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