add option to auto adjust levels using hsync to sync ratio - #314
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This was referenced Jul 17, 2026
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Description
Adds optional functionality to
--ire0_adjustthat fixes brightness variations caused by automatic gain control.Motivation
Some VCRs have automatic gain control that change the video levels of the source before recording to tape. When decoding a tape that had AGC enabled and active, this can result in sudden changes in amount of frequency deviation assigned to 1 IRE unit. This visually appears as sudden overall brightness changes.
This change automatically corrects levels on a per-field basis using the measured ratio between the hsync pulse levels and the black level so the video maintains a consistent brightness.
Changes Made
--ire0_adjustoptionbackporchWhatire0_adjustuses currently, and is defaulted when--ire0_adjustis supplied without an argumenthsyncThe new level correction that uses the ratio between the hsync pulse and the black level