atrac3: reimplement tonal encoding. Use flatness-based tonal extraction#66
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dcherednik
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Apr 19, 2026
dcherednik
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- Add shared CalcSpectralFlatnessPerBfu helper in atrac_psy_common with BFU-table mapping.
- Implement ATRAC3 tonal extraction: compute MDCT energy, estimate per-BFU flatness, extract up to 5-bin strongest tonal run in low-flatness BFUs, and zero extracted bins in residual.
- Map extracted tonal bins into TTonalBlocks and integrate them into bitstream coding.
- Update ATRAC3 bit allocation - reduce residual bits for BFUs with tonal blocks, and increase tonal quantizer selection.
- Restore --notonal CLI option in main.cpp for A/B comparison.
- Add shared CalcSpectralFlatnessPerBfu helper in atrac_psy_common with BFU-table mapping. - Implement ATRAC3 tonal extraction: compute MDCT energy, estimate per-BFU flatness, extract up to 5-bin strongest tonal run in low-flatness BFUs, and zero extracted bins in residual. - Map extracted tonal bins into TTonalBlocks and integrate them into bitstream coding. - Update ATRAC3 bit allocation - reduce residual bits for BFUs with tonal blocks, and increase tonal quantizer selection. - Restore --notonal CLI option in main.cpp for A/B comparison.
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