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ffmpeg/libavcodec/ac3dec.c
Justin Ruggles 1d0a6f5209 AC-3 decoder, soc revision 57, Aug 19 12:44:38 2006 UTC by cloud9 
Optimization as suggested by Benjamin.

Originally committed as revision 9665 to svn://svn.ffmpeg.org/ffmpeg/trunk
2007-07-14 16:02:08 +00:00

2017 lines
62 KiB
C
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/* AC3 Audio Decoder.
* This code is developed as part of Google Summer of Code 2006 Program.
*
* Acknowledgements:
*
* I would like to acknowledge my mentor Benjamin Larsson for his timely
* help and excelleng guidance throughout the project.
* Thanks a lot Benjamin.
*
* For exponent decoding the code is reused from liba52 by Michel Lespinasse
* and Aaron Holtzman.
* http://liba52.sourceforge.net
*
* Thanks Makoto Matsumoto and Takuji Nishimura for the Mersenne Twister.
*
* Kaiser-Bessel derived window by Justin Ruggles.
*
* Copyright (c) 2006 Kartikey Mahendra BHATT (bhattkm at gmail dot com).
* Something is wrong up on cloud # 9!
*
* 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 <string.h>
#define ALT_BITSTREAM_READER
#include "avcodec.h"
#include "ac3tab.h"
#include "ac3_decoder.h"
#include "bitstream.h"
#include "dsputil.h"
#define N 512 /* constant for IMDCT Block size */
#define MAX_CHANNELS 6
#define BLOCK_SIZE 256
#define AUDIO_BLOCKS 6
/* 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
/* 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
#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
/* Mersenne Twister */
#define NMT 624
#define MMT 397
#define MATRIX_A 0x9908b0df
#define UPPER_MASK 0x80000000
#define LOWER_MASK 0x7fffffff
typedef struct {
uint32_t mt[NMT];
int mti;
} dither_state;
/* Mersenne Twister */
typedef struct {
uint32_t flags;
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;
int lfeon;
float chcoeffs[6];
float cplco[5][18];
int ncplbnd;
int ncplsubnd;
int cplstrtmant;
int cplendmant;
int endmant[5];
uint8_t dcplexps[256];
uint8_t dexps[5][256];
uint8_t dlfeexps[256];
uint8_t cplbap[256];
uint8_t bap[5][256];
uint8_t lfebap[256];
int blkoutput;
DECLARE_ALIGNED_16(float, transform_coeffs[MAX_CHANNELS][BLOCK_SIZE]);
/* For IMDCT. */
MDCTContext imdct_512; //N/8 point IFFT context
MDCTContext imdct_256; //N/4 point IFFT context
DSPContext dsp; //for optimization
DECLARE_ALIGNED_16(float, output[MAX_CHANNELS][BLOCK_SIZE]);
DECLARE_ALIGNED_16(float, delay[MAX_CHANNELS][BLOCK_SIZE]);
DECLARE_ALIGNED_16(float, tmp_imdct[BLOCK_SIZE]);
DECLARE_ALIGNED_16(float, tmp_output[BLOCK_SIZE * 2]);
/* Miscellaneous. */
GetBitContext gb;
dither_state dith_state;
} AC3DecodeContext;
/* BEGIN Mersenne Twister Code. */
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 < NMT; 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 >= NMT) {
for (kk = 0; kk < NMT - MMT; kk++) {
y = (state->mt[kk] & UPPER_MASK) | (state->mt[kk + 1] & LOWER_MASK);
state->mt[kk] = state->mt[kk + MMT] ^ (y >> 1) ^ mag01[y & 0x01];
}
for (;kk < NMT - 1; kk++) {
y = (state->mt[kk] & UPPER_MASK) | (state->mt[kk + 1] & LOWER_MASK);
state->mt[kk] = state->mt[kk + (MMT - NMT)] ^ (y >> 1) ^ mag01[y & 0x01];
}
y = (state->mt[NMT - 1] & UPPER_MASK) | (state->mt[0] & LOWER_MASK);
state->mt[NMT - 1] = state->mt[MMT - 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 */
/**
* Generate a Kaiser Window.
*/
static void
k_window_init(int alpha, float *window, int n, int iter)
{
int j, k;
float a, x;
a = alpha * M_PI / n;
a = a*a;
for(k=0; k<n; k++) {
x = k * (n - k) * a;
window[k] = 1.0;
for(j=iter; j>0; j--) {
window[k] = (window[k] * x / (j*j)) + 1.0;
}
}
}
/**
* Generate a Kaiser-Bessel Derived Window.
* @param alpha determines window shape
* @param window array to fill with window values
* @param n length of the window
* @param iter number of iterations to use in BesselI0
*/
static void
kbd_window_init(int alpha, float *window, int n, int iter)
{
int k, n2;
float *kwindow;
n2 = n >> 1;
kwindow = &window[n2];
k_window_init(alpha, kwindow, n2, iter);
window[0] = kwindow[0];
for(k=1; k<n2; k++) {
window[k] = window[k-1] + kwindow[k];
}
for(k=0; k<n2; k++) {
window[k] = sqrt(window[k] / (window[n2-1]+1));
window[n-1-k] = window[k];
}
}
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;
}
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 = bndsz[i];
for(j=0;j<v;j++) masktab[k++]=i;
l += v;
}
masktab[253] = masktab[254] = masktab[255] = 0;
bndtab[50] = 0;
/* 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);
/* Kaiser-Bessel derived window. */
kbd_window_init(5, window, 256, 100);
}
static int ac3_decode_init(AVCodecContext *avctx)
{
AC3DecodeContext *ctx = avctx->priv_data;
ac3_tables_init();
ff_mdct_init(&ctx->imdct_256, 8, 1);
ff_mdct_init(&ctx->imdct_512, 9, 1);
dsputil_init(&ctx->dsp, avctx);
dither_seed(&ctx->dith_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)
{
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 = ac3_freqs[ctx->fscod];
ctx->bit_rate = 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;
}
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 = AC3_DBASTR_NONE;
ctx->cpldeltnseg = 0;
for (i = 0; i < 5; i++) {
ctx->deltbae[i] = AC3_DBASTR_NONE;
ctx->deltnseg[i] = 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 and stores them
* in decoded exponents (dexps).
* The code is derived from liba52.
* Uses liba52 tables.
*/
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 AC3_EXPSTR_D45:
*(dexps++) = absexp;
*(dexps++) = absexp;
case AC3_EXPSTR_D25:
*(dexps++) = absexp;
case AC3_EXPSTR_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 AC3_EXPSTR_D45:
*(dexps++) = absexp;
*(dexps++) = absexp;
case AC3_EXPSTR_D25:
*(dexps++) = absexp;
case AC3_EXPSTR_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 AC3_EXPSTR_D45:
*(dexps++) = absexp;
*(dexps++) = absexp;
case AC3_EXPSTR_D25:
*(dexps++) = absexp;
case AC3_EXPSTR_D15:
*(dexps++) = absexp;
}
}
return 0;
}
static inline int logadd(int a, int b)
{
int c = a - b;
int address;
address = FFMIN((ABS(c) >> 1), 255);
if (c >= 0)
return (a + latab[address]);
else
return (b + latab[address]);
}
static inline int calc_lowcomp(int a, int b0, int b1, int 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 void do_bit_allocation(AC3DecodeContext *ctx, int chnl)
{
int16_t psd[256], bndpsd[50], excite[50], mask[50], delta;
int sdecay, fdecay, sgain, dbknee, floor;
int lowcomp = 0, fgain = 0, snroffset = 0, fastleak = 0, slowleak = 0, do_delta = 0;
int start = 0, end = 0, bin = 0, i = 0, j = 0, k = 0, lastbin = 0, bndstrt = 0;
int bndend = 0, begin = 0, deltnseg = 0, band = 0, seg = 0, address = 0;
int fscod = ctx->fscod;
uint8_t *deltoffst = 0, *deltlen = 0, *deltba = 0;
uint8_t *exps = 0, *bap = 0;
/* initialization */
sdecay = sdecaytab[ctx->sdcycod];
fdecay = fdecaytab[ctx->fdcycod];
sgain = sgaintab[ctx->sgaincod];
dbknee = dbkneetab[ctx->dbpbcod];
floor = floortab[ctx->floorcod];
if (chnl == 5) {
start = ctx->cplstrtmant;
end = ctx->cplendmant;
fgain = fgaintab[ctx->cplfgaincod];
snroffset = (((ctx->csnroffst - 15) << 4) + ctx->cplfsnroffst) << 2;
fastleak = (ctx->cplfleak << 8) + 768;
slowleak = (ctx->cplsleak << 8) + 768;
exps = ctx->dcplexps;
bap = ctx->cplbap;
if (ctx->cpldeltbae == AC3_DBASTR_NEW || ctx->deltbae == AC3_DBASTR_REUSE) {
do_delta = 1;
deltnseg = ctx->cpldeltnseg;
deltoffst = ctx->cpldeltoffst;
deltlen = ctx->cpldeltlen;
deltba = ctx->cpldeltba;
}
}
else if (chnl == 6) {
start = 0;
end = 7;
lowcomp = 0;
fastleak = 0;
slowleak = 0;
fgain = fgaintab[ctx->lfefgaincod];
snroffset = (((ctx->csnroffst - 15) << 4) + ctx->lfefsnroffst) << 2;
exps = ctx->dlfeexps;
bap = ctx->lfebap;
}
else {
start = 0;
end = ctx->endmant[chnl];
lowcomp = 0;
fastleak = 0;
slowleak = 0;
fgain = fgaintab[ctx->fgaincod[chnl]];
snroffset = (((ctx->csnroffst - 15) << 4) + ctx->fsnroffst[chnl]) << 2;
exps = ctx->dexps[chnl];
bap = ctx->bap[chnl];
if (ctx->deltbae[chnl] == AC3_DBASTR_NEW || ctx->deltbae[chnl] == AC3_DBASTR_REUSE) {
do_delta = 1;
deltnseg = ctx->deltnseg[chnl];
deltoffst = ctx->deltoffst[chnl];
deltlen = ctx->deltlen[chnl];
deltba = ctx->deltba[chnl];
}
}
for (bin = start; bin < end; bin++) /* exponent mapping into psd */
psd[bin] = (3072 - (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)));
bap[i] = baptab[address];
i++;
}
j++;
} while (end > lastbin);
}
/* 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, dither_int16(&ctx->dith_state), 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], dither_int16(&ctx->dith_state), 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;
}
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;
}
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);
}
}
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
if (to == AC3_OUTPUT_UNMODIFIED)
return;
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 */
nf = 0.5;
ctx->chcoeffs[0] *= nf;
ctx->chcoeffs[1] *= nf;
break;
}
break;
case AC3_INPUT_MONO:
switch (to) {
case AC3_OUTPUT_STEREO:
nf = LEVEL_MINUS_3DB;
ctx->chcoeffs[0] *= nf;
break;
}
break;
case AC3_INPUT_STEREO:
switch (to) {
case AC3_OUTPUT_MONO:
nf = LEVEL_MINUS_3DB;
ctx->chcoeffs[0] *= nf;
ctx->chcoeffs[1] *= nf;
break;
}
break;
case AC3_INPUT_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_INPUT_2F_1R:
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_INPUT_3F_1R:
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_INPUT_2F_2R:
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_INPUT_3F_2R:
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;
}
}
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]));
}
static void do_downmix(AC3DecodeContext *ctx)
{
int from = ctx->acmod;
int to = ctx->blkoutput;
switch (from) {
case AC3_INPUT_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_INPUT_MONO:
switch (to) {
case AC3_OUTPUT_STEREO:
upmix_mono_to_stereo(ctx);
break;
}
break;
case AC3_INPUT_STEREO:
switch (to) {
case AC3_OUTPUT_MONO:
mix_stereo_to_mono(ctx);
break;
}
break;
case AC3_INPUT_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_INPUT_2F_1R:
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_INPUT_3F_1R:
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_INPUT_2F_2R:
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_INPUT_3F_2R:
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;
}
}
static void dump_floats(const char *name, int prec, const float *tab, int n)
{
int i;
av_log(NULL, AV_LOG_INFO, "%s[%d]:\n", name, n);
for(i=0;i<n;i++) {
if ((i & 7) == 0)
av_log(NULL, AV_LOG_INFO, "%4d: ", i);
av_log(NULL, AV_LOG_INFO, " %8.*f", prec, tab[i]);
if ((i & 7) == 7)
av_log(NULL, AV_LOG_INFO, "\n");
}
if ((i & 7) != 0)
av_log(NULL, AV_LOG_INFO, "\n");
}
#define CMUL(pre, pim, are, aim, bre, bim) \
{\
float _are = (are);\
float _aim = (aim);\
float _bre = (bre);\
float _bim = (bim);\
(pre) = _are * _bre - _aim * _bim;\
(pim) = _are * _bim + _aim * _bre;\
}
static void do_imdct_256(AC3DecodeContext *ctx, int chindex)
{
int k;
float x1[128], x2[128];
float *ptr;
for (k = 0; k < N / 4; k++) {
x1[k] = ctx->transform_coeffs[chindex][2 * k];
x2[k] = ctx->transform_coeffs[chindex][2 * k + 1];
}
ff_imdct_calc(&ctx->imdct_256, ctx->tmp_output, x1, ctx->tmp_imdct);
ff_imdct_calc(&ctx->imdct_256, ctx->tmp_output + 256, x2, ctx->tmp_imdct);
ptr = ctx->output[chindex];
ctx->dsp.vector_fmul_add_add(ptr, ctx->tmp_output, window, ctx->delay[chindex], 0, BLOCK_SIZE, 1);
ptr = ctx->delay[chindex];
ctx->dsp.vector_fmul_reverse(ptr, ctx->tmp_output + 256, window, BLOCK_SIZE);
/*for (k = 0; k < N / 2; k++) {
ctx->output[chindex][k] = ctx->tmp_output[k] * window[k] + ctx->delay[chindex][k];
//dump_floats("samples", 10, ctx->output[chindex], 256);
ctx->delay[chindex][k] = ctx->tmp_output[N / 2 + k] * window[255 - k];
}*/
}
static void do_imdct_512(AC3DecodeContext *ctx, int chindex)
{
//int k;
float *ptr;
ff_imdct_calc(&ctx->imdct_512, ctx->tmp_output,
ctx->transform_coeffs[chindex], ctx->tmp_imdct);
//ff_imdct_calc_ac3_512(&ctx->imdct_512, ctx->tmp_output, ctx->transform_coeffs[chindex],
// ctx->tmp_imdct, window);
ptr = ctx->output[chindex];
ctx->dsp.vector_fmul_add_add(ptr, ctx->tmp_output, window, ctx->delay[chindex], 0, BLOCK_SIZE, 1);
ptr = ctx->delay[chindex];
ctx->dsp.vector_fmul_reverse(ptr, ctx->tmp_output + 256, window, BLOCK_SIZE);
/*for (k = 0; k < N / 2; k++) {
ctx->output[chindex][k] = ctx->tmp_output[k] * window[k] + ctx->delay[chindex][k];
//dump_floats("samples", 10, ctx->output[chindex], 256);
ctx->delay[chindex][k] = ctx->tmp_output[N / 2 + k] * window[255 - k];
} */
}
static inline void do_imdct(AC3DecodeContext *ctx)
{
int i;
if (ctx->blkoutput & AC3_OUTPUT_LFEON) {
do_imdct_512(ctx, 0);
}
for (i = 0; i < ctx->nfchans; i++) {
if ((ctx->blksw >> i) & 1)
do_imdct_256(ctx, i + 1);
else
do_imdct_512(ctx, i + 1);
}
}
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;
float drange;
uint8_t *dexps;
int mstrcplco, cplcoexp, cplcomant;
int dynrng, chbwcod, ngrps, cplabsexp, skipl;
for (i = 0; i < 5; i++)
ctx->chcoeffs[i] = 2.0;
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);
drange = ((((dynrng & 0x1f) | 0x20) << 13) * scale_factors[3 - (dynrng >> 5)]);
for (i = 0; i < nfchans; i++)
ctx->chcoeffs[i] *= drange;
}
if (acmod == 0x00 && get_bits1(gb)) { /* dynamic range 1+1 mode */
dynrng = get_sbits(gb, 8);
drange = ((((dynrng & 0x1f) | 0x20) << 13) * scale_factors[3 - (dynrng >> 5)]);
ctx->chcoeffs[1] *= drange;
}
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 = AC3_EXPSTR_REUSE;
ctx->lfeexpstr = AC3_EXPSTR_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] != AC3_EXPSTR_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 != AC3_EXPSTR_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] != AC3_EXPSTR_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 != AC3_EXPSTR_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) { /* couling 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 == AC3_DBASTR_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] == AC3_DBASTR_RESERVED) {
av_log(NULL, AV_LOG_ERROR, "delta bit allocation strategy reserved\n");
return -1;
}
}
if (ctx->cplinu)
if (ctx->cpldeltbae == AC3_DBASTR_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] == AC3_DBASTR_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 {
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;
}
/*for (i = 0; i < nfchans; i++)
dump_floats("channel transform coefficients", 10, ctx->transform_coeffs[i + 1], BLOCK_SIZE);*/
/* recover coefficients if rematrixing is in use */
if (ctx->rematflg)
do_rematrixing(ctx);
do_imdct(ctx);
/*for(i = 0; i < nfchans; i++)
dump_floats("channel output", 10, ctx->output[i + 1], BLOCK_SIZE);*/
do_downmix(ctx);
return 0;
}
static inline int16_t convert(float f)
{
if (f >= 1.0)
return 32767;
else if (f <= -1.0)
return -32768;
else
return (lrintf(f * 32767.0));
}
static int frame_count = 0;
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, value;
av_log(NULL, AV_LOG_INFO, "decoding frame %d buf_size = %d\n", frame_count++, buf_size);
//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 < AUDIO_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;
}
for (k = 0; k < BLOCK_SIZE; k++) {
j = (ctx->blkoutput & AC3_OUTPUT_LFEON) ? 0 : 1;
for (; j <= avctx->channels; j++) {
value = convert(ctx->output[j][k]);
*(out_samples++) = value;
}
}
}
*data_size = AUDIO_BLOCKS * BLOCK_SIZE * avctx->channels * sizeof (int16_t);
return ctx->frame_size;
}
static int ac3_decode_end(AVCodecContext *ctx)
{
return 0;
}
AVCodec lgpl_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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