📄 layer3.cpp
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lines = -10;
}
lines--;
i--;
} // while (lines > 0)
} // for (sfb=12 ...
sfb = sfbcnt + 1;
if (sfb > max_sfb)
max_sfb = sfb;
while(sfb < 12) {
temp = sfBandIndex[sfreq].s[sfb];
sb = sfBandIndex[sfreq].s[sfb+1] - temp;
i = (temp << 2) - temp + j * sb;
for ( ; sb > 0; sb--) {
is_pos[i] = scalefac[1].s[j][sfb];
if (is_pos[i] != 7)
if (lsf)
i_stereo_k_values(is_pos[i], io_type, i);
else
is_ratio[i] = TAN12[is_pos[i]];
i++;
} // for (; sb>0...
sfb++;
} // while (sfb < 12)
sfb = sfBandIndex[sfreq].s[10];
sb = sfBandIndex[sfreq].s[11] - sfb;
sfb = (sfb << 2) - sfb + j * sb;
temp = sfBandIndex[sfreq].s[11];
sb = sfBandIndex[sfreq].s[12] - temp;
i = (temp << 2) - temp + j * sb;
for (; sb > 0; sb--) {
is_pos[i] = is_pos[sfb];
if (lsf) {
k[0][i] = k[0][sfb];
k[1][i] = k[1][sfb];
} else {
is_ratio[i] = is_ratio[sfb];
}
i++;
} // for (; sb > 0 ...
}
if (max_sfb <= 3) {
i = 2;
ss = 17;
sb = -1;
while (i >= 0) {
if (ro[1][i][ss] != 0.0f) {
sb = (i<<4) + (i<<1) + ss;
i = -1;
} else {
ss--;
if (ss < 0) {
i--;
ss = 17;
}
} // if (ro ...
} // while (i>=0)
i = 0;
while (sfBandIndex[sfreq].l[i] <= sb)
i++;
sfb = i;
i = sfBandIndex[sfreq].l[i];
for (; sfb<8; sfb++) {
sb = sfBandIndex[sfreq].l[sfb+1]-sfBandIndex[sfreq].l[sfb];
for (; sb>0; sb--) {
is_pos[i] = scalefac[1].l[sfb];
if (is_pos[i] != 7)
if (lsf)
i_stereo_k_values(is_pos[i], io_type, i);
else
is_ratio[i] = TAN12[is_pos[i]];
i++;
} // for (; sb>0 ...
} // for (; sfb<8 ...
} // for (j=0 ...
} else { // if (gr_info->mixed_block_flag)
for (uint32 j=0; j<3; j++) {
int32 sfbcnt;
sfbcnt = -1;
for( sfb=12; sfb >=0; sfb-- )
{
temp = sfBandIndex[sfreq].s[sfb];
lines = sfBandIndex[sfreq].s[sfb+1] - temp;
i = (temp << 2) - temp + (j+1) * lines - 1;
while (lines > 0) {
if (ro[1][ss_div[i]][ss_mod[i]] != 0.0f) {
sfbcnt = sfb;
sfb = -10;
lines = -10;
}
lines--;
i--;
} // while (lines > 0) */
} // for (sfb=12 ...
sfb = sfbcnt + 1;
while(sfb<12) {
temp = sfBandIndex[sfreq].s[sfb];
sb = sfBandIndex[sfreq].s[sfb+1] - temp;
i = (temp << 2) - temp + j * sb;
for ( ; sb > 0; sb--) {
is_pos[i] = scalefac[1].s[j][sfb];
if (is_pos[i] != 7)
if (lsf)
i_stereo_k_values(is_pos[i], io_type, i);
else
is_ratio[i] = TAN12[is_pos[i]];
i++;
} // for (; sb>0 ...
sfb++;
} // while (sfb<12)
temp = sfBandIndex[sfreq].s[10];
temp2= sfBandIndex[sfreq].s[11];
sb = temp2 - temp;
sfb = (temp << 2) - temp + j * sb;
sb = sfBandIndex[sfreq].s[12] - temp2;
i = (temp2 << 2) - temp2 + j * sb;
for (; sb>0; sb--) {
is_pos[i] = is_pos[sfb];
if (lsf) {
k[0][i] = k[0][sfb];
k[1][i] = k[1][sfb];
} else {
is_ratio[i] = is_ratio[sfb];
}
i++;
} // for (; sb>0 ...
} // for (sfb=12
} // for (j=0 ...
} else { // if (gr_info->window_switching_flag ...
i = 31;
ss = 17;
sb = 0;
while (i >= 0) {
if (ro[1][i][ss] != 0.0f) {
sb = (i<<4) + (i<<1) + ss;
i = -1;
} else {
ss--;
if (ss < 0) {
i--;
ss = 17;
}
}
}
i = 0;
while (sfBandIndex[sfreq].l[i] <= sb)
i++;
sfb = i;
i = sfBandIndex[sfreq].l[i];
for (; sfb<21; sfb++) {
sb = sfBandIndex[sfreq].l[sfb+1] - sfBandIndex[sfreq].l[sfb];
for (; sb > 0; sb--) {
is_pos[i] = scalefac[1].l[sfb];
if (is_pos[i] != 7)
if (lsf)
i_stereo_k_values(is_pos[i], io_type, i);
else
is_ratio[i] = TAN12[is_pos[i]];
i++;
}
}
sfb = sfBandIndex[sfreq].l[20];
for (sb = 576 - sfBandIndex[sfreq].l[21]; (sb > 0) && (i<576); sb--)
{
is_pos[i] = is_pos[sfb]; // error here : i >=576
if (lsf) {
k[0][i] = k[0][sfb];
k[1][i] = k[1][sfb];
} else {
is_ratio[i] = is_ratio[sfb];
}
i++;
} // if (gr_info->mixed_block_flag)
} // if (gr_info->window_switching_flag ...
} // if (i_stereo)
i = 0;
for(sb=0;sb<SBLIMIT;sb++)
for(ss=0;ss<SSLIMIT;ss++) {
if (is_pos[i] == 7) {
if (ms_stereo) {
lr[0][sb][ss] = (ro[0][sb][ss]+ro[1][sb][ss]) * 0.707106781f;
lr[1][sb][ss] = (ro[0][sb][ss]-ro[1][sb][ss]) * 0.707106781f;
} else {
lr[0][sb][ss] = ro[0][sb][ss];
lr[1][sb][ss] = ro[1][sb][ss];
}
}
else if (i_stereo) {
if (lsf) {
lr[0][sb][ss] = ro[0][sb][ss] * k[0][i];
lr[1][sb][ss] = ro[0][sb][ss] * k[1][i];
} else {
lr[1][sb][ss] = ro[0][sb][ss] / (real) (1 + is_ratio[i]);
lr[0][sb][ss] = lr[1][sb][ss] * is_ratio[i];
}
}
/* else {
printf("Error in stereo processing\n");
} */
i++;
}
} // channels == 2
}
void LayerIII_Decoder::antialias(uint32 ch, uint32 gr)
{
int32 sb18, ss, sb18lim;
gr_info_s *gr_info = &(si->ch[ch].gr[gr]);
// 31 alias-reduction operations between each pair of sub-bands
// with 8 butterflies between each pair
if (gr_info->window_switching_flag && (gr_info->block_type == 2) &&
!gr_info->mixed_block_flag )
return;
if (gr_info->window_switching_flag && gr_info->mixed_block_flag &&
(gr_info->block_type == 2)) {
sb18lim = 18;
} else {
sb18lim = 558;
}
for (sb18=0; sb18 < sb18lim; sb18+=18) {
for (ss=0;ss<8;ss++) {
int32 src_idx1 = sb18 + 17 - ss;
int32 src_idx2 = sb18 + 18 + ss;
real bu = out_1d[src_idx1];
real bd = out_1d[src_idx2];
out_1d[src_idx1] = (bu * cs[ss]) - (bd * ca[ss]);
out_1d[src_idx2] = (bd * cs[ss]) + (bu * ca[ss]);
}
}
}
void LayerIII_Decoder::hybrid(uint32 ch, uint32 gr)
{
real rawout[36];
uint32 bt;
int32 sb18;
gr_info_s *gr_info = &(si->ch[ch].gr[gr]);
real *tsOut;
real *prvblk;
for(sb18=0;sb18<576;sb18+=18) {
bt = (gr_info->window_switching_flag && gr_info->mixed_block_flag &&
(sb18 < 36)) ? 0 : gr_info->block_type;
tsOut = out_1d + sb18;
inv_mdct(tsOut, rawout, bt);
// overlap addition
prvblk = &prevblck[ch][sb18];
tsOut[0] = rawout[0] + prvblk[0];
prvblk[0] = rawout[18];
tsOut[1] = rawout[1] + prvblk[1];
prvblk[1] = rawout[19];
tsOut[2] = rawout[2] + prvblk[2];
prvblk[2] = rawout[20];
tsOut[3] = rawout[3] + prvblk[3];
prvblk[3] = rawout[21];
tsOut[4] = rawout[4] + prvblk[4];
prvblk[4] = rawout[22];
tsOut[5] = rawout[5] + prvblk[5];
prvblk[5] = rawout[23];
tsOut[6] = rawout[6] + prvblk[6];
prvblk[6] = rawout[24];
tsOut[7] = rawout[7] + prvblk[7];
prvblk[7] = rawout[25];
tsOut[8] = rawout[8] + prvblk[8];
prvblk[8] = rawout[26];
tsOut[9] = rawout[9] + prvblk[9];
prvblk[9] = rawout[27];
tsOut[10] = rawout[10] + prvblk[10];
prvblk[10] = rawout[28];
tsOut[11] = rawout[11] + prvblk[11];
prvblk[11] = rawout[29];
tsOut[12] = rawout[12] + prvblk[12];
prvblk[12] = rawout[30];
tsOut[13] = rawout[13] + prvblk[13];
prvblk[13] = rawout[31];
tsOut[14] = rawout[14] + prvblk[14];
prvblk[14] = rawout[32];
tsOut[15] = rawout[15] + prvblk[15];
prvblk[15] = rawout[33];
tsOut[16] = rawout[16] + prvblk[16];
prvblk[16] = rawout[34];
tsOut[17] = rawout[17] + prvblk[17];
prvblk[17] = rawout[35];
}
}
void LayerIII_Decoder::do_downmix()
{
for (uint32 sb=0; sb<SSLIMIT; sb++) {
for (uint32 ss=0; ss<SSLIMIT; ss+=3) {
lr[0][sb][ss] = (lr[0][sb][ss] + lr[1][sb][ss]) * 0.5f;
lr[0][sb][ss+1] = (lr[0][sb][ss+1] + lr[1][sb][ss+1]) * 0.5f;
lr[0][sb][ss+2] = (lr[0][sb][ss+2] + lr[1][sb][ss+2]) * 0.5f;
}
}
}
void LayerIII_Decoder::decode()
{
uint32 nSlots = header->slots();
uint32 flush_main;
uint32 gr, ch, ss, sb, sb18;
int32 main_data_end;
int32 bytes_to_discard;
uint32 i;
get_side_info();
for (i=0; i<nSlots; i++)
br->hputbuf(stream->get_bits(8));
main_data_end = br->hsstell() >> 3; // of previous frame
if (flush_main = (br->hsstell() & 7)) {
br->hgetbits(8 - flush_main);
main_data_end++;
}
bytes_to_discard = frame_start - main_data_end
- si->main_data_begin;
frame_start += nSlots;
if (bytes_to_discard < 0)
return;
if (main_data_end > 4096) {
frame_start -= 4096;
br->rewindNbytes(4096);
}
for (; bytes_to_discard > 0; bytes_to_discard--)
br->hgetbits(8);
for (gr=0;gr<max_gr;gr++) {
for (ch=0; ch<channels; ch++) {
part2_start = br->hsstell();
if (header->version() == MPEG1)
get_scale_factors(ch, gr);
else // MPEG-2 LSF
get_LSF_scale_factors(ch, gr);
huffman_decode(ch, gr);
dequantize_sample(ro[ch], ch, gr);
}
stereo(gr);
if ((which_channels == downmix) && (channels > 1))
do_downmix();
for (ch=first_channel; ch<=last_channel; ch++) {
reorder(lr[ch], ch, gr);
antialias(ch, gr);
hybrid(ch, gr);
for (sb18=18;sb18<576;sb18+=36) // Frequency inversion
for (ss=1;ss<SSLIMIT;ss+=2)
out_1d[sb18 + ss] = -out_1d[sb18 + ss];
if ((ch == 0) || (which_channels == right)) {
for (ss=0;ss<SSLIMIT;ss++) { // Polyphase synthesis
sb = 0;
for (sb18=0; sb18<576; sb18+=18) {
filter1->input_sample(out_1d[sb18+ss], sb);
sb++;
}
filter1->calculate_pcm_samples(buffer);
}
} else {
for (ss=0;ss<SSLIMIT;ss++) { // Polyphase synthesis
sb = 0;
for (sb18=0; sb18<576; sb18+=18) {
filter2->input_sample(out_1d[sb18+ss], sb);
sb++;
}
filter2->calculate_pcm_samples(buffer);
}
}
} // channels
} // granule
buffer->write_buffer(1);
}
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