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/*
Copyright (C) 2000 Stefan Westerfeld
stefan@space.twc.de
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public
License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) 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
Library General Public License for more details.
You should have received a copy of the GNU Library General Public License
along with this library; see the file COPYING.LIB. If not, write to
the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
Boston, MA 02110-1301, USA.
*/
#ifndef ARTS_FLOW_RESAMPLE_H
#define ARTS_FLOW_RESAMPLE_H
#include "arts_export.h"
/*
* BC - Status (2002-03-08): Resampler / Refiller.
*
* These classes will be kept binary compatible. Resampler has a private
* data pointer for this purpose.
*/
namespace Arts {
/**
* Refiller interface
*
* this is used by the resampler class
*/
class ARTS_EXPORT Refiller {
public:
/**
* callback method to supply data to the Resampler
*
* here you supply data in the encoding specified in the Resampler class
* (bits, channels, endianness) to the Resampler
*
* @param buffer a pointer to a buffer where the data can be filled to
* @param len the size of the buffer in bytes
*
* @returns the number of bytes really available
*/
virtual unsigned long read(unsigned char *buffer, unsigned long len) = 0;
virtual ~Refiller();
};
class ResamplerPrivate;
/**
* The Resampler class resamples data from an input stream, which is read
* through the Refiller interface, and renders it into the float format which
* aRts usually uses, converting the sampling rate and format as needed.
*/
class ARTS_EXPORT Resampler {
protected:
static const unsigned int bufferSize = 256; // 64 samples in buffer
static const unsigned int bufferWrap = 64; // + "wrap around"
/*
* BC: bufferWrap just needs channels * (filtersize - 1) * bytes per sample
* bytes wrap around - this used to be 4: 2 channels, linear interpolation,
* 16bit. However, for supporting float resampling and/or better filters,
* we'll make this 64 to be safe.
*/
int bufferSamples;
int sampleSize;
int dropBytes;
Refiller *refiller;
double pos, step;
int channels,bits;
unsigned char buffer[bufferSize+bufferWrap];
float fbuffer[bufferSize+bufferWrap];
long block, haveBlock;
class ResamplerPrivate *d;
void updateSampleSize();
void ensureRefill();
public:
/**
* constructor
*
*/
Resampler(Refiller *refiller);
~Resampler();
/**
* sets the resampling step in the input stream
*
* for instance, settings step to 2.0, the file would be played twice as
* fast - you can calculate the resampling step from the sampling rate
* the stream you resample was recorded at, and the sampling rate you want
* it to be resampled to, using
*
* step = originalSamplingRate / desiredSamplingRate
*
* for instance, if a stream recorded at 22050 Hz is to be played at 48000
* Hz, step would be
*
* step = 22050 / 48000 = 0.46
*/
void setStep(double step);
/**
* sets the number of channels in the input stream
*
* the channels are expected to be interleaved, thus if you have two
* channels, you will have one sample for the left stream, one for the
* right, one for the left, ... and so on
*
* currently only either mono (channels = 1) or stereo (channels = 2)
* streams are supported
*/
void setChannels(int channels);
/**
* sets the number of bits in the input stream
*
* currently, only 16 bit and 8 bit streams are supported
*/
void setBits(int bits);
enum Endianness { bigEndian, littleEndian };
/**
* sets the endianess of the input stream
*
* supported are bigEndian and littleEndian
*/
void setEndianness(Endianness endianness);
/**
* renders a buffer of float samples from the input stream
*
* the data is obtained by querying the refiller for data from the
* input stream and filling them into the float array pointed to by
* left and right - if reading data fails, the underrun flag is set
*/
void run(float *left, float *right, unsigned long samples);
/**
* query the underrun flag
*
* underruns occur if run is called, but no data is available from the
* Refiller object
*/
bool underrun();
};
}
#endif /* ARTS_FLOW_RESAMPLE_H */
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