/* * CDDL HEADER START * * The contents of this file are subject to the terms of the * Common Development and Distribution License, Version 1.0 only * (the "License"). You may not use this file except in compliance * with the License. * * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE * or http://www.opensolaris.org/os/licensing. * See the License for the specific language governing permissions * and limitations under the License. * * When distributing Covered Code, include this CDDL HEADER in each * file and include the License file at usr/src/OPENSOLARIS.LICENSE. * If applicable, add the following below this CDDL HEADER, with the * fields enclosed by brackets "[]" replaced with your own identifying * information: Portions Copyright [yyyy] [name of copyright owner] * * CDDL HEADER END */ /* * Copyright (c) 1992-2001 by Sun Microsystems, Inc. * All rights reserved. */ #ifndef _MULTIMEDIA_RESAMPLE_H #define _MULTIMEDIA_RESAMPLE_H #pragma ident "%Z%%M% %I% %E% SMI" /* * To convert the sampling rate of fi of input signal to fo of output signal, * the least common multiple fm = L * fi = M * fo needs to be derived first. * Then the input signal is * 1) up-sampled to fm by inserting (L - 1) zero-valued samples after each * input sample, * 2) low-pass filtered to half of the lower of fi and fo, and * 3) down-sampled to fo by saving one out of every M samples. * * The low-pass filter is implemented with an FIR filter which is a truncated * ideal low pass filter whose order is dependent on its bandwidth. * * Refer to Fir.h for explanations of filter() and flush(). * */ #include <Fir.h> #ifdef __cplusplus extern "C" { #endif class ResampleFilter : public Fir { int num_state; // interpolation requires less states int up; // upsampling ratio int down; // down sampling ratio int down_offset; // 0 <= index in down-sampling < down int up_offset; // -up < index in up_sampling <= 0 void updateState(double *in, int size); // if fi is a multiple of fo, LP filtering followed by down_sampling int decimate_noadjust(short *in, int size, short *out); int decimate_flush(short *); int decimate(short *in, int size, short *out); // if fo is a multiple of fi, up-sampling followed by LP filtering int interpolate_noadjust(short *in, int size, short *out); int interpolate_flush(short *); int interpolate(short *in, int size, short *out); int flush(short *out); public: ResampleFilter(int rate_in, int rate_out); virtual int filter_noadjust(short *in, int size, short *out); virtual int filter(short *in, int size, short *out); virtual int getFlushSize(void); }; #ifdef __cplusplus } #endif #endif /* !_MULTIMEDIA_RESAMPLE_H */