Hwaro::Content::Processors::WebpEncoder
Constants
AC_TABLE = Slice[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, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94, 96, 98, 100, 102, 104, 106, 108, 110, 112, 114, 116, 119, 122, 125, 128, 131, 134, 137, 140, 143, 146, 149, 152, 155, 158, 161, 164, 167, 170, 173, 177, 181, 185, 189, 193, 197, 201, 205, 209, 213, 217, 221, 225, 229, 234, 239, 245, 249, 254, 259, 264, 269, 274, 279, 284]
BANDS = Slice[0, 1, 2, 3, 6, 4, 5, 6, 6, 6, 6, 6, 6, 6, 6, 7, 0]
BMODE_PROBS = Bytes[231, 120, 48, 89, 115, 113, 120, 152, 112, 152, 179, 64, 126, 170, 118, 46, 70, 95, 175, 69, 143, 80, 85, 82, 72, 155, 103, 56, 58, 10, 171, 218, 189, 17, 13, 152, 114, 26, 17, 163, 44, 195, 21, 10, 173, 121, 24, 80, 195, 26, 62, 44, 64, 85, 144, 71, 10, 38, 171, 213, 144, 34, 26, 170, 46, 55, 19, 136, 160, 33, 206, 71, 63, 20, 8, 114, 114, 208, 12, 9, 226, 81, 40, 11, 96, 182, 84, 29, 16, 36, 134, 183, 89, 137, 98, 101, 106, 165, 148, 72, 187, 100, 130, 157, 111, 32, 75, 80, 66, 102, 167, 99, 74, 62, 40, 234, 128, 41, 53, 9, 178, 241, 141, 26, 8, 107, 74, 43, 26, 146, 73, 166, 49, 23, 157, 65, 38, 105, 160, 51, 52, 31, 115, 128, 104, 79, 12, 27, 217, 255, 87, 17, 7, 87, 68, 71, 44, 114, 51, 15, 186, 23, 47, 41, 14, 110, 182, 183, 21, 17, 194, 66, 45, 25, 102, 197, 189, 23, 18, 22, 88, 88, 147, 150, 42, 46, 45, 196, 205, 43, 97, 183, 117, 85, 38, 35, 179, 61, 39, 53, 200, 87, 26, 21, 43, 232, 171, 56, 34, 51, 104, 114, 102, 29, 93, 77, 39, 28, 85, 171, 58, 165, 90, 98, 64, 34, 22, 116, 206, 23, 34, 43, 166, 73, 107, 54, 32, 26, 51, 1, 81, 43, 31, 68, 25, 106, 22, 64, 171, 36, 225, 114, 34, 19, 21, 102, 132, 188, 16, 76, 124, 62, 18, 78, 95, 85, 57, 50, 48, 51, 193, 101, 35, 159, 215, 111, 89, 46, 111, 60, 148, 31, 172, 219, 228, 21, 18, 111, 112, 113, 77, 85, 179, 255, 38, 120, 114, 40, 42, 1, 196, 245, 209, 10, 25, 109, 88, 43, 29, 140, 166, 213, 37, 43, 154, 61, 63, 30, 155, 67, 45, 68, 1, 209, 100, 80, 8, 43, 154, 1, 51, 26, 71, 142, 78, 78, 16, 255, 128, 34, 197, 171, 41, 40, 5, 102, 211, 183, 4, 1, 221, 51, 50, 17, 168, 209, 192, 23, 25, 82, 138, 31, 36, 171, 27, 166, 38, 44, 229, 67, 87, 58, 169, 82, 115, 26, 59, 179, 63, 59, 90, 180, 59, 166, 93, 73, 154, 40, 40, 21, 116, 143, 209, 34, 39, 175, 47, 15, 16, 183, 34, 223, 49, 45, 183, 46, 17, 33, 183, 6, 98, 15, 32, 183, 57, 46, 22, 24, 128, 1, 54, 17, 37, 65, 32, 73, 115, 28, 128, 23, 128, 205, 40, 3, 9, 115, 51, 192, 18, 6, 223, 87, 37, 9, 115, 59, 77, 64, 21, 47, 104, 55, 44, 218, 9, 54, 53, 130, 226, 64, 90, 70, 205, 40, 41, 23, 26, 57, 54, 57, 112, 184, 5, 41, 38, 166, 213, 30, 34, 26, 133, 152, 116, 10, 32, 134, 39, 19, 53, 221, 26, 114, 32, 73, 255, 31, 9, 65, 234, 2, 15, 1, 118, 73, 75, 32, 12, 51, 192, 255, 160, 43, 51, 88, 31, 35, 67, 102, 85, 55, 186, 85, 56, 21, 23, 111, 59, 205, 45, 37, 192, 55, 38, 70, 124, 73, 102, 1, 34, 98, 125, 98, 42, 88, 104, 85, 117, 175, 82, 95, 84, 53, 89, 128, 100, 113, 101, 45, 75, 79, 123, 47, 51, 128, 81, 171, 1, 57, 17, 5, 71, 102, 57, 53, 41, 49, 38, 33, 13, 121, 57, 73, 26, 1, 85, 41, 10, 67, 138, 77, 110, 90, 47, 114, 115, 21, 2, 10, 102, 255, 166, 23, 6, 101, 29, 16, 10, 85, 128, 101, 196, 26, 57, 18, 10, 102, 102, 213, 34, 20, 43, 117, 20, 15, 36, 163, 128, 68, 1, 26, 102, 61, 71, 37, 34, 53, 31, 243, 192, 69, 60, 71, 38, 73, 119, 28, 222, 37, 68, 45, 128, 34, 1, 47, 11, 245, 171, 62, 17, 19, 70, 146, 85, 55, 62, 70, 37, 43, 37, 154, 100, 163, 85, 160, 1, 63, 9, 92, 136, 28, 64, 32, 201, 85, 75, 15, 9, 9, 64, 255, 184, 119, 16, 86, 6, 28, 5, 64, 255, 25, 248, 1, 56, 8, 17, 132, 137, 255, 55, 116, 128, 58, 15, 20, 82, 135, 57, 26, 121, 40, 164, 50, 31, 137, 154, 133, 25, 35, 218, 51, 103, 44, 131, 131, 123, 31, 6, 158, 86, 40, 64, 135, 148, 224, 45, 183, 128, 22, 26, 17, 131, 240, 154, 14, 1, 209, 45, 16, 21, 91, 64, 222, 7, 1, 197, 56, 21, 39, 155, 60, 138, 23, 102, 213, 83, 12, 13, 54, 192, 255, 68, 47, 28, 85, 26, 85, 85, 128, 128, 32, 146, 171, 18, 11, 7, 63, 144, 171, 4, 4, 246, 35, 27, 10, 146, 174, 171, 12, 26, 128, 190, 80, 35, 99, 180, 80, 126, 54, 45, 85, 126, 47, 87, 176, 51, 41, 20, 32, 101, 75, 128, 139, 118, 146, 116, 128, 85, 56, 41, 15, 176, 236, 85, 37, 9, 62, 71, 30, 17, 119, 118, 255, 17, 18, 138, 101, 38, 60, 138, 55, 70, 43, 26, 142, 146, 36, 19, 30, 171, 255, 97, 27, 20, 138, 45, 61, 62, 219, 1, 81, 188, 64, 32, 41, 20, 117, 151, 142, 20, 21, 163, 112, 19, 12, 61, 195, 128, 48, 4, 24]
CAT_PROBS = {Slice[173, 148, 140], Slice[176, 155, 140, 135], Slice[180, 157, 141, 134, 130], Slice[254, 254, 243, 230, 196, 177, 153, 140, 133, 130, 129]}
Extra-bit probabilities of the DCT_CAT3..CAT6 token values.
COEFF_PROBS = Bytes[128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 253, 136, 254, 255, 228, 219, 128, 128, 128, 128, 128, 189, 129, 242, 255, 227, 213, 255, 219, 128, 128, 128, 106, 126, 227, 252, 214, 209, 255, 255, 128, 128, 128, 1, 98, 248, 255, 236, 226, 255, 255, 128, 128, 128, 181, 133, 238, 254, 221, 234, 255, 154, 128, 128, 128, 78, 134, 202, 247, 198, 180, 255, 219, 128, 128, 128, 1, 185, 249, 255, 243, 255, 128, 128, 128, 128, 128, 184, 150, 247, 255, 236, 224, 128, 128, 128, 128, 128, 77, 110, 216, 255, 236, 230, 128, 128, 128, 128, 128, 1, 101, 251, 255, 241, 255, 128, 128, 128, 128, 128, 170, 139, 241, 252, 236, 209, 255, 255, 128, 128, 128, 37, 116, 196, 243, 228, 255, 255, 255, 128, 128, 128, 1, 204, 254, 255, 245, 255, 128, 128, 128, 128, 128, 207, 160, 250, 255, 238, 128, 128, 128, 128, 128, 128, 102, 103, 231, 255, 211, 171, 128, 128, 128, 128, 128, 1, 152, 252, 255, 240, 255, 128, 128, 128, 128, 128, 177, 135, 243, 255, 234, 225, 128, 128, 128, 128, 128, 80, 129, 211, 255, 194, 224, 128, 128, 128, 128, 128, 1, 1, 255, 128, 128, 128, 128, 128, 128, 128, 128, 246, 1, 255, 128, 128, 128, 128, 128, 128, 128, 128, 255, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 198, 35, 237, 223, 193, 187, 162, 160, 145, 155, 62, 131, 45, 198, 221, 172, 176, 220, 157, 252, 221, 1, 68, 47, 146, 208, 149, 167, 221, 162, 255, 223, 128, 1, 149, 241, 255, 221, 224, 255, 255, 128, 128, 128, 184, 141, 234, 253, 222, 220, 255, 199, 128, 128, 128, 81, 99, 181, 242, 176, 190, 249, 202, 255, 255, 128, 1, 129, 232, 253, 214, 197, 242, 196, 255, 255, 128, 99, 121, 210, 250, 201, 198, 255, 202, 128, 128, 128, 23, 91, 163, 242, 170, 187, 247, 210, 255, 255, 128, 1, 200, 246, 255, 234, 255, 128, 128, 128, 128, 128, 109, 178, 241, 255, 231, 245, 255, 255, 128, 128, 128, 44, 130, 201, 253, 205, 192, 255, 255, 128, 128, 128, 1, 132, 239, 251, 219, 209, 255, 165, 128, 128, 128, 94, 136, 225, 251, 218, 190, 255, 255, 128, 128, 128, 22, 100, 174, 245, 186, 161, 255, 199, 128, 128, 128, 1, 182, 249, 255, 232, 235, 128, 128, 128, 128, 128, 124, 143, 241, 255, 227, 234, 128, 128, 128, 128, 128, 35, 77, 181, 251, 193, 211, 255, 205, 128, 128, 128, 1, 157, 247, 255, 236, 231, 255, 255, 128, 128, 128, 121, 141, 235, 255, 225, 227, 255, 255, 128, 128, 128, 45, 99, 188, 251, 195, 217, 255, 224, 128, 128, 128, 1, 1, 251, 255, 213, 255, 128, 128, 128, 128, 128, 203, 1, 248, 255, 255, 128, 128, 128, 128, 128, 128, 137, 1, 177, 255, 224, 255, 128, 128, 128, 128, 128, 253, 9, 248, 251, 207, 208, 255, 192, 128, 128, 128, 175, 13, 224, 243, 193, 185, 249, 198, 255, 255, 128, 73, 17, 171, 221, 161, 179, 236, 167, 255, 234, 128, 1, 95, 247, 253, 212, 183, 255, 255, 128, 128, 128, 239, 90, 244, 250, 211, 209, 255, 255, 128, 128, 128, 155, 77, 195, 248, 188, 195, 255, 255, 128, 128, 128, 1, 24, 239, 251, 218, 219, 255, 205, 128, 128, 128, 201, 51, 219, 255, 196, 186, 128, 128, 128, 128, 128, 69, 46, 190, 239, 201, 218, 255, 228, 128, 128, 128, 1, 191, 251, 255, 255, 128, 128, 128, 128, 128, 128, 223, 165, 249, 255, 213, 255, 128, 128, 128, 128, 128, 141, 124, 248, 255, 255, 128, 128, 128, 128, 128, 128, 1, 16, 248, 255, 255, 128, 128, 128, 128, 128, 128, 190, 36, 230, 255, 236, 255, 128, 128, 128, 128, 128, 149, 1, 255, 128, 128, 128, 128, 128, 128, 128, 128, 1, 226, 255, 128, 128, 128, 128, 128, 128, 128, 128, 247, 192, 255, 128, 128, 128, 128, 128, 128, 128, 128, 240, 128, 255, 128, 128, 128, 128, 128, 128, 128, 128, 1, 134, 252, 255, 255, 128, 128, 128, 128, 128, 128, 213, 62, 250, 255, 255, 128, 128, 128, 128, 128, 128, 55, 93, 255, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 128, 202, 24, 213, 235, 186, 191, 220, 160, 240, 175, 255, 126, 38, 182, 232, 169, 184, 228, 174, 255, 187, 128, 61, 46, 138, 219, 151, 178, 240, 170, 255, 216, 128, 1, 112, 230, 250, 199, 191, 247, 159, 255, 255, 128, 166, 109, 228, 252, 211, 215, 255, 174, 128, 128, 128, 39, 77, 162, 232, 172, 180, 245, 178, 255, 255, 128, 1, 52, 220, 246, 198, 199, 249, 220, 255, 255, 128, 124, 74, 191, 243, 183, 193, 250, 221, 255, 255, 128, 24, 71, 130, 219, 154, 170, 243, 182, 255, 255, 128, 1, 182, 225, 249, 219, 240, 255, 224, 128, 128, 128, 149, 150, 226, 252, 216, 205, 255, 171, 128, 128, 128, 28, 108, 170, 242, 183, 194, 254, 223, 255, 255, 128, 1, 81, 230, 252, 204, 203, 255, 192, 128, 128, 128, 123, 102, 209, 247, 188, 196, 255, 233, 128, 128, 128, 20, 95, 153, 243, 164, 173, 255, 203, 128, 128, 128, 1, 222, 248, 255, 216, 213, 128, 128, 128, 128, 128, 168, 175, 246, 252, 235, 205, 255, 255, 128, 128, 128, 47, 116, 215, 255, 211, 212, 255, 255, 128, 128, 128, 1, 121, 236, 253, 212, 214, 255, 255, 128, 128, 128, 141, 84, 213, 252, 201, 202, 255, 219, 128, 128, 128, 42, 80, 160, 240, 162, 185, 255, 205, 128, 128, 128, 1, 1, 255, 128, 128, 128, 128, 128, 128, 128, 128, 244, 1, 255, 128, 128, 128, 128, 128, 128, 128, 128, 238, 1, 255, 128, 128, 128, 128, 128, 128, 128, 128]
Default token probabilities [type 4][band 8][context 3][node 11] (RFC 6386 §13.5), the probabilities that a frame may update (§13.4), and the key-frame B_PRED sub-block mode probabilities [above mode 10][left mode 10][node 9] (§11.5), all flattened.
COEFF_UPDATE_PROBS = Bytes[255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 176, 246, 255, 255, 255, 255, 255, 255, 255, 255, 255, 223, 241, 252, 255, 255, 255, 255, 255, 255, 255, 255, 249, 253, 253, 255, 255, 255, 255, 255, 255, 255, 255, 255, 244, 252, 255, 255, 255, 255, 255, 255, 255, 255, 234, 254, 254, 255, 255, 255, 255, 255, 255, 255, 255, 253, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 246, 254, 255, 255, 255, 255, 255, 255, 255, 255, 239, 253, 254, 255, 255, 255, 255, 255, 255, 255, 255, 254, 255, 254, 255, 255, 255, 255, 255, 255, 255, 255, 255, 248, 254, 255, 255, 255, 255, 255, 255, 255, 255, 251, 255, 254, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 253, 254, 255, 255, 255, 255, 255, 255, 255, 255, 251, 254, 254, 255, 255, 255, 255, 255, 255, 255, 255, 254, 255, 254, 255, 255, 255, 255, 255, 255, 255, 255, 255, 254, 253, 255, 254, 255, 255, 255, 255, 255, 255, 250, 255, 254, 255, 254, 255, 255, 255, 255, 255, 255, 254, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 217, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 225, 252, 241, 253, 255, 255, 254, 255, 255, 255, 255, 234, 250, 241, 250, 253, 255, 253, 254, 255, 255, 255, 255, 254, 255, 255, 255, 255, 255, 255, 255, 255, 255, 223, 254, 254, 255, 255, 255, 255, 255, 255, 255, 255, 238, 253, 254, 254, 255, 255, 255, 255, 255, 255, 255, 255, 248, 254, 255, 255, 255, 255, 255, 255, 255, 255, 249, 254, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 253, 255, 255, 255, 255, 255, 255, 255, 255, 255, 247, 254, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 253, 254, 255, 255, 255, 255, 255, 255, 255, 255, 252, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 254, 254, 255, 255, 255, 255, 255, 255, 255, 255, 253, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 254, 253, 255, 255, 255, 255, 255, 255, 255, 255, 250, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 254, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 186, 251, 250, 255, 255, 255, 255, 255, 255, 255, 255, 234, 251, 244, 254, 255, 255, 255, 255, 255, 255, 255, 251, 251, 243, 253, 254, 255, 254, 255, 255, 255, 255, 255, 253, 254, 255, 255, 255, 255, 255, 255, 255, 255, 236, 253, 254, 255, 255, 255, 255, 255, 255, 255, 255, 251, 253, 253, 254, 254, 255, 255, 255, 255, 255, 255, 255, 254, 254, 255, 255, 255, 255, 255, 255, 255, 255, 254, 254, 254, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 254, 255, 255, 255, 255, 255, 255, 255, 255, 255, 254, 254, 255, 255, 255, 255, 255, 255, 255, 255, 255, 254, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 254, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 248, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 250, 254, 252, 254, 255, 255, 255, 255, 255, 255, 255, 248, 254, 249, 253, 255, 255, 255, 255, 255, 255, 255, 255, 253, 253, 255, 255, 255, 255, 255, 255, 255, 255, 246, 253, 253, 255, 255, 255, 255, 255, 255, 255, 255, 252, 254, 251, 254, 254, 255, 255, 255, 255, 255, 255, 255, 254, 252, 255, 255, 255, 255, 255, 255, 255, 255, 248, 254, 253, 255, 255, 255, 255, 255, 255, 255, 255, 253, 255, 254, 254, 255, 255, 255, 255, 255, 255, 255, 255, 251, 254, 255, 255, 255, 255, 255, 255, 255, 255, 245, 251, 254, 255, 255, 255, 255, 255, 255, 255, 255, 253, 253, 254, 255, 255, 255, 255, 255, 255, 255, 255, 255, 251, 253, 255, 255, 255, 255, 255, 255, 255, 255, 252, 253, 254, 255, 255, 255, 255, 255, 255, 255, 255, 255, 254, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 252, 255, 255, 255, 255, 255, 255, 255, 255, 255, 249, 255, 254, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 254, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 253, 255, 255, 255, 255, 255, 255, 255, 255, 250, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 254, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255]
Cost in 1/256 bit of coding a 0 with probability p (of a 0) out of
256; a 1 costs COST[256 - p].
DC_TABLE = Slice[4, 5, 6, 7, 8, 9, 10, 10, 11, 12, 13, 14, 15, 16, 17, 17, 18, 19, 20, 20, 21, 21, 22, 22, 23, 23, 24, 25, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 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, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 91, 93, 95, 96, 98, 100, 101, 102, 104, 106, 108, 110, 112, 114, 116, 118, 122, 124, 126, 128, 130, 132, 134, 136, 138, 140, 143, 145, 148, 151, 154, 157]
Quantizer step for each of the 128 q indices (RFC 6386 §14.1).
MAX_DIMENSION = 16383
Largest width/height a WebP canvas can carry (14-bit fields).
ZIGZAG = Slice[0, 1, 4, 8, 5, 2, 3, 6, 9, 12, 13, 10, 7, 11, 14, 15]
Coding order of a 4x4 block's coefficients, and the probability band of each position (the 17th entry is the decoder's sentinel).
Instance methods
encode(pixels : Bytes, width : Int32, height : Int32, channels : Int32, quality : Int32) : Bytes | Nil
A complete .webp file for pixels: width×height samples of
channels interleaved bytes (1 gray, 2 gray+alpha, 3 RGB, 4 RGBA).
nil when the size is outside WebP's range or the frame cannot be
coded (a partition overflowing its 19-bit size field).