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tables.js
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tables.js
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/*
* These are the scalefactor values for Layer I and Layer II.
* The values are from Table B.1 of ISO/IEC 11172-3.
*
* Strictly speaking, Table B.1 has only 63 entries (0-62), thus a strict
* interpretation of ISO/IEC 11172-3 would suggest that a scalefactor index of
* 63 is invalid. However, for better compatibility with current practices, we
* add a 64th entry.
*/
exports.SF_TABLE = new Float32Array([
2.000000000000, 1.587401051968, 1.259921049895, 1.000000000000,
0.793700525984, 0.629960524947, 0.500000000000, 0.396850262992,
0.314980262474, 0.250000000000, 0.198425131496, 0.157490131237,
0.125000000000, 0.099212565748, 0.078745065618, 0.062500000000,
0.049606282874, 0.039372532809, 0.031250000000, 0.024803141437,
0.019686266405, 0.015625000000, 0.012401570719, 0.009843133202,
0.007812500000, 0.006200785359, 0.004921566601, 0.003906250000,
0.003100392680, 0.002460783301, 0.001953125000, 0.001550196340,
0.001230391650, 0.000976562500, 0.000775098170, 0.000615195825,
0.000488281250, 0.000387549085, 0.000307597913, 0.000244140625,
0.000193774542, 0.000153798956, 0.000122070313, 0.000096887271,
0.000076899478, 0.000061035156, 0.000048443636, 0.000038449739,
0.000030517578, 0.000024221818, 0.000019224870, 0.000015258789,
0.000012110909, 0.000009612435, 0.000007629395, 0.000006055454,
0.000004806217, 0.000003814697, 0.000003027727, 0.000002403109,
0.000001907349, 0.000001513864, 0.000001201554, 0.000000000000
]);
/*
* MPEG-1 scalefactor band widths
* derived from Table B.8 of ISO/IEC 11172-3
*/
const SFB_48000_LONG = new Uint8Array([
4, 4, 4, 4, 4, 4, 6, 6, 6, 8, 10,
12, 16, 18, 22, 28, 34, 40, 46, 54, 54, 192
]);
const SFB_44100_LONG = new Uint8Array([
4, 4, 4, 4, 4, 4, 6, 6, 8, 8, 10,
12, 16, 20, 24, 28, 34, 42, 50, 54, 76, 158
]);
const SFB_32000_LONG = new Uint8Array([
4, 4, 4, 4, 4, 4, 6, 6, 8, 10, 12,
16, 20, 24, 30, 38, 46, 56, 68, 84, 102, 26
]);
const SFB_48000_SHORT = new Uint8Array([
4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 6,
6, 6, 6, 6, 6, 10, 10, 10, 12, 12, 12, 14, 14,
14, 16, 16, 16, 20, 20, 20, 26, 26, 26, 66, 66, 66
]);
const SFB_44100_SHORT = new Uint8Array([
4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 6,
6, 6, 8, 8, 8, 10, 10, 10, 12, 12, 12, 14, 14,
14, 18, 18, 18, 22, 22, 22, 30, 30, 30, 56, 56, 56
]);
const SFB_32000_SHORT = new Uint8Array([
4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 6,
6, 6, 8, 8, 8, 12, 12, 12, 16, 16, 16, 20, 20,
20, 26, 26, 26, 34, 34, 34, 42, 42, 42, 12, 12, 12
]);
const SFB_48000_MIXED = new Uint8Array([
/* long */ 4, 4, 4, 4, 4, 4, 6, 6,
/* short */ 4, 4, 4, 6, 6, 6, 6, 6, 6, 10,
10, 10, 12, 12, 12, 14, 14, 14, 16, 16,
16, 20, 20, 20, 26, 26, 26, 66, 66, 66
]);
const SFB_44100_MIXED = new Uint8Array([
/* long */ 4, 4, 4, 4, 4, 4, 6, 6,
/* short */ 4, 4, 4, 6, 6, 6, 8, 8, 8, 10,
10, 10, 12, 12, 12, 14, 14, 14, 18, 18,
18, 22, 22, 22, 30, 30, 30, 56, 56, 56
]);
const SFB_32000_MIXED = new Uint8Array([
/* long */ 4, 4, 4, 4, 4, 4, 6, 6,
/* short */ 4, 4, 4, 6, 6, 6, 8, 8, 8, 12,
12, 12, 16, 16, 16, 20, 20, 20, 26, 26,
26, 34, 34, 34, 42, 42, 42, 12, 12, 12
]);
/*
* MPEG-2 scalefactor band widths
* derived from Table B.2 of ISO/IEC 13818-3
*/
const SFB_24000_LONG = new Uint8Array([
6, 6, 6, 6, 6, 6, 8, 10, 12, 14, 16,
18, 22, 26, 32, 38, 46, 54, 62, 70, 76, 36
]);
const SFB_22050_LONG = new Uint8Array([
6, 6, 6, 6, 6, 6, 8, 10, 12, 14, 16,
20, 24, 28, 32, 38, 46, 52, 60, 68, 58, 54
]);
const SFB_16000_LONG = SFB_22050_LONG;
const SFB_24000_SHORT = new Uint8Array([
4, 4, 4, 4, 4, 4, 4, 4, 4, 6, 6, 6, 8,
8, 8, 10, 10, 10, 12, 12, 12, 14, 14, 14, 18, 18,
18, 24, 24, 24, 32, 32, 32, 44, 44, 44, 12, 12, 12
]);
const SFB_22050_SHORT = new Uint8Array([
4, 4, 4, 4, 4, 4, 4, 4, 4, 6, 6, 6, 6,
6, 6, 8, 8, 8, 10, 10, 10, 14, 14, 14, 18, 18,
18, 26, 26, 26, 32, 32, 32, 42, 42, 42, 18, 18, 18
]);
const SFB_16000_SHORT = new Uint8Array([
4, 4, 4, 4, 4, 4, 4, 4, 4, 6, 6, 6, 8,
8, 8, 10, 10, 10, 12, 12, 12, 14, 14, 14, 18, 18,
18, 24, 24, 24, 30, 30, 30, 40, 40, 40, 18, 18, 18
]);
const SFB_24000_MIXED = new Uint8Array([
/* long */ 6, 6, 6, 6, 6, 6,
/* short */ 6, 6, 6, 8, 8, 8, 10, 10, 10, 12,
12, 12, 14, 14, 14, 18, 18, 18, 24, 24,
24, 32, 32, 32, 44, 44, 44, 12, 12, 12
]);
const SFB_22050_MIXED = new Uint8Array([
/* long */ 6, 6, 6, 6, 6, 6,
/* short */ 6, 6, 6, 6, 6, 6, 8, 8, 8, 10,
10, 10, 14, 14, 14, 18, 18, 18, 26, 26,
26, 32, 32, 32, 42, 42, 42, 18, 18, 18
]);
const SFB_16000_MIXED = new Uint8Array([
/* long */ 6, 6, 6, 6, 6, 6,
/* short */ 6, 6, 6, 8, 8, 8, 10, 10, 10, 12,
12, 12, 14, 14, 14, 18, 18, 18, 24, 24,
24, 30, 30, 30, 40, 40, 40, 18, 18, 18
]);
/*
* MPEG 2.5 scalefactor band widths
* derived from public sources
*/
const SFB_12000_LONG = SFB_16000_LONG;
const SFB_11025_LONG = SFB_12000_LONG;
const SFB_8000_LONG = new Uint8Array([
12, 12, 12, 12, 12, 12, 16, 20, 24, 28, 32,
40, 48, 56, 64, 76, 90, 2, 2, 2, 2, 2
]);
const SFB_12000_SHORT = SFB_16000_SHORT;
const SFB_11025_SHORT = SFB_12000_SHORT;
const SFB_8000_SHORT = new Uint8Array([
8, 8, 8, 8, 8, 8, 8, 8, 8, 12, 12, 12, 16,
16, 16, 20, 20, 20, 24, 24, 24, 28, 28, 28, 36, 36,
36, 2, 2, 2, 2, 2, 2, 2, 2, 2, 26, 26, 26
]);
const SFB_12000_MIXED = SFB_16000_MIXED;
const SFB_11025_MIXED = SFB_12000_MIXED;
/* the 8000 Hz short block scalefactor bands do not break after
the first 36 frequency lines, so this is probably wrong */
const SFB_8000_MIXED = new Uint8Array([
/* long */ 12, 12, 12,
/* short */ 4, 4, 4, 8, 8, 8, 12, 12, 12, 16, 16, 16,
20, 20, 20, 24, 24, 24, 28, 28, 28, 36, 36, 36,
2, 2, 2, 2, 2, 2, 2, 2, 2, 26, 26, 26
]);
exports.SFBWIDTH_TABLE = [
{ l: SFB_48000_LONG, s: SFB_48000_SHORT, m: SFB_48000_MIXED },
{ l: SFB_44100_LONG, s: SFB_44100_SHORT, m: SFB_44100_MIXED },
{ l: SFB_32000_LONG, s: SFB_32000_SHORT, m: SFB_32000_MIXED },
{ l: SFB_24000_LONG, s: SFB_24000_SHORT, m: SFB_24000_MIXED },
{ l: SFB_22050_LONG, s: SFB_22050_SHORT, m: SFB_22050_MIXED },
{ l: SFB_16000_LONG, s: SFB_16000_SHORT, m: SFB_16000_MIXED },
{ l: SFB_12000_LONG, s: SFB_12000_SHORT, m: SFB_12000_MIXED },
{ l: SFB_11025_LONG, s: SFB_11025_SHORT, m: SFB_11025_MIXED },
{ l: SFB_8000_LONG, s: SFB_8000_SHORT, m: SFB_8000_MIXED }
];
exports.PRETAB = new Uint8Array([
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 3, 3, 3, 2, 0
]);
/*
* fractional powers of two
* used for requantization and joint stereo decoding
*
* ROOT_TABLE[3 + x] = 2^(x/4)
*/
exports.ROOT_TABLE = new Float32Array([
/* 2^(-3/4) */ 0.59460355750136,
/* 2^(-2/4) */ 0.70710678118655,
/* 2^(-1/4) */ 0.84089641525371,
/* 2^( 0/4) */ 1.00000000000000,
/* 2^(+1/4) */ 1.18920711500272,
/* 2^(+2/4) */ 1.41421356237310,
/* 2^(+3/4) */ 1.68179283050743
]);
exports.CS = new Float32Array([
+0.857492926 , +0.881741997,
+0.949628649 , +0.983314592,
+0.995517816 , +0.999160558,
+0.999899195 , +0.999993155
]);
exports.CA = new Float32Array([
-0.514495755, -0.471731969,
-0.313377454, -0.181913200,
-0.094574193, -0.040965583,
-0.014198569, -0.003699975
]);
exports.COUNT1TABLE_SELECT = 0x01;
exports.SCALEFAC_SCALE = 0x02;
exports.PREFLAG = 0x04;
exports.MIXED_BLOCK_FLAG = 0x08;
exports.I_STEREO = 0x1;
exports.MS_STEREO = 0x2;
/*
* windowing coefficients for long blocks
* derived from section 2.4.3.4.10.3 of ISO/IEC 11172-3
*
* WINDOW_L[i] = sin((PI / 36) * (i + 1/2))
*/
exports.WINDOW_L = new Float32Array([
0.043619387, 0.130526192,
0.216439614, 0.300705800,
0.382683432, 0.461748613,
0.537299608, 0.608761429,
0.675590208, 0.737277337,
0.793353340, 0.843391446,
0.887010833, 0.923879533,
0.953716951, 0.976296007,
0.991444861, 0.999048222,
0.999048222, 0.991444861,
0.976296007, 0.953716951,
0.923879533, 0.887010833,
0.843391446, 0.793353340,
0.737277337, 0.675590208,
0.608761429, 0.537299608,
0.461748613, 0.382683432,
0.300705800, 0.216439614,
0.130526192, 0.043619387
]);
/*
* windowing coefficients for short blocks
* derived from section 2.4.3.4.10.3 of ISO/IEC 11172-3
*
* WINDOW_S[i] = sin((PI / 12) * (i + 1/2))
*/
exports.WINDOW_S = new Float32Array([
0.130526192, 0.382683432,
0.608761429, 0.793353340,
0.923879533, 0.991444861,
0.991444861, 0.923879533,
0.793353340, 0.608761429,
0.382683432, 0.130526192
]);
/*
* coefficients for intensity stereo processing
* derived from section 2.4.3.4.9.3 of ISO/IEC 11172-3
*
* is_ratio[i] = tan(i * (PI / 12))
* IS_TABLE[i] = is_ratio[i] / (1 + is_ratio[i])
*/
exports.IS_TABLE = new Float32Array([
0.000000000,
0.211324865,
0.366025404,
0.500000000,
0.633974596,
0.788675135,
1.000000000
]);
/*
* coefficients for LSF intensity stereo processing
* derived from section 2.4.3.2 of ISO/IEC 13818-3
*
* IS_LSF_TABLE[0][i] = (1 / sqrt(sqrt(2)))^(i + 1)
* IS_LSF_TABLE[1][i] = (1 / sqrt(2)) ^(i + 1)
*/
exports.IS_LSF_TABLE = [
new Float32Array([
0.840896415,
0.707106781,
0.594603558,
0.500000000,
0.420448208,
0.353553391,
0.297301779,
0.250000000,
0.210224104,
0.176776695,
0.148650889,
0.125000000,
0.105112052,
0.088388348,
0.074325445
]),
new Float32Array([
0.707106781,
0.500000000,
0.353553391,
0.250000000,
0.176776695,
0.125000000,
0.088388348,
0.062500000,
0.044194174,
0.031250000,
0.022097087,
0.015625000,
0.011048543,
0.007812500,
0.005524272
])
];
/*
* scalefactor bit lengths
* derived from section 2.4.2.7 of ISO/IEC 11172-3
*/
exports.SFLEN_TABLE = [
{ slen1: 0, slen2: 0 }, { slen1: 0, slen2: 1 }, { slen1: 0, slen2: 2 }, { slen1: 0, slen2: 3 },
{ slen1: 3, slen2: 0 }, { slen1: 1, slen2: 1 }, { slen1: 1, slen2: 2 }, { slen1: 1, slen2: 3 },
{ slen1: 2, slen2: 1 }, { slen1: 2, slen2: 2 }, { slen1: 2, slen2: 3 }, { slen1: 3, slen2: 1 },
{ slen1: 3, slen2: 2 }, { slen1: 3, slen2: 3 }, { slen1: 4, slen2: 2 }, { slen1: 4, slen2: 3 }
];
/*
* number of LSF scalefactor band values
* derived from section 2.4.3.2 of ISO/IEC 13818-3
*/
exports.NSFB_TABLE = [
[ [ 6, 5, 5, 5 ],
[ 9, 9, 9, 9 ],
[ 6, 9, 9, 9 ] ],
[ [ 6, 5, 7, 3 ],
[ 9, 9, 12, 6 ],
[ 6, 9, 12, 6 ] ],
[ [ 11, 10, 0, 0 ],
[ 18, 18, 0, 0 ],
[ 15, 18, 0, 0 ] ],
[ [ 7, 7, 7, 0 ],
[ 12, 12, 12, 0 ],
[ 6, 15, 12, 0 ] ],
[ [ 6, 6, 6, 3 ],
[ 12, 9, 9, 6 ],
[ 6, 12, 9, 6 ] ],
[ [ 8, 8, 5, 0 ],
[ 15, 12, 9, 0 ],
[ 6, 18, 9, 0 ] ]
];