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Increase caps/allocation accuracy.

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This stores the caps array in 32nd bits/sample instead of 1/2 bits
 scaled by LM and the channel count, which is slightly less
 less accurate for the last two bands, and much more accurate for
 all the other bands.
A constant offset is subtracted to allow it to represent values
 larger than 255 in 8 bits (the range of unoffset values is
 77...304).
In addition, this replaces the last modeline in the allocation table
 with the caps array, allowing the initial interpolation to
 allocate 8 bits/sample or more, which was otherwise impossible.
This commit is contained in:
Timothy B. Terriberry 2011-02-01 17:41:12 -08:00 • committed by Jean-Marc Valin
parent 424eb74279
commit ce6d0904a1
5 changed files with 25 additions and 18 deletions
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19
libcelt/celt.c
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@ -756,6 +756,17 @@ static void tf_decode(int start, int end, int isTransient, int *tf_res, int LM,
}
}
static void init_caps(const CELTMode *m,int *cap,int LM,int C)
{
int i;
for (i=0;i<m->nbEBands;i++)
{
int N;
N=(m->eBands[i+1]-m->eBands[i])<<LM;
cap[i] = (m->cache.caps[m->nbEBands*(2*LM+C-1)+i]+64)*C*N>>2;
}
}
static int alloc_trim_analysis(const CELTMode *m, const celt_norm *X,
const celt_word16 *bandLogE, int nbEBands, int LM, int C, int N0)
{
@ -1229,9 +1240,7 @@ int celt_encode_with_ec_float(CELTEncoder * restrict st, const celt_sig * pcm, i
ALLOC(cap, st->mode->nbEBands, int);
ALLOC(offsets, st->mode->nbEBands, int);
for (i=0;i<st->mode->nbEBands;i++)
cap[i] = st->mode->cache.caps[st->mode->nbEBands*(2*LM+C-1)+i]
<< C+LM+BITRES-2;
init_caps(st->mode,cap,LM,C);
for (i=0;i<st->mode->nbEBands;i++)
offsets[i] = 0;
/* Dynamic allocation code */
@ -2294,9 +2303,7 @@ int celt_decode_with_ec_float(CELTDecoder * restrict st, const unsigned char *da
ALLOC(offsets, st->mode->nbEBands, int);
ALLOC(fine_priority, st->mode->nbEBands, int);
for (i=0;i<st->mode->nbEBands;i++)
cap[i] = st->mode->cache.caps[st->mode->nbEBands*(2*LM+C-1)+i]
<< C+LM+BITRES-2;
init_caps(st->mode,cap,LM,C);
dynalloc_logp = 6;
total_bits<<=BITRES;