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Slight simplification of the bandwidth detection code

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New code is especially easier to justify
This commit is contained in:
Jean-Marc Valin 2013-05-13 22:35:09 -04:00
parent 3e6691a703
commit 6862b44e7d
1 changed files with 11 additions and 13 deletions
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24
src/analysis.c
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@ -225,7 +225,7 @@ void tonality_analysis(TonalityAnalysisState *tonal, AnalysisInfo *info_out, con
tonal->last_transition++;
alpha = 1.f/IMIN(20, 1+tonal->count);
alphaE = 1.f/IMIN(50, 1+tonal->count);
alphaE2 = 1.f/IMIN(6000, 1+tonal->count);
alphaE2 = 1.f/IMIN(1000, 1+tonal->count);
if (tonal->count<4)
tonal->music_prob = .5;
@ -375,8 +375,7 @@ void tonality_analysis(TonalityAnalysisState *tonal, AnalysisInfo *info_out, con
bandwidth_mask = 0;
bandwidth = 0;
for (b=0;b<NB_TOT_BANDS;b++)
maxE = MAX32(maxE, tonal->meanE[b]);
maxE = 0;
noise_floor = 5.7e-4f/(1<<(IMAX(0,lsb_depth-8)));
noise_floor *= noise_floor;
for (b=0;b<NB_TOT_BANDS;b++)
@ -392,19 +391,18 @@ void tonality_analysis(TonalityAnalysisState *tonal, AnalysisInfo *info_out, con
+ out[i].i*out[i].i + out[N-i].i*out[N-i].i;
E += binE;
}
E /= (band_end-band_start);
maxE = MAX32(maxE, E);
if (tonal->count>2)
{
tonal->meanE[b] = (1-alphaE2)*tonal->meanE[b] + alphaE2*E;
} else {
tonal->meanE[b] = E;
}
tonal->meanE[b] = MAX32((1-alphaE2)*tonal->meanE[b], E);
E = MAX32(E, tonal->meanE[b]);
/* 13 dB slope for spreading function */
/* Use a simple follower with 13 dB/Bark slope for spreading function */
bandwidth_mask = MAX32(.05f*bandwidth_mask, E);
/* Checks if band looks like stationary noise or if it's below a (trivial) masking curve */
if (E>.1*bandwidth_mask && E*1e10f > maxE && E > noise_floor)
/* Consider the band "active" only if all these conditions are met:
1) less than 10 dB below the simple follower
2) less than 90 dB below the peak band (maximal masking possible considering
both the ATH and the loudness-dependent slope of the spreading function)
3) above the PCM quantization noise floor
*/
if (E>.1*bandwidth_mask && E*1e9f > maxE && E > noise_floor*(band_end-band_start))
bandwidth = b;
}
if (tonal->count<=2)