videoFilter

A video filter chain attached at open: a compiled filter description, or a raw FFmpeg chain like scale=1280:720,eq=brightness=0.1. Every decoded frame runs through it before presentation. Filters run on SOFTWARE frames: under HwdecPolicy.Auto or Prefer the hardware route stands down with a warning, and under Require the video track is refused, because both demands cannot hold at once. Timebase-preserving chains only (scale, crop, eq, format and friends); runtime hot-swap is a documented non-goal.