RepoMirrors
/
ffmpeg
mirror of https://git.ffmpeg.org/ffmpeg.git
1
0
Fork 0
Code Issues Projects Releases Wiki Activity

merge decoding of coupling channel coefficients and regular channel coefficients 

Originally committed as revision 9883 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Justin Ruggles 2007-08-04 00:04:17 +00:00
parent d7dc7ad05c
commit 285bf28c67
1 changed files with 13 additions and 74 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

87
libavcodec/ac3dec.c
View File

@ -456,101 +456,40 @@ typedef struct { /* grouped mantissas for 3-level 5-leve and 11-level quantizati
int l11ptr;
} mant_groups;
/* 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 start, gcode, tbap;
float cplcoeff;
uint8_t *exps = ctx->dcplexps;
uint8_t *bap = ctx->cplbap;
start = ctx->cplstrtmant;
while (start < ctx->cplendmant) {
tbap = bap[start];
switch(tbap) {
case 0:
cplcoeff = (av_random(&ctx->dith_state) & 0xFFFF);
break;
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;
}
cplcoeff = m->l3_quantizers[m->l3ptr++];
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;
}
cplcoeff = m->l5_quantizers[m->l5ptr++];
break;
case 3:
cplcoeff = l7_quantizers[get_bits(gb, 3)];
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;
}
cplcoeff = m->l11_quantizers[m->l11ptr++];
break;
case 5:
cplcoeff = l15_quantizers[get_bits(gb, 4)];
break;
default:
cplcoeff = get_sbits(gb, qntztab[tbap]) << (16 - qntztab[tbap]);
}
ctx->transform_coeffs_cpl[start] = cplcoeff * scale_factors[exps[start]];
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;
int i, gcode, tbap, dithflag, start, end;
uint8_t *exps;
uint8_t *bap;
float *coeffs;
if (ch_index != -1) { /* fbw channels */
if (ch_index >= 0) { /* fbw channels */
dithflag = ctx->dithflag[ch_index];
exps = ctx->dexps[ch_index];
bap = ctx->bap[ch_index];
coeffs = ctx->transform_coeffs[ch_index + 1];
start = 0;
end = ctx->endmant[ch_index];
} else if (ch_index == -1) {
dithflag = 0;
exps = ctx->dlfeexps;
bap = ctx->lfebap;
coeffs = ctx->transform_coeffs[0];
start = 0;
end = 7;
} else {
dithflag = 0;
exps = ctx->dcplexps;
bap = ctx->cplbap;
coeffs = ctx->transform_coeffs_cpl;
start = ctx->cplstrtmant;
end = ctx->cplendmant;
}
for (i = 0; i < end; i++) {
for (i = start; i < end; i++) {
tbap = bap[i];
switch (tbap) {
case 0:
@ -632,7 +571,7 @@ static int get_transform_coeffs(AC3DecodeContext * ctx)
/* tranform coefficients for coupling channels */
if (ctx->chincpl[i]) {
if (!got_cplchan) {
if (get_transform_coeffs_cpling(ctx, &m)) {
if (get_transform_coeffs_ch(ctx, -2, &m)) {
av_log(NULL, AV_LOG_ERROR, "error in decoupling channels\n");
return -1;
}