/*
* The simplest AC3 encoder
- * Copyright (c) 2000 Gerard Lantau.
+ * Copyright (c) 2000 Fabrice Bellard.
*
- * This program 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.
+ * 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 program is distributed in the hope that it will be useful,
+ * 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 General Public License for more details.
+ * 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 General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ * 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
*/
-#include <stdlib.h>
-#include <stdio.h>
-#include <string.h>
-#include <math.h>
+//#define DEBUG
+//#define DEBUG_BITALLOC
#include "avcodec.h"
-#include "ac3enc.h"
-#include "ac3tab.h"
+#include "ac3.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;
-//#define DEBUG
-//#define DEBUG_BITALLOC
-#define NDEBUG
-#include <assert.h>
+#include "ac3tab.h"
#define MDCT_NBITS 9
#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 */
#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 ac3_crc_init(void);
}
/* AC3 bit allocation. The algorithm is the one described in the AC3
- spec with some optimizations because of our simplified encoding
- assumptions. */
-void parametric_bit_allocation(AC3EncodeContext *s, UINT8 *bap,
- INT8 *exp, int start, int end,
- int snroffset, int fgain)
+ spec. */
+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)
{
int bin,i,j,k,end1,v,v1,bndstrt,bndend,lowcomp,begin;
int fastleak,slowleak,address,tmp;
bndstrt = masktab[start];
bndend = masktab[end-1] + 1;
- lowcomp = 0;
- lowcomp = calc_lowcomp1(lowcomp, bndpsd[0], bndpsd[1]) ;
- excite[0] = bndpsd[0] - fgain - lowcomp ;
- lowcomp = calc_lowcomp1(lowcomp, bndpsd[1], bndpsd[2]) ;
- excite[1] = bndpsd[1] - fgain - lowcomp ;
- begin = 7 ;
- for (bin = 2; bin < 7; bin++) {
- lowcomp = calc_lowcomp1(lowcomp, bndpsd[bin], bndpsd[bin+1]) ;
- fastleak = bndpsd[bin] - fgain ;
- slowleak = bndpsd[bin] - s->sgain ;
- excite[bin] = fastleak - lowcomp ;
- if (bndpsd[bin] <= bndpsd[bin+1]) {
- begin = bin + 1 ;
- break ;
+ if (bndstrt == 0) {
+ lowcomp = 0;
+ lowcomp = calc_lowcomp1(lowcomp, bndpsd[0], bndpsd[1]) ;
+ excite[0] = bndpsd[0] - fgain - lowcomp ;
+ lowcomp = calc_lowcomp1(lowcomp, bndpsd[1], bndpsd[2]) ;
+ excite[1] = bndpsd[1] - fgain - lowcomp ;
+ begin = 7 ;
+ for (bin = 2; bin < 7; bin++) {
+ if (!(is_lfe && bin == 6))
+ lowcomp = calc_lowcomp1(lowcomp, bndpsd[bin], bndpsd[bin+1]) ;
+ fastleak = bndpsd[bin] - fgain ;
+ slowleak = bndpsd[bin] - s->sgain ;
+ excite[bin] = fastleak - lowcomp ;
+ if (!(is_lfe && bin == 6)) {
+ if (bndpsd[bin] <= bndpsd[bin+1]) {
+ begin = bin + 1 ;
+ break ;
+ }
+ }
}
- }
- end1=bndend;
- if (end1 > 22) end1=22;
+ end1=bndend;
+ if (end1 > 22) end1=22;
- for (bin = begin; bin < end1; bin++) {
- lowcomp = calc_lowcomp(lowcomp, bndpsd[bin], bndpsd[bin+1], bin) ;
+ for (bin = begin; bin < end1; bin++) {
+ if (!(is_lfe && bin == 6))
+ lowcomp = calc_lowcomp(lowcomp, bndpsd[bin], bndpsd[bin+1], bin) ;
- fastleak -= s->fdecay ;
- v = bndpsd[bin] - fgain;
- if (fastleak < v) fastleak = v;
+ fastleak -= s->fdecay ;
+ v = bndpsd[bin] - fgain;
+ if (fastleak < v) fastleak = v;
- slowleak -= s->sdecay ;
- v = bndpsd[bin] - s->sgain;
- if (slowleak < v) slowleak = v;
+ slowleak -= s->sdecay ;
+ v = bndpsd[bin] - s->sgain;
+ if (slowleak < v) slowleak = v;
- v=fastleak - lowcomp;
- if (slowleak > v) v=slowleak;
+ v=fastleak - lowcomp;
+ if (slowleak > v) v=slowleak;
- excite[bin] = v;
+ excite[bin] = v;
+ }
+ begin = 22;
+ } else {
+ /* coupling channel */
+ begin = bndstrt;
+
+ fastleak = (s->cplfleak << 8) + 768;
+ slowleak = (s->cplsleak << 8) + 768;
}
- for (bin = 22; bin < bndend; bin++) {
+ for (bin = begin; bin < bndend; bin++) {
fastleak -= s->fdecay ;
v = bndpsd[bin] - fgain;
if (fastleak < v) fastleak = 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 */
i = start ;
static void compute_exp_strategy(UINT8 exp_strategy[NB_BLOCKS][AC3_MAX_CHANNELS],
UINT8 exp[NB_BLOCKS][AC3_MAX_CHANNELS][N/2],
- int ch)
+ int ch, int is_lfe)
{
int i, j;
int exp_diff;
else
exp_strategy[i][ch] = EXP_REUSE;
}
+ if (is_lfe)
+ return;
+
/* now select the encoding strategy type : if exponents are often
recoded, we use a coarse encoding */
i = 0;
exp_strategy[i][ch] = EXP_D15;
break;
}
- i = j;
+ i = j;
}
}
s->mant1_cnt = 0;
s->mant2_cnt = 0;
s->mant4_cnt = 0;
- for(ch=0;ch<s->nb_channels;ch++) {
- parametric_bit_allocation(s, bap[i][ch], (INT8 *)encoded_exp[i][ch],
- 0, s->nb_coefs[ch],
- (((csnroffst-15) << 4) +
- fsnroffst) << 2,
- fgaintab[s->fgaincod[ch]]);
+ for(ch=0;ch<s->nb_all_channels;ch++) {
+ ac3_parametric_bit_allocation(&s->bit_alloc,
+ bap[i][ch], (INT8 *)encoded_exp[i][ch],
+ 0, s->nb_coefs[ch],
+ (((csnroffst-15) << 4) +
+ fsnroffst) << 2,
+ fgaintab[s->fgaincod[ch]],
+ ch == s->lfe_channel,
+ 2, 0, NULL, NULL, NULL);
frame_bits += compute_mantissa_size(s, bap[i][ch],
s->nb_coefs[ch]);
}
int i, ch;
int csnroffst, fsnroffst;
UINT8 bap1[NB_BLOCKS][AC3_MAX_CHANNELS][N/2];
+ static int frame_bits_inc[8] = { 0, 0, 2, 2, 2, 4, 2, 4 };
/* init default parameters */
s->sdecaycod = 2;
s->sgaincod = 1;
s->dbkneecod = 2;
s->floorcod = 4;
- for(ch=0;ch<s->nb_channels;ch++)
+ for(ch=0;ch<s->nb_all_channels;ch++)
s->fgaincod[ch] = 4;
/* compute real values */
- s->sdecay = sdecaytab[s->sdecaycod] >> s->halfratecod;
- s->fdecay = fdecaytab[s->fdecaycod] >> s->halfratecod;
- s->sgain = sgaintab[s->sgaincod];
- s->dbknee = dbkneetab[s->dbkneecod];
- s->floor = floortab[s->floorcod];
-
+ s->bit_alloc.fscod = s->fscod;
+ s->bit_alloc.halfratecod = s->halfratecod;
+ s->bit_alloc.sdecay = sdecaytab[s->sdecaycod] >> s->halfratecod;
+ s->bit_alloc.fdecay = fdecaytab[s->fdecaycod] >> s->halfratecod;
+ s->bit_alloc.sgain = sgaintab[s->sgaincod];
+ s->bit_alloc.dbknee = dbkneetab[s->dbkneecod];
+ s->bit_alloc.floor = floortab[s->floorcod];
+
/* header size */
frame_bits += 65;
- if (s->acmod == 2)
- frame_bits += 2;
+ // if (s->acmod == 2)
+ // frame_bits += 2;
+ frame_bits += frame_bits_inc[s->acmod];
/* audio blocks */
for(i=0;i<NB_BLOCKS;i++) {
- frame_bits += s->nb_channels * 2 + 2;
+ frame_bits += s->nb_channels * 2 + 2; /* blksw * c, dithflag * c, dynrnge, cplstre */
if (s->acmod == 2)
- frame_bits++;
- frame_bits += 2 * s->nb_channels;
+ frame_bits++; /* rematstr */
+ frame_bits += 2 * s->nb_channels; /* chexpstr[2] * c */
+ if (s->lfe)
+ frame_bits++; /* lfeexpstr */
for(ch=0;ch<s->nb_channels;ch++) {
if (exp_strategy[i][ch] != EXP_REUSE)
- frame_bits += 6 + 2;
+ frame_bits += 6 + 2; /* chbwcod[6], gainrng[2] */
}
frame_bits++; /* baie */
frame_bits++; /* snr */
}
frame_bits++; /* cplinu for block 0 */
/* bit alloc info */
- frame_bits += 2*4 + 3 + 6 + s->nb_channels * (4 + 3);
+ /* sdcycod[2], fdcycod[2], sgaincod[2], dbpbcod[2], floorcod[3] */
+ /* csnroffset[6] */
+ /* (fsnoffset[4] + fgaincod[4]) * c */
+ frame_bits += 2*4 + 3 + 6 + s->nb_all_channels * (4 + 3);
/* CRC */
frame_bits += 16;
csnroffst = s->csnroffst;
while (csnroffst >= 0 &&
- bit_alloc(s, bap, encoded_exp, exp_strategy, frame_bits, csnroffst, 0) < 0)
- csnroffst -= SNR_INC1;
+ bit_alloc(s, bap, encoded_exp, exp_strategy, frame_bits, csnroffst, 0) < 0)
+ csnroffst -= SNR_INC1;
if (csnroffst < 0) {
- fprintf(stderr, "Error !!!\n");
- return -1;
+ fprintf(stderr, "Yack, Error !!!\n");
+ return -1;
}
while ((csnroffst + SNR_INC1) <= 63 &&
bit_alloc(s, bap1, encoded_exp, exp_strategy, frame_bits,
}
s->csnroffst = csnroffst;
- for(ch=0;ch<s->nb_channels;ch++)
+ for(ch=0;ch<s->nb_all_channels;ch++)
s->fsnroffst[ch] = fsnroffst;
#if defined(DEBUG_BITALLOC)
{
int j;
for(i=0;i<6;i++) {
- for(ch=0;ch<s->nb_channels;ch++) {
+ for(ch=0;ch<s->nb_all_channels;ch++) {
printf("Block #%d Ch%d:\n", i, ch);
printf("bap=");
for(j=0;j<s->nb_coefs[ch];j++) {
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)
{
int freq = avctx->sample_rate;
int bitrate = avctx->bit_rate;
int channels = avctx->channels;
AC3EncodeContext *s = avctx->priv_data;
- int i, j, k, l, ch, v;
+ int i, j, ch;
float alpha;
- static unsigned short freqs[3] = { 48000, 44100, 32000 };
+ static const UINT8 acmod_defs[6] = {
+ 0x01, /* C */
+ 0x02, /* L R */
+ 0x03, /* L C R */
+ 0x06, /* L R SL SR */
+ 0x07, /* L C R SL SR */
+ 0x07, /* L C R SL SR (+LFE) */
+ };
avctx->frame_size = AC3_FRAME_SIZE;
- avctx->key_frame = 1; /* always key frame */
/* number of channels */
- if (channels == 1)
- s->acmod = 1;
- else if (channels == 2)
- s->acmod = 2;
- else
- return -1;
- s->nb_channels = channels;
+ if (channels < 1 || channels > 6)
+ return -1;
+ s->acmod = acmod_defs[channels - 1];
+ s->lfe = (channels == 6) ? 1 : 0;
+ s->nb_all_channels = channels;
+ s->nb_channels = channels > 5 ? 5 : channels;
+ s->lfe_channel = s->lfe ? 5 : -1;
/* frequency */
for(i=0;i<3;i++) {
for(j=0;j<3;j++)
- if ((freqs[j] >> i) == freq)
+ if ((ac3_freqs[j] >> i) == freq)
goto found;
}
return -1;
/* bitrate & frame size */
bitrate /= 1000;
for(i=0;i<19;i++) {
- if ((bitratetab[i] >> s->halfratecod) == bitrate)
+ if ((ac3_bitratetab[i] >> s->halfratecod) == bitrate)
break;
}
if (i == 19)
s->chbwcod[ch] = 50; /* sample bandwidth as mpeg audio layer 2 table 0 */
s->nb_coefs[ch] = ((s->chbwcod[ch] + 12) * 3) + 37;
}
+ if (s->lfe) {
+ s->nb_coefs[s->lfe_channel] = 7; /* fixed */
+ }
/* initial snr offset */
s->csnroffst = 40;
- /* 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;
+ ac3_common_init();
/* mdct init */
fft_init(MDCT_NBITS - 2);
}
ac3_crc_init();
+
+ avctx->coded_frame= avcodec_alloc_frame();
+ avctx->coded_frame->key_frame= 1;
return 0;
}
put_bits(&s->pb, 5, s->bsid);
put_bits(&s->pb, 3, s->bsmod);
put_bits(&s->pb, 3, s->acmod);
- if (s->acmod == 2) {
+ if ((s->acmod & 0x01) && s->acmod != 0x01)
+ put_bits(&s->pb, 2, 1); /* XXX -4.5 dB */
+ if (s->acmod & 0x04)
+ put_bits(&s->pb, 2, 1); /* XXX -6 dB */
+ if (s->acmod == 0x02)
put_bits(&s->pb, 2, 0); /* surround not indicated */
- }
- put_bits(&s->pb, 1, 0); /* no LFE */
+ put_bits(&s->pb, 1, s->lfe); /* LFE */
put_bits(&s->pb, 5, 31); /* dialog norm: -31 db */
put_bits(&s->pb, 1, 0); /* no compression control word */
put_bits(&s->pb, 1, 0); /* no lang code */
int v;
if (c >= 0) {
- v = (levels * (c << e)) >> 25;
+ v = (levels * (c << e)) >> 24;
+ v = (v + 1) >> 1;
v = (levels >> 1) + v;
} else {
- v = (levels * ((-c) << e)) >> 25;
+ v = (levels * ((-c) << e)) >> 24;
+ v = (v + 1) >> 1;
v = (levels >> 1) - v;
}
assert (v >= 0 && v < levels);
put_bits(&s->pb, 2, exp_strategy[ch]);
}
+ if (s->lfe) {
+ put_bits(&s->pb, 1, exp_strategy[s->lfe_channel]);
+ }
+
for(ch=0;ch<s->nb_channels;ch++) {
if (exp_strategy[ch] != EXP_REUSE)
put_bits(&s->pb, 6, s->chbwcod[ch]);
}
/* exponents */
- for (ch = 0; ch < s->nb_channels; ch++) {
+ for (ch = 0; ch < s->nb_all_channels; ch++) {
switch(exp_strategy[ch]) {
case EXP_REUSE:
continue;
group_size = 4;
break;
}
- nb_groups = (s->nb_coefs[ch] + (group_size * 3) - 4) / (3 * group_size);
+ nb_groups = (s->nb_coefs[ch] + (group_size * 3) - 4) / (3 * group_size);
p = encoded_exp[ch];
/* first exponent */
put_bits(&s->pb, 7, ((delta0 * 5 + delta1) * 5) + delta2);
}
- put_bits(&s->pb, 2, 0); /* no gain range info */
+ if (ch != s->lfe_channel)
+ put_bits(&s->pb, 2, 0); /* no gain range info */
}
/* bit allocation info */
put_bits(&s->pb, 1, baie); /* always present with bai */
if (baie) {
put_bits(&s->pb, 6, s->csnroffst);
- for(ch=0;ch<s->nb_channels;ch++) {
+ for(ch=0;ch<s->nb_all_channels;ch++) {
put_bits(&s->pb, 4, s->fsnroffst[ch]);
put_bits(&s->pb, 3, s->fgaincod[ch]);
}
mant1_cnt = mant2_cnt = mant4_cnt = 0;
qmant1_ptr = qmant2_ptr = qmant4_ptr = NULL;
- for (ch = 0; ch < s->nb_channels; ch++) {
+ for (ch = 0; ch < s->nb_all_channels; ch++) {
int b, c, e, v;
for(i=0;i<s->nb_coefs[ch];i++) {
}
/* second pass : output the values */
- for (ch = 0; ch < s->nb_channels; ch++) {
+ for (ch = 0; ch < s->nb_all_channels; ch++) {
int b, q;
for(i=0;i<s->nb_coefs[ch];i++) {
for(i=0;i<n;i++) {
v |= abs(tab[i]);
}
- return log2(v);
+ return av_log2(v);
}
static void lshift_tab(INT16 *tab, int n, int lshift)
flush_put_bits(&s->pb);
/* add zero bytes to reach the frame size */
frame = s->pb.buf;
- n = 2 * s->frame_size - (s->pb.buf_ptr - frame) - 2;
+ n = 2 * s->frame_size - (pbBufPtr(&s->pb) - frame) - 2;
assert(n >= 0);
- memset(s->pb.buf_ptr, 0, n);
+ memset(pbBufPtr(&s->pb), 0, n);
/* Now we must compute both crcs : this is not so easy for crc1
because it is at the beginning of the data... */
return frame_size * 2;
}
-int AC3_encode_frame(AVCodecContext *avctx,
- unsigned char *frame, int buf_size, void *data)
+static int AC3_encode_frame(AVCodecContext *avctx,
+ unsigned char *frame, int buf_size, void *data)
{
AC3EncodeContext *s = avctx->priv_data;
short *samples = data;
int frame_bits;
frame_bits = 0;
- for(ch=0;ch<s->nb_channels;ch++) {
+ for(ch=0;ch<s->nb_all_channels;ch++) {
/* fixed mdct to the six sub blocks & exponent computation */
for(i=0;i<NB_BLOCKS;i++) {
INT16 *sptr;
/* compute input samples */
memcpy(input_samples, s->last_samples[ch], N/2 * sizeof(INT16));
- sinc = s->nb_channels;
+ sinc = s->nb_all_channels;
sptr = samples + (sinc * (N/2) * i) + ch;
for(j=0;j<N/2;j++) {
v = *sptr;
if (v == 0)
e = 24;
else {
- e = 23 - log2(v) + exp_samples[i][ch];
+ e = 23 - av_log2(v) + exp_samples[i][ch];
if (e >= 24) {
e = 24;
mdct_coef[i][ch][j] = 0;
}
}
- compute_exp_strategy(exp_strategy, exp, ch);
+ compute_exp_strategy(exp_strategy, exp, ch, ch == s->lfe_channel);
/* compute the exponents as the decoder will see them. The
EXP_REUSE case must be handled carefully : we select the
return output_frame_end(s);
}
+static int AC3_encode_close(AVCodecContext *avctx)
+{
+ av_freep(&avctx->coded_frame);
+}
+
#if 0
/*************************************************************************/
/* TEST */
sizeof(AC3EncodeContext),
AC3_encode_init,
AC3_encode_frame,
+ AC3_encode_close,
NULL,
};
projects / ffmpeg / blobdiff