colconv 0.1.0

SIMD-dispatched color-conversion kernels covering the FFmpeg AVPixelFormat space, with a Sink-based API so consumers pick which derived outputs (RGB / Luma / HSV / custom) they want without paying for the ones they don't.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164

use super::super::*;
use crate::{ColorMatrix, row::scalar};

/// Build a deterministic pseudo-random VUYA packed stream.
/// Returns `width * 4` bytes with channels varying across all 8-bit values.
fn pseudo_random_vuya(width: usize, seed: usize) -> std::vec::Vec<u8> {
  (0..width * 4)
    .map(|i| {
      let s = i.wrapping_mul(seed).wrapping_add(seed.wrapping_mul(3));
      (s & 0xFF) as u8
    })
    .collect()
}

fn check_rgb<const ALPHA: bool, const ALPHA_SRC: bool>(
  width: usize,
  matrix: ColorMatrix,
  full_range: bool,
) {
  let p = pseudo_random_vuya(width, 0xAA55);
  let bpp = if ALPHA { 4 } else { 3 };
  let mut s = std::vec![0u8; width * bpp];
  let mut k = std::vec![0u8; width * bpp];
  scalar::vuya_to_rgb_or_rgba_row::<ALPHA, ALPHA_SRC>(&p, &mut s, width, matrix, full_range);
  unsafe {
    vuya_to_rgb_or_rgba_row::<ALPHA, ALPHA_SRC>(&p, &mut k, width, matrix, full_range);
  }
  assert_eq!(
    s,
    k,
    "AVX2 vuya<ALPHA={ALPHA}, ALPHA_SRC={ALPHA_SRC}>→{} diverges (width={width}, matrix={matrix:?}, full_range={full_range})",
    if ALPHA { "RGBA" } else { "RGB" }
  );
}

fn check_luma(width: usize) {
  let p = pseudo_random_vuya(width, 0xC001);
  let mut s = std::vec![0u8; width];
  let mut k = std::vec![0u8; width];
  scalar::vuya_to_luma_row(&p, &mut s, width);
  unsafe {
    vuya_to_luma_row(&p, &mut k, width);
  }
  assert_eq!(s, k, "AVX2 vuya→luma diverges (width={width})");
}

fn check_luma_u16(width: usize) {
  let p = pseudo_random_vuya(width, 0xBEEF);
  let mut s = std::vec![0u16; width];
  let mut k = std::vec![0u16; width];
  scalar::vuya_to_luma_u16_row(&p, &mut s, width);
  unsafe {
    vuya_to_luma_u16_row(&p, &mut k, width);
  }
  assert_eq!(s, k, "AVX2 vuya→luma_u16 diverges (width={width})");
}

/// Build a VUYA packed stream with Y[n] = n+1, A[n] = 2n+1, V=U=128.
///
/// VUYA layout per pixel: `[V(8), U(8), Y(8), A(8)]`. Source α is real
/// (not padding). Encoding:
/// - V = 128 (neutral 8-bit midpoint)
/// - U = 128 (neutral)
/// - Y[n] = n + 1
/// - A[n] = 2n + 1  (source α — distinct values per pixel)
fn build_vuya_packed_y_n_plus_1_a_2n_plus_1_u_v_neutral(width: usize) -> std::vec::Vec<u8> {
  let mut packed = std::vec![0u8; width * 4];
  for n in 0..width {
    packed[n * 4] = 128; // V
    packed[n * 4 + 1] = 128; // U
    packed[n * 4 + 2] = (n as u8) + 1; // Y = n+1
    packed[n * 4 + 3] = (n as u8) * 2 + 1; // A = 2n+1
  }
  packed
}

/// Multi-channel lane-order regression — encodes pixel index in
/// BOTH Y AND A so we catch per-channel asymmetric mask bugs that
/// the previous Y-only test would miss. Pattern from Ship 12d
/// AYUV64 backport. VUYA has source α — assert the α slot directly.
///
/// AVX2 SIMD threshold: 32 px/iter. W=64 covers exactly 2 full
/// SIMD iterations.
#[test]
#[cfg_attr(
  miri,
  ignore = "SIMD-dispatched row kernels use intrinsics unsupported by Miri"
)]
fn avx2_vuya_lane_order_per_pixel_y_and_a() {
  if !std::arch::is_x86_feature_detected!("avx2") {
    return;
  }
  const W: usize = 64;
  let packed = build_vuya_packed_y_n_plus_1_a_2n_plus_1_u_v_neutral(W);

  // Part 1: Luma natural-order (u8 path, Y is direct).
  let mut luma = std::vec![0u8; W];
  unsafe {
    vuya_to_luma_row(&packed, &mut luma, W);
  }
  let expected_luma: std::vec::Vec<u8> = (1..=W as u8).collect();
  assert_eq!(luma, expected_luma, "avx2 vuya luma reorder bug");

  // Part 2: u8 RGBA — α slot (every 4th byte) directly verifies
  // A-channel deinterleave. neutral U/V → chroma contribution is zero.
  let mut rgba = std::vec![0u8; W * 4];
  unsafe {
    vuya_to_rgb_or_rgba_row::<true, true>(&packed, &mut rgba, W, ColorMatrix::Bt709, false);
  }
  let alpha_out: std::vec::Vec<u8> = (0..W).map(|n| rgba[n * 4 + 3]).collect();
  let expected_alpha: std::vec::Vec<u8> = (0..W).map(|n| (n as u8) * 2 + 1).collect();
  assert_eq!(alpha_out, expected_alpha, "avx2 vuya rgba α reorder bug");
}

#[test]
#[cfg_attr(
  miri,
  ignore = "SIMD-dispatched row kernels use intrinsics unsupported by Miri"
)]
fn avx2_vuya_matches_scalar_widths() {
  if !std::arch::is_x86_feature_detected!("avx2") {
    return;
  }
  // Width sweep covers:
  //   - tail-only widths < 32 (no SIMD main loop)
  //   - the SIMD block-boundary 32 (one main-loop iteration, no tail)
  //   - partial-block-plus-tail 47/48/49 (one main-loop + 15/16/17-px tail)
  //   - production 1920p widths and odd tails (1921, 1923).
  for w in [
    1usize, 2, 3, 15, 16, 17, 31, 32, 33, 47, 48, 49, 1920, 1921, 1923,
  ] {
    check_rgb::<false, false>(w, ColorMatrix::Bt709, false);
    check_rgb::<true, true>(w, ColorMatrix::Bt709, true);
    check_rgb::<true, false>(w, ColorMatrix::Bt2020Ncl, true);
    check_luma(w);
    check_luma_u16(w);
  }
}

#[test]
#[cfg_attr(
  miri,
  ignore = "SIMD-dispatched row kernels use intrinsics unsupported by Miri"
)]
fn avx2_vuya_rgb_matches_scalar_all_matrices() {
  if !std::arch::is_x86_feature_detected!("avx2") {
    return;
  }
  for m in [
    ColorMatrix::Bt601,
    ColorMatrix::Bt709,
    ColorMatrix::Bt2020Ncl,
    ColorMatrix::Smpte240m,
    ColorMatrix::Fcc,
    ColorMatrix::YCgCo,
  ] {
    for full in [true, false] {
      // Width 32 = one main-loop iteration (no tail).
      check_rgb::<false, false>(32, m, full);
      check_rgb::<true, true>(32, m, full);
      check_rgb::<true, false>(32, m, full);
    }
  }
}