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/* ScummVM - Scumm Interpreter
* Copyright (C) 2001-2006 The ScummVM project
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
* This program 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 General Public License for more details.
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
* $URL$
* $Id$
*
*/
#ifndef SOUND_AUDIOSTREAM_H
#define SOUND_AUDIOSTREAM_H
#include "common/stdafx.h"
#include "common/util.h"
#include "common/scummsys.h"
namespace Audio {
/**
* Generic input stream for the resampling code.
*/
class AudioStream {
public:
virtual ~AudioStream() {}
/**
* Fill the given buffer with up to numSamples samples.
* Returns the actual number of samples read, or -1 if
* a critical error occured (note: you *must* check if
* this value is less than what you requested, this can
* happen when the stream is fully used up).
*
* Data has to be in native endianess, 16 bit per sample, signed.
* For stereo stream, buffer will be filled with interleaved
* left and right channel samples, starting with a left sample.
* Furthermore, the samples in the left and right are summed up.
* So if you request 4 samples from a stereo stream, you will get
* a total of two left channel and two right channel samples.
*/
virtual int readBuffer(int16 *buffer, const int numSamples) = 0;
/** Is this a stereo stream? */
virtual bool isStereo() const = 0;
/**
* End of data reached? If this returns true, it means that at this
* time there is no data available in the stream. However there may be
* more data in the future.
* This is used by e.g. a rate converter to decide whether to keep on
* converting data or stop.
*/
virtual bool endOfData() const = 0;
/**
* End of stream reached? If this returns true, it means that all data
* in this stream is used up and no additional data will appear in it
* in the future.
* This is used by the mixer to decide whether a given stream shall be
* removed from the list of active streams (and thus be destroyed).
* By default this maps to endOfData()
*/
virtual bool endOfStream() const { return endOfData(); }
/** Sample rate of the stream. */
virtual int getRate() const = 0;
/**
* Tries to load a file by trying all available formats.
* In case of an error, the file handle will be closed, but deleting
* it is still the responsibilty of the caller.
* @param filename a filename without an extension
* @return an Audiostream ready to use in case of success;
* NULL in case of an error (e.g. invalid/nonexisting file)
*/
static AudioStream* openStreamFile(const char *filename);
};
/**
* A simple AudioStream which represents a 'silent' stream,
* containing the specified number of zero samples.
*/
class ZeroInputStream : public AudioStream {
private:
int _len;
public:
ZeroInputStream(uint len) : _len(len) { }
int readBuffer(int16 *buffer, const int numSamples) {
int samples = MIN(_len, numSamples);
memset(buffer, 0, samples * 2);
_len -= samples;
return samples;
}
bool isStereo() const { return false; }
bool eos() const { return _len <= 0; }
int getRate() const { return -1; }
};
AudioStream *makeLinearInputStream(int rate, byte flags, const byte *ptr, uint32 len, uint loopOffset, uint loopLen);
// This used to be an inline template function, but
// buggy template function handling in MSVC6 forced
// us to go with the macro approach. So far this is
// the only template function that MSVC6 seemed to
// compile incorrectly. Knock on wood.
#define READ_ENDIAN_SAMPLE(is16Bit, isUnsigned, ptr, isLE) \
((is16Bit ? (isLE ? READ_LE_UINT16(ptr) : READ_BE_UINT16(ptr)) : (*ptr << 8)) ^ (isUnsigned ? 0x8000 : 0))
} // End of namespace Audio
#endif
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