quantize: restore short-window masking penalty to fix energy drops#103
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Commit 577c649 ("initial windows grouping support") split bmask() into short- and long-window branches and introduced `target *= 1.5` for short blocks. This inflated the psychoacoustic masking threshold 50%, causing the quantizer to allocate too few bits during transients and producing audible energy drops. Restore the pre-577c6499 multiplier of SHORT_PENALTY (0.45), which tightens the masking target for short-window blocks. Extract the formula constants as named macros: NOISETONE (noise-floor weight), TONEMASK (tone-masking component weight), and SHORT_PENALTY (short-window quality penalty) — keeping them separate so each can be tuned independently.
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@nschimme yes, I can confirm that this fixes the issue. Thank you very much for investigating this again! |
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@fabiangreffrath we're safe to merge then :-) |
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Commit 577c649 ("initial windows grouping support") split bmask() into short- and long-window branches and introduced
target *= 1.5for short blocks. This inflated the psychoacoustic masking threshold 50%, causing the quantizer to allocate too few bits during transients and producing audible energy drops.Restore the pre-577c6499 multiplier of SHORT_PENALTY (0.45), which tightens the masking target for short-window blocks. Extract the formula constants as named macros: NOISETONE (noise-floor weight), TONEMASK (tone-masking component weight), and SHORT_PENALTY (short-window quality penalty) — keeping them separate so each can be tuned independently.
Benchmark report shows no performance changes but some changes in psychoacoustic model as expected where the benefits outweigh the negatives: https://github.com/nschimme/faac/actions/runs/25871625558