aflibconverter.h

一个共享源码的音频库2

/*
 * Copyright: (C) 2000 Julius O. Smith
 *
 *   This library is free software; you can redistribute it and/or
 *   modify it under the terms of the GNU Lesser General Public
 *   License as published by the Free Software Foundation; either
 *   version 2.1 of the License, or any later version.
 *
 *   This library is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *   Lesser General Public License for more details.
 *
 *   You should have received a copy of the GNU Lesser General Public
 *   License along with this library; if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307  USA
 *
 *   Julius O. Smith  [e-mail]
 *
 */
/* This code was modified by Bruce Forsberg ([e-mail]) to make it
   into a C++ class
*/


#ifndef _AFLIBCONVERTER_H_
#define _AFLIBCONVERTER_H_

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#ifndef MAX
#define MAX(x,y) ((x)>(y) ?(x):(y))
#endif
#ifndef MIN
#define MIN(x,y) ((x)<(y) ?(x):(y))
#endif

#define MAX_HWORD (32767)
#define MIN_HWORD (-32768)

#define IBUFFSIZE 4096                         /* Input buffer size */

/*! \class aflibConverter
    \brief Provides sample rate conversion.

 This class will perform audio resampling. With the constructor you can choose the
 type of resampling to be done. Simple linear interpolation can be done by setting
 linear_interpolation to be TRUE in the constructor. The other two flags are 
 ignored if this is set. If linear_interpolation is FALSE then some form of filtering
 will be done. IF high_quality is FALSE then a small filter will be performed. 
 If high_quality is TRUE then a large filter (higher quality) will be performed. For
 both the small and large filters another parameter can be specified, filter_interpolation.
 With filter_interpolation set then the filter coefficients used for both the small and
 large filtering will be interpolated as well.

 This class was designed to stream audio data. It also expects audio data as 16 bit values.
 Each time a new stream is started some initialization needs to be done. Thus the function
 initialize should be called to initialize everything. This initialize function will set
 the conversion factor as well as a multiplecation factor for volume. The volume only
 applies to the small and large filter. Since this filter uses a history of the audio data
 it is possible for it to vary in amplitude. This allows users to scale the data. This
 class will work on any number of channels. Once everything is specified then resample
 should be called as many times as is necessary to process all the data. The value
 inCount will be returned indicating how many inArray samples were actually used to
 produce the output. This value can be used to indicate where the next block of
 inArray data should start. The resample function is driven by the outCount value
 specified. The inArray should contain at least:
    outCount / factor + extra_samples.
 extra_samples depends on the type of filtering done. As a rule of thumb 50 should be
 adequate for any type of filter.
*/

class aflibData;

class aflibConverter {

public:

   // Available contructors and destructors
   aflibConverter (
      bool  high_quality,
      bool  linear_interpolation,
      bool  filter_interpolation);

   ~aflibConverter();

   void
   initialize(
      double factor,   /* factor = Sndout/Sndin */
      int    channels, /* number of sound channels */
      double volume = 1.0); /* factor to multiply amplitude */

   int
   resample(           /* number of output samples returned */
      int& inCount,    /* number of input samples to convert */
    	int outCount,    /* number of output samples to compute */
      short inArray[], /* input array data (length inCount * nChans) */
      short outArray[]);/* output array data (length outCount * nChans) */
 
 
private:

   aflibConverter();

   aflibConverter(const aflibConverter& op);

   const aflibConverter&
   operator=(const aflibConverter& op);

   int
   err_ret(char *s);

   void
   deleteMemory();

   int
   readData(
      int   inCount,       /* _total_ number of frames in input file */
      short inArray[],     /* input data */
      short *outPtr[],     /* array receiving chan samps */
      int   dataArraySize, /* size of these arrays */
      int   Xoff,          /* read into input array starting at this index */
      bool  init_count);


   inline short
   WordToHword(int v, int scl)
   {
       short out;
       int llsb = (1<<(scl-1));
       v += llsb;          /* round */
       v >>= scl;
       if (v>MAX_HWORD) {
           v = MAX_HWORD;
       } else if (v < MIN_HWORD) {
           v = MIN_HWORD;
       }
       out = (short) v;
       return out;
   };

   int
   SrcLinear(
      short X[],
      short Y[],
      double factor,
      unsigned int *Time,
      unsigned short& Nx,
      unsigned short Nout);

   int
   SrcUp(
      short X[],
      short Y[],
      double factor,
      unsigned int *Time,
      unsigned short& Nx,
      unsigned short Nout,
      unsigned short Nwing,
      unsigned short LpScl,
      short Imp[],
      short ImpD[],
      bool Interp);

   int
   SrcUD(
      short X[],
      short Y[],
      double factor,
      unsigned int *Time,
      unsigned short& Nx,
      unsigned short Nout,
      unsigned short Nwing,
      unsigned short LpScl,
      short Imp[],
      short ImpD[],
      bool Interp);

   int
   FilterUp(
      short Imp[],
      short ImpD[],
      unsigned short Nwing,
      bool Interp,
      short *Xp,
      short Ph,
      short Inc);

   int
   FilterUD(
      short Imp[],
      short ImpD[],
      unsigned short Nwing,
      bool Interp,
      short *Xp,
      short Ph,
      short Inc,
      unsigned short dhb);

   int
   resampleFast(  /* number of output samples returned */
      int& inCount,     /* number of input samples to convert */
      int outCount,    /* number of output samples to compute */
      short inArray[], /* input array data (length inCount * nChans) */
      short outArray[]);/* output array data (length outCount * nChans) */
 
   int
   resampleWithFilter(  /* number of output samples returned */
      int& inCount,      /* number of input samples to convert */
      int outCount,     /* number of output samples to compute */
      short inArray[],  /* input array data (length inCount * nChans) */
      short outArray[], /* output array data (length outCount * nChans) */
      short Imp[], short ImpD[],
      unsigned short LpScl, unsigned short Nmult, unsigned short Nwing);


static short SMALL_FILTER_IMP[];
static short LARGE_FILTER_IMP[];

bool    interpFilt;
bool    largeFilter;
bool    linearInterp;
short  ** _X;
short  ** _Y;
unsigned int _Time;
double  _factor;
int     _nChans;
bool    _initial;
double  _vol;

};


#endif