diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/analysis.c | 51 |
1 files changed, 31 insertions, 20 deletions
diff --git a/src/analysis.c b/src/analysis.c index 1d6dd829..2e3913c9 100644 --- a/src/analysis.c +++ b/src/analysis.c @@ -432,6 +432,7 @@ static void tonality_analysis(TonalityAnalysisState *tonal, const CELTMode *celt float alpha, alphaE, alphaE2; float frame_loudness; float bandwidth_mask; + int is_masked[NB_TBANDS+1]; int bandwidth=0; float maxE = 0; float noise_floor; @@ -449,7 +450,9 @@ static void tonality_analysis(TonalityAnalysisState *tonal, const CELTMode *celt alpha = 1.f/IMIN(10, 1+tonal->count); alphaE = 1.f/IMIN(25, 1+tonal->count); - alphaE2 = 1.f/IMIN(500, 1+tonal->count); + /* Noise floor related decay for bandwidth detection: -2.2 dB/second */ + alphaE2 = 1.f/IMIN(100, 1+tonal->count); + if (tonal->count <= 1) alphaE2 = 1; if (tonal->Fs == 48000) { @@ -722,6 +725,7 @@ static void tonality_analysis(TonalityAnalysisState *tonal, const CELTMode *celt for (b=0;b<NB_TBANDS;b++) { float E=0; + float Em; int band_start, band_end; /* Keep a margin of 300 Hz for aliasing */ band_start = tbands[b]; @@ -735,40 +739,47 @@ static void tonality_analysis(TonalityAnalysisState *tonal, const CELTMode *celt E = SCALE_ENER(E); maxE = MAX32(maxE, E); tonal->meanE[b] = MAX32((1-alphaE2)*tonal->meanE[b], E); - E = MAX32(E, tonal->meanE[b]); - /* Use a simple follower with 13 dB/Bark slope for spreading function */ - bandwidth_mask = MAX32(.05f*bandwidth_mask, E); + Em = MAX32(E, tonal->meanE[b]); /* 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 + 1) 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 + 2) above the PCM quantization noise floor We use b+1 because the first CELT band isn't included in tbands[] */ - if (E>.1*bandwidth_mask && E*1e9f > maxE && E > noise_floor*(band_end-band_start)) + if (E*1e9f > maxE && (Em > 3*noise_floor*(band_end-band_start) || E > noise_floor*(band_end-band_start))) bandwidth = b+1; + /* Check if the band is masked (see below). */ + is_masked[b] = E < (tonal->prev_bandwidth >= b+1 ? .01f : .05f)*bandwidth_mask; + /* Use a simple follower with 13 dB/Bark slope for spreading function. */ + bandwidth_mask = MAX32(.05f*bandwidth_mask, E); } /* Special case for the last two bands, for which we don't have spectrum but only - the energy above 12 kHz. */ + the energy above 12 kHz. The difficulty here is that the high-pass we use + leaks some LF energy, so we need to increase the threshold without accidentally cutting + off the band. */ if (tonal->Fs == 48000) { - float ratio; - float E = hp_ener*(1.f/(240*240)); - ratio = tonal->prev_bandwidth==20 ? 0.03f : 0.07f; + float noise_ratio; + float Em; + float E = hp_ener*(1.f/(60*60)); + noise_ratio = tonal->prev_bandwidth==20 ? 10.f : 30.f; + #ifdef FIXED_POINT /* silk_resampler_down2_hp() shifted right by an extra 8 bits. */ E *= 256.f*(1.f/Q15ONE)*(1.f/Q15ONE); #endif - maxE = MAX32(maxE, E); tonal->meanE[b] = MAX32((1-alphaE2)*tonal->meanE[b], E); - E = MAX32(E, tonal->meanE[b]); - /* Use a simple follower with 13 dB/Bark slope for spreading function */ - bandwidth_mask = MAX32(.05f*bandwidth_mask, E); - if (E>ratio*bandwidth_mask && E*1e9f > maxE && E > noise_floor*160) - bandwidth = 20; - /* This detector is unreliable, so if the bandwidth is close to SWB, assume it's FB. */ - if (bandwidth >= 17) + Em = MAX32(E, tonal->meanE[b]); + if (Em > 3*noise_ratio*noise_floor*160 || E > noise_ratio*noise_floor*160) bandwidth = 20; + /* Check if the band is masked (see below). */ + is_masked[b] = E < (tonal->prev_bandwidth == 20 ? .01f : .05f)*bandwidth_mask; } + /* In some cases, resampling aliasing can create a small amount of energy in the first band + being cut. So if the last band is masked, we don't include it. */ + if (bandwidth == 20 && is_masked[NB_TBANDS]) + bandwidth-=2; + else if (bandwidth > 0 && bandwidth <= NB_TBANDS && is_masked[bandwidth-1]) + bandwidth--; if (tonal->count<=2) bandwidth = 20; frame_loudness = 20*(float)log10(frame_loudness); |