?? decode.c
字號:
/***********************************************
copyright by Haia Tech
www.haia2004.com
************************************************/
#include <math.h>
//#include <stdlib.h>
#include "common.h"
#include "decode.h"
extern struct Granule grle[2][2];
extern Bit_stream_struc bs;
extern frame_params fr_ps;
struct BandIndex sfBandIndex[3]=
{
{{0,4,8,12,16,20,24,30,36,44,52,62,74,90,110,134,162,196,238,288,342,418,576},
{0,4,8,12,16,22,30,40,52,66,84,106,136,192}},
{{0,4,8,12,16,20,24,30,36,42,50,60,72,88,106,128,156,190,230,276,330,384,576},
{0,4,8,12,16,22,28,38,50,64,80,100,126,192}},
{{0,4,8,12,16,20,24,30,36,44,54,66,82,102,126,156,194,240,296,364,448,550,576},
{0,4,8,12,16,22,30,42,58,78,104,138,180,192}}
};
void decode_info()
{
layer *hdr = fr_ps.header;
int x;
hdr->version = getbit(1);
hdr->lay = 4-getbit(2);
hdr->error_protection = !getbit(1); /* error protect. TRUE/FALSE */
hdr->bitrate_index = getbit(4);
hdr->sampling_frequency = getbit(2);
hdr->padding = getbit(1);
hdr->extension = getbit(1);
hdr->mode = getbit(2);
hdr->mode_ext = getbit(2);
hdr->copyright = getbit(1);
hdr->original = getbit(1);
hdr->emphasis = getbit(2);
}
void III_get_side_info(III_side_info_t *si)
{
int ch, gr, i;
int stereo = fr_ps.stereo;
si->main_data_begin = getbit(9); //SI 邊信息結構
if (stereo == 1)
si->private_bits = getbit(5);
else
si->private_bits = getbit(3);
for (ch=0; ch<stereo; ch++) //第二顆粒是否傳送信息
for (i=0; i<4; i++)
si->scfsi[ch][i] = getbit(1);
for (gr=0; gr<2; gr++) {
for (ch=0; ch<stereo; ch++) {
grle[ch][gr].part2_3_length = getbit(12);
grle[ch][gr].big_values = getbit(9);
grle[ch][gr].global_gain = getbit(8);
grle[ch][gr].scalefac_compress = getbit(4);
grle[ch][gr].window_switching_flag = getbit(1);
if (grle[ch][gr].window_switching_flag) { //窗開關為1
grle[ch][gr].block_type = getbit(2);
grle[ch][gr].mixed_block_flag = getbit(1);
for (i=0; i<2; i++)
grle[ch][gr].table_select[i] = getbit(5);
for (i=0; i<3; i++)
grle[ch][gr].subblock_gain[i] = getbit(3);
/* Set region_count parameters since they are implicit in this case. */
if (grle[ch][gr].block_type == 0) {
// printf("Side info bad: block_type == 0 in split block.\n");
// exit(0);
}
else if (grle[ch][gr].block_type == 2
&& grle[ch][gr].mixed_block_flag == 0)
grle[ch][gr].region0_count = 8; /* MI 9; */ //region0和1的缺省配置
else grle[ch][gr].region0_count = 7; /* MI 8; */
grle[ch][gr].region1_count = 20 - grle[ch][gr].region0_count;
}
else { //窗開關為0
for (i=0; i<3; i++)
grle[ch][gr].table_select[i] = getbit(5);
grle[ch][gr].region0_count = getbit(4);
grle[ch][gr].region1_count = getbit(3);
grle[ch][gr].block_type = 0;
}
grle[ch][gr].preflag = getbit(1);
grle[ch][gr].scalefac_scale = getbit(1);
grle[ch][gr].count1table_select = getbit(1);
}
}
}
struct {
int l[5];
int s[3];
} sfbtable = {
{0, 6, 11, 16, 21},
{0, 6, 12}
};
int slen[2][16]={
{0, 0, 0, 0, 3, 1, 1, 1, 2, 2, 2, 3, 3, 3, 4, 4},
{0, 1, 2, 3, 0, 1, 2, 3, 1, 2, 3, 1, 2, 3, 2, 3}
};
void III_get_scale_factors(III_scalefac_t *scalefac, III_side_info_t *si, int gr, int ch)
{
int sfb, i, window;
struct Granule *gr_info = &(grle[ch][gr]);
if (gr_info->window_switching_flag && (gr_info->block_type == 2)) {
if (gr_info->mixed_block_flag) { /* MIXED */ /* NEW - ag 11/25 */
for (sfb = 0; sfb < 8; sfb++)
(*scalefac)[ch].l[sfb] = hgetbits(
slen[0][gr_info->scalefac_compress]); //用 slen[0]
for (sfb = 3; sfb < 6; sfb++)
for (window=0; window<3; window++)
(*scalefac)[ch].s[window][sfb] = hgetbits(
slen[0][gr_info->scalefac_compress]); //用 slen[0]
for (sfb = 6; sfb < 12; sfb++)
for (window=0; window<3; window++)
(*scalefac)[ch].s[window][sfb] = hgetbits(
slen[1][gr_info->scalefac_compress]); //6-11用 slen[1]
for (sfb=12,window=0; window<3; window++)
(*scalefac)[ch].s[window][sfb] = 0;
}
else { /* SHORT*/
for (i=0; i<2; i++)
for (sfb = sfbtable.s[i]; sfb < sfbtable.s[i+1]; sfb++)
for (window=0; window<3; window++)
(*scalefac)[ch].s[window][sfb] = hgetbits(
slen[i][gr_info->scalefac_compress]);
for (sfb=12,window=0; window<3; window++)
(*scalefac)[ch].s[window][sfb] = 0;
}
}
else { /* LONG types 0,1,3 */
for (i=0; i<4; i++) {
if ((si->scfsi[ch][i] == 0) || (gr == 0))
for (sfb = sfbtable.l[i]; sfb < sfbtable.l[i+1]; sfb++)
(*scalefac)[ch].l[sfb] = hgetbits(
slen[(i<2)?0:1][gr_info->scalefac_compress]);
}
(*scalefac)[ch].l[22] = 0;
}
}
int pretab[22] = {0,0,0,0,0,0,0,0,0,0,0,1,1,1,1,2,2,3,3,3,2,0};
void III_dequantize_sample(int is[SBLIMIT][SSLIMIT], double xr[SBLIMIT][SSLIMIT], III_scalefac_t *scalefac, struct Granule *gr_info, int ch)
{
int ss,sb,cb=0,sfreq=fr_ps.header->sampling_frequency;
int next_cb_boundary, cb_begin, cb_width, sign;
double is43_table[1024],temp;
static int init=1;
if(init)
{
for(init=0;init<1024;init++)
is43_table[init]=1.33333333333*log(init);
init=0;
}
/* choose correct scalefactor band per block type, initalize boundary */
if (gr_info->window_switching_flag && (gr_info->block_type == 2) )
if (gr_info->mixed_block_flag)
next_cb_boundary=sfBandIndex[sfreq].l[1]; /* LONG blocks: 0,1,3 */
else
{
next_cb_boundary=sfBandIndex[sfreq].s[1]*3; /* pure SHORT block */
cb_width = sfBandIndex[sfreq].s[1];
cb_begin = 0;
}
else
next_cb_boundary=sfBandIndex[sfreq].l[1]; /* LONG blocks: 0,1,3 */
/* apply formula per block type */
for (sb=0 ; sb < SBLIMIT ; sb++) { //0-31
for (ss=0 ; ss < SSLIMIT ; ss++) { //0-17
/********* 由sb和ss計算cb(比例因子帶)和cb_width(比例因子帶寬) **************/
if ( (sb*18)+ss == next_cb_boundary)
{ /* Adjust critical band boundary */
if (gr_info->window_switching_flag && (gr_info->block_type == 2))
{
if (gr_info->mixed_block_flag)
{
if (((sb*18)+ss) == sfBandIndex[sfreq].l[8])
{
next_cb_boundary=sfBandIndex[sfreq].s[4]*3;
cb = 3;
cb_width = sfBandIndex[sfreq].s[cb+1] -
sfBandIndex[sfreq].s[cb];
cb_begin = sfBandIndex[sfreq].s[cb]*3;
}
else if (((sb*18)+ss) < sfBandIndex[sfreq].l[8])
next_cb_boundary = sfBandIndex[sfreq].l[(++cb)+1];
else {
next_cb_boundary = sfBandIndex[sfreq].s[(++cb)+1]*3;
cb_width = sfBandIndex[sfreq].s[cb+1] -
sfBandIndex[sfreq].s[cb];
cb_begin = sfBandIndex[sfreq].s[cb]*3;
}
}
else
{
next_cb_boundary = sfBandIndex[sfreq].s[(++cb)+1]*3;
cb_width = sfBandIndex[sfreq].s[cb+1] -
sfBandIndex[sfreq].s[cb];
cb_begin = sfBandIndex[sfreq].s[cb]*3;
}
}
else /* long blocks */
next_cb_boundary = sfBandIndex[sfreq].l[(++cb)+1];
}
/***************************************************************************************/
if(is[sb][ss]!=0)
{
/* Compute overall (global) scaling. */
xr[sb][ss] = (0.25 * (gr_info->global_gain - 210.0));
/* Do long/short dependent scaling operations. */
if (gr_info->window_switching_flag && (
((gr_info->block_type == 2) && (gr_info->mixed_block_flag == 0)) ||
((gr_info->block_type == 2) && gr_info->mixed_block_flag && (sb >= 2)) ))
{
xr[sb][ss] += (0.25 * -8.0 *gr_info->subblock_gain[(((sb*18)+ss) - cb_begin)/cb_width]);
xr[sb][ss] += (0.25 * -2.0 * (1.0+gr_info->scalefac_scale)
* (*scalefac)[ch].s[(((sb*18)+ss) - cb_begin)/cb_width][cb]);
}
else /* LONG block types 0,1,3 & 1st 2 subbands of switched blocks */
{
xr[sb][ss] += (-0.5 * (1.0+gr_info->scalefac_scale)
* ((*scalefac)[ch].l[cb]
+ gr_info->preflag * pretab[cb]));
}
/* Scale quantized value. */
//求出符號
sign=0;
if(is[sb][ss]<0)
{
sign=1;
is[sb][ss]=-is[sb][ss];
}
if(is[sb][ss]>1023)
temp=is43_table[(unsigned)is[sb][ss]>>3]+2.7725887;// 4/3*ln8
else
temp=is43_table[is[sb][ss]];
xr[sb][ss] *=0.69314318; //log(2);
xr[sb][ss] +=temp;
xr[sb][ss] =exp(xr[sb][ss]);
if (sign) xr[sb][ss] = -xr[sb][ss];
}
else
xr[sb][ss] =0;
}
}
}
void III_reorder(SS xr , struct Granule *gr_info)
{
int sfreq=fr_ps.header->sampling_frequency;
int sfb, sfb_start, sfb_lines;
int sb, ss, window, freq, src_line, des_line;
SS ro ;
if (gr_info->window_switching_flag && (gr_info->block_type == 2))
{
if (gr_info->mixed_block_flag)
{
/* NO REORDER FOR LOW 2 SUBBANDS */
for (sb=0 ; sb < 2 ; sb++)
for (ss=0 ; ss < SSLIMIT ; ss++)
ro[sb][ss] = xr[sb][ss];
/* REORDERING FOR REST SWITCHED SHORT */
for(sfb=3,sfb_start=sfBandIndex[sfreq].s[3],
sfb_lines=sfBandIndex[sfreq].s[4] - sfb_start;
sfb < 13; sfb++,sfb_start=sfBandIndex[sfreq].s[sfb],
(sfb_lines=sfBandIndex[sfreq].s[sfb+1] - sfb_start))
for(window=0; window<3; window++)
for(freq=0;freq<sfb_lines;freq++) {
src_line = sfb_start*3 + window*sfb_lines + freq;
des_line = (sfb_start*3) + window + (freq*3);
ro[des_line/SSLIMIT][des_line%SSLIMIT] =
xr[src_line/SSLIMIT][src_line%SSLIMIT];
}
}
?? 快捷鍵說明
復制代碼
Ctrl + C
搜索代碼
Ctrl + F
全屏模式
F11
切換主題
Ctrl + Shift + D
顯示快捷鍵
?
增大字號
Ctrl + =
減小字號
Ctrl + -