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113 lines
3.2 KiB
C++
113 lines
3.2 KiB
C++
/* ScummVM - Graphic Adventure Engine
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*
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* ScummVM is the legal property of its developers, whose names
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* are too numerous to list here. Please refer to the COPYRIGHT
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* file distributed with this source distribution.
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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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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*
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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, see <http://www.gnu.org/licenses/>.
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*
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*/
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#ifndef AUDIO_RATE_H
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#define AUDIO_RATE_H
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#include "common/frac.h"
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namespace Audio {
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/**
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* @defgroup audio_rate Sample rate
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* @ingroup audio
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*
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* @brief API for managing sound sample rate.
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* @{
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*/
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class AudioStream;
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typedef int16 st_sample_t;
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typedef uint16 st_volume_t;
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typedef uint32 st_size_t;
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typedef uint32 st_rate_t;
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/* Minimum and maximum values a sample can hold. */
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enum {
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ST_SAMPLE_MAX = 0x7fffL,
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ST_SAMPLE_MIN = (-ST_SAMPLE_MAX - 1L)
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};
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static inline void clampedAdd(int16& a, int b) {
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int val;
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#ifdef OUTPUT_UNSIGNED_AUDIO
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val = (a ^ 0x8000) + b;
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#else
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val = a + b;
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#endif
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if (val > ST_SAMPLE_MAX)
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val = ST_SAMPLE_MAX;
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else if (val < ST_SAMPLE_MIN)
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val = ST_SAMPLE_MIN;
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#ifdef OUTPUT_UNSIGNED_AUDIO
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a = ((int16)val) ^ 0x8000;
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#else
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a = val;
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#endif
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}
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/**
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* Helper class that handles resampling an AudioStream between an input and output
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* sample rate. Its regular use case is upsampling from the native stream rate
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* to the one used by the sound mixer. However, the input/output rates can be
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* manually adjusted to change playback speed and produce sound effects.
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*/
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class RateConverter {
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public:
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RateConverter() {}
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virtual ~RateConverter() {}
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/**
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* Convert the provided AudioStream to the target sample rate.
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*
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* @param input The AudioStream to read data from.
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* @param outBuffer The buffer that the resampled audio will be written to. Must have size of at least @p numSamples.
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* @param numSamples The desired number of samples to be written into the buffer.
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* @param vol_l Volume for left channel.
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* @param vol_r Volume for right channel.
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*
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* @return Number of sample pairs written into the buffer.
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*/
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virtual int convert(AudioStream &input, st_sample_t *outBuffer, st_size_t numSamples, st_volume_t vol_l, st_volume_t vol_r) = 0;
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virtual void setInputRate(st_rate_t inputRate) = 0;
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virtual void setOutputRate(st_rate_t outputRate) = 0;
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virtual st_rate_t getInputRate() const = 0;
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virtual st_rate_t getOutputRate() const = 0;
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/**
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* Does the internal buffer still have some leftover data?
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*
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* @return True if we need to drain, false otherwise
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*/
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virtual bool needsDraining() const = 0;
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};
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RateConverter *makeRateConverter(st_rate_t inRate, st_rate_t outRate, bool inStereo, bool outStereo, bool reverseStereo);
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/** @} */
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} // End of namespace Audio
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#endif
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