Function held_refresh_quality 

pub fn held_refresh_quality(
    settings: &CaptureSettings,
    encoder: EncoderQuality,
) -> u32

The quality index a refresh held in one frame (a predicted frame) is coded at: the paint-over one, or, where a constant rate last coded far coarser, as much finer than that as HELD_KEY_BUDGET_S of the target allows at six steps a doubling, since a refresh of a whole screen at the paint-over quantizer after heavy motion at a low rate would cost many frames of budget at once. The bands of the sweep a cleanup through the rate control falls back to, each sized to a frame’s budget, are coded at the paint-over quantizer instead: counted from the rate control’s last quantizer, which a key frame after a loss leaves at the coarsest, the sweep ended up to 13 dB short of it at 8 fps.