MrBesen/ffmpeg
1
0
Fork 0
Code Issues Pull Requests Releases Wiki Activity

utilize multi-stage AC-3 bit allocation. speeds up encoding by 25-30%

Browse Source 
Originally committed as revision 8477 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Justin Ruggles 2007-03-22 05:34:26 +00:00
parent 447caf7941
commit bbd16dea67
1 changed files with 43 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

55
libavcodec/ac3enc.c
View File

@ -431,10 +431,39 @@ static int compute_mantissa_size(AC3EncodeContext *s, uint8_t *m, int nb_coefs)
}
static void bit_alloc_masking(AC3EncodeContext *s,
uint8_t encoded_exp[NB_BLOCKS][AC3_MAX_CHANNELS][N/2],
uint8_t exp_strategy[NB_BLOCKS][AC3_MAX_CHANNELS],
int16_t psd[NB_BLOCKS][AC3_MAX_CHANNELS][N/2],
int16_t mask[NB_BLOCKS][AC3_MAX_CHANNELS][50])
{
int blk, ch;
int16_t bndpsd[NB_BLOCKS][AC3_MAX_CHANNELS][50];
for(blk=0; blk<NB_BLOCKS; blk++) {
for(ch=0;ch<s->nb_all_channels;ch++) {
if(exp_strategy[blk][ch] == EXP_REUSE) {
memcpy(psd[blk][ch], psd[blk-1][ch], (N/2)*sizeof(int16_t));
memcpy(mask[blk][ch], mask[blk-1][ch], 50*sizeof(int16_t));
} else {
ff_ac3_bit_alloc_calc_psd(encoded_exp[blk][ch], 0,
s->nb_coefs[ch],
psd[blk][ch], bndpsd[blk][ch]);
ff_ac3_bit_alloc_calc_mask(&s->bit_alloc, bndpsd[blk][ch],
0, s->nb_coefs[ch],
ff_fgaintab[s->fgaincod[ch]],
ch == s->lfe_channel,
2, 0, NULL, NULL, NULL,
mask[blk][ch]);
}
}
}
}
static int bit_alloc(AC3EncodeContext *s,
int16_t mask[NB_BLOCKS][AC3_MAX_CHANNELS][50],
int16_t psd[NB_BLOCKS][AC3_MAX_CHANNELS][N/2],
uint8_t bap[NB_BLOCKS][AC3_MAX_CHANNELS][N/2],
uint8_t encoded_exp[NB_BLOCKS][AC3_MAX_CHANNELS][N/2],
uint8_t exp_strategy[NB_BLOCKS][AC3_MAX_CHANNELS],
int frame_bits, int csnroffst, int fsnroffst)
{
int i, ch;
@ -445,14 +474,11 @@ static int bit_alloc(AC3EncodeContext *s,
s->mant2_cnt = 0;
s->mant4_cnt = 0;
for(ch=0;ch<s->nb_all_channels;ch++) {
ac3_parametric_bit_allocation(&s->bit_alloc,
bap[i][ch], (int8_t *)encoded_exp[i][ch],
ff_ac3_bit_alloc_calc_bap(mask[i][ch], psd[i][ch],
0, s->nb_coefs[ch],
(((csnroffst-15) << 4) +
fsnroffst) << 2,
ff_fgaintab[s->fgaincod[ch]],
ch == s->lfe_channel,
2, 0, NULL, NULL, NULL);
s->bit_alloc.floor, bap[i][ch]);
frame_bits += compute_mantissa_size(s, bap[i][ch],
s->nb_coefs[ch]);
}
@ -476,6 +502,8 @@ static int compute_bit_allocation(AC3EncodeContext *s,
int i, ch;
int csnroffst, fsnroffst;
uint8_t bap1[NB_BLOCKS][AC3_MAX_CHANNELS][N/2];
int16_t psd[NB_BLOCKS][AC3_MAX_CHANNELS][N/2];
int16_t mask[NB_BLOCKS][AC3_MAX_CHANNELS][50];
static int frame_bits_inc[8] = { 0, 0, 2, 2, 2, 4, 2, 4 };
/* init default parameters */
@ -533,38 +561,41 @@ static int compute_bit_allocation(AC3EncodeContext *s,
/* CRC */
frame_bits += 16;
/* calculate psd and masking curve before doing bit allocation */
bit_alloc_masking(s, encoded_exp, exp_strategy, psd, mask);
/* now the big work begins : do the bit allocation. Modify the snr
offset until we can pack everything in the requested frame size */
csnroffst = s->csnroffst;
while (csnroffst >= 0 &&
bit_alloc(s, bap, encoded_exp, exp_strategy, frame_bits, csnroffst, 0) < 0)
bit_alloc(s, mask, psd, bap, frame_bits, csnroffst, 0) < 0)
csnroffst -= SNR_INC1;
if (csnroffst < 0) {
av_log(NULL, AV_LOG_ERROR, "Bit allocation failed, try increasing the bitrate, -ab 384 for example!\n");
return -1;
}
while ((csnroffst + SNR_INC1) <= 63 &&
bit_alloc(s, bap1, encoded_exp, exp_strategy, frame_bits,
bit_alloc(s, mask, psd, bap1, frame_bits,
csnroffst + SNR_INC1, 0) >= 0) {
csnroffst += SNR_INC1;
memcpy(bap, bap1, sizeof(bap1));
}
while ((csnroffst + 1) <= 63 &&
bit_alloc(s, bap1, encoded_exp, exp_strategy, frame_bits, csnroffst + 1, 0) >= 0) {
bit_alloc(s, mask, psd, bap1, frame_bits, csnroffst + 1, 0) >= 0) {
csnroffst++;
memcpy(bap, bap1, sizeof(bap1));
}
fsnroffst = 0;
while ((fsnroffst + SNR_INC1) <= 15 &&
bit_alloc(s, bap1, encoded_exp, exp_strategy, frame_bits,
bit_alloc(s, mask, psd, bap1, frame_bits,
csnroffst, fsnroffst + SNR_INC1) >= 0) {
fsnroffst += SNR_INC1;
memcpy(bap, bap1, sizeof(bap1));
}
while ((fsnroffst + 1) <= 15 &&
bit_alloc(s, bap1, encoded_exp, exp_strategy, frame_bits,
bit_alloc(s, mask, psd, bap1, frame_bits,
csnroffst, fsnroffst + 1) >= 0) {
fsnroffst++;
memcpy(bap, bap1, sizeof(bap1));