gamut-av1 0.2.0

AV1 image encoder and decoder (intra-frame coding, the basis for AVIF).
Documentation 
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//! Default CDF tables (AV1 §9.4), the 4×4 scan (§9.2), and the constant context-offset tables
//! (§8.3.2) needed by the M0 lossless encoder.
//!
//! Only the slices the encoder touches are included: `base_q_idx == 0` ⇒ coefficient-CDF quant
//! context 0, and `TX_4X4` only. CDFs are stored in the spec's cumulative form (rising to 32768)
//! with the trailing adaptation-count element dropped, so each row is ready to pass straight to
//! [`gamut_bitstream::SymbolEncoder::encode_symbol`] (the M0 frame sets `disable_cdf_update = 1`,
//! so the tables are never adapted). These values are extracted verbatim from the specification.

// --- Partition CDFs (Default_Partition_W*_Cdf), indexed [ctx]. ---
/// `Default_Partition_W8_Cdf` (4 partitions: NONE/HORZ/VERT/SPLIT).
pub static PARTITION_W8: [[u16; 4]; 4] = [
    [19132, 25510, 30392, 32768],
    [13928, 19855, 28540, 32768],
    [12522, 23679, 28629, 32768],
    [9896, 18783, 25853, 32768],
];
/// `Default_Partition_W16_Cdf` (10 partition types).
pub static PARTITION_W16: [[u16; 10]; 4] = [
    [
        15597, 20929, 24571, 26706, 27664, 28821, 29601, 30571, 31902, 32768,
    ],
    [
        7925, 11043, 16785, 22470, 23971, 25043, 26651, 28701, 29834, 32768,
    ],
    [
        5414, 13269, 15111, 20488, 22360, 24500, 25537, 26336, 32117, 32768,
    ],
    [
        2662, 6362, 8614, 20860, 23053, 24778, 26436, 27829, 31171, 32768,
    ],
];
/// `Default_Partition_W32_Cdf`.
pub static PARTITION_W32: [[u16; 10]; 4] = [
    [
        18462, 20920, 23124, 27647, 28227, 29049, 29519, 30178, 31544, 32768,
    ],
    [
        7689, 9060, 12056, 24992, 25660, 26182, 26951, 28041, 29052, 32768,
    ],
    [
        6015, 9009, 10062, 24544, 25409, 26545, 27071, 27526, 32047, 32768,
    ],
    [
        1394, 2208, 2796, 28614, 29061, 29466, 29840, 30185, 31899, 32768,
    ],
];
/// `Default_Partition_W64_Cdf`.
pub static PARTITION_W64: [[u16; 10]; 4] = [
    [
        20137, 21547, 23078, 29566, 29837, 30261, 30524, 30892, 31724, 32768,
    ],
    [
        6732, 7490, 9497, 27944, 28250, 28515, 28969, 29630, 30104, 32768,
    ],
    [
        5945, 7663, 8348, 28683, 29117, 29749, 30064, 30298, 32238, 32768,
    ],
    [
        870, 1212, 1487, 31198, 31394, 31574, 31743, 31881, 32332, 32768,
    ],
];

/// `Default_Skip_Cdf`, indexed [ctx].
pub static SKIP: [[u16; 2]; 3] = [[31671, 32768], [16515, 32768], [4576, 32768]];

/// `Default_Intra_Frame_Y_Mode_Cdf[0][0]` (above/left both `DC_PRED`).
pub static INTRA_FRAME_Y_MODE_DC_DC: [u16; 13] = [
    15588, 17027, 19338, 20218, 20682, 21110, 21825, 23244, 24189, 28165, 29093, 30466, 32768,
];

/// `Default_Uv_Mode_Cfl_Not_Allowed_Cdf[DC_PRED]` (blocks larger than 4×4 in 4:4:4 lossless).
pub static UV_MODE_CFL_NOT_ALLOWED_DC: [u16; 13] = [
    22631, 24152, 25378, 25661, 25986, 26520, 27055, 27923, 28244, 30059, 30941, 31961, 32768,
];
/// `Default_Uv_Mode_Cfl_Allowed_Cdf[DC_PRED]` (4×4 blocks in lossless).
pub static UV_MODE_CFL_ALLOWED_DC: [u16; 14] = [
    10407, 11208, 12900, 13181, 13823, 14175, 14899, 15656, 15986, 20086, 20995, 22455, 24212,
    32768,
];

// --- Coefficient CDFs (quant context 0, TX_4X4). ---
/// `Default_Txb_Skip_Cdf[0][TX_4X4]`, indexed [ctx].
pub static TXB_SKIP: [[u16; 2]; 13] = [
    [31849, 32768],
    [5892, 32768],
    [12112, 32768],
    [21935, 32768],
    [20289, 32768],
    [27473, 32768],
    [32487, 32768],
    [7654, 32768],
    [19473, 32768],
    [29984, 32768],
    [9961, 32768],
    [30242, 32768],
    [32117, 32768],
];
/// `Default_Eob_Pt_16_Cdf[0]`, indexed [ptype][ctx].
pub static EOB_PT_16: [[[u16; 5]; 2]; 2] = [
    [
        [840, 1039, 1980, 4895, 32768],
        [370, 671, 1883, 4471, 32768],
    ],
    [
        [3247, 4950, 9688, 14563, 32768],
        [1904, 3354, 7763, 14647, 32768],
    ],
];
/// `Default_Eob_Extra_Cdf[0][TX_4X4]`, indexed [ptype][eobPt-3].
pub static EOB_EXTRA: [[[u16; 2]; 9]; 2] = [
    [
        [16961, 32768],
        [17223, 32768],
        [7621, 32768],
        [16384, 32768],
        [16384, 32768],
        [16384, 32768],
        [16384, 32768],
        [16384, 32768],
        [16384, 32768],
    ],
    [
        [19069, 32768],
        [22525, 32768],
        [13377, 32768],
        [16384, 32768],
        [16384, 32768],
        [16384, 32768],
        [16384, 32768],
        [16384, 32768],
        [16384, 32768],
    ],
];
/// `Default_Dc_Sign_Cdf[0]`, indexed [ptype][ctx].
pub static DC_SIGN: [[[u16; 2]; 3]; 2] = [
    [[16000, 32768], [13056, 32768], [18816, 32768]],
    [[15232, 32768], [12928, 32768], [17280, 32768]],
];
/// `Default_Coeff_Base_Eob_Cdf[0][TX_4X4]`, indexed [ptype][ctx].
pub static COEFF_BASE_EOB: [[[u16; 3]; 4]; 2] = [
    [
        [17837, 29055, 32768],
        [29600, 31446, 32768],
        [30844, 31878, 32768],
        [24926, 28948, 32768],
    ],
    [
        [21365, 30026, 32768],
        [30512, 32423, 32768],
        [31658, 32621, 32768],
        [29630, 31881, 32768],
    ],
];
/// `Default_Coeff_Base_Cdf[0][TX_4X4]`, indexed [ptype][ctx] (42 contexts).
pub static COEFF_BASE: [[[u16; 4]; 42]; 2] = [
    [
        [4034, 8930, 12727, 32768],
        [18082, 29741, 31877, 32768],
        [12596, 26124, 30493, 32768],
        [9446, 21118, 27005, 32768],
        [6308, 15141, 21279, 32768],
        [2463, 6357, 9783, 32768],
        [20667, 30546, 31929, 32768],
        [13043, 26123, 30134, 32768],
        [8151, 18757, 24778, 32768],
        [5255, 12839, 18632, 32768],
        [2820, 7206, 11161, 32768],
        [8192, 16384, 24576, 32768],
        [8192, 16384, 24576, 32768],
        [8192, 16384, 24576, 32768],
        [8192, 16384, 24576, 32768],
        [8192, 16384, 24576, 32768],
        [8192, 16384, 24576, 32768],
        [8192, 16384, 24576, 32768],
        [8192, 16384, 24576, 32768],
        [8192, 16384, 24576, 32768],
        [8192, 16384, 24576, 32768],
        [15736, 27553, 30604, 32768],
        [11210, 23794, 28787, 32768],
        [5947, 13874, 19701, 32768],
        [4215, 9323, 13891, 32768],
        [2833, 6462, 10059, 32768],
        [19605, 30393, 31582, 32768],
        [13523, 26252, 30248, 32768],
        [8446, 18622, 24512, 32768],
        [3818, 10343, 15974, 32768],
        [1481, 4117, 6796, 32768],
        [22649, 31302, 32190, 32768],
        [14829, 27127, 30449, 32768],
        [8313, 17702, 23304, 32768],
        [3022, 8301, 12786, 32768],
        [1536, 4412, 7184, 32768],
        [22354, 29774, 31372, 32768],
        [14723, 25472, 29214, 32768],
        [6673, 13745, 18662, 32768],
        [2068, 5766, 9322, 32768],
        [8192, 16384, 24576, 32768],
        [8192, 16384, 24576, 32768],
    ],
    [
        [6302, 16444, 21761, 32768],
        [23040, 31538, 32475, 32768],
        [15196, 28452, 31496, 32768],
        [10020, 22946, 28514, 32768],
        [6533, 16862, 23501, 32768],
        [3538, 9816, 15076, 32768],
        [24444, 31875, 32525, 32768],
        [15881, 28924, 31635, 32768],
        [9922, 22873, 28466, 32768],
        [6527, 16966, 23691, 32768],
        [4114, 11303, 17220, 32768],
        [8192, 16384, 24576, 32768],
        [8192, 16384, 24576, 32768],
        [8192, 16384, 24576, 32768],
        [8192, 16384, 24576, 32768],
        [8192, 16384, 24576, 32768],
        [8192, 16384, 24576, 32768],
        [8192, 16384, 24576, 32768],
        [8192, 16384, 24576, 32768],
        [8192, 16384, 24576, 32768],
        [8192, 16384, 24576, 32768],
        [20201, 30770, 32209, 32768],
        [14754, 28071, 31258, 32768],
        [8378, 20186, 26517, 32768],
        [5916, 15299, 21978, 32768],
        [4268, 11583, 17901, 32768],
        [24361, 32025, 32581, 32768],
        [18673, 30105, 31943, 32768],
        [10196, 22244, 27576, 32768],
        [5495, 14349, 20417, 32768],
        [2676, 7415, 11498, 32768],
        [24678, 31958, 32585, 32768],
        [18629, 29906, 31831, 32768],
        [9364, 20724, 26315, 32768],
        [4641, 12318, 18094, 32768],
        [2758, 7387, 11579, 32768],
        [25433, 31842, 32469, 32768],
        [18795, 29289, 31411, 32768],
        [7644, 17584, 23592, 32768],
        [3408, 9014, 15047, 32768],
        [8192, 16384, 24576, 32768],
        [8192, 16384, 24576, 32768],
    ],
];
/// `Default_Coeff_Br_Cdf[0][TX_4X4]`, indexed [ptype][ctx] (21 level contexts).
pub static COEFF_BR: [[[u16; 4]; 21]; 2] = [
    [
        [14298, 20718, 24174, 32768],
        [12536, 19601, 23789, 32768],
        [8712, 15051, 19503, 32768],
        [6170, 11327, 15434, 32768],
        [4742, 8926, 12538, 32768],
        [3803, 7317, 10546, 32768],
        [1696, 3317, 4871, 32768],
        [14392, 19951, 22756, 32768],
        [15978, 23218, 26818, 32768],
        [12187, 19474, 23889, 32768],
        [9176, 15640, 20259, 32768],
        [7068, 12655, 17028, 32768],
        [5656, 10442, 14472, 32768],
        [2580, 4992, 7244, 32768],
        [12136, 18049, 21426, 32768],
        [13784, 20721, 24481, 32768],
        [10836, 17621, 21900, 32768],
        [8372, 14444, 18847, 32768],
        [6523, 11779, 16000, 32768],
        [5337, 9898, 13760, 32768],
        [3034, 5860, 8462, 32768],
    ],
    [
        [15967, 22905, 26286, 32768],
        [13534, 20654, 24579, 32768],
        [9504, 16092, 20535, 32768],
        [6975, 12568, 16903, 32768],
        [5364, 10091, 14020, 32768],
        [4357, 8370, 11857, 32768],
        [2506, 4934, 7218, 32768],
        [23032, 28815, 30936, 32768],
        [19540, 26704, 29719, 32768],
        [15158, 22969, 27097, 32768],
        [11408, 18865, 23650, 32768],
        [8885, 15448, 20250, 32768],
        [7108, 12853, 17416, 32768],
        [4231, 8041, 11480, 32768],
        [19823, 26490, 29156, 32768],
        [18890, 25929, 28932, 32768],
        [15660, 23491, 27433, 32768],
        [12147, 19776, 24488, 32768],
        [9728, 16774, 21649, 32768],
        [7919, 14277, 19066, 32768],
        [5440, 10170, 14185, 32768],
    ],
];

/// `Default_Scan_4x4` (§9.2): up-right diagonal scan order over the 16 positions.
pub static DEFAULT_SCAN_4X4: [usize; 16] = [0, 1, 4, 8, 5, 2, 3, 6, 9, 12, 13, 10, 7, 11, 14, 15];

/// `Coeff_Base_Ctx_Offset[TX_4X4]` (§8.3.2), indexed `[min(row,4)][min(col,4)]`.
pub static COEFF_BASE_CTX_OFFSET_4X4: [[u8; 5]; 5] = [
    [0, 1, 6, 6, 0],
    [1, 6, 6, 21, 0],
    [6, 6, 21, 21, 0],
    [6, 21, 21, 21, 0],
    [0, 0, 0, 0, 0],
];

/// `Sig_Ref_Diff_Offset[TX_CLASS_2D]` (§8.3.2): `(row, col)` neighbour offsets for `coeff_base`.
pub static SIG_REF_DIFF_OFFSET_2D: [(usize, usize); 5] = [(0, 1), (1, 0), (1, 1), (0, 2), (2, 0)];

/// `Mag_Ref_Offset_With_Tx_Class[TX_CLASS_2D]` (§8.3.2): neighbour offsets for `coeff_br`.
pub static MAG_REF_OFFSET_2D: [(usize, usize); 3] = [(0, 1), (1, 0), (1, 1)];