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Tim just rewrote half of the bit allocator -- hope it works now

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Making sure we never waste bits due to band skip and also making
sure we don't skip bands "in the middle".
This commit is contained in:
Jean-Marc Valin 2010-12-15 00:36:41 -05:00
parent 9651ffdbb5
commit ffe1057419
1 changed files with 65 additions and 32 deletions
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95
libcelt/rate.c
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@ -151,6 +151,10 @@ static inline int interp_bits2pulses(const CELTMode *m, int start, int end,
const int C = CHANNELS(_C);
int codedBands=-1;
int alloc_floor;
int left, percoeff;
int force_skipping;
int unforced_skips;
int done;
SAVE_STACK;
alloc_floor = C<<BITRES;
@ -162,14 +166,19 @@ static inline int interp_bits2pulses(const CELTMode *m, int start, int end,
{
int mid = (lo+hi)>>1;
psum = 0;
done = 0;
for (j=start;j<end;j++)
{
int tmp = bits1[j] + (mid*bits2[j]>>ALLOC_STEPS);
/* Don't allocate more than we can actually use */
if (tmp >= thresh[j])
if (tmp >= thresh[j] && !done)
{
psum += tmp;
else if (tmp >= alloc_floor + (1<<BITRES))
psum += alloc_floor + (1<<BITRES);
} else {
done = 1;
if (tmp >= alloc_floor)
psum += alloc_floor;
}
}
if (psum > (total<<BITRES))
hi = mid;
@ -178,13 +187,15 @@ static inline int interp_bits2pulses(const CELTMode *m, int start, int end,
}
psum = 0;
/*printf ("interp bisection gave %d\n", lo);*/
done = 0;
for (j=start;j<end;j++)
{
int tmp = bits1[j] + (lo*bits2[j]>>ALLOC_STEPS);
if (tmp < thresh[j])
if (tmp < thresh[j] || done)
{
if (tmp >= alloc_floor + (1<<BITRES))
tmp = alloc_floor + (1<<BITRES);
done = 1;
if (tmp >= alloc_floor)
tmp = alloc_floor;
else
tmp = 0;
}
@ -193,47 +204,69 @@ static inline int interp_bits2pulses(const CELTMode *m, int start, int end,
bits[j] = tmp;
psum += tmp;
}
for (j=start;j<end;j++)
{
if (bits[j] < thresh[j])
break;
}
codedBands = j;
if (*skip==-1)
force_skipping = 1;
unforced_skips = *skip;
*skip = 0;
codedBands=end;
for (j=end;j-->start;)
{
*skip=0;
for (j=codedBands-1;j>=0;j--)
int band_width;
int band_bits;
int rem;
/*Figure out how many left-over bits we would be adding to this band.
This can include bits we've stolen back from higher, skipped bands.*/
left = (total<<BITRES)-psum;
percoeff = left/(m->eBands[codedBands]-m->eBands[start]);
left -= (m->eBands[codedBands]-m->eBands[start])*percoeff;
rem = IMAX(left-m->eBands[j],0);
band_width = m->eBands[codedBands]-m->eBands[j];
band_bits = bits[j] + percoeff*band_width + rem;
/*As long as, even after adding these bits, we're below the threshold for
this band, it is force-skipped.*/
force_skipping = force_skipping && band_bits < thresh[j];
if (!force_skipping)
{
if ((bits[j] > (7*(m->eBands[j+1]-m->eBands[j])<<LM<<BITRES)>>4 && j<prev)
|| (bits[j] > (9*(m->eBands[j+1]-m->eBands[j])<<LM<<BITRES)>>4))
/*If we have enough for the fine energy, but not more than a full bit
beyond that, or no more than one bit total, then don't bother
skipping this band: there's no extra bits to redistribute.*/
if ((band_bits >= alloc_floor && band_bits <= alloc_floor + (1<<BITRES))
|| band_bits < (1<<BITRES))
break;
/*Never skip the first band: we'd be coding a bit to signal that we're
going to waste all of the other bits.*/
if (j==start)break;
if (unforced_skips == -1)
{
/*Choose a threshold with some hysteresis to keep bands from
fluctuating in and out.*/
if (band_bits > ((j<prev?7:9)*band_width<<LM<<BITRES)>>4)
break;
} else if(unforced_skips--<=0)
break;
else
(*skip)++;
/*Use a bit to skip this band.*/
psum += 1<<BITRES;
band_bits -= 1<<BITRES;
}
*skip = IMIN(*skip, codedBands-start-1);
}
for (i=0;i<*skip;i++)
{
/* We add (1<<BITRES) to account for the skip bit */
psum = psum - bits[codedBands-1] + (1<<BITRES);
if (bits[codedBands-1] >= alloc_floor + (1<<BITRES))
/*Reclaim the bits originally allocated to this band.*/
psum -= bits[j];
if (band_bits >= alloc_floor + (1<<BITRES))
{
/*If we have enough for a fine energy bit per channel, use it.*/
psum += alloc_floor;
bits[codedBands-1] = alloc_floor;
} else {
/*Otherwise this band gets nothing at all.*/
bits[codedBands-1] = 0;
}
codedBands--;
}
/* Allocate the remaining bits */
if (codedBands) {
int left, perband;
left = (total<<BITRES)-psum;
perband = left/(m->eBands[codedBands]-m->eBands[start]);
if (codedBands>start) {
for (j=start;j<codedBands;j++)
bits[j] += perband*(m->eBands[j+1]-m->eBands[j]);
left = left-(m->eBands[codedBands]-m->eBands[start])*perband;
bits[j] += percoeff*(m->eBands[j+1]-m->eBands[j]);
for (j=start;j<codedBands;j++)
{
int tmp = IMIN(left, m->eBands[j+1]-m->eBands[j]);