kolibrios/programs/media/ac97 mp3/trunk/mp3dec/l1dec.c
Sergey Semyonov (Serge) 1634ac97c2 ac97_mp3 source code
git-svn-id: svn://kolibrios.org@165 a494cfbc-eb01-0410-851d-a64ba20cac60
2006-10-06 06:20:41 +00:00

203 lines
4.6 KiB
C

#include "bstream.h"
#include "mp3dec.h"
extern MPEG_DECODE_OPTION m_option;
extern float m_sample[2304];
extern int m_nsb_limit;
extern SBT_PROC m_sbt_proc;
extern int m_max_sb;
extern int m_stereo_sb;
extern int m_bat[4][16];
extern int m_ballo[64];
extern unsigned int m_samp_dispatch[66];
extern float m_c_value[64];
extern unsigned int m_sf_dispatch[66];
extern float m_sf_table[64];
extern float m_cs_factor[3][64];
float m_look_c_valueL1[18];
float *m_cs_factorL1 = m_cs_factor[0];
int m_nbatL1;
int m_bit_skip;
static const int look_joint[16] =
{ /* lookup stereo sb's by mode+ext */
64, 64, 64, 64, /* stereo */
2 * 4, 2 * 8, 2 * 12, 2 * 16, /* joint */
64, 64, 64, 64, /* dual */
32, 32, 32, 32, /* mono */
};
static const int bat_bit_masterL1[] =
{
0, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16
};
void unpack_baL1();
void unpack_sfL1();
void unpack_sampL1();
void L1decode_frame(MPEG_HEADER* h, byte* mpeg, byte* pcm)
{
int crc_size;
crc_size = (h->error_prot) ? 2 : 0;
bitget_init(mpeg + 4 + crc_size);
m_stereo_sb = look_joint[(h->mode << 2) + h->mode_ext];
unpack_baL1(); /* unpack bit allocation */
unpack_sfL1(); /* unpack scale factor */
unpack_sampL1(); /* unpack samples */
m_sbt_proc(m_sample, pcm, 12);
}
void unpack_baL1()
{
int j;
int nstereo;
m_bit_skip = 0;
nstereo = m_stereo_sb;
for (j = 0; j < m_nbatL1; j++)
{
bitget_check(4);
m_ballo[j] = m_samp_dispatch[j] = mac_bitget(4);
if (j >= m_nsb_limit)
m_bit_skip += bat_bit_masterL1[m_samp_dispatch[j]];
m_c_value[j] = m_look_c_valueL1[m_samp_dispatch[j]];
if (--nstereo < 0)
{
m_ballo[j + 1] = m_ballo[j];
// flag as joint
m_samp_dispatch[j] += 15;
// flag for sf
m_samp_dispatch[j + 1] = m_samp_dispatch[j];
m_c_value[j + 1] = m_c_value[j];
j++;
}
}
// terminate with bit skip and end
m_samp_dispatch[m_nsb_limit] = 31;
m_samp_dispatch[j] = 30;
}
// unpack scale factor
// combine dequant and scale factors
void unpack_sfL1()
{
int i;
for (i = 0; i < m_nbatL1; i++)
{
if (m_ballo[i])
{
bitget_check(6);
m_cs_factorL1[i] = m_c_value[i] * m_sf_table[mac_bitget(6)];
}
}
}
// unpack samples
#define UNPACKL1_N(n) \
s[k] = m_cs_factorL1[k]*(bitget(n)-((1 << n-1) -1)); \
goto dispatch;
#define UNPACKL1J_N(n) \
tmp = (bitget(n)-((1 << n-1) -1)); \
s[k] = m_cs_factorL1[k]*tmp; \
s[k+1] = m_cs_factorL1[k+1]*tmp; \
k++; \
goto dispatch;
void unpack_sampL1()
{
int j, k;
float *s;
long tmp;
s = m_sample;
for (j = 0; j < 12; j++)
{
k = -1;
dispatch:
switch (m_samp_dispatch[++k])
{
case 0:
s[k] = 0.0F;
goto dispatch;
case 1:
UNPACKL1_N(2) /* 3 levels */
case 2:
UNPACKL1_N(3) /* 7 levels */
case 3:
UNPACKL1_N(4) /* 15 levels */
case 4:
UNPACKL1_N(5) /* 31 levels */
case 5:
UNPACKL1_N(6) /* 63 levels */
case 6:
UNPACKL1_N(7) /* 127 levels */
case 7:
UNPACKL1_N(8) /* 255 levels */
case 8:
UNPACKL1_N(9) /* 511 levels */
case 9:
UNPACKL1_N(10) /* 1023 levels */
case 10:
UNPACKL1_N(11) /* 2047 levels */
case 11:
UNPACKL1_N(12) /* 4095 levels */
case 12:
UNPACKL1_N(13) /* 8191 levels */
case 13:
UNPACKL1_N(14) /* 16383 levels */
case 14:
UNPACKL1_N(15) /* 32767 levels */
/* -- joint ---- */
case 15 + 0:
s[k + 1] = s[k] = 0.0F;
k++; /* skip right chan dispatch */
goto dispatch;
/* -- joint ---- */
case 15 + 1:
UNPACKL1J_N(2) /* 3 levels */
case 15 + 2:
UNPACKL1J_N(3) /* 7 levels */
case 15 + 3:
UNPACKL1J_N(4) /* 15 levels */
case 15 + 4:
UNPACKL1J_N(5) /* 31 levels */
case 15 + 5:
UNPACKL1J_N(6) /* 63 levels */
case 15 + 6:
UNPACKL1J_N(7) /* 127 levels */
case 15 + 7:
UNPACKL1J_N(8) /* 255 levels */
case 15 + 8:
UNPACKL1J_N(9) /* 511 levels */
case 15 + 9:
UNPACKL1J_N(10) /* 1023 levels */
case 15 + 10:
UNPACKL1J_N(11) /* 2047 levels */
case 15 + 11:
UNPACKL1J_N(12) /* 4095 levels */
case 15 + 12:
UNPACKL1J_N(13) /* 8191 levels */
case 15 + 13:
UNPACKL1J_N(14) /* 16383 levels */
case 15 + 14:
UNPACKL1J_N(15) /* 32767 levels */
/* -- end of dispatch -- */
case 31:
bitget_skip(m_bit_skip);
case 30:
s += 64;
} /* end switch */
} /* end j loop */
}