aleleba/effectcraft
1
0
Fork 0
mirror of https://github.com/storytold/effectcraft.git synced 2026-10-30 04:57:54 -06:00
Code Issues Packages Projects Releases Wiki Activity

vp9enc: forward transform accumulates all outputs together (#2412)

Browse Source 
The 16 outputs of the 4x4 forward transform are accumulated together in the
same order as before (no serial add chain per output) and the quantiser
truncates instead of calling floor on a non-negative value. The output is
byte-identical.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
This commit is contained in:
vangel76
2026-10-26 00:33:55 +01:00
co-authored by Claude Sonnet 5.5
parent 966719d449
commit f3fcea8297
1 changed files with 24 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files
crates/vp9enc/src/transform.rs
+24 -3
View File
@@ -144,6 +144,16 @@ pub fn forward_matrices() -> &'static [[[f64; 16]; 16]; 4] {
})
}
/// [`forward_matrices`] transposed: `[type][q][k]`.
fn forward_matrices_t() -> &'static [[[f64; 16]; 16]; 4] {
use std::sync::OnceLock;
static M: OnceLock<[[[f64; 16]; 16]; 4]> = OnceLock::new();
M.get_or_init(|| {
let f = forward_matrices();
std::array::from_fn(|t| std::array::from_fn(|q| std::array::from_fn(|k| f[t][k][q])))
})
}
fn invert16(m: [[f64; 16]; 16]) -> [[f64; 16]; 16] {
let mut a = m;
let mut inv = [[0.0; 16]; 16];
@@ -191,12 +201,23 @@ impl Quant {
if self.lossless {
return forward_wht(res);
}
let f = &forward_matrices()[tx_type as usize];
let ft = &forward_matrices_t()[tx_type as usize];
// Every output accumulates its 16 products in the same order (q ascending) as a
// per-output sum, but the 16 outputs advance together: 16 independent chains that
// vectorize instead of one serial chain per output.
let mut acc = [-0.0f64; 16];
for (q, col) in ft.iter().enumerate() {
let r = res[q] as f64;
for k in 0..16 {
acc[k] += col[k] * r;
}
}
let mut lv = [0i32; 16];
for k in 0..16 {
let coef: f64 = (0..16).map(|q| f[k][q] * res[q] as f64).sum();
let coef = acc[k];
let (qs, rnd) = if k == 0 { (self.dcq, self.round_dc) } else { (self.acq, self.round_ac) };
let l = (coef.abs() / qs as f64 + rnd).floor() as i32;
// Non-negative: truncation is floor.
let l = (coef.abs() / qs as f64 + rnd) as i32;
lv[k] = if coef < 0.0 { -l } else { l };
}
lv