1*7c478bd9Sstevel@tonic-gate /*
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21*7c478bd9Sstevel@tonic-gate  */
22*7c478bd9Sstevel@tonic-gate /*
23*7c478bd9Sstevel@tonic-gate  * Copyright (c) 1992-2001 by Sun Microsystems, Inc.
24*7c478bd9Sstevel@tonic-gate  * All rights reserved.
25*7c478bd9Sstevel@tonic-gate  */
26*7c478bd9Sstevel@tonic-gate 
27*7c478bd9Sstevel@tonic-gate #ifndef _MULTIMEDIA_RESAMPLE_H
28*7c478bd9Sstevel@tonic-gate #define	_MULTIMEDIA_RESAMPLE_H
29*7c478bd9Sstevel@tonic-gate 
30*7c478bd9Sstevel@tonic-gate /*
31*7c478bd9Sstevel@tonic-gate  * To convert the sampling rate of fi of input signal to fo of output signal,
32*7c478bd9Sstevel@tonic-gate  * the least common multiple fm = L * fi = M * fo needs to be derived first.
33*7c478bd9Sstevel@tonic-gate  * Then the input signal is
34*7c478bd9Sstevel@tonic-gate  * 1) up-sampled to fm by inserting (L - 1) zero-valued samples after each
35*7c478bd9Sstevel@tonic-gate  *    input sample,
36*7c478bd9Sstevel@tonic-gate  * 2) low-pass filtered to half of the lower of fi and fo, and
37*7c478bd9Sstevel@tonic-gate  * 3) down-sampled to fo by saving one out of every M samples.
38*7c478bd9Sstevel@tonic-gate  *
39*7c478bd9Sstevel@tonic-gate  * The low-pass filter is implemented with an FIR filter which is a truncated
40*7c478bd9Sstevel@tonic-gate  * ideal low pass filter whose order is dependent on its bandwidth.
41*7c478bd9Sstevel@tonic-gate  *
42*7c478bd9Sstevel@tonic-gate  * Refer to Fir.h for explanations of filter() and flush().
43*7c478bd9Sstevel@tonic-gate  *
44*7c478bd9Sstevel@tonic-gate  */
45*7c478bd9Sstevel@tonic-gate #include <Fir.h>
46*7c478bd9Sstevel@tonic-gate 
47*7c478bd9Sstevel@tonic-gate #ifdef __cplusplus
48*7c478bd9Sstevel@tonic-gate extern "C" {
49*7c478bd9Sstevel@tonic-gate #endif
50*7c478bd9Sstevel@tonic-gate 
51*7c478bd9Sstevel@tonic-gate class ResampleFilter : public Fir {
52*7c478bd9Sstevel@tonic-gate 	int	num_state;		// interpolation requires less states
53*7c478bd9Sstevel@tonic-gate 	int	up;			// upsampling ratio
54*7c478bd9Sstevel@tonic-gate 	int	down;			// down sampling ratio
55*7c478bd9Sstevel@tonic-gate 	int	down_offset;		// 0 <= index in down-sampling < down
56*7c478bd9Sstevel@tonic-gate 	int	up_offset;		// -up < index in up_sampling <= 0
57*7c478bd9Sstevel@tonic-gate 
58*7c478bd9Sstevel@tonic-gate 	void updateState(double *in, int size);
59*7c478bd9Sstevel@tonic-gate 
60*7c478bd9Sstevel@tonic-gate 	// if fi is a multiple of fo, LP filtering followed by down_sampling
61*7c478bd9Sstevel@tonic-gate 	int decimate_noadjust(short *in, int size, short *out);
62*7c478bd9Sstevel@tonic-gate 	int decimate_flush(short *);
63*7c478bd9Sstevel@tonic-gate 	int decimate(short *in, int size, short *out);
64*7c478bd9Sstevel@tonic-gate 
65*7c478bd9Sstevel@tonic-gate 	// if fo is a multiple of fi, up-sampling followed by LP filtering
66*7c478bd9Sstevel@tonic-gate 	int interpolate_noadjust(short *in, int size, short *out);
67*7c478bd9Sstevel@tonic-gate 	int interpolate_flush(short *);
68*7c478bd9Sstevel@tonic-gate 	int interpolate(short *in, int size, short *out);
69*7c478bd9Sstevel@tonic-gate 
70*7c478bd9Sstevel@tonic-gate 	int flush(short *out);
71*7c478bd9Sstevel@tonic-gate 
72*7c478bd9Sstevel@tonic-gate public:
73*7c478bd9Sstevel@tonic-gate 	ResampleFilter(int rate_in, int rate_out);
74*7c478bd9Sstevel@tonic-gate 	virtual int	filter_noadjust(short *in, int size, short *out);
75*7c478bd9Sstevel@tonic-gate 	virtual int	filter(short *in, int size, short *out);
76*7c478bd9Sstevel@tonic-gate 	virtual int	getFlushSize(void);
77*7c478bd9Sstevel@tonic-gate };
78*7c478bd9Sstevel@tonic-gate 
79*7c478bd9Sstevel@tonic-gate #ifdef __cplusplus
80*7c478bd9Sstevel@tonic-gate }
81*7c478bd9Sstevel@tonic-gate #endif
82*7c478bd9Sstevel@tonic-gate 
83*7c478bd9Sstevel@tonic-gate #endif /* !_MULTIMEDIA_RESAMPLE_H */
84