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Avoid dropping the 1024-point FFT until at least ratio 1.5

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Chris Cannam
2022-06-15 09:40:09 +01:00
parent 136c546955
commit a61a4f3201
1 changed files with 12 additions and 6 deletions
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18
src/finer/R3StretcherImpl.cpp
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@@ -248,12 +248,18 @@ R3StretcherImpl::calculateHop()
// outhop = 256 at ratios around 1, reducing down to 128 for
// ratios far below 1 and up to 512 for ratios far above. As soon
// as outhop exceeds 256 we have to drop the 1024-bin FFT, as the
// overlap will be inadequate for it. That's among the jobs of the
// Guide class. (We can't go above 512 without changing the window
// shape or dropping the 2048-bin FFT, and we can't do either of
// those dynamically.)
double proposedOuthop = pow(2.0, 8.0 + 2.0 * log10(ratio));
// overlap will be inadequate for it (that's among the jobs of the
// Guide class) so we don't want to go above 256 until at least
// factor 1.5. Also we can't go above 512 without changing the
// window shape or dropping the 2048-bin FFT, and we can't do
// either of those dynamically.
double proposedOuthop = 256.0;
if (ratio > 1.5) {
proposedOuthop = pow(2.0, 8.0 + 2.0 * log10(ratio - 0.5));
} else if (ratio < 1.0) {
proposedOuthop = pow(2.0, 8.0 + 2.0 * log10(ratio));
}
if (proposedOuthop > 512.0) proposedOuthop = 512.0;
if (proposedOuthop < 128.0) proposedOuthop = 128.0;