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ffmpeg/libavcodec/ac3dec.c
Justin Ruggles 0de73a46ff fix the 256-point MDCT 
Originally committed as revision 9685 to svn://svn.ffmpeg.org/ffmpeg/trunk
2007-07-15 14:47:39 +00:00

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/*
* AC-3 Audio Decoder
* This code is developed as part of Google Summer of Code 2006 Program.
*
* Copyright (c) 2006 Kartikey Mahendra BHATT (bhattkm at gmail dot com).
*
* For exponent decoding the code is inspired by the code in liba52 by
* Michel Lespinasse and Aaron Holtzman.
* http://liba52.sourceforge.net
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* FFmpeg 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
* General Public License for more details.
*
* You should have received a copy of the GNU General Public
* License along with FFmpeg; 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 <string.h>
#define ALT_BITSTREAM_READER
#include "avcodec.h"
#include "ac3.h"
#include "ac3tab.h"
#include "bitstream.h"
#include "dsputil.h"
#include "random.h"
static uint8_t bndtab[51];
static uint8_t masktab[253];
static const int nfchans_tbl[8] = { 2, 1, 2, 3, 3, 4, 4, 5 };
/* table for exponent to scale_factor mapping
* scale_factor[i] = 2 ^ -(i + 15)
*/
static float scale_factors[25];
static int16_t psdtab[25];
static int8_t exp_1[128];
static int8_t exp_2[128];
static int8_t exp_3[128];
static int16_t l3_quantizers_1[32];
static int16_t l3_quantizers_2[32];
static int16_t l3_quantizers_3[32];
static int16_t l5_quantizers_1[128];
static int16_t l5_quantizers_2[128];
static int16_t l5_quantizers_3[128];
static int16_t l7_quantizers[7];
static int16_t l11_quantizers_1[128];
static int16_t l11_quantizers_2[128];
static int16_t l15_quantizers[15];
static const uint8_t qntztab[16] = { 0, 5, 7, 3, 7, 4, 5, 6, 7, 8, 9, 10, 11, 12, 14, 16 };
/* Adjustmens in dB gain */
#define LEVEL_MINUS_3DB 0.7071067811865476
#define LEVEL_MINUS_4POINT5DB 0.5946035575013605
#define LEVEL_MINUS_6DB 0.5000000000000000
#define LEVEL_PLUS_3DB 1.4142135623730951
#define LEVEL_PLUS_6DB 2.0000000000000000
#define LEVEL_ZERO 0.0000000000000000
static const float clevs[4] = { LEVEL_MINUS_3DB, LEVEL_MINUS_4POINT5DB,
LEVEL_MINUS_6DB, LEVEL_MINUS_4POINT5DB };
static const float slevs[4] = { LEVEL_MINUS_3DB, LEVEL_MINUS_6DB, LEVEL_ZERO, LEVEL_MINUS_6DB };
#define BLOCK_SIZE 256
/* Output and input configurations. */
#define AC3_OUTPUT_UNMODIFIED 0x01
#define AC3_OUTPUT_MONO 0x02
#define AC3_OUTPUT_STEREO 0x04
#define AC3_OUTPUT_DOLBY 0x08
#define AC3_OUTPUT_LFEON 0x10
typedef struct {
uint16_t crc1;
uint8_t fscod;
uint8_t acmod;
uint8_t cmixlev;
uint8_t surmixlev;
uint8_t dsurmod;
uint8_t blksw;
uint8_t dithflag;
uint8_t cplinu;
uint8_t chincpl;
uint8_t phsflginu;
uint8_t cplbegf;
uint8_t cplendf;
uint8_t cplcoe;
uint32_t cplbndstrc;
uint8_t rematstr;
uint8_t rematflg;
uint8_t cplexpstr;
uint8_t lfeexpstr;
uint8_t chexpstr[5];
uint8_t sdcycod;
uint8_t fdcycod;
uint8_t sgaincod;
uint8_t dbpbcod;
uint8_t floorcod;
uint8_t csnroffst;
uint8_t cplfsnroffst;
uint8_t cplfgaincod;
uint8_t fsnroffst[5];
uint8_t fgaincod[5];
uint8_t lfefsnroffst;
uint8_t lfefgaincod;
uint8_t cplfleak;
uint8_t cplsleak;
uint8_t cpldeltbae;
uint8_t deltbae[5];
uint8_t cpldeltnseg;
uint8_t cpldeltoffst[8];
uint8_t cpldeltlen[8];
uint8_t cpldeltba[8];
uint8_t deltnseg[5];
uint8_t deltoffst[5][8];
uint8_t deltlen[5][8];
uint8_t deltba[5][8];
/* Derived Attributes. */
int sampling_rate;
int bit_rate;
int frame_size;
int nfchans; //number of channels
int lfeon; //lfe channel in use
float dynrng; //dynamic range gain
float dynrng2; //dynamic range gain for 1+1 mode
float chcoeffs[6]; //normalized channel coefficients
float cplco[5][18]; //coupling coordinates
int ncplbnd; //number of coupling bands
int ncplsubnd; //number of coupling sub bands
int cplstrtmant; //coupling start mantissa
int cplendmant; //coupling end mantissa
int endmant[5]; //channel end mantissas
AC3BitAllocParameters bit_alloc_params; ///< bit allocation parameters
uint8_t dcplexps[256]; //decoded coupling exponents
uint8_t dexps[5][256]; //decoded fbw channel exponents
uint8_t dlfeexps[256]; //decoded lfe channel exponents
uint8_t cplbap[256]; //coupling bit allocation pointers
uint8_t bap[5][256]; //fbw channel bit allocation pointers
uint8_t lfebap[256]; //lfe channel bit allocation pointers
int blkoutput; //output configuration for block
DECLARE_ALIGNED_16(float, transform_coeffs[AC3_MAX_CHANNELS][BLOCK_SIZE]); //transform coefficients
/* For IMDCT. */
MDCTContext imdct_512; //for 512 sample imdct transform
MDCTContext imdct_256; //for 256 sample imdct transform
DSPContext dsp; //for optimization
DECLARE_ALIGNED_16(float, output[AC3_MAX_CHANNELS][BLOCK_SIZE]); //output after imdct transform and windowing
DECLARE_ALIGNED_16(float, delay[AC3_MAX_CHANNELS][BLOCK_SIZE]); //delay - added to the next block
DECLARE_ALIGNED_16(float, tmp_imdct[BLOCK_SIZE]); //temporary storage for imdct transform
DECLARE_ALIGNED_16(float, tmp_output[BLOCK_SIZE * 2]); //temporary storage for output before windowing
DECLARE_ALIGNED_16(float, window[BLOCK_SIZE]); //window coefficients
/* Miscellaneous. */
GetBitContext gb;
AVRandomState dith_state; //for dither generation
} AC3DecodeContext;
/*********** BEGIN INIT HELPER FUNCTIONS ***********/
/**
* Generate a Kaiser-Bessel Derived Window.
*/
static void ac3_window_init(float *window)
{
int i, j;
double sum = 0.0, bessel, tmp;
double local_window[256];
double alpha2 = (5.0 * M_PI / 256.0) * (5.0 * M_PI / 256.0);
for (i = 0; i < 256; i++) {
tmp = i * (256 - i) * alpha2;
bessel = 1.0;
for (j = 100; j > 0; j--) /* defaul to 100 iterations */
bessel = bessel * tmp / (j * j) + 1;
sum += bessel;
local_window[i] = sum;
}
sum++;
for (i = 0; i < 256; i++)
window[i] = sqrt(local_window[i] / sum);
}
/*
* Generate quantizer tables.
*/
static void generate_quantizers_table(int16_t quantizers[], int level, int length)
{
int i;
for (i = 0; i < length; i++)
quantizers[i] = ((2 * i - level + 1) << 15) / level;
}
static void generate_quantizers_table_1(int16_t quantizers[], int level, int length1, int length2, int size)
{
int i, j;
int16_t v;
for (i = 0; i < length1; i++) {
v = ((2 * i - level + 1) << 15) / level;
for (j = 0; j < length2; j++)
quantizers[i * length2 + j] = v;
}
for (i = length1 * length2; i < size; i++)
quantizers[i] = 0;
}
static void generate_quantizers_table_2(int16_t quantizers[], int level, int length1, int length2, int size)
{
int i, j;
int16_t v;
for (i = 0; i < length1; i++) {
v = ((2 * (i % level) - level + 1) << 15) / level;
for (j = 0; j < length2; j++)
quantizers[i * length2 + j] = v;
}
for (i = length1 * length2; i < size; i++)
quantizers[i] = 0;
}
static void generate_quantizers_table_3(int16_t quantizers[], int level, int length1, int length2, int size)
{
int i, j;
for (i = 0; i < length1; i++)
for (j = 0; j < length2; j++)
quantizers[i * length2 + j] = ((2 * (j % level) - level + 1) << 15) / level;
for (i = length1 * length2; i < size; i++)
quantizers[i] = 0;
}
/*
* Initialize tables at runtime.
*/
static void ac3_tables_init(void)
{
int i, j, k, l, v;
/* compute bndtab and masktab from bandsz */
k = 0;
l = 0;
for(i=0;i<50;i++) {
bndtab[i] = l;
v = ff_ac3_bndsz[i];
for(j=0;j<v;j++) masktab[k++]=i;
l += v;
}
masktab[253] = masktab[254] = masktab[255] = 0;
bndtab[50] = 0;
/* PSD Table For Mapping Exponents To PSD. */
for (i = 0; i < 25; i++)
psdtab[i] = 3072 - (i << 7);
/* Exponent Decoding Tables */
for (i = 0; i < 5; i++) {
v = i - 2;
for (j = 0; j < 25; j++)
exp_1[i * 25 + j] = v;
}
for (i = 0; i < 25; i++) {
v = (i % 5) - 2;
for (j = 0; j < 5; j++)
exp_2[i * 5 + j] = v;
}
for (i = 0; i < 25; i++) {
v = -2;
for (j = 0; j < 5; j++)
exp_3[i * 5 + j] = v++;
}
for (i = 125; i < 128; i++)
exp_1[i] = exp_2[i] = exp_3[i] = 25;
/* End Exponent Decoding Tables */
/* Quantizer ungrouping tables. */
// for level-3 quantizers
generate_quantizers_table_1(l3_quantizers_1, 3, 3, 9, 32);
generate_quantizers_table_2(l3_quantizers_2, 3, 9, 3, 32);
generate_quantizers_table_3(l3_quantizers_3, 3, 9, 3, 32);
//for level-5 quantizers
generate_quantizers_table_1(l5_quantizers_1, 5, 5, 25, 128);
generate_quantizers_table_2(l5_quantizers_2, 5, 25, 5, 128);
generate_quantizers_table_3(l5_quantizers_3, 5, 25, 5, 128);
//for level-7 quantizers
generate_quantizers_table(l7_quantizers, 7, 7);
//for level-4 quantizers
generate_quantizers_table_2(l11_quantizers_1, 11, 11, 11, 128);
generate_quantizers_table_3(l11_quantizers_2, 11, 11, 11, 128);
//for level-15 quantizers
generate_quantizers_table(l15_quantizers, 15, 15);
/* End Quantizer ungrouping tables. */
//generate scale factors
for (i = 0; i < 25; i++)
scale_factors[i] = pow(2.0, -(i + 15));
}
static int ac3_decode_init(AVCodecContext *avctx)
{
AC3DecodeContext *ctx = avctx->priv_data;
ac3_common_init();
ac3_tables_init();
ff_mdct_init(&ctx->imdct_256, 8, 1);
ff_mdct_init(&ctx->imdct_512, 9, 1);
ac3_window_init(ctx->window);
dsputil_init(&ctx->dsp, avctx);
av_init_random(0, &ctx->dith_state);
return 0;
}
/*********** END INIT FUNCTIONS ***********/
/* Synchronize to ac3 bitstream.
* This function searches for the syncword '0xb77'.
*
* @param buf Pointer to "probable" ac3 bitstream buffer
* @param buf_size Size of buffer
* @return Returns the position where syncword is found, -1 if no syncword is found
*/
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;
}
/* Parse the 'sync_info' from the ac3 bitstream.
* This function extracts the sync_info from ac3 bitstream.
* GetBitContext within AC3DecodeContext must point to
* start of the synchronized ac3 bitstream.
*
* @param ctx AC3DecodeContext
* @return Returns framesize, returns 0 if fscod, frmsizecod or bsid is not valid
*/
static int ac3_parse_sync_info(AC3DecodeContext *ctx)
{
GetBitContext *gb = &ctx->gb;
int frmsizecod, bsid;
skip_bits(gb, 16); //skip the sync_word, sync_info->sync_word = get_bits(gb, 16);
ctx->crc1 = get_bits(gb, 16);
ctx->fscod = get_bits(gb, 2);
if (ctx->fscod == 0x03)
return 0;
frmsizecod = get_bits(gb, 6);
if (frmsizecod >= 38)
return 0;
ctx->sampling_rate = ff_ac3_freqs[ctx->fscod];
ctx->bit_rate = ff_ac3_bitratetab[frmsizecod >> 1];
/* we include it here in order to determine validity of ac3 frame */
bsid = get_bits(gb, 5);
if (bsid > 0x08)
return 0;
skip_bits(gb, 3); //skip the bsmod, bsi->bsmod = get_bits(gb, 3);
switch (ctx->fscod) {
case 0x00:
ctx->frame_size = 4 * ctx->bit_rate;
return ctx->frame_size;
case 0x01:
ctx->frame_size = 2 * (320 * ctx->bit_rate / 147 + (frmsizecod & 1));
return ctx->frame_size;
case 0x02:
ctx->frame_size = 6 * ctx->bit_rate;
return ctx->frame_size;
}
/* never reached */
return 0;
}
/* Parse bsi from ac3 bitstream.
* This function extracts the bitstream information (bsi) from ac3 bitstream.
*
* @param ctx AC3DecodeContext after processed by ac3_parse_sync_info
*/
static void ac3_parse_bsi(AC3DecodeContext *ctx)
{
GetBitContext *gb = &ctx->gb;
int i;
ctx->cmixlev = 0;
ctx->surmixlev = 0;
ctx->dsurmod = 0;
ctx->nfchans = 0;
ctx->cpldeltbae = DBA_NONE;
ctx->cpldeltnseg = 0;
for (i = 0; i < 5; i++) {
ctx->deltbae[i] = DBA_NONE;
ctx->deltnseg[i] = 0;
}
ctx->dynrng = 1.0;
ctx->dynrng2 = 1.0;
ctx->acmod = get_bits(gb, 3);
ctx->nfchans = nfchans_tbl[ctx->acmod];
if (ctx->acmod & 0x01 && ctx->acmod != 0x01)
ctx->cmixlev = get_bits(gb, 2);
if (ctx->acmod & 0x04)
ctx->surmixlev = get_bits(gb, 2);
if (ctx->acmod == 0x02)
ctx->dsurmod = get_bits(gb, 2);
ctx->lfeon = get_bits1(gb);
i = !(ctx->acmod);
do {
skip_bits(gb, 5); //skip dialog normalization
if (get_bits1(gb))
skip_bits(gb, 8); //skip compression
if (get_bits1(gb))
skip_bits(gb, 8); //skip language code
if (get_bits1(gb))
skip_bits(gb, 7); //skip audio production information
} while (i--);
skip_bits(gb, 2); //skip copyright bit and original bitstream bit
if (get_bits1(gb))
skip_bits(gb, 14); //skip timecode1
if (get_bits1(gb))
skip_bits(gb, 14); //skip timecode2
if (get_bits1(gb)) {
i = get_bits(gb, 6); //additional bsi length
do {
skip_bits(gb, 8);
} while(i--);
}
}
/* Decodes the grouped exponents.
* This function decodes the coded exponents according to exponent strategy
* and stores them in the decoded exponents buffer.
*
* @param gb GetBitContext which points to start of coded exponents
* @param expstr Exponent coding strategy
* @param ngrps Number of grouped exponetns
* @param absexp Absolute exponent
* @param dexps Decoded exponents are stored in dexps
* @return Returns 0 if exponents are decoded successfully, -1 if error occurs
*/
static int decode_exponents(GetBitContext *gb, int expstr, int ngrps, uint8_t absexp, uint8_t *dexps)
{
int exps;
while (ngrps--) {
exps = get_bits(gb, 7);
absexp += exp_1[exps];
if (absexp > 24) {
av_log(NULL, AV_LOG_ERROR, "Absolute Exponent > 24, ngrp = %d\n", ngrps);
return -ngrps;
}
switch (expstr) {
case EXP_D45:
*(dexps++) = absexp;
*(dexps++) = absexp;
case EXP_D25:
*(dexps++) = absexp;
case EXP_D15:
*(dexps++) = absexp;
}
absexp += exp_2[exps];
if (absexp > 24) {
av_log(NULL, AV_LOG_ERROR, "Absolute Exponent > 24, ngrp = %d\n", ngrps);
return -ngrps;
}
switch (expstr) {
case EXP_D45:
*(dexps++) = absexp;
*(dexps++) = absexp;
case EXP_D25:
*(dexps++) = absexp;
case EXP_D15:
*(dexps++) = absexp;
}
absexp += exp_3[exps];
if (absexp > 24) {
av_log(NULL, AV_LOG_ERROR, "Absolute Exponent > 24, ngrp = %d\n", ngrps);
return -ngrps;
}
switch (expstr) {
case EXP_D45:
*(dexps++) = absexp;
*(dexps++) = absexp;
case EXP_D25:
*(dexps++) = absexp;
case EXP_D15:
*(dexps++) = absexp;
}
}
return 0;
}
/* Performs bit allocation.
* This function performs bit allocation for the requested chanenl.
*/
static void do_bit_allocation(AC3DecodeContext *ctx, int chnl)
{
int fgain, snroffset;
if (chnl == 5) {
fgain = ff_fgaintab[ctx->cplfgaincod];
snroffset = (((ctx->csnroffst - 15) << 4) + ctx->cplfsnroffst) << 2;
ac3_parametric_bit_allocation(&ctx->bit_alloc_params, ctx->cplbap,
ctx->dcplexps, ctx->cplstrtmant,
ctx->cplendmant, snroffset, fgain, 0,
ctx->cpldeltbae, ctx->cpldeltnseg,
ctx->cpldeltoffst, ctx->cpldeltlen,
ctx->cpldeltba);
}
else if (chnl == 6) {
fgain = ff_fgaintab[ctx->lfefgaincod];
snroffset = (((ctx->csnroffst - 15) << 4) + ctx->lfefsnroffst) << 2;
ac3_parametric_bit_allocation(&ctx->bit_alloc_params, ctx->lfebap,
ctx->dlfeexps, 0, 7, snroffset, fgain, 1,
DBA_NONE, 0, NULL, NULL, NULL);
}
else {
fgain = ff_fgaintab[ctx->fgaincod[chnl]];
snroffset = (((ctx->csnroffst - 15) << 4) + ctx->fsnroffst[chnl]) << 2;
ac3_parametric_bit_allocation(&ctx->bit_alloc_params, ctx->bap[chnl],
ctx->dexps[chnl], 0, ctx->endmant[chnl],
snroffset, fgain, 0, ctx->deltbae[chnl],
ctx->deltnseg[chnl], ctx->deltoffst[chnl],
ctx->deltlen[chnl], ctx->deltba[chnl]);
}
}
/* Check if snroffsets are zero. */
static int is_snr_offsets_zero(AC3DecodeContext *ctx)
{
int i;
if ((ctx->csnroffst) || (ctx->cplinu && ctx->cplfsnroffst) ||
(ctx->lfeon && ctx->lfefsnroffst))
return 0;
for (i = 0; i < ctx->nfchans; i++)
if (ctx->fsnroffst[i])
return 0;
return 1;
}
typedef struct { /* grouped mantissas for 3-level 5-leve and 11-level quantization */
int16_t l3_quantizers[3];
int16_t l5_quantizers[3];
int16_t l11_quantizers[2];
int l3ptr;
int l5ptr;
int l11ptr;
} mant_groups;
#define TRANSFORM_COEFF(tc, m, e, f) (tc) = (m) * (f)[(e)]
/* Get the transform coefficients for coupling channel and uncouple channels.
* The coupling transform coefficients starts at the the cplstrtmant, which is
* equal to endmant[ch] for fbw channels. Hence we can uncouple channels before
* getting transform coefficients for the channel.
*/
static int get_transform_coeffs_cpling(AC3DecodeContext *ctx, mant_groups *m)
{
GetBitContext *gb = &ctx->gb;
int ch, start, end, cplbndstrc, bnd, gcode, tbap;
float cplcos[5], cplcoeff;
uint8_t *exps = ctx->dcplexps;
uint8_t *bap = ctx->cplbap;
cplbndstrc = ctx->cplbndstrc;
start = ctx->cplstrtmant;
bnd = 0;
while (start < ctx->cplendmant) {
end = start + 12;
while (cplbndstrc & 1) {
end += 12;
cplbndstrc >>= 1;
}
cplbndstrc >>= 1;
for (ch = 0; ch < ctx->nfchans; ch++)
cplcos[ch] = ctx->chcoeffs[ch] * ctx->cplco[ch][bnd];
bnd++;
while (start < end) {
tbap = bap[start];
switch(tbap) {
case 0:
for (ch = 0; ch < ctx->nfchans; ch++)
if (((ctx->chincpl) >> ch) & 1) {
if ((ctx->dithflag >> ch) & 1) {
TRANSFORM_COEFF(cplcoeff, av_random(&ctx->dith_state) & 0xFFFF, exps[start], scale_factors);
ctx->transform_coeffs[ch + 1][start] = cplcoeff * cplcos[ch] * LEVEL_MINUS_3DB;
} else
ctx->transform_coeffs[ch + 1][start] = 0;
}
start++;
continue;
case 1:
if (m->l3ptr > 2) {
gcode = get_bits(gb, 5);
m->l3_quantizers[0] = l3_quantizers_1[gcode];
m->l3_quantizers[1] = l3_quantizers_2[gcode];
m->l3_quantizers[2] = l3_quantizers_3[gcode];
m->l3ptr = 0;
}
TRANSFORM_COEFF(cplcoeff, m->l3_quantizers[m->l3ptr++], exps[start], scale_factors);
break;
case 2:
if (m->l5ptr > 2) {
gcode = get_bits(gb, 7);
m->l5_quantizers[0] = l5_quantizers_1[gcode];
m->l5_quantizers[1] = l5_quantizers_2[gcode];
m->l5_quantizers[2] = l5_quantizers_3[gcode];
m->l5ptr = 0;
}
TRANSFORM_COEFF(cplcoeff, m->l5_quantizers[m->l5ptr++], exps[start], scale_factors);
break;
case 3:
TRANSFORM_COEFF(cplcoeff, l7_quantizers[get_bits(gb, 3)], exps[start], scale_factors);
break;
case 4:
if (m->l11ptr > 1) {
gcode = get_bits(gb, 7);
m->l11_quantizers[0] = l11_quantizers_1[gcode];
m->l11_quantizers[1] = l11_quantizers_2[gcode];
m->l11ptr = 0;
}
TRANSFORM_COEFF(cplcoeff, m->l11_quantizers[m->l11ptr++], exps[start], scale_factors);
break;
case 5:
TRANSFORM_COEFF(cplcoeff, l15_quantizers[get_bits(gb, 4)], exps[start], scale_factors);
break;
default:
TRANSFORM_COEFF(cplcoeff, get_sbits(gb, qntztab[tbap]) << (16 - qntztab[tbap]),
exps[start], scale_factors);
}
for (ch = 0; ch < ctx->nfchans; ch++)
if ((ctx->chincpl >> ch) & 1)
ctx->transform_coeffs[ch + 1][start] = cplcoeff * cplcos[ch];
start++;
}
}
return 0;
}
/* Get the transform coefficients for particular channel */
static int get_transform_coeffs_ch(AC3DecodeContext *ctx, int ch_index, mant_groups *m)
{
GetBitContext *gb = &ctx->gb;
int i, gcode, tbap, dithflag, end;
uint8_t *exps;
uint8_t *bap;
float *coeffs;
float factors[25];
for (i = 0; i < 25; i++)
factors[i] = scale_factors[i] * ctx->chcoeffs[ch_index];
if (ch_index != -1) { /* fbw channels */
dithflag = (ctx->dithflag >> ch_index) & 1;
exps = ctx->dexps[ch_index];
bap = ctx->bap[ch_index];
coeffs = ctx->transform_coeffs[ch_index + 1];
end = ctx->endmant[ch_index];
} else if (ch_index == -1) {
dithflag = 0;
exps = ctx->dlfeexps;
bap = ctx->lfebap;
coeffs = ctx->transform_coeffs[0];
end = 7;
}
for (i = 0; i < end; i++) {
tbap = bap[i];
switch (tbap) {
case 0:
if (!dithflag) {
coeffs[i] = 0;
continue;
}
else {
TRANSFORM_COEFF(coeffs[i], av_random(&ctx->dith_state) & 0xFFFF, exps[i], factors);
coeffs[i] *= LEVEL_MINUS_3DB;
continue;
}
case 1:
if (m->l3ptr > 2) {
gcode = get_bits(gb, 5);
m->l3_quantizers[0] = l3_quantizers_1[gcode];
m->l3_quantizers[1] = l3_quantizers_2[gcode];
m->l3_quantizers[2] = l3_quantizers_3[gcode];
m->l3ptr = 0;
}
TRANSFORM_COEFF(coeffs[i], m->l3_quantizers[m->l3ptr++], exps[i], factors);
continue;
case 2:
if (m->l5ptr > 2) {
gcode = get_bits(gb, 7);
m->l5_quantizers[0] = l5_quantizers_1[gcode];
m->l5_quantizers[1] = l5_quantizers_2[gcode];
m->l5_quantizers[2] = l5_quantizers_3[gcode];
m->l5ptr = 0;
}
TRANSFORM_COEFF(coeffs[i], m->l5_quantizers[m->l5ptr++], exps[i], factors);
continue;
case 3:
TRANSFORM_COEFF(coeffs[i], l7_quantizers[get_bits(gb, 3)], exps[i], factors);
continue;
case 4:
if (m->l11ptr > 1) {
gcode = get_bits(gb, 7);
m->l11_quantizers[0] = l11_quantizers_1[gcode];
m->l11_quantizers[1] = l11_quantizers_2[gcode];
m->l11ptr = 0;
}
TRANSFORM_COEFF(coeffs[i], m->l11_quantizers[m->l11ptr++], exps[i], factors);
continue;
case 5:
TRANSFORM_COEFF(coeffs[i], l15_quantizers[get_bits(gb, 4)], exps[i], factors);
continue;
default:
TRANSFORM_COEFF(coeffs[i], get_sbits(gb, qntztab[tbap]) << (16 - qntztab[tbap]), exps[i], factors);
continue;
}
}
return 0;
}
/* Get the transform coefficients.
* This function extracts the tranform coefficients form the ac3 bitstream.
* This function is called after bit allocation is performed.
*/
static int get_transform_coeffs(AC3DecodeContext * ctx)
{
int i, end;
int got_cplchan = 0;
mant_groups m;
m.l3ptr = m.l5ptr = m.l11ptr = 3;
for (i = 0; i < ctx->nfchans; i++) {
/* transform coefficients for individual channel */
if (get_transform_coeffs_ch(ctx, i, &m))
return -1;
/* tranform coefficients for coupling channels */
if ((ctx->chincpl >> i) & 1) {
if (!got_cplchan) {
if (get_transform_coeffs_cpling(ctx, &m)) {
av_log(NULL, AV_LOG_ERROR, "error in decoupling channels\n");
return -1;
}
got_cplchan = 1;
}
end = ctx->cplendmant;
} else
end = ctx->endmant[i];
do
ctx->transform_coeffs[i + 1][end] = 0;
while(++end < 256);
}
if (ctx->lfeon) {
if (get_transform_coeffs_ch(ctx, -1, &m))
return -1;
for (i = 7; i < 256; i++) {
ctx->transform_coeffs[0][i] = 0;
}
}
return 0;
}
/* Rematrixing routines. */
static void do_rematrixing1(AC3DecodeContext *ctx, int start, int end)
{
float tmp0, tmp1;
while (start < end) {
tmp0 = ctx->transform_coeffs[1][start];
tmp1 = ctx->transform_coeffs[2][start];
ctx->transform_coeffs[1][start] = tmp0 + tmp1;
ctx->transform_coeffs[2][start] = tmp0 - tmp1;
start++;
}
}
static void do_rematrixing(AC3DecodeContext *ctx)
{
int bnd1 = 13, bnd2 = 25, bnd3 = 37, bnd4 = 61;
int end, bndend;
end = FFMIN(ctx->endmant[0], ctx->endmant[1]);
if (ctx->rematflg & 1)
do_rematrixing1(ctx, bnd1, bnd2);
if (ctx->rematflg & 2)
do_rematrixing1(ctx, bnd2, bnd3);
bndend = bnd4;
if (bndend > end) {
bndend = end;
if (ctx->rematflg & 4)
do_rematrixing1(ctx, bnd3, bndend);
} else {
if (ctx->rematflg & 4)
do_rematrixing1(ctx, bnd3, bnd4);
if (ctx->rematflg & 8)
do_rematrixing1(ctx, bnd4, end);
}
}
/* This function sets the normalized channel coefficients.
* Transform coefficients are multipllied by the channel
* coefficients to get normalized transform coefficients.
*/
static void get_downmix_coeffs(AC3DecodeContext *ctx)
{
int from = ctx->acmod;
int to = ctx->blkoutput;
float clev = clevs[ctx->cmixlev];
float slev = slevs[ctx->surmixlev];
float nf = 1.0; //normalization factor for downmix coeffs
int i;
if (!ctx->acmod) {
ctx->chcoeffs[0] = 2 * ctx->dynrng;
ctx->chcoeffs[1] = 2 * ctx->dynrng2;
} else {
for (i = 0; i < ctx->nfchans; i++)
ctx->chcoeffs[i] = 2 * ctx->dynrng;
}
if (to == AC3_OUTPUT_UNMODIFIED)
return;
switch (from) {
case AC3_ACMOD_DUALMONO:
switch (to) {
case AC3_OUTPUT_MONO:
case AC3_OUTPUT_STEREO: /* We Assume that sum of both mono channels is requested */
nf = 0.5;
ctx->chcoeffs[0] *= nf;
ctx->chcoeffs[1] *= nf;
break;
}
break;
case AC3_ACMOD_MONO:
switch (to) {
case AC3_OUTPUT_STEREO:
nf = LEVEL_MINUS_3DB;
ctx->chcoeffs[0] *= nf;
break;
}
break;
case AC3_ACMOD_STEREO:
switch (to) {
case AC3_OUTPUT_MONO:
nf = LEVEL_MINUS_3DB;
ctx->chcoeffs[0] *= nf;
ctx->chcoeffs[1] *= nf;
break;
}
break;
case AC3_ACMOD_3F:
switch (to) {
case AC3_OUTPUT_MONO:
nf = LEVEL_MINUS_3DB / (1.0 + clev);
ctx->chcoeffs[0] *= (nf * LEVEL_MINUS_3DB);
ctx->chcoeffs[2] *= (nf * LEVEL_MINUS_3DB);
ctx->chcoeffs[1] *= ((nf * clev * LEVEL_MINUS_3DB) / 2.0);
break;
case AC3_OUTPUT_STEREO:
nf = 1.0 / (1.0 + clev);
ctx->chcoeffs[0] *= nf;
ctx->chcoeffs[2] *= nf;
ctx->chcoeffs[1] *= (nf * clev);
break;
}
break;
case AC3_ACMOD_2F1R:
switch (to) {
case AC3_OUTPUT_MONO:
nf = 2.0 * LEVEL_MINUS_3DB / (2.0 + slev);
ctx->chcoeffs[0] *= (nf * LEVEL_MINUS_3DB);
ctx->chcoeffs[1] *= (nf * LEVEL_MINUS_3DB);
ctx->chcoeffs[2] *= (nf * slev * LEVEL_MINUS_3DB);
break;
case AC3_OUTPUT_STEREO:
nf = 1.0 / (1.0 + (slev * LEVEL_MINUS_3DB));
ctx->chcoeffs[0] *= nf;
ctx->chcoeffs[1] *= nf;
ctx->chcoeffs[2] *= (nf * slev * LEVEL_MINUS_3DB);
break;
case AC3_OUTPUT_DOLBY:
nf = 1.0 / (1.0 + LEVEL_MINUS_3DB);
ctx->chcoeffs[0] *= nf;
ctx->chcoeffs[1] *= nf;
ctx->chcoeffs[2] *= (nf * LEVEL_MINUS_3DB);
break;
}
break;
case AC3_ACMOD_3F1R:
switch (to) {
case AC3_OUTPUT_MONO:
nf = LEVEL_MINUS_3DB / (1.0 + clev + (slev / 2.0));
ctx->chcoeffs[0] *= (nf * LEVEL_MINUS_3DB);
ctx->chcoeffs[2] *= (nf * LEVEL_MINUS_3DB);
ctx->chcoeffs[1] *= (nf * clev * LEVEL_PLUS_3DB);
ctx->chcoeffs[3] *= (nf * slev * LEVEL_MINUS_3DB);
break;
case AC3_OUTPUT_STEREO:
nf = 1.0 / (1.0 + clev + (slev * LEVEL_MINUS_3DB));
ctx->chcoeffs[0] *= nf;
ctx->chcoeffs[2] *= nf;
ctx->chcoeffs[1] *= (nf * clev);
ctx->chcoeffs[3] *= (nf * slev * LEVEL_MINUS_3DB);
break;
case AC3_OUTPUT_DOLBY:
nf = 1.0 / (1.0 + (2.0 * LEVEL_MINUS_3DB));
ctx->chcoeffs[0] *= nf;
ctx->chcoeffs[1] *= nf;
ctx->chcoeffs[1] *= (nf * LEVEL_MINUS_3DB);
ctx->chcoeffs[3] *= (nf * LEVEL_MINUS_3DB);
break;
}
break;
case AC3_ACMOD_2F2R:
switch (to) {
case AC3_OUTPUT_MONO:
nf = LEVEL_MINUS_3DB / (1.0 + slev);
ctx->chcoeffs[0] *= (nf * LEVEL_MINUS_3DB);
ctx->chcoeffs[1] *= (nf * LEVEL_MINUS_3DB);
ctx->chcoeffs[2] *= (nf * slev * LEVEL_MINUS_3DB);
ctx->chcoeffs[3] *= (nf * slev * LEVEL_MINUS_3DB);
break;
case AC3_OUTPUT_STEREO:
nf = 1.0 / (1.0 + slev);
ctx->chcoeffs[0] *= nf;
ctx->chcoeffs[1] *= nf;
ctx->chcoeffs[2] *= (nf * slev);
ctx->chcoeffs[3] *= (nf * slev);
break;
case AC3_OUTPUT_DOLBY:
nf = 1.0 / (1.0 + (2.0 * LEVEL_MINUS_3DB));
ctx->chcoeffs[0] *= nf;
ctx->chcoeffs[1] *= nf;
ctx->chcoeffs[2] *= (nf * LEVEL_MINUS_3DB);
ctx->chcoeffs[3] *= (nf * LEVEL_MINUS_3DB);
break;
}
break;
case AC3_ACMOD_3F2R:
switch (to) {
case AC3_OUTPUT_MONO:
nf = LEVEL_MINUS_3DB / (1.0 + clev + slev);
ctx->chcoeffs[0] *= (nf * LEVEL_MINUS_3DB);
ctx->chcoeffs[2] *= (nf * LEVEL_MINUS_3DB);
ctx->chcoeffs[1] *= (nf * clev * LEVEL_PLUS_3DB);
ctx->chcoeffs[3] *= (nf * slev * LEVEL_MINUS_3DB);
ctx->chcoeffs[4] *= (nf * slev * LEVEL_MINUS_3DB);
break;
case AC3_OUTPUT_STEREO:
nf = 1.0 / (1.0 + clev + slev);
ctx->chcoeffs[0] *= nf;
ctx->chcoeffs[2] *= nf;
ctx->chcoeffs[1] *= (nf * clev);
ctx->chcoeffs[3] *= (nf * slev);
ctx->chcoeffs[4] *= (nf * slev);
break;
case AC3_OUTPUT_DOLBY:
nf = 1.0 / (1.0 + (3.0 * LEVEL_MINUS_3DB));
ctx->chcoeffs[0] *= nf;
ctx->chcoeffs[1] *= nf;
ctx->chcoeffs[1] *= (nf * LEVEL_MINUS_3DB);
ctx->chcoeffs[3] *= (nf * LEVEL_MINUS_3DB);
ctx->chcoeffs[4] *= (nf * LEVEL_MINUS_3DB);
break;
}
break;
}
}
/*********** BEGIN DOWNMIX FUNCTIONS ***********/
static inline void mix_dualmono_to_mono(AC3DecodeContext *ctx)
{
int i;
float (*output)[BLOCK_SIZE] = ctx->output;
for (i = 0; i < 256; i++)
output[1][i] += output[2][i];
memset(output[2], 0, sizeof(output[2]));
}
static inline void mix_dualmono_to_stereo(AC3DecodeContext *ctx)
{
int i;
float tmp;
float (*output)[BLOCK_SIZE] = ctx->output;
for (i = 0; i < 256; i++) {
tmp = output[1][i] + output[2][i];
output[1][i] = output[2][i] = tmp;
}
}
static inline void upmix_mono_to_stereo(AC3DecodeContext *ctx)
{
int i;
float (*output)[BLOCK_SIZE] = ctx->output;
for (i = 0; i < 256; i++)
output[2][i] = output[1][i];
}
static inline void mix_stereo_to_mono(AC3DecodeContext *ctx)
{
int i;
float (*output)[BLOCK_SIZE] = ctx->output;
for (i = 0; i < 256; i++)
output[1][i] += output[2][i];
memset(output[2], 0, sizeof(output[2]));
}
static inline void mix_3f_to_mono(AC3DecodeContext *ctx)
{
int i;
float (*output)[BLOCK_SIZE] = ctx->output;
for (i = 0; i < 256; i++)
output[1][i] += (output[2][i] + output[3][i]);
memset(output[2], 0, sizeof(output[2]));
memset(output[3], 0, sizeof(output[3]));
}
static inline void mix_3f_to_stereo(AC3DecodeContext *ctx)
{
int i;
float (*output)[BLOCK_SIZE] = ctx->output;
for (i = 0; i < 256; i++) {
output[1][i] += output[2][i];
output[2][i] += output[3][i];
}
memset(output[3], 0, sizeof(output[3]));
}
static inline void mix_2f_1r_to_mono(AC3DecodeContext *ctx)
{
int i;
float (*output)[BLOCK_SIZE] = ctx->output;
for (i = 0; i < 256; i++)
output[1][i] += (output[2][i] + output[3][i]);
memset(output[2], 0, sizeof(output[2]));
memset(output[3], 0, sizeof(output[3]));
}
static inline void mix_2f_1r_to_stereo(AC3DecodeContext *ctx)
{
int i;
float (*output)[BLOCK_SIZE] = ctx->output;
for (i = 0; i < 256; i++) {
output[1][i] += output[2][i];
output[2][i] += output[3][i];
}
memset(output[3], 0, sizeof(output[3]));
}
static inline void mix_2f_1r_to_dolby(AC3DecodeContext *ctx)
{
int i;
float (*output)[BLOCK_SIZE] = ctx->output;
for (i = 0; i < 256; i++) {
output[1][i] -= output[3][i];
output[2][i] += output[3][i];
}
memset(output[3], 0, sizeof(output[3]));
}
static inline void mix_3f_1r_to_mono(AC3DecodeContext *ctx)
{
int i;
float (*output)[BLOCK_SIZE] = ctx->output;
for (i = 0; i < 256; i++)
output[1][i] = (output[2][i] + output[3][i] + output[4][i]);
memset(output[2], 0, sizeof(output[2]));
memset(output[3], 0, sizeof(output[3]));
memset(output[4], 0, sizeof(output[4]));
}
static inline void mix_3f_1r_to_stereo(AC3DecodeContext *ctx)
{
int i;
float (*output)[BLOCK_SIZE] = ctx->output;
for (i = 0; i < 256; i++) {
output[1][i] += (output[2][i] + output[4][i]);
output[2][i] += (output[3][i] + output[4][i]);
}
memset(output[3], 0, sizeof(output[3]));
memset(output[4], 0, sizeof(output[4]));
}
static inline void mix_3f_1r_to_dolby(AC3DecodeContext *ctx)
{
int i;
float (*output)[BLOCK_SIZE] = ctx->output;
for (i = 0; i < 256; i++) {
output[1][i] += (output[2][i] - output[4][i]);
output[2][i] += (output[3][i] + output[4][i]);
}
memset(output[3], 0, sizeof(output[3]));
memset(output[4], 0, sizeof(output[4]));
}
static inline void mix_2f_2r_to_mono(AC3DecodeContext *ctx)
{
int i;
float (*output)[BLOCK_SIZE] = ctx->output;
for (i = 0; i < 256; i++)
output[1][i] = (output[2][i] + output[3][i] + output[4][i]);
memset(output[2], 0, sizeof(output[2]));
memset(output[3], 0, sizeof(output[3]));
memset(output[4], 0, sizeof(output[4]));
}
static inline void mix_2f_2r_to_stereo(AC3DecodeContext *ctx)
{
int i;
float (*output)[BLOCK_SIZE] = ctx->output;
for (i = 0; i < 256; i++) {
output[1][i] += output[3][i];
output[2][i] += output[4][i];
}
memset(output[3], 0, sizeof(output[3]));
memset(output[4], 0, sizeof(output[4]));
}
static inline void mix_2f_2r_to_dolby(AC3DecodeContext *ctx)
{
int i;
float (*output)[BLOCK_SIZE] = ctx->output;
for (i = 0; i < 256; i++) {
output[1][i] -= output[3][i];
output[2][i] += output[4][i];
}
memset(output[3], 0, sizeof(output[3]));
memset(output[4], 0, sizeof(output[4]));
}
static inline void mix_3f_2r_to_mono(AC3DecodeContext *ctx)
{
int i;
float (*output)[BLOCK_SIZE] = ctx->output;
for (i = 0; i < 256; i++)
output[1][i] += (output[2][i] + output[3][i] + output[4][i] + output[5][i]);
memset(output[2], 0, sizeof(output[2]));
memset(output[3], 0, sizeof(output[3]));
memset(output[4], 0, sizeof(output[4]));
memset(output[5], 0, sizeof(output[5]));
}
static inline void mix_3f_2r_to_stereo(AC3DecodeContext *ctx)
{
int i;
float (*output)[BLOCK_SIZE] = ctx->output;
for (i = 0; i < 256; i++) {
output[1][i] += (output[2][i] + output[4][i]);
output[2][i] += (output[3][i] + output[5][i]);
}
memset(output[3], 0, sizeof(output[3]));
memset(output[4], 0, sizeof(output[4]));
memset(output[5], 0, sizeof(output[5]));
}
static inline void mix_3f_2r_to_dolby(AC3DecodeContext *ctx)
{
int i;
float (*output)[BLOCK_SIZE] = ctx->output;
for (i = 0; i < 256; i++) {
output[1][i] += (output[2][i] - output[4][i] - output[5][i]);
output[2][i] += (output[3][i] + output[4][i] + output[5][i]);
}
memset(output[3], 0, sizeof(output[3]));
memset(output[4], 0, sizeof(output[4]));
memset(output[5], 0, sizeof(output[5]));
}
/*********** END DOWNMIX FUNCTIONS ***********/
/* Downmix the output.
* This function downmixes the output when the number of input
* channels is not equal to the number of output channels requested.
*/
static void do_downmix(AC3DecodeContext *ctx)
{
int from = ctx->acmod;
int to = ctx->blkoutput;
if (to == AC3_OUTPUT_UNMODIFIED)
return;
switch (from) {
case AC3_ACMOD_DUALMONO:
switch (to) {
case AC3_OUTPUT_MONO:
mix_dualmono_to_mono(ctx);
break;
case AC3_OUTPUT_STEREO: /* We assume that sum of both mono channels is requested */
mix_dualmono_to_stereo(ctx);
break;
}
break;
case AC3_ACMOD_MONO:
switch (to) {
case AC3_OUTPUT_STEREO:
upmix_mono_to_stereo(ctx);
break;
}
break;
case AC3_ACMOD_STEREO:
switch (to) {
case AC3_OUTPUT_MONO:
mix_stereo_to_mono(ctx);
break;
}
break;
case AC3_ACMOD_3F:
switch (to) {
case AC3_OUTPUT_MONO:
mix_3f_to_mono(ctx);
break;
case AC3_OUTPUT_STEREO:
mix_3f_to_stereo(ctx);
break;
}
break;
case AC3_ACMOD_2F1R:
switch (to) {
case AC3_OUTPUT_MONO:
mix_2f_1r_to_mono(ctx);
break;
case AC3_OUTPUT_STEREO:
mix_2f_1r_to_stereo(ctx);
break;
case AC3_OUTPUT_DOLBY:
mix_2f_1r_to_dolby(ctx);
break;
}
break;
case AC3_ACMOD_3F1R:
switch (to) {
case AC3_OUTPUT_MONO:
mix_3f_1r_to_mono(ctx);
break;
case AC3_OUTPUT_STEREO:
mix_3f_1r_to_stereo(ctx);
break;
case AC3_OUTPUT_DOLBY:
mix_3f_1r_to_dolby(ctx);
break;
}
break;
case AC3_ACMOD_2F2R:
switch (to) {
case AC3_OUTPUT_MONO:
mix_2f_2r_to_mono(ctx);
break;
case AC3_OUTPUT_STEREO:
mix_2f_2r_to_stereo(ctx);
break;
case AC3_OUTPUT_DOLBY:
mix_2f_2r_to_dolby(ctx);
break;
}
break;
case AC3_ACMOD_3F2R:
switch (to) {
case AC3_OUTPUT_MONO:
mix_3f_2r_to_mono(ctx);
break;
case AC3_OUTPUT_STEREO:
mix_3f_2r_to_stereo(ctx);
break;
case AC3_OUTPUT_DOLBY:
mix_3f_2r_to_dolby(ctx);
break;
}
break;
}
}
/* This function performs the imdct on 256 sample transform
* coefficients.
*/
static void do_imdct_256(AC3DecodeContext *ctx, int chindex)
{
int i, k;
float x[128];
FFTComplex z[2][64];
float *o_ptr = ctx->tmp_output;
for(i=0; i<2; i++) {
/* de-interleave coefficients */
for(k=0; k<128; k++) {
x[k] = ctx->transform_coeffs[chindex][2*k+i];
}
/* run standard IMDCT */
ctx->imdct_256.fft.imdct_calc(&ctx->imdct_256, o_ptr, x, ctx->tmp_imdct);
/* reverse the post-rotation & reordering from standard IMDCT */
for(k=0; k<32; k++) {
z[i][32+k].re = -o_ptr[128+2*k];
z[i][32+k].im = -o_ptr[2*k];
z[i][31-k].re = o_ptr[2*k+1];
z[i][31-k].im = o_ptr[128+2*k+1];
}
}
/* apply AC-3 post-rotation & reordering */
for(k=0; k<64; k++) {
o_ptr[ 2*k ] = -z[0][ k].im;
o_ptr[ 2*k+1] = z[0][63-k].re;
o_ptr[128+2*k ] = -z[0][ k].re;
o_ptr[128+2*k+1] = z[0][63-k].im;
o_ptr[256+2*k ] = -z[1][ k].re;
o_ptr[256+2*k+1] = z[1][63-k].im;
o_ptr[384+2*k ] = z[1][ k].im;
o_ptr[384+2*k+1] = -z[1][63-k].re;
}
}
/* IMDCT Transform. */
static inline void do_imdct(AC3DecodeContext *ctx)
{
int ch;
if (ctx->blkoutput & AC3_OUTPUT_LFEON) {
ctx->imdct_512.fft.imdct_calc(&ctx->imdct_512, ctx->tmp_output,
ctx->transform_coeffs[0], ctx->tmp_imdct);
}
for (ch=1; ch<=ctx->nfchans; ch++) {
if ((ctx->blksw >> (ch-1)) & 1)
do_imdct_256(ctx, ch);
else
ctx->imdct_512.fft.imdct_calc(&ctx->imdct_512, ctx->tmp_output,
ctx->transform_coeffs[ch],
ctx->tmp_imdct);
ctx->dsp.vector_fmul_add_add(ctx->output[ch], ctx->tmp_output,
ctx->window, ctx->delay[ch], 384, 256, 1);
ctx->dsp.vector_fmul_reverse(ctx->delay[ch], ctx->tmp_output+256,
ctx->window, 256);
}
}
/* Parse the audio block from ac3 bitstream.
* This function extract the audio block from the ac3 bitstream
* and produces the output for the block. This function must
* be called for each of the six audio block in the ac3 bitstream.
*/
static int ac3_parse_audio_block(AC3DecodeContext * ctx)
{
int nfchans = ctx->nfchans;
int acmod = ctx->acmod;
int i, bnd, rbnd, seg, grpsize;
GetBitContext *gb = &ctx->gb;
int bit_alloc_flags = 0;
uint8_t *dexps;
int mstrcplco, cplcoexp, cplcomant;
int dynrng, chbwcod, ngrps, cplabsexp, skipl;
ctx->blksw = 0;
for (i = 0; i < nfchans; i++) /*block switch flag */
ctx->blksw |= get_bits1(gb) << i;
ctx->dithflag = 0;
for (i = 0; i < nfchans; i++) /* dithering flag */
ctx->dithflag |= get_bits1(gb) << i;
if (get_bits1(gb)) { /* dynamic range */
dynrng = get_sbits(gb, 8);
ctx->dynrng = ((((dynrng & 0x1f) | 0x20) << 13) * scale_factors[3 - (dynrng >> 5)]);
}
if (acmod == 0x00 && get_bits1(gb)) { /* dynamic range 1+1 mode */
dynrng = get_sbits(gb, 8);
ctx->dynrng2 = ((((dynrng & 0x1f) | 0x20) << 13) * scale_factors[3 - (dynrng >> 5)]);
}
get_downmix_coeffs(ctx);
if (get_bits1(gb)) { /* coupling strategy */
ctx->cplinu = get_bits1(gb);
ctx->cplbndstrc = 0;
ctx->chincpl = 0;
if (ctx->cplinu) { /* coupling in use */
for (i = 0; i < nfchans; i++)
ctx->chincpl |= get_bits1(gb) << i;
if (acmod == 0x02)
ctx->phsflginu = get_bits1(gb); //phase flag in use
ctx->cplbegf = get_bits(gb, 4);
ctx->cplendf = get_bits(gb, 4);
if (3 + ctx->cplendf - ctx->cplbegf < 0) {
av_log(NULL, AV_LOG_ERROR, "cplendf = %d < cplbegf = %d\n", ctx->cplendf, ctx->cplbegf);
return -1;
}
ctx->ncplbnd = ctx->ncplsubnd = 3 + ctx->cplendf - ctx->cplbegf;
ctx->cplstrtmant = ctx->cplbegf * 12 + 37;
ctx->cplendmant = ctx->cplendf * 12 + 73;
for (i = 0; i < ctx->ncplsubnd - 1; i++) /* coupling band structure */
if (get_bits1(gb)) {
ctx->cplbndstrc |= 1 << i;
ctx->ncplbnd--;
}
}
}
if (ctx->cplinu) {
ctx->cplcoe = 0;
for (i = 0; i < nfchans; i++)
if ((ctx->chincpl) >> i & 1)
if (get_bits1(gb)) { /* coupling co-ordinates */
ctx->cplcoe |= 1 << i;
mstrcplco = 3 * get_bits(gb, 2);
for (bnd = 0; bnd < ctx->ncplbnd; bnd++) {
cplcoexp = get_bits(gb, 4);
cplcomant = get_bits(gb, 4);
if (cplcoexp == 15)
cplcomant <<= 14;
else
cplcomant = (cplcomant | 0x10) << 13;
ctx->cplco[i][bnd] = cplcomant * scale_factors[cplcoexp + mstrcplco];
}
}
if (acmod == 0x02 && ctx->phsflginu && (ctx->cplcoe & 1 || ctx->cplcoe & 2))
for (bnd = 0; bnd < ctx->ncplbnd; bnd++)
if (get_bits1(gb))
ctx->cplco[1][bnd] = -ctx->cplco[1][bnd];
}
if (acmod == 0x02) {/* rematrixing */
ctx->rematstr = get_bits1(gb);
if (ctx->rematstr) {
ctx->rematflg = 0;
if (!(ctx->cplinu) || ctx->cplbegf > 2)
for (rbnd = 0; rbnd < 4; rbnd++)
ctx->rematflg |= get_bits1(gb) << rbnd;
if (ctx->cplbegf > 0 && ctx->cplbegf <= 2 && ctx->cplinu)
for (rbnd = 0; rbnd < 3; rbnd++)
ctx->rematflg |= get_bits1(gb) << rbnd;
if (ctx->cplbegf == 0 && ctx->cplinu)
for (rbnd = 0; rbnd < 2; rbnd++)
ctx->rematflg |= get_bits1(gb) << rbnd;
}
}
ctx->cplexpstr = EXP_REUSE;
ctx->lfeexpstr = EXP_REUSE;
if (ctx->cplinu) /* coupling exponent strategy */
ctx->cplexpstr = get_bits(gb, 2);
for (i = 0; i < nfchans; i++) /* channel exponent strategy */
ctx->chexpstr[i] = get_bits(gb, 2);
if (ctx->lfeon) /* lfe exponent strategy */
ctx->lfeexpstr = get_bits1(gb);
for (i = 0; i < nfchans; i++) /* channel bandwidth code */
if (ctx->chexpstr[i] != EXP_REUSE) {
if ((ctx->chincpl >> i) & 1)
ctx->endmant[i] = ctx->cplstrtmant;
else {
chbwcod = get_bits(gb, 6);
if (chbwcod > 60) {
av_log(NULL, AV_LOG_ERROR, "chbwcod = %d > 60", chbwcod);
return -1;
}
ctx->endmant[i] = chbwcod * 3 + 73;
}
}
if (ctx->cplexpstr != EXP_REUSE) {/* coupling exponents */
bit_alloc_flags = 64;
cplabsexp = get_bits(gb, 4) << 1;
ngrps = (ctx->cplendmant - ctx->cplstrtmant) / (3 << (ctx->cplexpstr - 1));
if (decode_exponents(gb, ctx->cplexpstr, ngrps, cplabsexp, ctx->dcplexps + ctx->cplstrtmant)) {
av_log(NULL, AV_LOG_ERROR, "error decoding coupling exponents\n");
return -1;
}
}
for (i = 0; i < nfchans; i++) /* fbw channel exponents */
if (ctx->chexpstr[i] != EXP_REUSE) {
bit_alloc_flags |= 1 << i;
grpsize = 3 << (ctx->chexpstr[i] - 1);
ngrps = (ctx->endmant[i] + grpsize - 4) / grpsize;
dexps = ctx->dexps[i];
dexps[0] = get_bits(gb, 4);
if (decode_exponents(gb, ctx->chexpstr[i], ngrps, dexps[0], dexps + 1)) {
av_log(NULL, AV_LOG_ERROR, "error decoding channel %d exponents\n", i);
return -1;
}
skip_bits(gb, 2); /* skip gainrng */
}
if (ctx->lfeexpstr != EXP_REUSE) { /* lfe exponents */
bit_alloc_flags |= 32;
ctx->dlfeexps[0] = get_bits(gb, 4);
if (decode_exponents(gb, ctx->lfeexpstr, 2, ctx->dlfeexps[0], ctx->dlfeexps + 1)) {
av_log(NULL, AV_LOG_ERROR, "error decoding lfe exponents\n");
return -1;
}
}
if (get_bits1(gb)) { /* bit allocation information */
bit_alloc_flags = 127;
ctx->sdcycod = get_bits(gb, 2);
ctx->fdcycod = get_bits(gb, 2);
ctx->sgaincod = get_bits(gb, 2);
ctx->dbpbcod = get_bits(gb, 2);
ctx->floorcod = get_bits(gb, 3);
}
if (get_bits1(gb)) { /* snroffset */
bit_alloc_flags = 127;
ctx->csnroffst = get_bits(gb, 6);
if (ctx->cplinu) { /* coupling fine snr offset and fast gain code */
ctx->cplfsnroffst = get_bits(gb, 4);
ctx->cplfgaincod = get_bits(gb, 3);
}
for (i = 0; i < nfchans; i++) { /* channel fine snr offset and fast gain code */
ctx->fsnroffst[i] = get_bits(gb, 4);
ctx->fgaincod[i] = get_bits(gb, 3);
}
if (ctx->lfeon) { /* lfe fine snr offset and fast gain code */
ctx->lfefsnroffst = get_bits(gb, 4);
ctx->lfefgaincod = get_bits(gb, 3);
}
}
if (ctx->cplinu && get_bits1(gb)) { /* coupling leak information */
bit_alloc_flags |= 64;
ctx->cplfleak = get_bits(gb, 3);
ctx->cplsleak = get_bits(gb, 3);
}
if (get_bits1(gb)) { /* delta bit allocation information */
bit_alloc_flags = 127;
if (ctx->cplinu) {
ctx->cpldeltbae = get_bits(gb, 2);
if (ctx->cpldeltbae == DBA_RESERVED) {
av_log(NULL, AV_LOG_ERROR, "coupling delta bit allocation strategy reserved\n");
return -1;
}
}
for (i = 0; i < nfchans; i++) {
ctx->deltbae[i] = get_bits(gb, 2);
if (ctx->deltbae[i] == DBA_RESERVED) {
av_log(NULL, AV_LOG_ERROR, "delta bit allocation strategy reserved\n");
return -1;
}
}
if (ctx->cplinu)
if (ctx->cpldeltbae == DBA_NEW) { /*coupling delta offset, len and bit allocation */
ctx->cpldeltnseg = get_bits(gb, 3);
for (seg = 0; seg <= ctx->cpldeltnseg; seg++) {
ctx->cpldeltoffst[seg] = get_bits(gb, 5);
ctx->cpldeltlen[seg] = get_bits(gb, 4);
ctx->cpldeltba[seg] = get_bits(gb, 3);
}
}
for (i = 0; i < nfchans; i++)
if (ctx->deltbae[i] == DBA_NEW) {/*channel delta offset, len and bit allocation */
ctx->deltnseg[i] = get_bits(gb, 3);
for (seg = 0; seg <= ctx->deltnseg[i]; seg++) {
ctx->deltoffst[i][seg] = get_bits(gb, 5);
ctx->deltlen[i][seg] = get_bits(gb, 4);
ctx->deltba[i][seg] = get_bits(gb, 3);
}
}
}
if (bit_alloc_flags) {
if (is_snr_offsets_zero(ctx)) {
memset(ctx->cplbap, 0, sizeof (ctx->cplbap));
memset(ctx->lfebap, 0, sizeof (ctx->lfebap));
for (i = 0; i < nfchans; i++)
memset(ctx->bap[i], 0, sizeof(ctx->bap[i]));
} else {
/* set bit allocation parameters */
ctx->bit_alloc_params.fscod = ctx->fscod;
ctx->bit_alloc_params.halfratecod = 0;
ctx->bit_alloc_params.sdecay = ff_sdecaytab[ctx->sdcycod];
ctx->bit_alloc_params.fdecay = ff_fdecaytab[ctx->fdcycod];
ctx->bit_alloc_params.sgain = ff_sgaintab[ctx->sgaincod];
ctx->bit_alloc_params.dbknee = ff_dbkneetab[ctx->dbpbcod];
ctx->bit_alloc_params.floor = ff_floortab[ctx->floorcod];
ctx->bit_alloc_params.cplfleak = ctx->cplfleak;
ctx->bit_alloc_params.cplsleak = ctx->cplsleak;
if (ctx->chincpl && (bit_alloc_flags & 64))
do_bit_allocation(ctx, 5);
for (i = 0; i < nfchans; i++)
if ((bit_alloc_flags >> i) & 1)
do_bit_allocation(ctx, i);
if (ctx->lfeon && (bit_alloc_flags & 32))
do_bit_allocation(ctx, 6);
}
}
if (get_bits1(gb)) { /* unused dummy data */
skipl = get_bits(gb, 9);
while(skipl--)
skip_bits(gb, 8);
}
/* 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 (ctx->rematflg)
do_rematrixing(ctx);
do_downmix(ctx);
do_imdct(ctx);
return 0;
}
static inline int16_t convert(int32_t i)
{
if (i > 0x43c07fff)
return 32767;
else if (i <= 0x43bf8000)
return -32768;
else
return (i - 0x43c00000);
}
/* Decode ac3 frame.
*
* @param avctx Pointer to AVCodecContext
* @param data Pointer to pcm smaples
* @param data_size Set to number of pcm samples produced by decoding
* @param buf Data to be decoded
* @param buf_size Size of the buffer
*/
static int ac3_decode_frame(AVCodecContext * avctx, void *data, int *data_size, uint8_t *buf, int buf_size)
{
AC3DecodeContext *ctx = (AC3DecodeContext *)avctx->priv_data;
int frame_start;
int16_t *out_samples = (int16_t *)data;
int i, j, k, start;
int32_t *int_ptr[6];
for (i = 0; i < 6; i++)
int_ptr[i] = (int32_t *)(&ctx->output[i]);
//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 buf_size;
}
//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' or 'bsid' is not valid the decoder shall mute as per the standard.
if (!ac3_parse_sync_info(ctx)) {
av_log(avctx, AV_LOG_ERROR, "\n");
*data_size = 0;
return buf_size;
}
//Parse the BSI.
//If 'bsid' is not valid decoder shall not decode the audio as per the standard.
ac3_parse_bsi(ctx);
avctx->sample_rate = ctx->sampling_rate;
avctx->bit_rate = ctx->bit_rate;
if (avctx->channels == 0) {
ctx->blkoutput |= AC3_OUTPUT_UNMODIFIED;
if (ctx->lfeon)
ctx->blkoutput |= AC3_OUTPUT_LFEON;
avctx->channels = ctx->nfchans + ctx->lfeon;
}
else if (avctx->channels == 1)
ctx->blkoutput |= AC3_OUTPUT_MONO;
else if (avctx->channels == 2) {
if (ctx->dsurmod == 0x02)
ctx->blkoutput |= AC3_OUTPUT_DOLBY;
else
ctx->blkoutput |= AC3_OUTPUT_STEREO;
}
else {
if (avctx->channels < (ctx->nfchans + ctx->lfeon))
av_log(avctx, AV_LOG_INFO, "ac3_decoder: AC3 Source Channels Are Less Then Specified %d: Output to %d Channels\n",avctx->channels, ctx->nfchans + ctx->lfeon);
ctx->blkoutput |= AC3_OUTPUT_UNMODIFIED;
if (ctx->lfeon)
ctx->blkoutput |= AC3_OUTPUT_LFEON;
avctx->channels = ctx->nfchans + ctx->lfeon;
}
//av_log(avctx, AV_LOG_INFO, "channels = %d \t bit rate = %d \t sampling rate = %d \n", avctx->channels, avctx->bit_rate * 1000, avctx->sample_rate);
//Parse the Audio Blocks.
for (i = 0; i < NB_BLOCKS; i++) {
if (ac3_parse_audio_block(ctx)) {
av_log(avctx, AV_LOG_ERROR, "error parsing the audio block\n");
*data_size = 0;
return ctx->frame_size;
}
start = (ctx->blkoutput & AC3_OUTPUT_LFEON) ? 0 : 1;
for (k = 0; k < BLOCK_SIZE; k++)
for (j = start; j <= avctx->channels; j++)
*(out_samples++) = convert(int_ptr[j][k]);
}
*data_size = NB_BLOCKS * BLOCK_SIZE * avctx->channels * sizeof (int16_t);
return ctx->frame_size;
}
/* Uninitialize ac3 decoder.
*/
static int ac3_decode_end(AVCodecContext *avctx)
{
AC3DecodeContext *ctx = (AC3DecodeContext *)avctx->priv_data;
ff_mdct_end(&ctx->imdct_512);
ff_mdct_end(&ctx->imdct_256);
return 0;
}
AVCodec ac3_decoder = {
.name = "ac3",
.type = CODEC_TYPE_AUDIO,
.id = CODEC_ID_AC3,
.priv_data_size = sizeof (AC3DecodeContext),
.init = ac3_decode_init,
.close = ac3_decode_end,
.decode = ac3_decode_frame,
};
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