ref: fac68ce189a768b4f18bba88d33c10b5cec11649
parent: 06d443266ddc0fc7dbacc27d42eba55f5e70c306
author: Jean-Marc Valin <[email protected]>
date: Fri Nov 2 12:32:37 EDT 2012
New transient detection algorithm This one is explicitly based on a simple temporal masking model
--- a/celt/celt.c
+++ b/celt/celt.c
@@ -306,44 +306,43 @@
#endif
}
-static int transient_analysis(const opus_val32 * OPUS_RESTRICT in, int len, int C,
- int overlap, opus_val16 *tf_estimate, int *tf_chan, AnalysisInfo *analysis)
+ int transient_analysis(const opus_val32 * OPUS_RESTRICT in, int len, int C,
+ opus_val16 *tf_estimate, int *tf_chan)
{int i;
VARDECL(opus_val16, tmp);
opus_val32 mem0,mem1;
int is_transient = 0;
- int block;
- int c, N;
- opus_val16 maxbin;
+ opus_int32 mask_metric = 0;
+ int c;
int tf_max;
- VARDECL(opus_val16, bins);
- opus_val16 T1, T2, T3, T4, T5;
- opus_val16 follower;
- int metric=0;
- int fmetric=0, bmetric=0;
- int count1, count2, count3, count4, count5;
-
+ /* Table of 6*64/x, trained on real data to minimize the average error */
+ static const unsigned char inv_table[128] = {+ 255,255,156,110, 86, 70, 59, 51, 45, 40, 37, 33, 31, 28, 26, 25,
+ 23, 22, 21, 20, 19, 18, 17, 16, 16, 15, 15, 14, 13, 13, 12, 12,
+ 12, 12, 11, 11, 11, 10, 10, 10, 9, 9, 9, 9, 9, 9, 8, 8,
+ 8, 8, 8, 7, 7, 7, 7, 7, 7, 6, 6, 6, 6, 6, 6, 6,
+ 6, 6, 6, 6, 6, 6, 6, 6, 6, 5, 5, 5, 5, 5, 5, 5,
+ 5, 5, 5, 5, 5, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
+ 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 3, 3,
+ 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 2,
+ };
SAVE_STACK;
ALLOC(tmp, len, opus_val16);
- block = overlap/4;
- N=len/block-1;
- ALLOC(bins, N, opus_val16);
-
tf_max = 0;
for (c=0;c<C;c++)
{+ opus_val32 mean;
+ opus_int32 unmask=0;
+ opus_val32 norm;
mem0=0;
mem1=0;
- for (i=0;i<len;i++)
- tmp[i] = SHR32(in[i+c*len],SIG_SHIFT);
-
/* High-pass filter: (1 - 2*z^-1 + z^-2) / (1 - z^-1 + .5*z^-2) */
for (i=0;i<len;i++)
{opus_val32 x,y;
- x = tmp[i];
+ x = SHR32(in[i+c*len],SIG_SHIFT);
y = ADD32(mem0, x);
#ifdef FIXED_POINT
mem0 = mem1 + y - SHL32(x,1);
@@ -352,83 +351,100 @@
mem0 = mem1 + y - 2*x;
mem1 = x - .5f*y;
#endif
- tmp[i] = EXTRACT16(SHR(y,2));
+ tmp[i] = EXTRACT16(SHR32(y,2));
+ /*printf("%f ", tmp[i]);*/}
+ /*printf("\n");*//* First few samples are bad because we don't propagate the memory */
for (i=0;i<12;i++)
tmp[i] = 0;
- maxbin=0;
- for (i=0;i<N;i++)
+#ifdef FIXED_POINT
+ /* Normalize tmp to max range */
{- int j;
- opus_val16 max_abs=0;
- for (j=0;j<2*block;j++)
- max_abs = MAX16(max_abs, ABS16(tmp[i*block+j]));
- bins[i] = max_abs;
- maxbin = MAX16(maxbin, bins[i]);
+ int shift=0;
+ shift = 14-celt_ilog2(1+celt_maxabs16(tmp, len));
+ if (shift!=0)
+ {+ for (i=0;i<len;i++)
+ tmp[i] = SHL16(tmp[i], shift);
+ }
}
+#endif
- T1 = QCONST16(.09f, 15);
- T2 = QCONST16(.12f, 15);
- T3 = QCONST16(.18f, 15);
- T4 = QCONST16(.28f, 15);
- T5 = QCONST16(.4f, 15);
-
- follower = 0;
- count1=count2=count3=count4=count5=0;
- for (i=0;i<N;i++)
+ mean=EPSILON;
+ mem0=0;
+ /* Grouping by two to reduce complexity */
+ len/=2;
+ /* Forward pass to compute the post-echo threshold*/
+ for (i=0;i<len;i++)
{- follower = MAX16(bins[i], MULT16_16_Q15(QCONST16(0.97f, 15), follower));
- if (bins[i] < MULT16_16_Q15(T1, follower))
- count1++;
- if (bins[i] < MULT16_16_Q15(T2, follower))
- count2++;
- if (bins[i] < MULT16_16_Q15(T3, follower))
- count3++;
- if (bins[i] < MULT16_16_Q15(T4, follower))
- count4++;
- if (bins[i] < MULT16_16_Q15(T5, follower))
- count5++;
+ opus_val16 x2 = SHR32(MULT16_16(tmp[2*i],tmp[2*i]) + MULT16_16(tmp[2*i+1],tmp[2*i+1]),15);
+ mean += x2;
+#ifdef FIXED_POINT
+ tmp[i] = mem0 + SHR16(x2-mem0,4);
+#else
+ tmp[i] = mem0 + MULT16_16_P15(QCONST16(.0625f,15),x2-mem0);
+#endif
+ mem0 = tmp[i];
}
- fmetric = (5*count1 + 4*count2 + 3*count3 + 2*count4 + count5)/2;
- follower=0;
- count1=count2=count3=count4=count5=0;
- for (i=N-1;i>=0;i--)
+
+ mem0=0;
+ /* Backward pass to compute the pre-echo threshold */
+ for (i=len-1;i>=0;i--)
{- follower = MAX16(bins[i], MULT16_16_Q15(QCONST16(0.97f, 15), follower));
- if (bins[i] < MULT16_16_Q15(T1, follower))
- count1++;
- if (bins[i] < MULT16_16_Q15(T2, follower))
- count2++;
- if (bins[i] < MULT16_16_Q15(T3, follower))
- count3++;
- if (bins[i] < MULT16_16_Q15(T4, follower))
- count4++;
- if (bins[i] < MULT16_16_Q15(T5, follower))
- count5++;
+#ifdef FIXED_POINT
+ tmp[i] = mem0 + SHR16(tmp[i]-mem0,3);
+#else
+ tmp[i] = mem0 + MULT16_16_P15(QCONST16(0.125f,15),tmp[i]-mem0);
+#endif
+ mem0 = tmp[i];
}
- bmetric = 5*count1 + 4*count2 + 3*count3 + 2*count4 + count5;
- metric = fmetric+bmetric;
+ /*for (i=0;i<len;i++)printf("%f ", tmp[i]/mean);printf("\n");*/- /*if (metric>40)*/
- if (metric>20+50*MAX16(analysis->tonality, analysis->noisiness))
- is_transient=1;
+ /* Compute the ratio of the mean energy over the harmonic mean of the energy.
+ This essentially corresponds to a bitrate-normalized temporal noise-to-mask
+ ratio */
- if (metric>tf_max)
+ /* Inverse of the mean energy in Q15+6 */
+ norm = SHL32(EXTEND32(len),6+14)/SHR32(mean,1);
+ /* Compute harmonic mean discarding the unreliable boundaries
+ The data is smooth, so we only take 1/4th of the samples */
+ unmask=0;
+ for (i=12;i<len-5;i+=4)
{+ int id;
+#ifdef FIXED_POINT
+ if (MULT16_16(len,tmp[i]) >= SHL32(mean,1)-SHR32(mean,6))
+ id = 127;
+ else
+ id = MULT16_32_Q15(tmp[i],norm); /* Do not round to nearest */
+#else
+ id = IMIN(127,floor(64*norm*tmp[i])); /* Do not round to nearest */
+#endif
+ unmask += inv_table[id];
+ }
+ /*printf("%d\n", unmask);*/+ /* Normalize, compensate for the 1/4th of the sample and the factor of 6 in the inverse table */
+ unmask = 64*unmask*4/(6*(len-17));
+ if (unmask>mask_metric)
+ {*tf_chan = c;
- tf_max = metric;
+ mask_metric = unmask;
}
}
+ is_transient = mask_metric>141;
+
+ /* Arbitrary metric for VBR boost */
+ tf_max = MAX16(0,celt_sqrt(64*mask_metric)-64);
/* *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);*/RESTORE_STACK;
#ifdef FUZZING
is_transient = rand()&0x1;
#endif
- /*printf("%d %f %f %f %f\n", is_transient, *tf_estimate, tf_max, analysis->tonality, analysis->noisiness);*/+ /*printf("%d %f %d\n", is_transient, (float)*tf_estimate, tf_max);*/return is_transient;
}
@@ -1469,7 +1485,7 @@
if (st->complexity > 1)
{isTransient = transient_analysis(in, N+st->overlap, CC,
- st->overlap, &tf_estimate, &tf_chan, &st->analysis);
+ &tf_estimate, &tf_chan);
if (isTransient)
shortBlocks = M;
}
@@ -1656,7 +1672,6 @@
follower[i] = HALF16(follower[i]);
follower[i] = MIN16(follower[i], QCONST16(4, DB_SHIFT));
- /* FIXME: Adaptively reduce follower at low rate or for cbr/cvbr */
width = C*(eBands[i+1]-eBands[i])<<LM;
if (width<6)
{