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Improved transient_analysis() by adding one frame of memory.

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This commit is contained in:
Jean-Marc Valin 2010-04-19 13:32:15 -04:00
parent b450ed48ae
commit 9c30de571d
1 changed files with 31 additions and 16 deletions
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47
libcelt/celt.c
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@ -95,6 +95,7 @@ struct CELTEncoder {
celt_word16 tonal_average;
int fold_decision;
celt_word16 gain_prod;
celt_word32 frame_max;
/* VBR-related parameters */
celt_int32 vbr_reservoir;
@ -266,48 +267,61 @@ static inline celt_word16 SIG2WORD16(celt_sig x)
#endif
}
static int transient_analysis(celt_word32 *in, int len, int C, int *transient_time, int *transient_shift)
static int transient_analysis(const celt_word32 * restrict in, int len, int C,
int *transient_time, int *transient_shift,
celt_word32 *frame_max)
{
int c, i, n;
int i, n;
celt_word32 ratio;
celt_word32 threshold;
VARDECL(celt_word32, begin);
SAVE_STACK;
ALLOC(begin, len, celt_word32);
for (i=0;i<len;i++)
begin[i] = ABS32(SHR32(in[C*i],SIG_SHIFT));
for (c=1;c<C;c++)
ALLOC(begin, len+1, celt_word32);
begin[0] = 0;
if (C==1)
{
for (i=0;i<len;i++)
begin[i] = MAX32(begin[i], ABS32(SHR32(in[C*i+c],SIG_SHIFT)));
begin[i+1] = MAX32(begin[i], ABS32(in[i]));
} else {
for (i=0;i<len;i++)
begin[i+1] = MAX32(begin[i], MAX32(ABS32(in[C*i]),
ABS32(in[C*i+1])));
}
for (i=1;i<len;i++)
begin[i] = MAX32(begin[i-1],begin[i]);
n = -1;
for (i=8;i<len-8;i++)
threshold = MULT16_32_Q15(QCONST16(.2f,15),begin[len]);
/* If the following condition isn't met, there's just no way
we'll have a transient*/
if (*frame_max < threshold)
{
if (begin[i] < MULT16_32_Q15(QCONST16(.2f,15),begin[len-1]))
n=i;
/* It's likely we have a transient, now find it */
for (i=8;i<len-8;i++)
{
if (begin[i+1] < threshold)
n=i;
}
}
if (n<32)
{
n = -1;
ratio = 0;
} else {
ratio = DIV32(begin[len-1],1+begin[n-16]);
ratio = DIV32(begin[len],1+MAX32(*frame_max, begin[n-16]));
}
if (ratio < 0)
ratio = 0;
if (ratio > 1000)
ratio = 1000;
ratio *= ratio;
if (ratio > 2048)
*transient_shift = 3;
else
*transient_shift = 0;
*transient_time = n;
*frame_max = begin[len];
RESTORE_STACK;
return ratio > 20;
}
@ -613,7 +627,7 @@ int celt_encode_float(CELTEncoder * restrict st, const celt_sig * pcm, celt_sig
resynth = st->pitch_available>0 || optional_synthesis!=NULL;
if (st->mode->nbShortMdcts > 1 && transient_analysis(in, N+st->overlap, C, &transient_time, &transient_shift))
if (st->mode->nbShortMdcts > 1 && transient_analysis(in, N+st->overlap, C, &transient_time, &transient_shift, &st->frame_max))
{
#ifndef FIXED_POINT
float gain_1;
@ -1059,6 +1073,7 @@ int celt_encoder_ctl(CELTEncoder * restrict st, int request, ...)
st->vbr_offset = 0;
st->vbr_count = 0;
st->xmem = 0;
st->frame_max = 0;
CELT_MEMSET(st->pitch_buf, 0, (MAX_PERIOD>>1)+2);
}
break;