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Browse / github.com/storytold/effectcraft / patch
vp9enc: fixed-size SAD kernels and a revisit cache in the motion search
vp9enc: motion search evaluates a full SAD plus mv_cost for every candidate (E4) ## Proposal `crates/vp9enc/src/tile.rs`: fixed-size SAD kernels and a revisit cache in the motion search (same candidates are tested again and again). Byte-identical. A further idea (balancing the SADs of the 16x16 vector) changes the result (class c) and needs a BD-rate check; estimate -20..-30 % of the search. ## Measured Included in the encoder prototype (-54 % total); SAD search was 16 % of the base profile. Files: `crates/vp9enc/src/tile.rs`. Overlap: open PR #720 touches `tile.rs`. Measured at upstream/main on a Ryzen 7 7800X3D, release build, one thread pinned to a core, `perf stat -
- Status
- open
- Score
- 0.00
- Adopters
- 0 other operators
- Author
- vangel76 (imported from pull request #2447, open)
- Base
966719d449f0fe5a81b19d1266e4a76ac90d6bca- Size
- +43 −7 in 1 file
- Review
- pending
- Shared
- 2026-10-28
- Id
d67bc08ac33671d304f63a9c
How it went
No other operator has reported using it yet.
Diff
raw · crates/vp9enc/src/tile.rs
@@ -211,6 +211,21 @@ fn probs_defaults() -> &'static probs::Probs { D.get_or_init(probs::Probs::defaults) } +/// SAD of two N×N blocks: per-column 16-bit sums (at most 16 · 255), summed once.+#[inline(always)]+fn sad_n<const N: usize>(a: &[u8], sa: usize, b: &[u8], sb: usize) -> u32 {+ let mut acc = [0u16; N];+ for i in 0..N {+ let (Some(ra), Some(rb)) = (a.get(i * sa..).and_then(|r| r.first_chunk::<N>()), b.get(i * sb..).and_then(|r| r.first_chunk::<N>())) else {+ return u32::MAX / 4;+ };+ for j in 0..N {+ acc[j] += ra[j].abs_diff(rb[j]) as u16;+ }+ }+ acc.iter().map(|&v| v as u32).sum()+}+ // ---------------------------------------------------------------- the tile /// Per-frame coding parameters shared by the tiles.@@ -592,12 +607,18 @@ impl<'a> Tile<'a> { let (x16, y16) = (((c * 8) << 4) as i32 + 2 * mv.col, ((r * 8) << 4) as i32 + 2 * mv.row); let mut s = 0u32; if let Some((pl, o, st)) = self.f.phases.as_ref().and_then(|ph| ph.block(x16, y16, n)) {- for i in 0..n {- let a = &p.src[(r * 8 + i) * p.w + c * 8..][..n];- let b = &pl[o + i * st..o + i * st + n];- s += a.iter().zip(b).map(|(a, b)| (*a as i32 - *b as i32).unsigned_abs()).sum::<u32>();- }- return s;+ let a = &p.src[(r * 8) * p.w + c * 8..];+ let b = &pl[o..];+ return match n {+ 8 => sad_n::<8>(a, p.w, b, st),+ 16 => sad_n::<16>(a, p.w, b, st),+ _ => {+ for i in 0..n {+ s += a[i * p.w..][..n].iter().zip(&b[i * st..][..n]).map(|(a, b)| a.abs_diff(*b) as u32).sum::<u32>();+ }+ s+ }+ }; } // Inter search only runs on frames with a reference. let Some(refs) = self.f.refs.as_ref() else { return u32::MAX / 4 };@@ -621,7 +642,7 @@ impl<'a> Tile<'a> { let d = &probs_defaults().0; let mb: [u32; 4] = std::array::from_fn(|m| tree_cost(&INTER_MODE_TREE, &d[probs::INTER_MODE + mctx * 3..], m as u8)); let mode_bits = |m: u8| mb[(m - NEARESTMV) as usize];- let cost = |mv: Mv| -> f64 {+ let cost_raw = |mv: Mv| -> f64 { let bits = if mv == nearest { mode_bits(NEARESTMV) } else if mv == Mv::ZERO {@@ -633,6 +654,21 @@ impl<'a> Tile<'a> { }; self.sad(r, c, n, mv) as f64 + lambda * bits as f64 };+ // The cost is a pure function of the vector: points the search revisits (the centre it+ // came from, candidates on the diamond) are looked up instead of predicted again.+ let mut seen = [(Mv::ZERO, 0.0f64); 64];+ let mut nseen = 0usize;+ let mut cost = |mv: Mv| -> f64 {+ if let Some(&(_, j)) = seen[..nseen].iter().find(|e| e.0 == mv) {+ return j;+ }+ let j = cost_raw(mv);+ if nseen < seen.len() {+ seen[nseen] = (mv, j);+ nseen += 1;+ }+ j+ }; let mut best = (Mv::ZERO, cost(Mv::ZERO)); let prev = self.f.prev_mvs.map(|p| p[r * self.f.mi_cols + c]); for cand in [Some(nearest), Some(near), prev].into_iter().flatten() {