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LGPL version of ac3_decode_transform_coeffs_ch, ~12.4% faster. 

Originally committed as revision 18875 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Jason Garrett-Glaser 2009-05-19 21:29:21 +00:00
parent bae3abb02c
commit d869a460db
1 changed files with 54 additions and 55 deletions
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109
libavcodec/ac3dec.c
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@ -439,12 +439,12 @@ static void calc_transform_coeffs_cpl(AC3DecodeContext *s)
* Grouped mantissas for 3-level 5-level and 11-level quantization
*/
typedef struct {
int b1_mant[3];
int b2_mant[3];
int b4_mant[2];
int b1ptr;
int b2ptr;
int b4ptr;
int b1_mant[2];
int b2_mant[2];
int b4_mant;
int b1;
int b2;
int b4;
} mant_groups;
/**
@ -453,73 +453,72 @@ typedef struct {
*/
static void ac3_decode_transform_coeffs_ch(AC3DecodeContext *s, int ch_index, mant_groups *m)
{
int start_freq = s->start_freq[ch_index];
int end_freq = s->end_freq[ch_index];
uint8_t *baps = s->bap[ch_index];
int8_t *exps = s->dexps[ch_index];
int *coeffs = s->fixed_coeffs[ch_index];
GetBitContext *gbc = &s->gbc;
int i, gcode, tbap, start, end;
uint8_t *exps;
uint8_t *bap;
int *coeffs;
int freq;
exps = s->dexps[ch_index];
bap = s->bap[ch_index];
coeffs = s->fixed_coeffs[ch_index];
start = s->start_freq[ch_index];
end = s->end_freq[ch_index];
for (i = start; i < end; i++) {
tbap = bap[i];
switch (tbap) {
for(freq = start_freq; freq < end_freq; freq++){
int bap = baps[freq];
int mantissa;
switch(bap){
case 0:
coeffs[i] = (av_lfg_get(&s->dith_state) & 0x7FFFFF) - 0x400000;
mantissa = (av_lfg_get(&s->dith_state) & 0x7FFFFF) - 0x400000;
break;
case 1:
if(m->b1ptr > 2) {
gcode = get_bits(gbc, 5);
m->b1_mant[0] = b1_mantissas[gcode][0];
m->b1_mant[1] = b1_mantissas[gcode][1];
m->b1_mant[2] = b1_mantissas[gcode][2];
m->b1ptr = 0;
if(m->b1){
m->b1--;
mantissa = m->b1_mant[m->b1];
}
else{
int bits = get_bits(gbc, 5);
mantissa = b1_mantissas[bits][0];
m->b1_mant[1] = b1_mantissas[bits][1];
m->b1_mant[0] = b1_mantissas[bits][2];
m->b1 = 2;
}
coeffs[i] = m->b1_mant[m->b1ptr++];
break;
case 2:
if(m->b2ptr > 2) {
gcode = get_bits(gbc, 7);
m->b2_mant[0] = b2_mantissas[gcode][0];
m->b2_mant[1] = b2_mantissas[gcode][1];
m->b2_mant[2] = b2_mantissas[gcode][2];
m->b2ptr = 0;
if(m->b2){
m->b2--;
mantissa = m->b2_mant[m->b2];
}
else{
int bits = get_bits(gbc, 7);
mantissa = b2_mantissas[bits][0];
m->b2_mant[1] = b2_mantissas[bits][1];
m->b2_mant[0] = b2_mantissas[bits][2];
m->b2 = 2;
}
coeffs[i] = m->b2_mant[m->b2ptr++];
break;
case 3:
coeffs[i] = b3_mantissas[get_bits(gbc, 3)];
mantissa = b3_mantissas[get_bits(gbc, 3)];
break;
case 4:
if(m->b4ptr > 1) {
gcode = get_bits(gbc, 7);
m->b4_mant[0] = b4_mantissas[gcode][0];
m->b4_mant[1] = b4_mantissas[gcode][1];
m->b4ptr = 0;
if(m->b4){
m->b4 = 0;
mantissa = m->b4_mant;
}
else{
int bits = get_bits(gbc, 7);
mantissa = b4_mantissas[bits][0];
m->b4_mant = b4_mantissas[bits][1];
m->b4 = 1;
}
coeffs[i] = m->b4_mant[m->b4ptr++];
break;
case 5:
coeffs[i] = b5_mantissas[get_bits(gbc, 4)];
mantissa = b5_mantissas[get_bits(gbc, 4)];
break;
default: {
/* asymmetric dequantization */
int qlevel = quantization_tab[tbap];
coeffs[i] = get_sbits(gbc, qlevel) << (24 - qlevel);
default: /* 6 to 15 */
mantissa = get_bits(gbc, quantization_tab[bap]);
/* Shift mantissa and sign-extend it. */
mantissa = (mantissa << (32-quantization_tab[bap]))>>8;
break;
}
}
coeffs[i] >>= exps[i];
coeffs[freq] = mantissa >> exps[freq];
}
}
@ -582,7 +581,7 @@ static void decode_transform_coeffs(AC3DecodeContext *s, int blk)
int got_cplchan = 0;
mant_groups m;
m.b1ptr = m.b2ptr = m.b4ptr = 3;
m.b1 = m.b2 = m.b4 = 0;
for (ch = 1; ch <= s->channels; ch++) {
/* transform coefficients for full-bandwidth channel */