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preparing integration of new AC3 decoder

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Originally committed as revision 1089 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Fabrice Bellard 2002-10-28 00:39:05 +00:00
parent bb6f569072
commit 6107fa87b4
4 changed files with 206 additions and 121 deletions
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56
libavcodec/ac3.h Normal file
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@ -0,0 +1,56 @@
/*
* Common code between AC3 encoder and decoder
* Copyright (c) 2000, 2001, 2002 Fabrice Bellard.
*
* 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#define AC3_MAX_CODED_FRAME_SIZE 3840 /* in bytes */
#define AC3_MAX_CHANNELS 6 /* including LFE channel */
#define NB_BLOCKS 6 /* number of PCM blocks inside an AC3 frame */
#define AC3_FRAME_SIZE (NB_BLOCKS * 256)
/* exponent encoding strategy */
#define EXP_REUSE 0
#define EXP_NEW 1
#define EXP_D15 1
#define EXP_D25 2
#define EXP_D45 3
typedef struct AC3BitAllocParameters {
int fscod; /* frequency */
int halfratecod;
int sgain, sdecay, fdecay, dbknee, floor;
int cplfleak, cplsleak;
} AC3BitAllocParameters;
extern const UINT16 ac3_freqs[3];
extern const UINT16 ac3_bitratetab[19];
extern const INT16 ac3_window[256];
extern const UINT8 sdecaytab[4];
extern const UINT8 fdecaytab[4];
extern const UINT16 sgaintab[4];
extern const UINT16 dbkneetab[4];
extern const UINT16 floortab[8];
extern const UINT16 fgaintab[8];
void ac3_common_init(void);
void ac3_parametric_bit_allocation(AC3BitAllocParameters *s, UINT8 *bap,
INT8 *exp, int start, int end,
int snroffset, int fgain, int is_lfe,
int deltbae,int deltnseg,
UINT8 *deltoffst, UINT8 *deltlen, UINT8 *deltba);

138
libavcodec/ac3enc.c
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@ -20,25 +20,46 @@
//#define DEBUG_BITALLOC //#define DEBUG_BITALLOC
#include "avcodec.h" #include "avcodec.h"
#include "ac3enc.h" #include "ac3.h"
#include "ac3tab.h"
typedef struct AC3EncodeContext {
PutBitContext pb;
int nb_channels;
int nb_all_channels;
int lfe_channel;
int bit_rate;
int sample_rate;
int bsid;
int frame_size_min; /* minimum frame size in case rounding is necessary */
int frame_size; /* current frame size in words */
int halfratecod;
int frmsizecod;
int fscod; /* frequency */
int acmod;
int lfe;
int bsmod;
short last_samples[AC3_MAX_CHANNELS][256];
int chbwcod[AC3_MAX_CHANNELS];
int nb_coefs[AC3_MAX_CHANNELS];
/* bitrate allocation control */
int sgaincod, sdecaycod, fdecaycod, dbkneecod, floorcod;
AC3BitAllocParameters bit_alloc;
int csnroffst;
int fgaincod[AC3_MAX_CHANNELS];
int fsnroffst[AC3_MAX_CHANNELS];
/* mantissa encoding */
int mant1_cnt, mant2_cnt, mant4_cnt;
} AC3EncodeContext;
#include "ac3tab.h"
#define MDCT_NBITS 9 #define MDCT_NBITS 9
#define N (1 << MDCT_NBITS) #define N (1 << MDCT_NBITS)
#define NB_BLOCKS 6 /* number of PCM blocks inside an AC3 frame */
/* new exponents are sent if their Norm 1 exceed this number */ /* new exponents are sent if their Norm 1 exceed this number */
#define EXP_DIFF_THRESHOLD 1000 #define EXP_DIFF_THRESHOLD 1000
/* exponent encoding strategy */
#define EXP_REUSE 0
#define EXP_NEW 1
#define EXP_D15 1
#define EXP_D25 2
#define EXP_D45 3
static void fft_init(int ln); static void fft_init(int ln);
static void ac3_crc_init(void); static void ac3_crc_init(void);
@ -88,11 +109,12 @@ static inline int calc_lowcomp(int a, int b0, int b1, int bin)
} }
/* AC3 bit allocation. The algorithm is the one described in the AC3 /* AC3 bit allocation. The algorithm is the one described in the AC3
spec with some optimizations because of our simplified encoding spec. */
assumptions. */ void ac3_parametric_bit_allocation(AC3BitAllocParameters *s, UINT8 *bap,
void parametric_bit_allocation(AC3EncodeContext *s, UINT8 *bap,
INT8 *exp, int start, int end, INT8 *exp, int start, int end,
int snroffset, int fgain, int is_lfe) int snroffset, int fgain, int is_lfe,
int deltbae,int deltnseg,
UINT8 *deltoffst, UINT8 *deltlen, UINT8 *deltba)
{ {
int bin,i,j,k,end1,v,v1,bndstrt,bndend,lowcomp,begin; int bin,i,j,k,end1,v,v1,bndstrt,bndend,lowcomp,begin;
int fastleak,slowleak,address,tmp; int fastleak,slowleak,address,tmp;
@ -138,6 +160,7 @@ void parametric_bit_allocation(AC3EncodeContext *s, UINT8 *bap,
bndstrt = masktab[start]; bndstrt = masktab[start];
bndend = masktab[end-1] + 1; bndend = masktab[end-1] + 1;
if (bndstrt == 0) {
lowcomp = 0; lowcomp = 0;
lowcomp = calc_lowcomp1(lowcomp, bndpsd[0], bndpsd[1]) ; lowcomp = calc_lowcomp1(lowcomp, bndpsd[0], bndpsd[1]) ;
excite[0] = bndpsd[0] - fgain - lowcomp ; excite[0] = bndpsd[0] - fgain - lowcomp ;
@ -178,8 +201,16 @@ void parametric_bit_allocation(AC3EncodeContext *s, UINT8 *bap,
excite[bin] = v; excite[bin] = v;
} }
begin = 22;
} else {
/* coupling channel */
begin = bndstrt;
for (bin = 22; bin < bndend; bin++) { fastleak = (s->cplfleak << 8) + 768;
slowleak = (s->cplsleak << 8) + 768;
}
for (bin = begin; bin < bndend; bin++) {
fastleak -= s->fdecay ; fastleak -= s->fdecay ;
v = bndpsd[bin] - fgain; v = bndpsd[bin] - fgain;
if (fastleak < v) fastleak = v; if (fastleak < v) fastleak = v;
@ -205,6 +236,25 @@ void parametric_bit_allocation(AC3EncodeContext *s, UINT8 *bap,
mask[bin] = v; mask[bin] = v;
} }
/* delta bit allocation */
if (deltbae == 0 || deltbae == 1) {
int band, seg, delta;
band = 0 ;
for (seg = 0; seg < deltnseg; 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 bit allocation */ /* compute bit allocation */
i = start ; i = start ;
@ -600,12 +650,14 @@ static int bit_alloc(AC3EncodeContext *s,
s->mant2_cnt = 0; s->mant2_cnt = 0;
s->mant4_cnt = 0; s->mant4_cnt = 0;
for(ch=0;ch<s->nb_all_channels;ch++) { for(ch=0;ch<s->nb_all_channels;ch++) {
parametric_bit_allocation(s, bap[i][ch], (INT8 *)encoded_exp[i][ch], ac3_parametric_bit_allocation(&s->bit_alloc,
bap[i][ch], (INT8 *)encoded_exp[i][ch],
0, s->nb_coefs[ch], 0, s->nb_coefs[ch],
(((csnroffst-15) << 4) + (((csnroffst-15) << 4) +
fsnroffst) << 2, fsnroffst) << 2,
fgaintab[s->fgaincod[ch]], fgaintab[s->fgaincod[ch]],
ch == s->lfe_channel); ch == s->lfe_channel,
2, 0, NULL, NULL, NULL);
frame_bits += compute_mantissa_size(s, bap[i][ch], frame_bits += compute_mantissa_size(s, bap[i][ch],
s->nb_coefs[ch]); s->nb_coefs[ch]);
} }
@ -641,11 +693,13 @@ static int compute_bit_allocation(AC3EncodeContext *s,
s->fgaincod[ch] = 4; s->fgaincod[ch] = 4;
/* compute real values */ /* compute real values */
s->sdecay = sdecaytab[s->sdecaycod] >> s->halfratecod; s->bit_alloc.fscod = s->fscod;
s->fdecay = fdecaytab[s->fdecaycod] >> s->halfratecod; s->bit_alloc.halfratecod = s->halfratecod;
s->sgain = sgaintab[s->sgaincod]; s->bit_alloc.sdecay = sdecaytab[s->sdecaycod] >> s->halfratecod;
s->dbknee = dbkneetab[s->dbkneecod]; s->bit_alloc.fdecay = fdecaytab[s->fdecaycod] >> s->halfratecod;
s->floor = floortab[s->floorcod]; s->bit_alloc.sgain = sgaintab[s->sgaincod];
s->bit_alloc.dbknee = dbkneetab[s->dbkneecod];
s->bit_alloc.floor = floortab[s->floorcod];
/* header size */ /* header size */
frame_bits += 65; frame_bits += 65;
@ -738,16 +792,31 @@ static int compute_bit_allocation(AC3EncodeContext *s,
return 0; return 0;
} }
void ac3_common_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;
}
bndtab[50] = 0;
}
static int AC3_encode_init(AVCodecContext *avctx) static int AC3_encode_init(AVCodecContext *avctx)
{ {
int freq = avctx->sample_rate; int freq = avctx->sample_rate;
int bitrate = avctx->bit_rate; int bitrate = avctx->bit_rate;
int channels = avctx->channels; int channels = avctx->channels;
AC3EncodeContext *s = avctx->priv_data; AC3EncodeContext *s = avctx->priv_data;
int i, j, k, l, ch, v; int i, j, ch;
float alpha; float alpha;
static unsigned short freqs[3] = { 48000, 44100, 32000 }; static const UINT8 acmod_defs[6] = {
static int acmod_defs[6] = {
0x01, /* C */ 0x01, /* C */
0x02, /* L R */ 0x02, /* L R */
0x03, /* L C R */ 0x03, /* L C R */
@ -771,7 +840,7 @@ static int AC3_encode_init(AVCodecContext *avctx)
/* frequency */ /* frequency */
for(i=0;i<3;i++) { for(i=0;i<3;i++) {
for(j=0;j<3;j++) for(j=0;j<3;j++)
if ((freqs[j] >> i) == freq) if ((ac3_freqs[j] >> i) == freq)
goto found; goto found;
} }
return -1; return -1;
@ -785,7 +854,7 @@ static int AC3_encode_init(AVCodecContext *avctx)
/* bitrate & frame size */ /* bitrate & frame size */
bitrate /= 1000; bitrate /= 1000;
for(i=0;i<19;i++) { for(i=0;i<19;i++) {
if ((bitratetab[i] >> s->halfratecod) == bitrate) if ((ac3_bitratetab[i] >> s->halfratecod) == bitrate)
break; break;
} }
if (i == 19) if (i == 19)
@ -810,16 +879,7 @@ static int AC3_encode_init(AVCodecContext *avctx)
/* initial snr offset */ /* initial snr offset */
s->csnroffst = 40; s->csnroffst = 40;
/* compute bndtab and masktab from bandsz */ ac3_common_init();
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;
}
bndtab[50] = 0;
/* mdct init */ /* mdct init */
fft_init(MDCT_NBITS - 2); fft_init(MDCT_NBITS - 2);
@ -1282,7 +1342,7 @@ static int output_frame_end(AC3EncodeContext *s)
return frame_size * 2; return frame_size * 2;
} }
int AC3_encode_frame(AVCodecContext *avctx, static int AC3_encode_frame(AVCodecContext *avctx,
unsigned char *frame, int buf_size, void *data) unsigned char *frame, int buf_size, void *data)
{ {
AC3EncodeContext *s = avctx->priv_data; AC3EncodeContext *s = avctx->priv_data;

34
libavcodec/ac3enc.h
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@ -1,34 +0,0 @@
#define AC3_FRAME_SIZE (6*256)
#define AC3_MAX_CODED_FRAME_SIZE 3840 /* in bytes */
#define AC3_MAX_CHANNELS 6
typedef struct AC3EncodeContext {
PutBitContext pb;
int nb_channels;
int nb_all_channels;
int lfe_channel;
int bit_rate;
int sample_rate;
int bsid;
int frame_size_min; /* minimum frame size in case rounding is necessary */
int frame_size; /* current frame size in words */
int halfratecod;
int frmsizecod;
int fscod; /* frequency */
int acmod;
int lfe;
int bsmod;
short last_samples[AC3_MAX_CHANNELS][256];
int chbwcod[AC3_MAX_CHANNELS];
int nb_coefs[AC3_MAX_CHANNELS];
/* bitrate allocation control */
int sgaincod, sdecaycod, fdecaycod, dbkneecod, floorcod;
int sgain, sdecay, fdecay, dbknee, floor;
int csnroffst;
int fgaincod[AC3_MAX_CHANNELS];
int fsnroffst[AC3_MAX_CHANNELS];
/* mantissa encoding */
int mant1_cnt, mant2_cnt, mant4_cnt;
} AC3EncodeContext;

19
libavcodec/ac3tab.h
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@ -1,7 +1,10 @@
/* tables taken directly from AC3 spec */ /* tables taken directly from AC3 spec */
/* possible frequencies */
const UINT16 ac3_freqs[3] = { 48000, 44100, 32000 };
/* possible bitrates */ /* possible bitrates */
static const UINT16 bitratetab[19] = { const UINT16 ac3_bitratetab[19] = {
32, 40, 48, 56, 64, 80, 96, 112, 128, 32, 40, 48, 56, 64, 80, 96, 112, 128,
160, 192, 224, 256, 320, 384, 448, 512, 576, 640 160, 192, 224, 256, 320, 384, 448, 512, 576, 640
}; };
@ -9,7 +12,7 @@ static const UINT16 bitratetab[19] = {
/* AC3 MDCT window */ /* AC3 MDCT window */
/* MDCT window */ /* MDCT window */
static const INT16 ac3_window[256]= { const INT16 ac3_window[256] = {
4, 7, 12, 16, 21, 28, 34, 42, 4, 7, 12, 16, 21, 28, 34, 42,
51, 61, 72, 84, 97, 111, 127, 145, 51, 61, 72, 84, 97, 111, 127, 145,
164, 184, 207, 231, 257, 285, 315, 347, 164, 184, 207, 231, 257, 285, 315, 347,
@ -138,27 +141,27 @@ static const UINT8 baptab[64]= {
15, 15, 15, 15, 15, 15, 15, 15,
}; };
static const UINT8 sdecaytab[4]={ const UINT8 sdecaytab[4]={
0x0f, 0x11, 0x13, 0x15, 0x0f, 0x11, 0x13, 0x15,
}; };
static const UINT8 fdecaytab[4]={ const UINT8 fdecaytab[4]={
0x3f, 0x53, 0x67, 0x7b, 0x3f, 0x53, 0x67, 0x7b,
}; };
static const UINT16 sgaintab[4]= { const UINT16 sgaintab[4]= {
0x540, 0x4d8, 0x478, 0x410, 0x540, 0x4d8, 0x478, 0x410,
}; };
static const UINT16 dbkneetab[4]= { const UINT16 dbkneetab[4]= {
0x000, 0x700, 0x900, 0xb00, 0x000, 0x700, 0x900, 0xb00,
}; };
static const UINT16 floortab[8]= { const UINT16 floortab[8]= {
0x2f0, 0x2b0, 0x270, 0x230, 0x1f0, 0x170, 0x0f0, 0xf800, 0x2f0, 0x2b0, 0x270, 0x230, 0x1f0, 0x170, 0x0f0, 0xf800,
}; };
static const UINT16 fgaintab[8]= { const UINT16 fgaintab[8]= {
0x080, 0x100, 0x180, 0x200, 0x280, 0x300, 0x380, 0x400, 0x080, 0x100, 0x180, 0x200, 0x280, 0x300, 0x380, 0x400,
}; };