Skip to main content

amf_av1_params

codec::encode::tuning

Function amf_av1_params 

Source 
pub fn amf_av1_params(
    target: QualityTarget,
    tier: SpeedTier,
    width: u32,
    height: u32,
) -> AmfAv1Params
Expand description

Derive AMD AMF AV1 params for a given quality target + speed tier + resolution.

AMF’s AV1 q-index scale is 0..255 (the full AV1 quantizer range, not the NVENC-style 0..63 CQ band). Start point is rav1e’s 4 × libaom_cq rule, then apply an 8-point calibration shift down to compensate for VCN’s documented compression-efficiency gap vs libaom (same goughlui study that calibrated NVENC’s 3-4-point CQ shift tested AMF VCN and reported an analogous ~2-point CQ-equivalent shift; 2 points × 4 ≈ 8 in the 0..255 space).

TODO(calibrate): replace these seed anchors with calibrated values once av1-tuning-eng runs the offline VMAF pass on RDNA3 hardware. See docs/av1-tuning-research.md §2.5 for the calibration protocol.