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AAC: simplify some calculations in decode_spectrum_and_dequant()

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Simplify cur_band_type, group_len, and coef/offset calculations.  This
makes the code easier to read and slightly faster.

Originally committed as revision 21189 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Måns Rullgård 2010-01-13 16:46:32 +00:00
parent c816d3d042
commit 05f9d8fcaa
1 changed files with 31 additions and 27 deletions
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58
libavcodec/aac.c
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@ -950,41 +950,44 @@ static int decode_spectrum_and_dequant(AACContext *ac, float coef[1024],
memset(coef + g * 128 + offsets[ics->max_sfb], 0, sizeof(float) * (c - offsets[ics->max_sfb]));
for (g = 0; g < ics->num_window_groups; g++) {
unsigned g_len = ics->group_len[g];
for (i = 0; i < ics->max_sfb; i++, idx++) {
const int cur_band_type = band_type[idx];
const unsigned cbt_m1 = band_type[idx] - 1;
float *cfo = coef + offsets[i];
int off_len = offsets[i + 1] - offsets[i];
int group;
if (cur_band_type == ZERO_BT || cur_band_type == INTENSITY_BT2 || cur_band_type == INTENSITY_BT) {
for (group = 0; group < ics->group_len[g]; group++) {
memset(coef + group * 128 + offsets[i], 0, (offsets[i + 1] - offsets[i]) * sizeof(float));
if (cbt_m1 >= INTENSITY_BT2 - 1) {
for (group = 0; group < g_len; group++, cfo+=128) {
memset(cfo, 0, off_len * sizeof(float));
}
} else if (cur_band_type == NOISE_BT) {
for (group = 0; group < ics->group_len[g]; group++) {
} else if (cbt_m1 == NOISE_BT - 1) {
for (group = 0; group < g_len; group++, cfo+=128) {
float scale;
float band_energy;
float *cf = coef + group * 128 + offsets[i];
int len = offsets[i+1] - offsets[i];
for (k = 0; k < len; k++) {
for (k = 0; k < off_len; k++) {
ac->random_state = lcg_random(ac->random_state);
cf[k] = ac->random_state;
cfo[k] = ac->random_state;
}
band_energy = ac->dsp.scalarproduct_float(cf, cf, len);
band_energy = ac->dsp.scalarproduct_float(cfo, cfo, off_len);
scale = sf[idx] / sqrtf(band_energy);
ac->dsp.vector_fmul_scalar(cf, cf, scale, len);
ac->dsp.vector_fmul_scalar(cfo, cfo, scale, off_len);
}
} else {
const float *vq = ff_aac_codebook_vector_vals[cur_band_type-1];
const uint16_t *cb_vector_idx = ff_aac_codebook_vector_idx[cur_band_type-1];
VLC_TYPE (*vlc_tab)[2] = vlc_spectral[cur_band_type - 1].table;
const int cb_size = ff_aac_spectral_sizes[cur_band_type-1];
const float *vq = ff_aac_codebook_vector_vals[cbt_m1];
const uint16_t *cb_vector_idx = ff_aac_codebook_vector_idx[cbt_m1];
VLC_TYPE (*vlc_tab)[2] = vlc_spectral[cbt_m1].table;
const int cb_size = ff_aac_spectral_sizes[cbt_m1];
for (group = 0; group < ics->group_len[g]; group++) {
float *cf = coef + (group << 7) + offsets[i];
for (group = 0; group < g_len; group++, cfo+=128) {
float *cf = cfo;
uint32_t *icf = (uint32_t *) cf;
int len = offsets[i + 1] - offsets[i];
int len = off_len;
switch ((cur_band_type-1) >> 1) {
switch (cbt_m1 >> 1) {
case 0:
do {
const int index = get_vlc2(gb, vlc_tab, 6, 3);
@ -1051,7 +1054,7 @@ static int decode_spectrum_and_dequant(AACContext *ac, float coef[1024],
} while (len -= 2);
break;
default:
for (k = 0; k < len; k += 2, icf += 2) {
do {
const int index = get_vlc2(gb, vlc_tab, 6, 3);
unsigned nzt, nnz;
unsigned cb_idx;
@ -1059,7 +1062,8 @@ static int decode_spectrum_and_dequant(AACContext *ac, float coef[1024],
int j;
if (!index) {
icf[0] = icf[1] = 0;
*icf++ = 0;
*icf++ = 0;
continue;
}
@ -1084,23 +1088,23 @@ static int decode_spectrum_and_dequant(AACContext *ac, float coef[1024],
return -1;
}
n = (1 << n) + get_bits(gb, n);
icf[j] = cbrt_tab[n] | (bits & 1<<31);
*icf++ = cbrt_tab[n] | (bits & 1<<31);
bits <<= 1;
} else {
unsigned v = ((const uint32_t*)vq)[cb_idx & 15];
icf[j] = (bits & 1<<31) | v;
*icf++ = (bits & 1<<31) | v;
bits <<= !!v;
}
cb_idx >>= 4;
}
}
} while (len -= 2);
ac->dsp.vector_fmul_scalar(cf, cf, sf[idx], len);
ac->dsp.vector_fmul_scalar(cfo, cfo, sf[idx], off_len);
}
}
}
}
coef += ics->group_len[g] << 7;
coef += g_len << 7;
}
if (pulse_present) {