Struct NvencTuning 

pub(crate) struct NvencTuning {
    pub preset: GUID,
    pub multipass: NV_ENC_MULTI_PASS,
    pub spatial_aq: bool,
    pub temporal_aq: bool,
    pub hevc_high_tier: bool,
    pub slices: Option<u32>,
}

The encoder-side quality knobs of a session: the preset, the rate-control passes of a CBR session, and adaptive quantization. Production sessions take the default, which the tuning bench (gpu_bench_tuning) measures against the alternatives: P3 encodes a 1080p H.264 frame in 3.7 ms where P4 takes 5.2 ms on a V100, for 0.001 of SSIM at the same bitrate, and the presets above P4 buy nothing; a single pass saves half a millisecond but overshoots a CBR target by five to twelve percent; adaptive quantization moves neither time nor quality measurably. The quarter-resolution first pass needs the 1.5-frame VBV vbv_bits gives it: on a one-frame buffer its miss on a scene cut runs an 8 Mbit/s H.264 session at 13.7 Mbit/s (gpu_bench_cbr_rate_control). P3 holds on real content as well (gpu_bench_tuning_on_content, scrolling text and a panned texture at 1080p to 2160p): on a GTX 1080 and an RTX 4090 P1 encodes 0.5 to 2.4 ms sooner and P2 less, at most about 5% of the glass to glass latency a session of that size measures (25, 41, and 81 ms over WebSockets), and both code the text worse, by up to 0.8 dB in H.264 and 2.4 dB in AV1.

Fields

preset: GUID

multipass: NV_ENC_MULTI_PASS

spatial_aq: bool

temporal_aq: bool

Temporal adaptive quantization, refused at open where the driver reports no support for it: a Volta HEVC session given it faults inside its first encode instead of failing to open.

hevc_high_tier: bool

Whether an HEVC session declares the tier h265_tier names for its level; off opens the same session at Main tier, the ceiling gpu_hevc_high_tier_opens_above_the_main_tier_ceiling measures.

slices: Option<u32>

Slices per H.264 and HEVC frame outside a band frame’s: None in production, which is SLICES_PER_FRAME for H.264 and one for HEVC; a count to measure what slices cost (gpu_bench_slices).

Trait Implementations

impl Clone for NvencTuning

fn clone(&self) -> NvencTuning

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for NvencTuning

impl Debug for NvencTuning

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for NvencTuning

fn default() -> Self

Returns the “default value” for a type.