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New fine energy allocation tuning.

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Based on 1/2*log2(N)-19/8, but with the 2-bit and 3-bit thresholds
shifted by 2*log2(N)/8 bit and log2(N)/8 bit, respectively.
This commit is contained in:
Jean-Marc Valin 2010-08-30 21:34:11 -04:00
parent 6d3829f266
commit fffae794ea
2 changed files with 7 additions and 12 deletions
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18
libcelt/rate.c
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@ -181,25 +181,19 @@ static inline void interp_bits2pulses(const CELTMode *m, int start, int end, int
{ {
int N0, N, den; int N0, N, den;
int offset; int offset;
int fine_offset;
N0 = m->eBands[j+1]-m->eBands[j]; N0 = m->eBands[j+1]-m->eBands[j];
N=M*N0; N=M*N0;
/* Compensate for the extra DoF in stereo */ /* Compensate for the extra DoF in stereo */
den=(C*N+ ((C==2 && N>2) ? 1 : 0)); den=(C*N+ ((C==2 && N>2) ? 1 : 0));
if (N0==1)
fine_offset = 19;
else if (N0<=4)
fine_offset = 14;
else
fine_offset = 12;
/* Offset for the number of fine bits compared to their "fair share" of total/N */ /* Offset for the number of fine bits compared to their "fair share" of total/N */
offset = N*C*((m->logN[j] + logM - 2*fine_offset)>>1); offset = N*C*(((m->logN[j] + logM)>>1)-FINE_OFFSET);
/* Compensate for the prediction gain in stereo */ /* Changing the offset for allocating the second and third fine energy bit */
if (C==2) if (bits[j] + offset < den*2<<BITRES)
offset -= 1<<BITRES; offset += (m->logN[j] + logM)*N*C>>BITRES-1;
else if (bits[j] + offset < den*3<<BITRES)
offset += (m->logN[j] + logM)*N*C>>BITRES;
ebits[j] = (bits[j] + offset + (den<<(BITRES-1))) / (den<<BITRES); ebits[j] = (bits[j] + offset + (den<<(BITRES-1))) / (den<<BITRES);

1
libcelt/rate.h
View file

@ -40,6 +40,7 @@
#define LOG_MAX_PULSES 7 #define LOG_MAX_PULSES 7
#define BITRES 3 #define BITRES 3
#define FINE_OFFSET 19
#define QTHETA_OFFSET 6 #define QTHETA_OFFSET 6
#define QTHETA_OFFSET_STEREO 4 #define QTHETA_OFFSET_STEREO 4