smallfilter.h

音频信号的重采样程序,如44.1K的WAV转换成采样频率为48K的WAV.

/* Included by resamplesubs.c */
#define SMALL_FILTER_NMULT ((HWORD)13)
#define SMALL_FILTER_SCALE 13128 /* Unity-gain scale factor */
#define SMALL_FILTER_NWING 1536 /* Filter table length */
static HWORD SMALL_FILTER_IMP[] /* Impulse response */ = {
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437,
425,
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318,
307,
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272,
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217,
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195,
184,
173,
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152,
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131,
121,
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70,
60,
51,
41,
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22,
12,
3,
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4,
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3,
3,
2,
2,
2,
2,
2,
1,
1,
1,
1,
1,
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-1,
-1,
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-1,
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-2,
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-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1,
-1
};

static HWORD SMALL_FILTER_IMPD[] = {
-1,
-2,
-4,
-5,
-6,
-8,
-10,
-10,
-13,
-13,
-16,
-16,
-18,
-20,
-21,
-22,
-24,
-25,
-27,
-28,
-30,
-31,
-32,
-34,
-35,
-37,
-38,
-39,
-41,
-42,
-44,
-45,
-46,
-48,
-49,
-51,
-52,
-53,
-55,
-56,
-57,
-59,
-60,
-61,
-63,
-64,
-65,
-67,
-68,
-69,
-71,
-71,
-74,
-74,
-76,
-77,
-78,
-79,
-81,
-82,
-83,
-84,
-86,
-87,
-88,
-89,
-90,
-92,
-92,
-94,
-95,
-96,
-98,
-98,
-100,
-100,
-102,
-103,
-104,
-105,
-106,
-107,
-108,
-109,
-111,
-111,
-112,
-113,
-115,
-115,
-116,
-117,
-119,
-119,
-120,
-121,
-121,
-123,
-124,
-124,
-126,
-126,
-127,
-128,
-129,
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