Hifi Decode Filters and Expander fixes#181

Merged

harrypm merged 4 commits intooyvindln:vhs_decodefrom

eshaz:hifi-decode-enhance

Jan 25, 2025

eshaz commented Jan 25, 2025

Merge in recent changes in vhs-decode/hifi-decode and improve expander to more closely match baseband output.

Use shelving filters for expander gate weighting and audio deemphasis
- See https://github.com/oyvindln/vhs-decode/blob/20f89dd4de1782bd315caecc0c274160455da5fd/vhsdecode/hifi/HiFiDecode.py
Rewire filters to match VHS Hi-Fi Spec.
- See rewire filters to match spec diagram #180
- Spec docs: https://archive.org/details/video-technical-guide/page/7-6/mode/2up
Use 1:2 logarithic expander to match VHS Hi-Fi spec
- Spec docs: https://archive.org/details/iec60774-2-1999/page/n12/mode/1up
Tune envelope gain to match VHS Hi-Fi baseband output levels.

eshaz and others added 4 commits

January 24, 2025 21:49


          apply videomem shelving filters commit

b44bbc0

Co-authored-by: VideoMem <sebastian.wilwerth@gmail.com>


          rewire filters to match spec diagram

c1fba8b


          use steeper log curve for expander

73c102a


          tune expander parameters

3b4a91f

harrypm merged commit 0d2767c into oyvindln:vhs_decode

eshaz deleted the hifi-decode-enhance branch

January 25, 2025 10:28

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