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