void mpeg3audio_ac3_ba_compute_psd(int start,
int end,
short exps[],
short psd[],
short bndpsd[])
{
int bin,i,j,k;
int lastbin = 0;
/* Map the exponents into dBs */
for (bin = start; bin < end; bin++)
{
psd[bin] = (3072 - (exps[bin] << 7));
}
/* Integrate the psd function over each bit allocation band */
j = start;
k = mpeg3_masktab[start];
do
{
lastbin = mpeg3_min(mpeg3_bndtab[k] + mpeg3_bndsz[k], end);
bndpsd[k] = psd[j];
j++;
for(i = j; i < lastbin; i++)
{
bndpsd[k] = logadd(bndpsd[k], psd[j]);
j++;
}
k++;
}while(end > lastbin);
}
/* This routine simply does stereo rematrixing for the 2 channel
* stereo mode */
int mpeg3audio_ac3_rematrix(mpeg3_ac3audblk_t *audblk,
mpeg3ac3_stream_samples_t samples)
{
int num_bands;
int start;
int end;
int i, j;
float left, right;
if(audblk->cplinu || audblk->cplbegf > 2)
num_bands = 4;
else if (audblk->cplbegf > 0)
num_bands = 3;
else
num_bands = 2;
for(i = 0; i < num_bands; i++)
{
if(!audblk->rematflg[i])
continue;
start = mpeg3_rematrix_band[i].start;
end = mpeg3_min(mpeg3_rematrix_band[i].end, 12 * audblk->cplbegf + 36);
for(j = start; j < end; j++)
{
left = samples[0][j] + samples[1][j];
right = samples[0][j] - samples[1][j];
samples[0][j] = left;
samples[1][j] = right;
}
}
return 0;
}
void mpeg3audio_ac3_ba_compute_excitation(mpeg3audio_t *audio,
int start,
int end,
int fgain,
int fastleak,
int slowleak,
int is_lfe,
short bndpsd[],
short excite[])
{
int bin;
int bndstrt;
int bndend;
int lowcomp = 0;
int begin = 0;
/* Compute excitation function */
bndstrt = mpeg3_masktab[start];
bndend = mpeg3_masktab[end - 1] + 1;
if(bndstrt == 0) /* For fbw and lfe channels */
{
lowcomp = mpeg3audio_ac3_calc_lowcomp(lowcomp, bndpsd[0], bndpsd[1], 0);
excite[0] = bndpsd[0] - fgain - lowcomp;
lowcomp = mpeg3audio_ac3_calc_lowcomp(lowcomp, bndpsd[1], bndpsd[2], 1);
excite[1] = bndpsd[1] - fgain - lowcomp;
begin = 7 ;
/* Note: Do not call mpeg3audio_ac3_calc_lowcomp() for the last band of the lfe channel, (bin = 6) */
for (bin = 2; bin < 7; bin++)
{
if(!(is_lfe && (bin == 6)))
lowcomp = mpeg3audio_ac3_calc_lowcomp(lowcomp, bndpsd[bin], bndpsd[bin+1], bin);
fastleak = bndpsd[bin] - fgain;
slowleak = bndpsd[bin] - audio->ac3_bit_allocation.sgain;
excite[bin] = fastleak - lowcomp;
if(!(is_lfe && (bin == 6)))
{
if(bndpsd[bin] <= bndpsd[bin+1])
{
begin = bin + 1 ;
break;
}
}
}
for (bin = begin; bin < mpeg3_min(bndend, 22); bin++)
{
if (!(is_lfe && (bin == 6)))
lowcomp = mpeg3audio_ac3_calc_lowcomp(lowcomp, bndpsd[bin], bndpsd[bin+1], bin);
fastleak -= audio->ac3_bit_allocation.fdecay;
fastleak = mpeg3_max(fastleak, bndpsd[bin] - fgain);
slowleak -= audio->ac3_bit_allocation.sdecay;
slowleak = mpeg3_max(slowleak, bndpsd[bin] - audio->ac3_bit_allocation.sgain);
excite[bin] = mpeg3_max(fastleak - lowcomp, slowleak);
}
begin = 22;
}
else /* For coupling channel */
{
begin = bndstrt;
}
for (bin = begin; bin < bndend; bin++)
{
fastleak -= audio->ac3_bit_allocation.fdecay;
fastleak = mpeg3_max(fastleak, bndpsd[bin] - fgain);
slowleak -= audio->ac3_bit_allocation.sdecay;
slowleak = mpeg3_max(slowleak, bndpsd[bin] - audio->ac3_bit_allocation.sgain);
excite[bin] = mpeg3_max(fastleak, slowleak) ;
}
}