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b=865241 always leave 20 samples of headroom when extracting group delay, removing the discontinuity at delay = 20 r=ehsan

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--HG--
extra : rebase_source : 30515ea2236b7503ff7e446d50930f91135bc7e0
This commit is contained in:
Karl Tomlinson 2013-08-08 21:38:29 +12:00
parent 7ec61fbe98
commit f2b27a4c67
1 changed files with 6 additions and 5 deletions
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11
content/media/webaudio/FFTBlock.cpp
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@ -165,6 +165,9 @@ double FFTBlock::ExtractAverageGroupDelay()
const double kSamplePhaseDelay = (2.0 * M_PI) / double(FFTSize());
// Remove DC offset
dft[0].r = 0.0f;
// Calculate weighted average group delay
for (int i = 1; i < halfSize; i++) {
Complex c(dft[i].r, dft[i].i);
@ -189,15 +192,13 @@ double FFTBlock::ExtractAverageGroupDelay()
double aveSampleDelay = -ave / kSamplePhaseDelay;
// Leave 20 sample headroom (for leading edge of impulse)
if (aveSampleDelay > 20.0)
aveSampleDelay -= 20.0;
aveSampleDelay -= 20.0;
if (aveSampleDelay <= 0.0)
return 0.0;
// Remove average group delay (minus 20 samples for headroom)
AddConstantGroupDelay(-aveSampleDelay);
// Remove DC offset
dft[0].r = 0.0f;
return aveSampleDelay;
}