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sbr: fix parameter resolution in VBR mode and transient normalization #178

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Merged
fabiangreffrath merged 1 commit into from
Aug 25, 2026
+3 −2
Merged

sbr: fix parameter resolution in VBR mode and transient normalization #178

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3 changes: 2 additions & 1 deletion libfaac/frame.c
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Expand Up @@ -308,7 +308,8 @@ int faacEncApplyConfig(faacEncStruct* hEncoder,

if (hEncoder->config.aacObjectType == HE_V1) {
SBRContext *sCtx = hEncoder->sbrContext;
SbrContextUpdateConfig(sCtx, hEncoder->numChannels, hEncoder->config.bitRate * hEncoder->numChannels, &hEncoder->fft_tables);
unsigned long sbr_bitrate = hEncoder->config.bitRate ? (hEncoder->config.bitRate * hEncoder->numChannels) : ((unsigned long)hEncoder->config.quantqual * 1280);
SbrContextUpdateConfig(sCtx, hEncoder->numChannels, sbr_bitrate, &hEncoder->fft_tables);
/* kx * Fs / (2*64): each QMF band is Fs/(2*SBR_QMF_BANDS_64) Hz wide.
* Matching core bandwidth to the SBR crossover avoids a gap or overlap. */
hEncoder->config.bandWidth = SbrContextGetXOverBandwidth(sCtx);
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2 changes: 1 addition & 1 deletion libfaac/sbr_analysis.c
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Expand Up @@ -70,7 +70,7 @@ void SbrAnalyze(SignalAnalysis *sa, float *fullPtrs[], int nch, int numSamples,
}
sa->ch[ch].lastVal = val_in;

sa->ch[ch].transientStrength = smax * (float)sampled / (ssum + SBR_ENERGY_FLOOR);
sa->ch[ch].transientStrength = smax * (float)num_slots / (ssum + SBR_ENERGY_FLOOR);
sa->ch[ch].transientSlot = smax_idx;

/* Evaluate relative energy jumps to inform block switching. */
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