citra/src/audio_core/interpolate.h
2019-02-17 23:41:48 -05:00

49 lines
1.7 KiB
C++

// Copyright 2016 Citra Emulator Project
// Licensed under GPLv2 or any later version
// Refer to the license.txt file included.
#pragma once
#include <array>
#include <deque>
#include "audio_core/audio_types.h"
#include "common/common_types.h"
namespace AudioCore::AudioInterp {
/// A variable length buffer of signed PCM16 stereo samples.
using StereoBuffer16 = std::deque<std::array<s16, 2>>;
struct State {
/// Two historical samples.
std::array<s16, 2> xn1 = {}; ///< x[n-1]
std::array<s16, 2> xn2 = {}; ///< x[n-2]
/// Current fractional position.
u64 fposition = 0;
};
/**
* No interpolation. This is equivalent to a zero-order hold. There is a two-sample predelay.
* @param state Interpolation state.
* @param input Input buffer.
* @param rate Stretch factor. Must be a positive non-zero value.
* rate > 1.0 performs decimation and rate < 1.0 performs upsampling.
* @param output The resampled audio buffer.
* @param outputi The index of output to start writing to.
*/
void None(State& state, StereoBuffer16& input, float rate, StereoFrame16& output,
std::size_t& outputi);
/**
* Linear interpolation. This is equivalent to a first-order hold. There is a two-sample predelay.
* @param state Interpolation state.
* @param input Input buffer.
* @param rate Stretch factor. Must be a positive non-zero value.
* rate > 1.0 performs decimation and rate < 1.0 performs upsampling.
* @param output The resampled audio buffer.
* @param outputi The index of output to start writing to.
*/
void Linear(State& state, StereoBuffer16& input, float rate, StereoFrame16& output,
std::size_t& outputi);
} // namespace AudioCore::AudioInterp