= 0x1fe0;
mask[j] += floor;
for (k = i; k < lastbin; k++) {
address = (psd[i] - mask[j]) >> 5;
address = FFMIN(63, (FFMAX(0, address)));
baps[i] = baptab[address];
i++;
}
j++;
} while (end > lastbin);
return 0;
}
static int do_bit_allocation(AC3DecodeContext *ctx, int flags)
{
ac3_audio_block *ab = &ctx->audio_block;
int i, snroffst = 0;
if (!flags) /* bit allocation is not required */
return 0;
if (ab->flags & AC3_AB_SNROFFSTE) { /* check whether snroffsts are zero */
snroffst += ab->csnroffst;
if (ab->flags & AC3_AB_CPLINU)
snroffst += ab->cplfsnroffst;
for (i = 0; i < ctx->bsi.nfchans; i++)
snroffst += ab->fsnroffst[i];
if (ctx->bsi.flags & AC3_BSI_LFEON)
snroffst += ab->lfefsnroffst;
if (!snroffst) {
memset(ab->cplbap, 0, sizeof (ab->cplbap));
for (i = 0; i < ctx->bsi.nfchans; i++)
memset(ab->bap[i], 0, sizeof (ab->bap[i]));
memset(ab->lfebap, 0, sizeof (ab->lfebap));
return 0;
}
}
/* perform bit allocation */
if ((ab->flags & AC3_AB_CPLINU) && (flags & 64))
if (_do_bit_allocation(ctx, 5))
return -1;
for (i = 0; i < ctx->bsi.nfchans; i++)
if (flags & (1 << i))
if (_do_bit_allocation(ctx, i))
return -1;
if ((ctx->bsi.flags & AC3_BSI_LFEON) && (flags & 32))
if (_do_bit_allocation(ctx, 6))
return -1;
return 0;
}
static inline float to_float(uint8_t exp, int16_t mantissa)
{
return ((float) (mantissa * scale_factors[exp]));
}
typedef struct { /* grouped mantissas for 3-level 5-leve and 11-level quantization */
uint8_t gcodes[3];
uint8_t gcptr;
} mant_group;
/* Get the transform coefficients for particular channel */
static int _get_transform_coeffs(uint8_t *exps, uint8_t *bap, float chcoeff,
float *samples, int start, int end, int dith_flag, GetBitContext *gb,
dither_state *state)
{
int16_t mantissa;
int i;
int gcode;
mant_group l3_grp, l5_grp, l11_grp;
for (i = 0; i < 3; i++)
l3_grp.gcodes[i] = l5_grp.gcodes[i] = l11_grp.gcodes[i] = -1;
l3_grp.gcptr = l5_grp.gcptr = 3;
l11_grp.gcptr = 2;
i = 0;
while (i < start)
samples[i++] = 0;
for (i = start; i < end; i++) {
switch (bap[i]) {
case 0:
if (!dith_flag)
mantissa = 0;
else
mantissa = dither_int16(state);
samples[i] = to_float(exps[i], mantissa) * chcoeff;
break;
case 1:
if (l3_grp.gcptr > 2) {
gcode = get_bits(gb, qntztab[1]);
if (gcode > 26)
return -1;
l3_grp.gcodes[0] = gcode / 9;
l3_grp.gcodes[1] = (gcode % 9) / 3;
l3_grp.gcodes[2] = (gcode % 9) % 3;
l3_grp.gcptr = 0;
}
mantissa = l3_q_tab[l3_grp.gcodes[l3_grp.gcptr++]];
samples[i] = to_float(exps[i], mantissa) * chcoeff;
break;
case 2:
if (l5_grp.gcptr > 2) {
gcode = get_bits(gb, qntztab[2]);
if (gcode > 124)
return -1;
l5_grp.gcodes[0] = gcode / 25;
l5_grp.gcodes[1] = (gcode % 25) / 5;
l5_grp.gcodes[2] = (gcode % 25) % 5;
l5_grp.gcptr = 0;
}
mantissa = l5_q_tab[l5_grp.gcodes[l5_grp.gcptr++]];
samples[i] = to_float(exps[i], mantissa) * chcoeff;
break;
case 3:
mantissa = get_bits(gb, qntztab[3]);
if (mantissa > 6)
return -1;
mantissa = l7_q_tab[mantissa];
samples[i] = to_float(exps[i], mantissa);
break;
case 4:
if (l11_grp.gcptr > 1) {
gcode = get_bits(gb, qntztab[4]);
if (gcode > 120)
return -1;
l11_grp.gcodes[0] = gcode / 11;
l11_grp.gcodes[1] = gcode % 11;
}
mantissa = l11_q_tab[l11_grp.gcodes[l11_grp.gcptr++]];
samples[i] = to_float(exps[i], mantissa) * chcoeff;
break;
case 5:
mantissa = get_bits(gb, qntztab[5]);
if (mantissa > 14)
return -1;
mantissa = l15_q_tab[mantissa];
samples[i] = to_float(exps[i], mantissa) * chcoeff;
break;
default:
mantissa = get_bits(gb, qntztab[bap[i]]) << (16 - qntztab[bap[i]]);
samples[i] = to_float(exps[i], mantissa) * chcoeff;
break;
}
}
i = end;
while (i < 256)
samples[i++] = 0;
return 0;
}
static int uncouple_channels(AC3DecodeContext * ctx)
{
ac3_audio_block *ab = &ctx->audio_block;
int ch, sbnd, bin;
int index;
float (*samples)[256];
int16_t mantissa;
samples = (float (*)[256])((ctx->bsi.flags & AC3_BSI_LFEON) ? (ctx->samples + 256) : (ctx->samples));
/* uncouple channels */
for (ch = 0; ch < ctx->bsi.nfchans; ch++)
if (ab->chincpl & (1 << ch))
for (sbnd = ab->cplbegf; sbnd < 3 + ab->cplendf; sbnd++)
for (bin = 0; bin < 12; bin++) {
index = sbnd * 12 + bin + 37;
samples[ch][index] = ab->cplcoeffs[index] * ab->cplco[ch][sbnd] * ab->chcoeffs[ch];
}
/* generate dither if required */
for (ch = 0; ch < ctx->bsi.nfchans; ch++)
if ((ab->chincpl & (1 << ch)) && (ab->dithflag & (1 << ch)))
for (index = 0; index < ab->endmant[ch]; index++)
if (!ab->bap[ch][index]) {
mantissa = dither_int16(&ctx->state);
samples[ch][index] = to_float(ab->dexps[ch][index], mantissa) * ab->chcoeffs[ch];
}
return 0;
}
static int get_transform_coeffs(AC3DecodeContext * ctx)
{
int i;
ac3_audio_block *ab = &ctx->audio_block;
float *samples = ctx->samples;
int got_cplchan = 0;
int dithflag = 0;
samples += (ctx->bsi.flags & AC3_BSI_LFEON) ? 256 : 0;
for (i = 0; i < ctx->bsi.nfchans; i++) {
if ((ab->flags & AC3_AB_CPLINU) && (ab->chincpl & (1 << i)))
dithflag = 0; /* don't generate dither until channels are decoupled */
else
dithflag = ab->dithflag & (1 << i);
/* transform coefficients for individual channel */
if (_get_transform_coeffs(ab->dexps[i], ab->bap[i], ab->chcoeffs[i], samples + (i * 256),
0, ab->endmant[i], dithflag, &ctx->gb, &ctx->state))
return -1;
/* tranform coefficients for coupling channels */
if ((ab->flags & AC3_AB_CPLINU) && (ab->chincpl & (1 << i)) && !got_cplchan) {
if (_get_transform_coeffs(ab->dcplexps, ab->cplbap, 1.0f, ab->cplcoeffs,
ab->cplstrtmant, ab->cplendmant, 0, &ctx->gb, &ctx->state))
return -1;
got_cplchan = 1;
}
}
if (ctx->bsi.flags & AC3_BSI_LFEON)
if (_get_transform_coeffs(ab->lfeexps, ab->lfebap, 1.0f, samples - 256, 0, 7, 0, &ctx->gb, &ctx->state))
return -1;
/* uncouple the channels from the coupling channel */
if (ab->flags & AC3_AB_CPLINU)
if (uncouple_channels(ctx))
return -1;
return 0;
}
/* generate coupling co-ordinates for each coupling subband
* from coupling co-ordinates of each band and coupling band
* structure information
*/
static int generate_coupling_coordinates(AC3DecodeContext * ctx)
{
ac3_audio_block *ab = &ctx->audio_block;
uint8_t exp, mstrcplco;
int16_t mant;
uint32_t cplbndstrc = (1 << ab->ncplsubnd) >> 1;
int ch, bnd, sbnd;
float cplco;
if (ab->cplcoe)
for (ch = 0; ch < ctx->bsi.nfchans; ch++)
if (ab->cplcoe & (1 << ch)) {
mstrcplco = 3 * ab->mstrcplco[ch];
sbnd = ab->cplbegf;
for (bnd = 0; bnd < ab->ncplbnd; bnd++) {
exp = ab->cplcoexp[ch][bnd];
if (exp == 15)
mant = ab->cplcomant[ch][bnd] <<= 14;
else
mant = (ab->cplcomant[ch][bnd] | 0x10) << 13;
cplco = to_float(exp + mstrcplco, mant);
if (ctx->bsi.acmod == 0x02 && (ab->flags & AC3_AB_PHSFLGINU) && ch == 1
&& (ab->phsflg & (1 << bnd)))
cplco = -cplco; /* invert the right channel */
ab->cplco[ch][sbnd++] = cplco;
while (cplbndstrc & ab->cplbndstrc) {
cplbndstrc >>= 1;
ab->cplco[ch][sbnd++] = cplco;
}
cplbndstrc >>= 1;
}
}
return 0;
}
static int _do_rematrixing(AC3DecodeContext *ctx, int start, int end)
{
float tmp0, tmp1;
while (start < end) {
tmp0 = ctx->samples[start];
tmp1 = (ctx->samples + 256)[start];
ctx->samples[start] = tmp0 + tmp1;
(ctx->samples + 256)[start] = tmp0 - tmp1;
start++;
}
return 0;
}
static void do_rematrixing(AC3DecodeContext *ctx)
{
ac3_audio_block *ab = &ctx->audio_block;
uint8_t bnd1 = 13, bnd2 = 25, bnd3 = 37, bnd4 = 61;
uint8_t bndend;
bndend = FFMIN(ab->endmant[0], ab->endmant[1]);
if (ab->rematflg & 1)
_do_rematrixing(ctx, bnd1, bnd2);
if (ab->rematflg & 2)
_do_rematrixing(ctx, bnd2, bnd3);
if (ab->rematflg & 4) {
if (ab->cplbegf > 0 && ab->cplbegf <= 2 && (ab->flags & AC3_AB_CPLINU))
_do_rematrixing(ctx, bnd3, bndend);
else {
_do_rematrixing(ctx, bnd3, bnd4);
if (ab->rematflg & 8)
_do_rematrixing(ctx, bnd4, bndend);
}
}
}
static void get_downmix_coeffs(AC3DecodeContext *ctx)
{
int from = ctx->bsi.acmod;
int to = ctx->output;
float clev = clevs[ctx->bsi.cmixlev];
float slev = slevs[ctx->bsi.surmixlev];
ac3_audio_block *ab = &ctx->audio_block;
if (to == AC3_OUTPUT_UNMODIFIED)
return 0;
switch (from) {
case AC3_INPUT_DUALMONO:
switch (to) {
case AC3_OUTPUT_MONO:
case AC3_OUTPUT_STEREO: /* We Assume that sum of both mono channels is requested */
ab->chcoeffs[0] *= LEVEL_MINUS_6DB;
ab->chcoeffs[1] *= LEVEL_MINUS_6DB;
break;
}
break;
case AC3_INPUT_MONO:
switch (to) {
case AC3_OUTPUT_STEREO:
ab->chcoeffs[0] *= LEVEL_MINUS_3DB;
break;
}
break;
case AC3_INPUT_STEREO:
switch (to) {
case AC3_OUTPUT_MONO:
ab->chcoeffs[0] *= LEVEL_MINUS_3DB;
ab->chcoeffs[1] *= LEVEL_MINUS_3DB;
break;
}
break;
case AC3_INPUT_3F:
switch (to) {
case AC3_OUTPUT_MONO:
ab->chcoeffs[0] *= LEVEL_MINUS_3DB;
ab->chcoeffs[2] *= LEVEL_MINUS_3DB;
ab->chcoeffs[1] *= clev * LEVEL_PLUS_3DB;
break;
case AC3_OUTPUT_STEREO:
ab->chcoeffs[1] *= clev;
break;
}
break;
case AC3_INPUT_2F_1R:
switch (to) {
case AC3_OUTPUT_MONO:
ab->chcoeffs[0] *= LEVEL_MINUS_3DB;
ab->chcoeffs[1] *= LEVEL_MINUS_3DB;
ab->chcoeffs[2] *= slev * LEVEL_MINUS_3DB;
break;
case AC3_OUTPUT_STEREO:
ab->chcoeffs[2] *= slev * LEVEL_MINUS_3DB;
break;
case AC3_OUTPUT_DOLBY:
ab->chcoeffs[2] *= LEVEL_MINUS_3DB;
break;
}
break;
case AC3_INPUT_3F_1R:
switch (to) {
case AC3_OUTPUT_MONO:
ab->chcoeffs[0] *= LEVEL_MINUS_3DB;
ab->chcoeffs[2] *= LEVEL_MINUS_3DB;
ab->chcoeffs[1] *= clev * LEVEL_PLUS_3DB;
ab->chcoeffs[3] *= slev * LEVEL_MINUS_3DB;
break;
case AC3_OUTPUT_STEREO:
ab->chcoeffs[1] *= clev;
ab->chcoeffs[3] *= slev * LEVEL_MINUS_3DB;
break;
case AC3_OUTPUT_DOLBY:
ab->chcoeffs[1] *= LEVEL_MINUS_3DB;
ab->chcoeffs[3] *= LEVEL_MINUS_3DB;
break;
}
break;
case AC3_INPUT_2F_2R:
switch (to) {
case AC3_OUTPUT_MONO:
ab->chcoeffs[0] *= LEVEL_MINUS_3DB;
ab->chcoeffs[1] *= LEVEL_MINUS_3DB;
ab->chcoeffs[2] *= slev * LEVEL_MINUS_3DB;
ab->chcoeffs[3] *= slev * LEVEL_MINUS_3DB;
break;
case AC3_OUTPUT_STEREO:
ab->chcoeffs[2] *= slev;
ab->chcoeffs[3] *= slev;
break;
case AC3_OUTPUT_DOLBY:
ab->chcoeffs[2] *= LEVEL_MINUS_3DB;
ab->chcoeffs[3] *= LEVEL_MINUS_3DB;
break;
}
break;
case AC3_INPUT_3F_2R:
switch (to) {
case AC3_OUTPUT_MONO:
ab->chcoeffs[0] *= LEVEL_MINUS_3DB;
ab->chcoeffs[2] *= LEVEL_MINUS_3DB;
ab->chcoeffs[1] *= clev * LEVEL_PLUS_3DB;
ab->chcoeffs[3] *= slev * LEVEL_MINUS_3DB;
ab->chcoeffs[4] *= slev * LEVEL_MINUS_3DB;
break;
case AC3_OUTPUT_STEREO:
ab->chcoeffs[1] *= clev;
ab->chcoeffs[3] *= slev;
ab->chcoeffs[4] *= slev;
break;
case AC3_OUTPUT_DOLBY:
ab->chcoeffs[1] *= LEVEL_MINUS_3DB;
ab->chcoeffs[3] *= LEVEL_MINUS_3DB;
ab->chcoeffs[4] *= LEVEL_MINUS_3DB;
break;
}
break;
}
}
static inline void downmix_dualmono_to_mono(float *samples)
{
int i;
for (i = 0; i < 256; i++) {
samples[i] += samples[i + 256];
samples[i + 256] = 0;
}
}
static inline void downmix_dualmono_to_stereo(float *samples)
{
int i;
float tmp;
for (i = 0; i < 256; i++) {
tmp = samples[i] + samples[i + 256];
samples[i] = samples[i + 256] = tmp;
}
}
static inline void downmix_mono_to_stereo(float *samples)
{
int i;
for (i = 0; i < 256; i++)
samples[i + 256] = samples[i];
}
static inline void downmix_stereo_to_mono(float *samples)
{
int i;
for (i = 0; i < 256; i++) {
samples[i] += samples[i + 256];
samples[i + 256] = 0;
}
}
static inline void downmix_3f_to_mono(float *samples)
{
int i;
for (i = 0; i < 256; i++) {
samples[i] += (samples[i + 256] + samples[i + 512]);
samples[i + 256] = samples[i + 512] = 0;
}
}
static inline void downmix_3f_to_stereo(float *samples)
{
int i;
for (i = 0; i < 256; i++) {
samples[i] += samples[i + 256];
samples[i + 256] = samples[i + 512];
samples[i + 512] = 0;
}
}
static inline void downmix_2f_1r_to_mono(float *samples)
{
int i;
for (i = 0; i < 256; i++) {
samples[i] += (samples[i + 256] + samples[i + 512]);
samples[i + 256] = samples[i + 512] = 0;
}
}
static inline void downmix_2f_1r_to_stereo(float *samples)
{
int i;
for (i = 0; i < 256; i++) {
samples[i] += samples[i + 512];
samples[i + 256] += samples[i + 512];
samples[i + 512] = 0;
}
}
static inline void downmix_2f_1r_to_dolby(float *samples)
{
int i;
for (i = 0; i < 256; i++) {
samples[i] -= samples[i + 512];
samples[i + 256] += samples[i + 512];
samples[i + 512] = 0;
}
}
static inline void downmix_3f_1r_to_mono(float *samples)
{
int i;
for (i = 0; i < 256; i++) {
samples[i] += (samples[i + 256] + samples[i + 512] + samples[i + 768]);
samples[i + 256] = samples[i + 512] = samples[i + 768] = 0;
}
}
static inline void downmix_3f_1r_to_stereo(float *samples)
{
int i;
for (i = 0; i < 256; i++) {
samples[i] += (samples[i + 256] + samples[i + 768]);
samples[i + 256] += (samples[i + 512] + samples[i + 768]);
samples[i + 512] = samples[i + 768] = 0;
}
}
static inline void downmix_3f_1r_to_dolby(float *samples)
{
int i;
for (i = 0; i < 256; i++) {
samples[i] += (samples[i + 256] - samples[i + 768]);
samples[i + 256] += (samples[i + 512] + samples[i + 768]);
samples[i + 512] = samples[i + 768] = 0;
}
}
static inline void downmix_2f_2r_to_mono(float *samples)
{
int i;
for (i = 0; i < 256; i++) {
samples[i] += (samples[i + 256] + samples[i + 512] + samples[i + 768]);
samples[i + 256] = samples[i + 512] = samples[i + 768] = 0;
}
}
static inline void downmix_2f_2r_to_stereo(float *samples)
{
int i;
for (i = 0; i < 256; i++) {
samples[i] += samples[i + 512];
samples[i + 256] = samples[i + 768];
samples[i + 512] = samples[i + 768] = 0;
}
}
static inline void downmix_2f_2r_to_dolby(float *samples)
{
int i;
for (i = 0; i < 256; i++) {
samples[i] -= samples[i + 512];
samples[i + 256] += samples[i + 768];
samples[i + 512] = samples[i + 768] = 0;
}
}
static inline void downmix_3f_2r_to_mono(float *samples)
{
int i;
for (i = 0; i < 256; i++) {
samples[i] += (samples[i + 256] + samples[i + 512] + samples[i + 768] + samples[i + 1024]);
samples[i + 256] = samples[i + 512] = samples[i + 768] = samples[i + 1024] = 0;
}
}
static inline void downmix_3f_2r_to_stereo(float *samples)
{
int i;
for (i = 0; i < 256; i++) {
samples[i] += (samples[i + 256] + samples[i + 768]);
samples[i + 256] = (samples[i + 512] + samples[i + 1024]);
samples[i + 512] = samples[i + 768] = samples[i + 1024] = 0;
}
}
static inline void downmix_3f_2r_to_dolby(float *samples)
{
int i;
for (i = 0; i < 256; i++) {
samples[i] += (samples[i + 256] - samples[i + 768]);
samples[i + 256] = (samples[i + 512] + samples[i + 1024]);
samples[i + 512] = samples[i + 768] = samples[i + 1024] = 0;
}
}
static void do_downmix(AC3DecodeContext *ctx)
{
int from = ctx->bsi.acmod;
int to = ctx->output;
float *samples = ctx->samples + ((ctx->bsi.flags & AC3_BSI_LFEON) ? 256 : 0);
switch (from) {
case AC3_INPUT_DUALMONO:
switch (to) {
case AC3_OUTPUT_MONO:
downmix_dualmono_to_mono(samples);
break;
case AC3_OUTPUT_STEREO: /* We Assume that sum of both mono channels is requested */
downmix_dualmono_to_stereo(samples);
break;
}
break;
case AC3_INPUT_MONO:
switch (to) {
case AC3_OUTPUT_STEREO:
downmix_mono_to_stereo(samples);
break;
}
break;
case AC3_INPUT_STEREO:
switch (to) {
case AC3_OUTPUT_MONO:
downmix_stereo_to_mono(samples);
break;
}
break;
case AC3_INPUT_3F:
switch (to) {
case AC3_OUTPUT_MONO:
downmix_3f_to_mono(samples);
break;
case AC3_OUTPUT_STEREO:
downmix_3f_to_stereo(samples);
break;
}
break;
case AC3_INPUT_2F_1R:
switch (to) {
case AC3_OUTPUT_MONO:
downmix_2f_1r_to_mono(samples);
break;
case AC3_OUTPUT_STEREO:
downmix_2f_1r_to_stereo(samples);
break;
case AC3_OUTPUT_DOLBY:
downmix_2f_1r_to_dolby(samples);
break;
}
break;
case AC3_INPUT_3F_1R:
switch (to) {
case AC3_OUTPUT_MONO:
downmix_3f_1r_to_mono(samples);
break;
case AC3_OUTPUT_STEREO:
downmix_3f_1r_to_stereo(samples);
break;
case AC3_OUTPUT_DOLBY:
downmix_3f_1r_to_dolby(samples);
break;
}
break;
case AC3_INPUT_2F_2R:
switch (to) {
case AC3_OUTPUT_MONO:
downmix_2f_2r_to_mono(samples);
break;
case AC3_OUTPUT_STEREO:
downmix_2f_2r_to_stereo(samples);
break;
case AC3_OUTPUT_DOLBY:
downmix_2f_2r_to_dolby(samples);
break;
}
break;
case AC3_INPUT_3F_2R:
switch (to) {
case AC3_OUTPUT_MONO:
downmix_3f_2r_to_mono(samples);
break;
case AC3_OUTPUT_STEREO:
downmix_3f_2r_to_stereo(samples);
break;
case AC3_OUTPUT_DOLBY:
downmix_3f_2r_to_dolby(samples);
break;
}
break;
}
}
static int ac3_parse_audio_block(AC3DecodeContext * ctx, int index)
{
ac3_audio_block *ab = &ctx->audio_block;
int nfchans = ctx->bsi.nfchans;
int acmod = ctx->bsi.acmod;
int i, bnd, rbnd, grp, seg;
GetBitContext *gb = &ctx->gb;
uint32_t *flags = &ab->flags;
int bit_alloc_flags = 0;
float drange;
*flags = 0;
ab->blksw = 0;
for (i = 0; i < 5; i++)
ab->chcoeffs[i] = 1.0;
for (i = 0; i < nfchans; i++) /*block switch flag */
ab->blksw |= get_bits(gb, 1) << i;
ab->dithflag = 0;
for (i = 0; i < nfchans; i++) /* dithering flag */
ab->dithflag |= get_bits(gb, 1) << i;
if (get_bits(gb, 1)) { /* dynamic range */
*flags |= AC3_AB_DYNRNGE;
ab->dynrng = get_bits(gb, 8);
drange = ((((ab->dynrng & 0x1f) | 0x20) << 13) * scale_factors[3 - (ab->dynrng >> 5)]);
for (i = 0; i < nfchans; i++)
ab->chcoeffs[i] *= drange;
}
if (acmod == 0x00) { /* dynamic range 1+1 mode */
if (get_bits(gb, 1)) {
*flags |= AC3_AB_DYNRNG2E;
ab->dynrng2 = get_bits(gb, 8);
drange = ((((ab->dynrng2 & 0x1f) | 0x20) << 13) * scale_factors[3 - (ab->dynrng2 >> 5)]);
ab->chcoeffs[1] *= drange;
}
}
get_downmix_coeffs(ctx);
ab->chincpl = 0;
if (get_bits(gb, 1)) { /* coupling strategy */
*flags |= AC3_AB_CPLSTRE;
ab->cplbndstrc = 0;
if (get_bits(gb, 1)) { /* coupling in use */
*flags |= AC3_AB_CPLINU;
for (i = 0; i < nfchans; i++)
ab->chincpl |= get_bits(gb, 1) << i;
if (acmod == 0x02)
if (get_bits(gb, 1)) /* phase flag in use */
*flags |= AC3_AB_PHSFLGINU;
ab->cplbegf = get_bits(gb, 4);
ab->cplendf = get_bits(gb, 4);
assert((ab->ncplsubnd = 3 + ab->cplendf - ab->cplbegf) > 0);
ab->ncplbnd = ab->ncplsubnd;
for (i = 0; i < ab->ncplsubnd - 1; i++) /* coupling band structure */
if (get_bits(gb, 1)) {
ab->cplbndstrc |= 1 << i;
ab->ncplbnd--;
}
}
}
if (*flags & AC3_AB_CPLINU) {
ab->cplcoe = 0;
for (i = 0; i < nfchans; i++)
if (ab->chincpl & (1 << i))
if (get_bits(gb, 1)) { /* coupling co-ordinates */
ab->cplcoe |= 1 << i;
ab->mstrcplco[i] = get_bits(gb, 2);
for (bnd = 0; bnd < ab->ncplbnd; bnd++) {
ab->cplcoexp[i][bnd] = get_bits(gb, 4);
ab->cplcomant[i][bnd] = get_bits(gb, 4);
}
}
}
ab->phsflg = 0;
if ((acmod == 0x02) && (*flags & AC3_AB_PHSFLGINU) && (ab->cplcoe & 1 || ab->cplcoe & (1 << 1))) {
for (bnd = 0; bnd < ab->ncplbnd; bnd++)
if (get_bits(gb, 1))
ab->phsflg |= 1 << bnd;
}
generate_coupling_coordinates(ctx);
ab->rematflg = 0;
if (acmod == 0x02) /* rematrixing */
if (get_bits(gb, 1)) {
*flags |= AC3_AB_REMATSTR;
if (ab->cplbegf > 2 || !(*flags & AC3_AB_CPLINU))
for (rbnd = 0; rbnd < 4; rbnd++)
ab->rematflg |= get_bits(gb, 1) << bnd;
else if (ab->cplbegf > 0 && ab->cplbegf <= 2 && *flags & AC3_AB_CPLINU)
for (rbnd = 0; rbnd < 3; rbnd++)
ab->rematflg |= get_bits(gb, 1) << bnd;
else if (!(ab->cplbegf) && *flags & AC3_AB_CPLINU)
for (rbnd = 0; rbnd < 2; rbnd++)
ab->rematflg |= get_bits(gb, 1) << bnd;
}
if (*flags & AC3_AB_CPLINU) /* coupling exponent strategy */
ab->cplexpstr = get_bits(gb, 2);
for (i = 0; i < nfchans; i++) /* channel exponent strategy */
ab->chexpstr[i] = get_bits(gb, 2);
if (ctx->bsi.flags & AC3_BSI_LFEON) /* lfe exponent strategy */
ab->lfeexpstr = get_bits(gb, 1);
for (i = 0; i < nfchans; i++) /* channel bandwidth code */
if (ab->chexpstr[i] != AC3_EXPSTR_REUSE)
if (!(ab->chincpl & (1 << i))) {
ab->chbwcod[i] = get_bits(gb, 6);
assert (ab->chbwcod[i] <= 60);
}
if (*flags & AC3_AB_CPLINU)
if (ab->cplexpstr != AC3_EXPSTR_REUSE) {/* coupling exponents */
bit_alloc_flags |= 64;
ab->cplabsexp = get_bits(gb, 4) << 1;
ab->cplstrtmant = (ab->cplbegf * 12) + 37;
ab->cplendmant = ((ab->cplendmant + 3) * 12) + 37;
ab->ncplgrps = (ab->cplendmant - ab->cplstrtmant) / (3 << (ab->cplexpstr - 1));
for (grp = 0; grp < ab->ncplgrps; grp++)
ab->cplexps[grp] = get_bits(gb, 7);
}
for (i = 0; i < nfchans; i++) /* fbw channel exponents */
if (ab->chexpstr[i] != AC3_EXPSTR_REUSE) {
bit_alloc_flags |= 1 << i;
if (ab->chincpl & (1 << i))
ab->endmant[i] = (ab->cplbegf * 12) + 37;
else
ab->endmant[i] = ((ab->chbwcod[i] + 3) * 12) + 37;
ab->nchgrps[i] =
(ab->endmant[i] + (3 << (ab->chexpstr[i] - 1)) - 4) / (3 << (ab->chexpstr[i] - 1));
ab->exps[i][0] = ab->dexps[i][0] = get_bits(gb, 4);
for (grp = 1; grp <= ab->nchgrps[i]; grp++)
ab->exps[i][grp] = get_bits(gb, 7);
ab->gainrng[i] = get_bits(gb, 2);
}
if (ctx->bsi.flags & AC3_BSI_LFEON) /* lfe exponents */
if (ab->lfeexpstr != AC3_EXPSTR_REUSE) {
bit_alloc_flags |= 32;
ab->lfeexps[0] = ab->dlfeexps[0] = get_bits(gb, 4);
ab->lfeexps[1] = get_bits(gb, 7);
ab->lfeexps[2] = get_bits(gb, 7);
}
if (decode_exponents(ctx)) {/* decode the exponents for this block */
av_log(NULL, AV_LOG_ERROR, "Error parsing exponents\n");
return -1;
}
if (get_bits(gb, 1)) { /* bit allocation information */
*flags |= AC3_AB_BAIE;
bit_alloc_flags |= 127;
ab->sdcycod = get_bits(gb, 2);
ab->fdcycod = get_bits(gb, 2);
ab->sgaincod = get_bits(gb, 2);
ab->dbpbcod = get_bits(gb, 2);
ab->floorcod = get_bits(gb, 3);
}
if (get_bits(gb, 1)) { /* snroffset */
*flags |= AC3_AB_SNROFFSTE;
bit_alloc_flags |= 127;
ab->csnroffst = get_bits(gb, 6);
if (*flags & AC3_AB_CPLINU) { /* couling fine snr offset and fast gain code */
ab->cplfsnroffst = get_bits(gb, 4);
ab->cplfgaincod = get_bits(gb, 3);
}
for (i = 0; i < nfchans; i++) { /* channel fine snr offset and fast gain code */
ab->fsnroffst[i] = get_bits(gb, 4);
ab->fgaincod[i] = get_bits(gb, 3);
}
if (ctx->bsi.flags & AC3_BSI_LFEON) { /* lfe fine snr offset and fast gain code */
ab->lfefsnroffst = get_bits(gb, 4);
ab->lfefgaincod = get_bits(gb, 3);
}
}
if (*flags & AC3_AB_CPLINU)
if (get_bits(gb, 1)) { /* coupling leak information */
bit_alloc_flags |= 64;
*flags |= AC3_AB_CPLLEAKE;
ab->cplfleak = get_bits(gb, 3);
ab->cplsleak = get_bits(gb, 3);
}
if (get_bits(gb, 1)) { /* delta bit allocation information */
*flags |= AC3_AB_DELTBAIE;
bit_alloc_flags |= 127;
if (*flags & AC3_AB_CPLINU) {
ab->cpldeltbae = get_bits(gb, 2);
if (ab->cpldeltbae == AC3_DBASTR_RESERVED) {
av_log(NULL, AV_LOG_ERROR, "coupling delta bit allocation strategy reserved\n");
return -1;
}
}
for (i = 0; i < nfchans; i++) {
ab->deltbae[i] = get_bits(gb, 2);
if (ab->deltbae[i] == AC3_DBASTR_RESERVED) {
av_log(NULL, AV_LOG_ERROR, "delta bit allocation strategy reserved\n");
return -1;
}
}
if (*flags & AC3_AB_CPLINU)
if (ab->cpldeltbae == AC3_DBASTR_NEW) { /*coupling delta offset, len and bit allocation */
ab->cpldeltnseg = get_bits(gb, 3);
for (seg = 0; seg <= ab->cpldeltnseg; seg++) {
ab->cpldeltoffst[seg] = get_bits(gb, 5);
ab->cpldeltlen[seg] = get_bits(gb, 4);
ab->cpldeltba[seg] = get_bits(gb, 3);
}
}
for (i = 0; i < nfchans; i++)
if (ab->deltbae[i] == AC3_DBASTR_NEW) {/*channel delta offset, len and bit allocation */
ab->deltnseg[i] = get_bits(gb, 3);
for (seg = 0; seg <= ab->deltnseg[i]; seg++) {
ab->deltoffst[i][seg] = get_bits(gb, 5);
ab->deltlen[i][seg] = get_bits(gb, 4);
ab->deltba[i][seg] = get_bits(gb, 3);
}
}
}
if (do_bit_allocation (ctx, bit_alloc_flags)) /* perform the bit allocation */ {
av_log(NULL, AV_LOG_ERROR, "Error in bit allocation routine\n");
return -1;
}
if (get_bits(gb, 1)) { /* unused dummy data */
*flags |= AC3_AB_SKIPLE;
ab->skipl = get_bits(gb, 9);
while (ab->skipl) {
get_bits(gb, 8);
ab->skipl--;
}
}
/* unpack the transform coefficients
* * this also uncouples channels if coupling is in use.
*/
if (get_transform_coeffs(ctx)) {
av_log(NULL, AV_LOG_ERROR, "Error in routine get_transform_coeffs\n");
return -1;
}
/* recover coefficients if rematrixing is in use */
if (*flags & AC3_AB_REMATSTR)
do_rematrixing(ctx);
if (ctx->output != AC3_OUTPUT_UNMODIFIED)
do_downmix(ctx);
return 0;
}
/**** the following two functions comes from ac3dec */
static inline int blah (int32_t i)
{
if (i > 0x43c07fff)
return 32767;
else if (i < 0x43bf8000)
return -32768;
else
return i - 0x43c00000;
}
static inline void float_to_int (float * _f, int16_t * s16, int samples)
{
int32_t * f = (int32_t *) _f; // XXX assumes IEEE float format
int i;
for (i = 0; i < samples; i++) {
s16[i] = blah (f[i]);
}
}
/**** end */
static int ac3_decode_frame(AVCodecContext * avctx, void *data, int *data_size, uint8_t * buf, int buf_size)
{
AC3DecodeContext *ctx = avctx->priv_data;
int frame_start;
int i, j, k, l;
float tmp0[128], tmp1[128], tmp[512];
short *out_samples = (short *)data;
float *samples = ctx->samples;
//Synchronize the frame.
frame_start = ac3_synchronize(buf, buf_size);
if (frame_start == -1) {
av_log(avctx, AV_LOG_ERROR, "frame is not synchronized\n");
*data_size = 0;
return -1;
}
//Initialize the GetBitContext with the start of valid AC3 Frame.
init_get_bits(&(ctx->gb), buf + frame_start, (buf_size - frame_start) * 8);
//Parse the syncinfo.
////If 'fscod' is not valid the decoder shall mute as per the standard.
if (ac3_parse_sync_info(ctx)) {
av_log(avctx, AV_LOG_ERROR, "fscod is not valid\n");
*data_size = 0;
return -1;
}
//Check for the errors.
/* if (ac3_error_check(ctx)) {
*data_size = 0;
return -1;
} */
//Parse the BSI.
//If 'bsid' is not valid decoder shall not decode the audio as per the standard.
if (ac3_parse_bsi(ctx)) {
av_log(avctx, AV_LOG_ERROR, "bsid is not valid\n");
*data_size = 0;
return -1;
}
avctx->sample_rate = ctx->sync_info.sampling_rate;
if (avctx->channels == 0) {
avctx->channels = ctx->bsi.nfchans + ((ctx->bsi.flags & AC3_BSI_LFEON) ? 1 : 0);
ctx->output = AC3_OUTPUT_UNMODIFIED;
}
else if ((ctx->bsi.nfchans + ((ctx->bsi.flags & AC3_BSI_LFEON) ? 1 : 0)) < avctx->channels) {
av_log(avctx, AV_LOG_INFO, "ac3_decoder: AC3 Source Channels Are Less Then Specified %d: Output to %d Channels\n",
avctx->channels, (ctx->bsi.nfchans + ((ctx->bsi.flags & AC3_BSI_LFEON) ? 1 : 0)));
avctx->channels = ctx->bsi.nfchans + ((ctx->bsi.flags & AC3_BSI_LFEON) ? 1 : 0);
ctx->output = AC3_OUTPUT_UNMODIFIED;
}
else if (avctx->channels == 1) {
ctx->output = AC3_OUTPUT_MONO;
} else if (avctx->channels == 2) {
if (ctx->bsi.dsurmod == 0x02)
ctx->output = AC3_OUTPUT_DOLBY;
else
ctx->output = AC3_OUTPUT_STEREO;
}
avctx->bit_rate = ctx->sync_info.bit_rate;
av_log(avctx, AV_LOG_INFO, "channels = %d \t bit rate = %d \t sampling rate = %d \n", avctx->channels, avctx->sample_rate, avctx->bit_rate);
//Parse the Audio Blocks.
for (i = 0; i < 6; i++) {
if (ac3_parse_audio_block(ctx, i)) {
av_log(avctx, AV_LOG_ERROR, "error parsing the audio block\n");
*data_size = 0;
return -1;
}
samples = ctx->samples;
if (ctx->bsi.flags & AC3_BSI_LFEON) {
ff_imdct_calc(&ctx->imdct_ctx_512, ctx->samples + 1536, samples, tmp);
for (l = 0; l < 256; l++)
samples[l] = (ctx->samples + 1536)[l];
float_to_int(samples, out_samples, 256);
samples += 256;
out_samples += 256;
}
for (j = 0; j < ctx->bsi.nfchans; j++) {
if (ctx->audio_block.blksw & (1 << j)) {
for (k = 0; k < 128; k++) {
tmp0[k] = samples[2 * k];
tmp1[k] = samples[2 * k + 1];
}
ff_imdct_calc(&ctx->imdct_ctx_256, ctx->samples + 1536, tmp0, tmp);
for (l = 0; l < 256; l++)
samples[l] = (ctx->samples + 1536)[l] * window[l] + (ctx->samples + 2048)[l] * window[255 - l];
ff_imdct_calc(&ctx->imdct_ctx_256, ctx->samples + 2048, tmp1, tmp);
float_to_int(samples, out_samples, 256);
samples += 256;
out_samples += 256;
}
else {
ff_imdct_calc(&ctx->imdct_ctx_512, ctx->samples + 1536, samples, tmp);
for (l = 0; l < 256; l++)
samples[l] = (ctx->samples + 1536)[l] * window[l] + (ctx->samples + 2048)[l] * window[255 - l];
float_to_int(samples, out_samples, 256);
memcpy(ctx->samples + 2048, ctx->samples + 1792, 256 * sizeof (float));
samples += 256;
out_samples += 256;
}
}
}
*data_size = 6 * ctx->bsi.nfchans * 256 * sizeof (int16_t);
return (buf_size - frame_start);
}
static int ac3_decode_end(AVCodecContext *ctx)
{
return 0;
}
AVCodec lgpl_ac3_decoder = {
"ac3",
CODEC_TYPE_AUDIO,
CODEC_ID_AC3,
sizeof (AC3DecodeContext),
ac3_decode_init,
NULL,
ac3_decode_end,
ac3_decode_frame,
};
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