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Tweaks to the new transient detector

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Instead of using the average energy over the frame, we use a half-way
point between the average energy and the max energy.
This commit is contained in:
Jean-Marc Valin 2012-11-19 16:36:22 -05:00
parent 14454c49a8
commit 413caa00c5
1 changed files with 16 additions and 5 deletions
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21
celt/celt_encoder.c
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@ -238,6 +238,7 @@ static int transient_analysis(const opus_val32 * OPUS_RESTRICT in, int len, int
opus_val32 mean;
opus_int32 unmask=0;
opus_val32 norm;
opus_val16 maxE;
mem0=0;
mem1=0;
/* High-pass filter: (1 - 2*z^-1 + z^-2) / (1 - z^-1 + .5*z^-2) */
@ -276,7 +277,7 @@ static int transient_analysis(const opus_val32 * OPUS_RESTRICT in, int len, int
mean=0;
mem0=0;
/* Grouping by two to reduce complexity */
/* Grouping by two to reduce complexity */
/* Forward pass to compute the post-echo threshold*/
for (i=0;i<len2;i++)
{
@ -292,6 +293,7 @@ static int transient_analysis(const opus_val32 * OPUS_RESTRICT in, int len, int
}
mem0=0;
maxE=0;
/* Backward pass to compute the pre-echo threshold */
for (i=len2-1;i>=0;i--)
{
@ -302,13 +304,22 @@ static int transient_analysis(const opus_val32 * OPUS_RESTRICT in, int len, int
tmp[i] = mem0 + MULT16_16_P15(QCONST16(0.125f,15),tmp[i]-mem0);
#endif
mem0 = tmp[i];
maxE = MAX16(maxE, mem0);
}
/*for (i=0;i<len;i++)printf("%f ", tmp[i]/mean);printf("\n");*/
/*for (i=0;i<len2;i++)printf("%f ", tmp[i]/mean);printf("\n");*/
/* Compute the ratio of the mean energy over the harmonic mean of the energy.
/* Compute the ratio of the "frame energy" over the harmonic mean of the energy.
This essentially corresponds to a bitrate-normalized temporal noise-to-mask
ratio */
/* As a compromise with the old transient detector, frame energy is the
geometric mean of the energy and half the max */
#ifdef FIXED_POINT
/* Costs two sqrt() to avoid overflows */
mean = MULT16_16(celt_sqrt(mean), celt_sqrt(MULT16_16(maxE,len2>>1)));
#else
mean = sqrt(mean * maxE*.5*len2);
#endif
/* Inverse of the mean energy in Q15+6 */
norm = SHL32(EXTEND32(len2),6+14)/ADD32(EPSILON,SHR32(mean,1));
/* Compute harmonic mean discarding the unreliable boundaries
@ -333,10 +344,10 @@ static int transient_analysis(const opus_val32 * OPUS_RESTRICT in, int len, int
mask_metric = unmask;
}
}
is_transient = mask_metric>141;
is_transient = mask_metric>200;
/* Arbitrary metric for VBR boost */
tf_max = MAX16(0,celt_sqrt(64*mask_metric)-64);
tf_max = MAX16(0,celt_sqrt(27*mask_metric)-42);
/* *tf_estimate = 1 + MIN16(1, sqrt(MAX16(0, tf_max-30))/20); */
*tf_estimate = QCONST16(1.f, 14) + celt_sqrt(MAX16(0, SHL32(MULT16_16(QCONST16(0.0069,14),IMIN(163,tf_max)),14)-QCONST32(0.139,28)));
/*printf("%d %f\n", tf_max, mask_metric);*/