tests/ref/fate/filter-curves

#tb 0: 1001/30000
0,          0,          0,        1,   921600, 0xcf426780
0,          1,          1,        1,   921600, 0x7642892d
0,          2,          2,        1,   921600, 0x13c1ab7e
0,          3,          3,        1,   921600, 0x3eca04bf
0,          4,          4,        1,   921600, 0x61539162